Posters

Little is known about the environments of Green Pea (GP) and Blueberry (BB) galaxies, low-mass, compact starbursts that are local analogs to high-redshift galaxies. We analyze the clustering of 339 GPs (0.1<z≤0.33) and 56 BBs (z≤0.1), comparing them to control samples binned by stellar mass and sSFR from SDSS and to galaxies from the TNG300 simulation. Using neighbor counts within 5 Mpc, we find clustering strongly depends on star-formation activity: passive galaxies are more clustered than star-forming ones with GPs and BBs at the extreme end, exhibiting the lowest environmental densities. BBs also have lower-mass nearest neighbors. Simulations agree with these trends. Their low metallicities and weak clustering instead support scenarios in which recent starbursts are driven by internal processes or pristine gas accretion, reinforcing their role as nearby analogs of young, low-mass galaxies in the early Universe.

The Central Molecular Zone (CMZ; the central ~ 500 pc of the Milky Way) hosts molecular clouds in an extreme environment of strong shear, high gas pressure and density, and complex chemistry. While the CMZ region contains a large reservoir of dense gas, it is forming stars at a rate much lower than theoretical predictions. In this contribution I will compare the properties of hydrodynamical simulations of CMZ clouds to those of ALMA observations, with a particular focus on G0.253+0.016, also known as `the Brick’. I will focus on the structure and kinematics of the dense gas. To facilitate the comparison, we post-process the simulations and create synthetic ALMA maps of molecular line emission. I will demonstrate that including the effects of the Galactic potential in the simulations can reproduce global cloud properties, but additional physical processes are needed to explain the gas structure on smaller scales.

Sgr A*'s variable emission has now been detected in the radio, submillimeter, IR, and X-rays. The first detection of a mid-IR flare was made by JWST/MIRI at 5-21 μm in 2024 April. In our initial analysis, we normalized the mid-IR data to remove the unknown interstellar extinction. In this talk, we report a new mid-IR extinction law based on MIRI data in the central 3″×3″ of the Galactic Center. The new extinction law fixes the dereddened mid-IR SED of Sgr A* during the flare. During the flare, the largest 5-21 μm spectral index was α ~ 0.45, and we detected a sudden increase in the spectral index Δα = 0.33, which we propose as a quantitative definition of the flare's start. Extrapolating the corrected mid-IR spectrum to the submm yields a flux consistent with the 220 GHz peak observed by the SMA. These results support a physical connection between the submm and at least a fraction of mid-IR flares, providing a robust framework for interpreting Sgr A*'s time-variable mid-IR emission.

We present JWST MIRI-MRS observations sampling of two very different regimes in the central parsec of the Galaxy: 1) a portion of the Circumnuclear Disk (CND), the largest reservoir of matter near the central SMBH and 2) the CND inner cavity, which is exposed to intense radiation from the central cluster of massive stars, but nevertheless shows the presence of both molecular and ionized gas, as well as dust. We present the first spatially resolved mid-IR spectroscopic view of these regions by detecting and mapping over 100 spectral features. These observations provide crucial insights into the physical conditions of the CND, addressing whether current conditions support ongoing star formation. Additionally, analysis of pure rotational $H_2$ lines in the CND cavity reveals localized molecular gas, challenging current models by confirming $H_2$ survival in extreme UV fields. More broadly, these results inform models of feedback, and inward transport toward the Galactic center.

We investigate the 7′ radio halo surrounding the Sgr A complex toward the Galactic center (GC) using HI 21 cm absorption measurements to constrain its distance and physical association. Strong HI absorption detected near −53 km s⁻¹ toward all halo regions is attributed to the 3 kpc arm, placing the halo at a minimum distance of ≳5 kpc. We further examine HI absorption toward five distinct halo parts. Absorption associated with the +50 km s⁻¹ GC cloud is observed toward only three regions. However, strong CO and CS emission from the same cloud is detected toward all five parts. This combination implies the halo is situated partly behind and partly in front of the +50 km s⁻¹ cloud. These results provide the first clear evidence locating the 7′ halo at the same distance as the +50 km s⁻¹ cloud, firmly within the GC region, likely created by energetic activity approximately 10^5 years ago.

We present the first JWST NIRCam image of the Milky Way’s nuclear star cluster (NSC) extending beyond its half-light radius, providing the cornerstone for measuring stellar proper motions (PMs) and inferring the formation history of the NSC. We present the luminosity function and the color-magnitude diagram of the NSC based on our source detection. The depth and uncertainties of the images are compared with previous HST observations in the region. We expect to combine JWST observations with HST results and utilize the derived kinematics to (1) measure fundamental properties of the NSC, such as the stellar density distribution, rotation curve, and axis symmetry; (2) identify kinematic substructures and constrain the formation and evolution of the NSC by comparing them with simulations based on theories. This study helps build a comprehensive dynamical census of the NSC and clarifies its interaction with the Galactic Center’s supermassive black hole and galaxy formation.

The Galactic center provides an ideal laboratory to study star formation and stellar evolution under extreme conditions through star-by-star observations. In this work, we reconstruct the SFH of the NSD using deep near-infrared photometry and CMD fitting technique. We analyze HST/WFC3-IR observations of the Quintuplet field in the F127M and F153M filters, using the same dataset as Hosek+2022 and Schödel+2023, but performing fully independent PSF photometry and PM measurements. We generate synthetic CMDs incorporating the main observational effects and fit them to the observed CMD to estimate the SFH, enabling a direct comparison with previous NSD SFH determinations based on luminosity functions. We extend this analysis to multiple WFC3-IR fields observed in the same filters around the NSC and plan to apply the same methodology to deep JWST/NIRCam observations, which reach at least two magnitudes below the MSTO, enabling a comprehensive view of the formation and evolution of the NSD.

We study the role of supernova (SNe) feedback in shaping the interstellar medium of a Milky Way type Central Molecular Zone using 3-D MHD simulations that include non-equilibrium chemistry, magnetic fields, and an external barred Galactic potential. We explore models with spatially distributed Type Ia SNe at different rates, as well as clustered Type II SNe associated with a massive stellar cluster. We find that Type Ia SNe significantly suppress gas inflow into the central ≈100 pc, with higher rates leading to reduced mass accumulation, while bar-driven inflow on larger scales (R ≲ 500 pc) remains efficient during CMZ formation before stabilising at a level that decreases with increasing SNe activity. Type II SNe feedback preferentially depletes low-density gas, while the dense nuclear ring remains largely resilient, though temporarily distorted at high SNe rates. Feedback also alters magnetic-field evolution and enhances turbulence, especially vertically.

The innermost parsec of the Galactic centre is expected to host a significant population of stellar black holes. Its parameters, however, are not known as black holes cannot be directly observed. One of the indirect ways to map their population is to track the impact of these black holes on the composition of the embedding stellar population. We suggest that direct collisions and grazing encounters between the black holes and the stars within the S-cluster led to the there observed lack of massive O-stars and Wolf-Rayet stars that are otherwise abundant farther away from Sgr A*. We derive an order of magnitude radial density profile for the black hole cluster and find that it is compatible with the possible black hole formation history in this region.

We explore the question if expanding shells driven by stellar winds, radiation and supernovae redistribute the gas mass and angular momentum in rotating galactic disks. We apply the simplified hydrodynamical code RING using the thin shell approximation, and measure how the gas distribution and dynamics are changed statistically by a succession of expanding shells. We analyze two different regimes: one on the periphery of the Milky Way and another in the rotating disk close to the Galactic center within 100 pc of the supermassive black hole SgrA*.

While mounting observational evidence suggests that intermediate-mass black holes (IMBHs) play an important role in shaping dwarf galaxies, the physical mechanisms governing their growth remain poorly understood. We perform high-resolution simulations of an isolated dwarf galaxy hosting a central IMBH, reaching a peak spatial resolution of ≲0.01 pc. Our model includes a fully multiphase interstellar medium with explicit sampling of stars from the initial mass function, photoionization, individual supernovae, and a Shakura–Sunyaev accretion disc to track BH mass and spin evolution. We find that a nuclear star cluster efficiently captures gas and promotes the formation of a circumnuclear disc (CND) on ∼7 pc scales. The CND is prone to fragmentation, leading to the formation of massive young stars. Our results highlight the complexity of IMBH accretion in a multiphase ISM and pave the way for future studies of IMBH growth in a fully cosmological context.

The Central Molecular Zone (CMZ) of our Galaxy is a prime laboratory for interstellar chemistry because of its extreme conditions, such as shocks and high cosmic-ray ionisation rates. It is an efficient factory of molecules, with many species first discovered in CMZ sources. This talk reviews key results from the study of the CMZ G+0.693–0.027 molecular cloud. Using ultra-sensitive broadband spectral surveys together with laboratory spectroscopy, more than 140 molecules have been identified, including 28 detected for the first time in the interstellar medium. These discoveries include prebiotic precursors of biomolecules, increasingly complex members of known molecular families, molecules containing periodic third-row elements (S, P, Na, Mg), high-energy stereo- and structural isomers, and new cations. Overall, these findings extend the known limits of interstellar chemical complexity and highlight the CMZ’s potential to provide the molecular ingredients for prebiotic chemistry.

The Central Molecular Zone (CMZ) hosts numerous compact molecular clouds with extremely broad velocity widths (dV > 50 km/s), known as high velocity dispersion compact clouds (HVCCs). Some HVCCs may be gravitationally accelerated by intermediate-mass black holes, yet no clear counterparts at other wavelengths have been identified. From JCMT CO survey (CHIMPS2) and MeerKAT 1.28 GHz archival data, we found two compact clouds containing point-like nonthermal radio sources. ALMA follow-up revealed that one shows a bipolar molecular structure with a steep velocity gradient centered on the radio source, while the other appears to exhibit symmetric molecular jets and bow shocks. These features suggest relics of jet activity. The radio spectra and no X-ray detection indicate that these sources are “radio-loud” black hole candidates rather than typical X-ray binaries. We report the discovery of new black hole candidates in the CMZ and discuss their impact on the surrounding interstellar medium.

1E 1740.7-2942 (the Great Annihilator) is one of the brightest X-ray sources in the Galactic center. It exhibits a double-sided radio jet, recognized as a microquasar powered by a stellar-mass black hole. Using the Nobeyama 45 m telescope and ALMA archival data, we discovered a bipolar molecular outflow associated with the relativistic jet. The outflow extends over a total length of ∼9 pc, much longer than the 2.4 pc radio jet. The compact SiO clumps with broad velocity widths in the southern extension suggest strong shocks by jet–ISM interactions. The absence of HCO+ emission could reflect destruction through dissociative recombination with electrons. The position–velocity structure and shock properties indicate possible long-term jet precession. In this presentation, we introduce these new molecular features and discuss their morphology, dynamics, and chemistry in the context of black hole feedback and cosmic-ray acceleration in the Galactic center.

High-velocity compact clouds (HVCCs) are a peculiar population of molecular features with large velocity widths, mainly found in the CMZ, where interactions with compact massive objects have been proposed. Outside the CMZ, a notable example is the "Bullet" in the supernova remnant W44, which shows a Y-shaped structure in position–velocity (PV) space, interpreted as a high-velocity plunge of a compact object, possibly a black hole. Earlier ALMA observations revealed eight compact, broad-velocity-width features ("Petit–Bullets") around the Bullet, implying multiple plunging sources. We present ALMA Cycle 12 observations of the Petit-Bullets. These features are detected in HCO+ and HCN emission, with curved V-shaped PV structures and spatial variations in the HCN/HCO⁺ ratio, tracing dense, highly inhomogeneous gas. Our results further support a scenario in which clustered impacts of compact objects shape the Bullet system, providing a rare Galactic-disk counterpart to HVCC-like phenomena.

We report the discovery of high-velocity dispersion compact clouds (HVCCs) associated with point-like radio continuum sources in the Central Molecular Zone (CMZ) of our Galaxy. By comparing the HVCC catalog and our Nobeyama 45-m CMZ survey data with the archival MeerKAT 1.28 GHz image, we identified four point-like radio sources as possible driving objects for HVCCs. One HVCC with a non-thermal radio source lies within the ACES field. Analysis of the archival H13CN J=1-0 data reveals a ring-like structure exhibiting a steep velocity gradient suggestive of rotation around the radio source. If gravitationally bound, the inferred central mass is approximately 10^5 Msun, implying that the radio source may be an intermediate-mass black hole. In addition, strong bipolar SiO emission indicates shocked regions, possibly tracing relics of past jet-ISM interaction. These results suggest that some HVCCs may preserve fossil signatures of black hole activity in the Galactic Center.

We study multi-wavelength emission from radiatively inefficient accretion flows in Sgr A* based on a Keplerian shell model, i.e., a phenomenological axisymmetric 2D model, by performing general relativistic Monte-Carlo radiative transfer calculations. It is found that higher black holes spin results in more remarkable X-ray emission via the synchrotron-self-Compton process in the horizon-scale accretion flow, even if the radio luminosity is almost unchanged. Rapidly spinning prograde/retrograde black holes show highest/lowest X-ray luminosity, while the non-spinning black hole presents moderate one. Although the bremsstrahlung emission from the distant plasma will dominate the quiescent X-ray emission in Sgr A*, future X-ray interferometry missions will resolve the horizon-scale emission and may enable us to constrain the magnitude of black hole spin.

The Nuclear Stellar Disk (NSD) is mainly composed of old stars. The origin of the NSD remains obscure. Key information is expected to be obtained from the kinematics of these stars. Mira variables, which are AGB stars, often exhibit SiO maser activity. The strength of the emission line makes it easy to measure the radial velocities of these stars. Survey data of the Central Molecular Zone (CMZ) obtained with ALMA has been released (2021.1.00172.L). Because this survey intends to image molecular clouds in the CMZ, the angular resolution is not so high (~2"). However, the frequency range contains the SiO v=1 J=2-1 maser line. The survey area covers most of the NSD. We searched SiO masers in the NSD using the data. Over 1000 stars had been detected and their LSR radial velocities were measured at the accuracy of 1 km/s. In this paper, we would discuss the distribution and kinematics of SiO masers in the NSD.

The Galactic center environment within the sphere influence of the supermassive black hole (SMBH) gives exciting opportunities for testing fundamental physics. A hypothetical 5th force or intermediate-mass black-hole (IMBH) companion close to the SMBH perturbes the orbits of closest stars – those most dominated by the SMBH gravitational potential. Here we measure the orbits of three of these stars – S0-2, S0-8, and S0-38 — to investigate the possibility of an additional Yakawa force, and separately, an IMBH orbiting in close proximity to the SMBH. With both these models, we present to 95% upper credible constraints and posteriors of the potential parameter in a Yakawa potential, and posteriors of and mass and separation of a close IMBH. We also show that these results are highly sensitive to the reference construction and explore the impact of reference frame priors on these results.

We present the first uncontaminated X-ray view of the supernova remnant (SNR) Sgr A East by applying component separation methods (Generalized Morphological Component Analysis) to deep, stacked Chandra ACIS-I observations of the Galactic Center. This approach cleanly disentangles the remnant from the overlapping Sgr A* Wolf–Rayet stellar-wind plasma, enabling a fundamentally new characterization of the SNR. We produce spatially resolved maps of Fe & S/Ar/Ca emission that reveal clear chemical stratification typical of mixed-morphology remnants. Comparison with multiwavelength data supports dust survival through the identified reflected shock and that Sgr A East exploded within a molecular filament flowing towards Sgr A*. Isolating the SNR emission in spectral modeling yields revised plasma properties, including a lower ionization temperature and substantially higher electron density than previously inferred, consistent with the interaction with the surrounding molecular material.

SgrA* is the nearest quiescent massive BH, and its proximity offers a unique opportunity to study its surrounding fuel supply. Using JWST/MIRI observations, we peer through galactic dust to measure the spatial, kinematic, and intensity distribution of ionized gas within the central ~0.1 parsec of SgrA*. We use forbidden lines to derive gas radial velocities, line ratios, and abundances for multiple distinct kinematic components that overlap along the line of sight. The three dominant emitting structures that we identify are: the minispiral’s Northern Arm, the Bar region, and high-velocity (>~ 600 km/s) gas clumps likely produced by Wolf–Rayet stellar winds or SgrA* outflows. We infer the radiation field hardness and metallicity of each of these emitting gas structures. This study sheds light on the origins of the galactic fuel reservoir and how it is physically shaped and ionized by stellar as well as SgrA*'s activity.

Flares are characteristic for the Sgr A* activity, they are seen in X-rays, in near-IR, and they were recently discovered in Mid-IR band. The emission is most likely a synchrotron emission, and the emitting plasma is mostly thermal, but with non-thermal contribution. However, the source of energy for these flares is an open question. Three interesting possibilities can be listed: (i) magnetic field reconnection (ii) variability of the accretion flow related to the formation and disappearance of the MAD (magnetically arrested disk) state (iii) hydrodynamical instabilities close to the subsonic/supersonic transition of the flow. In our project we evaluate the energy content of the flares, we compare it with the time averaged accretion efficiency, and at this basis we try to distinguish between the options listed above.

The Sickle H II region is the only location in the Galactic Center with photo-ionized columns similar to the “Pillars of Creation” as seen in the M 16. We will present results from JWST MIRI and NIRCam observations of the northern edge of the Sickle that confirm at least three of these columns are indeed strong M 16 analogs. “Pillar 4” is likely something else entirely. This column seems to be parsec scale protostellar outflow typically indicative of an accreting low to medium mass YSO. The bipolar outflow is interacting with both the radiation and/or winds from the Quintuplet Cluster, and the adjacent molecular cloud associated with the Sickle. The JWST observations have revealed the location of a probable circumstellar disk coincident with a Class I methanol maser, a collimated jet, an outflow cavity, and have discovered a bright bow shock where the jet outflow appears to terminate into the adjacent molecular cloud; the first Herbig-Haro -like object identified in the GC.

An asymmetric rotating neutron star may emit quasi-monochromatic gravitational waves. Detecting such signals with second-generation detectors requires long observation times due to their low GW amplitudes. If the signal is also microlensed, the lens's mass temporarily magnifies the signal amplitude, aiding detection and providing a distinct microlensing pattern. We explore the prospects for detecting microlensed continuous gravitational wave signals from the Galactic center using the point-mass lens approximation, with Intermediate Black Holes candidates in the Globular cluster acting as the lensing objects. To identify the microlensing pattern, we employ both traditional data analysis techniques and machine learning methods using simulated data from ground-based detectors, specifically applying the semi-coherent Time Domain F-statistic method.

Standard galaxy formation theory predicts the presence of virialized hot plasma around Milky Way-like galaxies, emitting X-rays. Recent studies suggest also the presence of a hotter super-virial component (~0.7 keV) detected in both absorption and emission; however, the nature of this component is still unclear. Using deep archival observations from the Chandra X-ray Observatory, we analyzed a ∼ 4°x6° region centered on Galactic Center, specifically around the Galactic Center chimneys. From spectral analysis of Chandra data, we obtained the surface brightness of the 0.7keV component for a subset of low absorption lines of sight. Using a stellar mass distribution model, we computed the expected X-ray surface brightness from hot coronae of low-mass stars. By comparing the two results, we estimated the contribution of the unresolved X-ray sources to the ~0.7 keV diffuse X-ray emission.

The Central Molecular Zone (CMZ) has a star-forming environment that is different from those of nearby star-forming regions. In the CMZ, the magnetic field is strong, and the cosmic-ray ionization rate is higher than in nearby star-forming regions. In such strongly magnetized environments, ambipolar diffusion (AD) could play an important role because gravitational collapse is slowed by the strong magnetic field. On the other hand, a high cosmic-ray ionization rate reduces the efficiency of AD. Therefore, the importance of AD in the CMZ remains unclear. We perform non-ideal magnetohydrodynamic simulations to investigate the impact of AD on the physical properties of cores in a CMZ-like environment. Our results show that the core formation timescale becomes shorter and that the resulting core angular momentum is larger than that in the ideal MHD case by a factor of two. These results indicate that non-ideal MHD affects the star formation efficiency.

The dense stellar environment of the Galactic Center makes detailed studies of Sgr A* emission challenging, especially in highly extincted regimes such as the mid-infrared. In this work, we propose a machine learning framework using score-based diffusion models to deblend galactic foreground emission and instrumental noise from Sgr A* emission. This data-driven method flexibly learns the underlying image probability distributions of individual components with minimal preprocessing, then uses a Bayesian framework to generate deblended samples for independent study. We test this methodology with mid-infrared images of Sgr A* from the James Webb Space Telescope, and recover visually plausible separated components. As the nearest supermassive black hole, Sgr A* remains an important observational target for understanding low-luminosity accretion, and continued development of signal separation techniques will further enhance the reliability of precision measurements.

The study of the chemical composition of star-forming regions is key for constraining the initial inventory of planetary systems. Protostellar heating can modify this reservoir through thermal processing, complicating access to pristine material. Shocked regions offer an alternative sputtering dust grains and releasing mantle species into the gas phase through molecular outflows or cloud–cloud collisions on short timescales, limiting subsequent chemical processing. We present a comparative analysis based on >30 molecules in five shock-dominated environments observed with the Yebes 40m, IRAM 30m, and ALMA. The sample spans low- and high-mass protostellar outflows to molecular clouds in the Galactic Center and in the galaxy NGC 253. Despite large differences in scale and location, molecular abundance ratios are remarkably similar, and clearly distinct from thermally processed star-forming regions. This suggests a shock-driven chemistry and a relatively homogeneous ice mantle composition.

The Galactic Center is the region with the highest gas density in the whole Milky Way. This gas accumulates in clouds which constitute the Central Molecular Zone (CMZ). How these clouds are distributed in the CMZ is still an open question. Even though we can see their position on the skyplane we are not able to measure their distance from the Sun and we have to rely on indirect methods, which are affected by large uncertainties. I will present a new method to derive a 3D map of the CMZ based on the observed proper motions of the Nuclear Stellar Disc (NSD) stars and their extinction. My results clearly show that this method can distinguish the clouds in the foreground from those in the background and can also located them in their correct position. I will present these results obtained adopting mock data in preparation to the application of the method to the already available and forthcoming NSD data.

The IRS13 stellar association near the Galactic Centre has been proposed to host an intermediate-mass black hole (IMBH), which should bind this cluster together and prevent its dissolution in the extreme tidal field of Sgr A*. Our recent study (Pavlik+24, A&A, 692, A104) challenges this. We performed high-precision dynamical simulations, which show that even a hypothetical IMBH with thousands of solar masses cannot prevent the dissolution of IRS13. Moreover, the timescale required for the formation of an IMBH of such a mass significantly exceeds the estimated age of IRS13. We also argue that the observed high stellar velocity dispersion in IRS13, which was considered one of the signatures of an IMBH, can be explained by a tidal disruption of a more massive cluster (i.e., the presumed origin of this association). While some aspects of IRS13's dynamics are still open for discussion, our results suggest that it is a transient stellar association rather than a bound system with an IMBH.

Since the central regions of galaxies can preserve key signatures of early evolution, we study galaxy centers in the CIELO cosmological hydrodynamical zoom-in simulations (Tissera et al. 2025) and compare them with the observed properties of the Milky Way (MW) bulge. In several simulated galaxies, we identify an overdensity of stellar populations in the bulge at the lowest energies in the circularity-energy plane, tracing highly bound populations, hereafter referred to as ‘knots’ (Rix et al. 2024; Horta et al. 2025). Motivated by the observed central peak in radial velocity dispersion in the MW bulge, we investigate whether such knots produce similar kinematic signatures and how these depend on line-of-sight and bar orientation. We characterize their formation pathways, chemical properties, and ages, and assess the balance between secular evolution and accreted material. Projecting simulations into observable space places MW bulge observables in a broader cosmological context.

The Far-InfraREd Polarimetric Large Area CMZ Exploration (FIREPLACE) survey is a legacy survey of the Stratospheric Observatory for Infrared Astronomy (SOFIA) that observed the entire Central Molecular Zone (CMZ) polarimetrically at 214 um with a resolution of 19.6” using the High-resolution Airborne Wideband Camera Plus (HAWC+) instrument. The final observations of the CMZ were obtained in late 2022 and the reduction and analysis of the FIREPLACE observations has resulted in six publications so far. In this talk I present an overview of the FIREPLACE observations and the results obtained from the survey so far. FIREPLACE has greatly enhanced our understanding of the magnetic field in the molecular clouds of the CMZ. The FIREPLACE results so far indicate that shear likely plays a significant role in preventing cloud collapse in the CMZ, serving as a possible explanation for the unexpectedly low star formation efficiency in the region.

The Far-InfraREd Polarimetric Large Area CMZ Exploration (FIREPLACE) survey is a legacy survey of the Stratospheric Observatory for Infrared Astronomy (SOFIA) that observed the entire Central Molecular Zone (CMZ) polarimetrically at 214 um with a resolution of 19.6” using the High-resolution Airborne Wideband Camera Plus (HAWC+) instrument. The final observations of the CMZ were obtained in late 2022 and the reduction and analysis of the FIREPLACE observations has resulted in six publications so far. In this talk I present an overview of the FIREPLACE observations and the results obtained from the survey so far. FIREPLACE has greatly enhanced our understanding of the magnetic field in the molecular clouds of the CMZ. The FIREPLACE results so far indicate that shear likely plays a significant role in preventing cloud collapse in the CMZ, serving as a possible explanation for the unexpectedly low star formation efficiency in the region.

The Nuclear Bulge of the Milky Way harbors stellar populations that provide crucial insights into galaxy formation processes, which are hindered by extreme and highly variable interstellar extinction. We developed a method to determine the extinction law towards the Nuclear Bulge by kinematically selecting red clump stars belonging to this region. We created a high-spatial-resolution extinction map and computed the stellar mass using completeness-corrected red clump star counts, scaled from empirical measurements. We find a total-to-selective extinction ratio and an extinction ratio that are consistent with previous works. The high-spatial resolution extinction map shows clear filamentary structures, and a gradient in the extinction over the giant molecular cloud G0.253+0.016 (i.e., the Brick). From the star counts, we measured a stellar mass of 12.2 x 10^8 solar masses for the Nuclear Bulge, in agreement with other mass estimates.

An understanding of the assembly history of Omega Centauri has long been sought after, with many studies separating the stars on the color-magnitude diagram into multiple groupings across small magnitude ranges. Utilizing the oMEGACat combined astro-photometric and spectroscopic dataset we parse 14 subpopulations from the upper red-giant branch to below the main-sequence turnoff. We combine our results with previous works to estimate the age and age spread of each population. We find that the chemically enhanced (P2) populations are all ~1 Gyr younger and have significantly higher intrinsic age spreads than the primordial (P1) populations, with the intermediate (Im) populations falling in between the two. Additionally, we connect for the first time the Chromosome Diagram to the two-stream age-metallicity relation, allowing us to link the P1 and P2 stars to the distinct star formation tracks, proposed to be in-situ and ex-situ contributions to the cluster's assembly.

The structure of the Milky Way’s Central Molecular Zone (CMZ) is crucial for understanding the evolution of gas, dust, and star formation in the inner Galaxy. However, the CMZ’s geometry remains a lingering mystery. The Galactic Center dust ridge seems to be a stream of dense gas represented by infrared dark clouds passing in front of the CMZ, putting some constraints on the positions of the clouds relative to the Galactic Center, but not to each other. We investigate the properties of a subset of dust ridge clouds using JWST and ALMA. We determine the CO ice content of the clouds, finding that the ice to dust ratio varies from cloud to cloud. We present a method for estimating the relative distances between clouds into the CMZ using stellar densities with JWST. These measurements show that each cloud in the CMZ carries a measurable chemistry that traces its formation history.

The origin of the Galactic ridge X-ray emission (GRXE) and its prominent 6.7 keV Fe XXV line remains debated. The XMM-Newton heritage survey, covering the central 20x2.5 deg2 of the Galactic disk with 20 ks exposures, provides an unprecedentedly deep and comprehensive sample of the X-ray source populations toward the Galactic center. By cross-matching the XMM-Newton source catalog with Gaia and the eROSITA all-sky survey, we present a systematic study of the identification and characteristics of X-ray sources within the inner Galactic disk. We characterize the spectral properties of diverse source classes, ranging from stellar coronal emitters to luminous X-ray binaries. Crucially, we highlight the significant, yet previously overlooked, contribution of symbiotic stars to the GRXE Fe XXV flux. Our results provide a detailed census of the discrete stellar components of the inner Galaxy and offer new insights into the unresolved mystery of the Galactic ridge emission.

Using data obtained with the UKIRT telescope, including observations from UIST, UFTI, and WFCAM camera, together with PSF photometry of these regions, we have identified pulsating Asymptotic Giant Branch (AGB) stars. Using the method developed by Javadi et al. (2011), we have investigated the star formation history of these regions. This analysis was initially carried out separately using UIST and WFCAM data; in the final step, we determined the star formation history using a combined dataset comprising all high-quality PSF photometry from these observations. We identified two main epochs of star formation, one of which is associated with the interaction between the M33 and M31 galaxies. We interpret our results as evidence for an old, pressure-supported stellar component and a younger disc formed approximately 6 Gyr ago, with a subsequent accretion event around 250 Myr ago giving rise to the compact nucleus of M33.

The Galactic centre hosts a supermassive black hole surrounded by the S-cluster. The best-studied member is the B-type main-sequence star S2. Although such stars are commonly in binaries, no companion to S2 has been detected, possibly due to observational biases or a dynamically hostile environment involving tidal disruption or mergers. Using an N-body code with post-Newtonian corrections, we test whether S2 could host a companion, performing {10}^5 simulations. We find that companions can survive for periods below 100 days, eccentricities under 0.8, and all mutual inclinations, with survival favored for shorter periods, lower eccentricities, and coplanar orbits. Disruption occurs through Lidov-Kozai driven mergers and breakups when the binary exceeds the Hill radius. A companion would bias S2's astrometric signal by 5\mu as. Radial-velocity limits allow 4.4% of stellar binaries, reduced to 4.3% with astrometry and to 3.0% when requiring masses \lesssim 2 M_\odot.

The nuclear stellar disc is a dense stellar structure at the centre of the Galaxy, containing approximately 10^9 solar masses of stars. It has long been assumed to be different from the much larger Galactic bulge, although a recent study has questioned whether they are truly distinct (Zocalli et al. 2024). Using a pilot study from the VVVX-GalCen ESO public survey, we spectroscopically characterise stars in the innermost regions of the Galactic bulge and the nuclear stellar disc, obtaining a homogeneous data set with the KMOS spectrograph at the VLT and the same observational setup for both structures. We find systematic differences in metallicities, line-of-sight velocities, and alpha abundances, providing further evidence that they are indeed different structures.

The Sagittarius C region is a prominent HII region in the nuclear stellar disc, where previous work indicates the presence of several hundred thousand young stars. We have analysed JWST/NIRCam data of Sagittarius C, the deepest photometry ever obtained for this region, to characterise the extinction curve over 1.15–4.8 μm and determine its stellar population. We confirm the presence of a significant population of young massive stars, that clearly exceeds that of control regions in the nuclear stellar disc. We also find a substantial contribution of intermediate-age stars, supporting an inside-out formation scenario for the nuclear stellar disc. I will present our preliminary results and what they reveal about the star formation history and structure of the centre of the Galaxy.

Modeling the orbital dynamics of our Galaxy’s Central Molecular Zone (CMZ) holds key information to understanding galactic energy cycles and evolution, including the onset of AGN activity and nuclear starbursts. Full accounting for the star formation, inflows, and outflows of galaxy centers requires knowledge of their 3D structure and dynamics. I will present my work combining multi-wavelegnth data and theoretical orbits to obtain a new 3D orbital model of our CMZ. The results include a top-down view of the CMZ with estimated distances to all molecular clouds. I will also introduce future endeavors to combine new high-resolution MHD simulations with ALMA and JWST observations to study inflow from 100 to 10pc-scale orbits. Understanding the energy cycles in galactic nuclei will contextualize our own Galaxy within the local universe and illuminate what events may control the secular evolution of galaxies.

Negative stellar age gradients are observed in nuclear stellar disks of disk galaxies, indicating an inside-out formation scenario. It remains unclear how such gradients persist during secular evolution. We investigate orbital migration in the NSD driven by an expanding molecular ring using test-particle simulations. Stellar orbits are evolved in a Milky Way NSD potential that includes a time-dependent, expanding molecular ring potential. As the ring expands, a fraction of stars gain angular momentum and migrate outward, indicating efficient radial redistribution. However, despite this migration, the global negative age gradient of the NSD is largely preserved. We further identify age-dependent patterns in the proper motion mu_l, suggesting potential kinematic signatures of migration. These results indicate that expanding molecular structures can drive orbital migration in NSDs without fully erasing their age gradients.

The spatial-temporal variability of the galactic center X-ray emission adds extra complexities when performing data analysis. Using adapted methods from the large-scale galaxy cluster community, we have tried to mitigate this my creating 2D spatially resolved thermodynamic maps of the galactic center using several timing windows, beginning with the assumption that the X-ray emission in the center is in collisional ionization equilibrium.

Ultraviolet (UV) time-domain observations of active galactic nuclei (AGN) provide a probe of accretion disk structure by tracing wavelength-dependent time delays across the disk. This work is motivated by the need to optimize the observational strategy of the upcoming Quick Ultraviolet Kilonova Surveyor (QUVIK) mission. We evaluate how different observing cadences and monitoring durations affect the measurability of UV time lags and the detectability of quasi-periodic eruptions (QPEs) arising from perturber–SMBH systems. By modeling QPE flares across multiple UV bands, we investigate how black hole mass, perturber properties, and observational cadence affect signals in synthetic light curves, using power-spectrum analysis to identify signatures. This analysis allows us to identify the regions of parameter space in which QPE flares are observable and to determine the cadence strategies that maximize QPE detectability for future UV monitoring campaigns.

We propose to extend recent studies of red giant–jet interactions in galactic nuclei by examining their long-term impact on stellar evolution, with a particular focus on red supergiants (RSGs). Previous three-dimensional hydrodynamical simulations have primarily investigated the ablation of red giant envelopes during repeated passages through galactic jets. In contrast, our work explores how jet-induced mass loss and surface heating influence the internal structure, luminosity, and spectral evolution of massive evolved stars. By coupling hydrodynamical interaction models with detailed stellar evolution calculations, we aim to quantify the extent to which repeated jet encounters can accelerate RSG evolution, alter their observable properties, and potentially contribute to the depletion or transformation of evolved stellar populations in galactic nuclei. This study provides a new link between jet–star interactions and the evolutionary pathways of massive stars in extreme environments.

The Enhanced Resolution Imager and Spectrograph (ERIS) is a next-generation instrument on the Very Large Telescope, combining a new imager and an integral field spectrograph with advanced adaptive optics. Its higher spectral resolution marks a major improvement for spectroscopic studies of the Galactic Center. We assess ERIS’s ability to measure radial velocities of S-stars orbiting Sagittarius A*. Such measurements are key to constraining the black hole’s spin and testing fundamental physics. Previous studies (e.g., Waisberg et al., 2018) have explored this approach, but they assumed velocity precisions of only a few tens of km/s. Our results show that ERIS can achieve precisions of a few hundred m/s, an improvement of two orders of magnitude. This precision enables tests of the no-hair theorem. We also present tests designed to assess the capabilities of MICADO in this context.

A variety of objects has been observed in the Galactic Centre (GC), including S-stars, G objects, hypervelocity stars (HVSs), and black holes that, spiralling into SgrA*, emit gravitational waves (Extreme Mass Ratio Inspirals, or EMRIs). Understanding these systems provides information on how the GC is populated and on the origin and assembly history of SgrA*. A common origin may be the tidal interaction between stellar or black-hole binaries and SgrA*, an interaction known as the Hills mechanism. In this talk, I will introduce a novel framework for tracing the evolution of an initial binary population through multiple encounters with SgrA*. I will especially focus on EMRIs' properties and characteristic signatures, in comparison with EMRIs from the classical two-body relaxation channel of single black holes. I will illustrate the characteristic fingerprints of each formation scenario, highlighting their potential observability with LISA.

The inner 100 pc of the CMZ hosts dense, turbulent gas but forms only 10% of the expected number of stars. Using JCMT/BISTRO 850 µm polarization and the ALMA/ACES HC3N(11–10) cube, we map a magnetized gas stream in the western CMZ, measure mG POS fields and show this stream is magnetically subcritical, sub-Alfvénic, with magnetic+turbulent pressure greater than self-gravity. Combining BISTRO with SOFIA/HAWC+ 214 µm polarization, HROs+velocity gradients reveal a shear–compression–shear sequence: in shear zones B is parallel to the density structures and perpendicular to the gradients, while in the compression region, B is perpendicular to the structures and aligns with the gradients. Finally, we reconstruct the 3D B-field, finding a curved geometry more LOS-aligned at 214 µm than at 850 µm. This first 3D view of the B-field in a CMZ stream shows it can regulate gas flows and suppress star formation.

In this work, we examine the effects of solar radiation pressure, albedo and oblateness in the dynamics of homoclinic and heteroclinic connections in the frame of Circular Restricted Three-Body Problem. The smaller primary is assumed to produces the albedo effect, while the larger primary is treated as a radiating body. We also consider the smaller primary to be oblate, represented by the zonal harmonic coefficient J_2. The zero-velocity curves (ZVCs) are computed to gain more insight into the permissible regions of motion. Moreover, using these permissible regions, we construct the trajectories of the homoclinic and heteroclinic connections between collinear points L_1 and L_2. The results provide improved insight into the influence of non-gravitational forces on the trajectory connecting the collinear points L_1 and L_2, which function as natural low-energy transport pathways between these equilibrium points.

The Central Parsec of the Galaxy hosts numerous binary and multiple star systems immersed in strong radiation fields and embedded non-spherical dusty structures. This study models the local stellar dynamics around a binary star system using a modified Circular Restricted Three-Body Problem (CRTBP). The binary is represented by a massive radiating primary and a non-spherical secondary star whose gravitational asymmetry, arising from tidal distortion, extended envelopes, or circumstellar material, is modeled using a continued-fractional potential. Within this framework, we examine the phase-space structure by computing Lyapunov periodic orbits under the influence of the continued-fractional potential and propagating their invariant manifolds to identify heteroclinic connections between the dynamical regions of the two stars. These pathways act as natural low-energy transport channels, offering insight into the migration of matter and small bodies in the dense Galactic Center environment.

The CMZ presents a unique environment for studying high mass star formation, with conditions that are extreme compared to the Galactic disc. Unlike extragalactic analogues, the CMZ is near enough for us to observe the scales of individual protostars. Beyond a few well-studied regions, our understanding of how and where high mass stars are forming is limited. I will showcase results from a 1mm survey which has observed all known potential sites of high mass star formation throughout the CMZ with ALMA at 1000 AU resolution. The observations reveal a lack of compact cores despite high gas densities. Where there are cores, we find clustered low and high mass star formation, molecular outflows, candidate high mass accretion discs, and potential precursors to very massive stars. I will discuss how this survey is a CMZ counterpart to the ALMA LPs ALMAGAL and ALMA-IMF, which provides crucial context in understanding how (pre-)stellar mass distributions are shaped by their natal environment.

Bright near-infrared sources remain poorly measured because existing single-epoch catalogs suffer from saturation at ks < ~5.5 mag (2MASS) or cover only very bright northern stars (K < ~3 mag; TMSS), leaving a gap at Ks = 3-6 mag with no J/H data. Time-domain surveys such as ZTF, Pan-STARRS, and VVV also saturate for bright objects, providing little reliable multi-epoch photometry; for example, VVV saturates near 10–11 mag, so many bulge biright variables (e.g., Miras) remain unmeasured. To fill this long-standing gap, we built the Thirty MilliMeter Telescope (TMMT) and conducted JHKs observations over |b| < 5, δ > -30 deg, followed by a 6-year monitoring campaign (2016–2022). We present bright variables detected toward the Galactic center, based on this multi-epoch survey.

The Circumnuclear Disk (CND) is a ring of dense molecular gas surrounding the Milky Way’s central supermassive black hole at a radius of 2-5 parsecs. It represents the closest reservoir of gas for studying the feeding of the central supermassive black hole. Despite extensive study, the 3D structure of the CND and its connection to the surrounding remains uncertain. To address this need, we present high-resolution 1.5" maps of the CND using Atacama Large Millimeter/submillimeter Array (ALMA) observations of three high-density gas tracers, HNC, SO and CH₃OH. We perform a kinematic spectral decomposition of the data by fitting the spectra with Gaussian profiles to capture the complex gas motions. These results provide new constraints on the geometry and dynamics of the CND, and help us understand gas inflow from the ~100 pc CMZ orbit into the inner few parsecs around Sgr A*.

Recent observations of the Galactic Center challenge our understanding of stellar feedback and outflows. The detection of cold, dense molecular gas in nuclear outflows above the CMZ, together with the large Fermi and eROSITA bubbles, is unexpected given the rather low current star formation rate and the relative quiescence of Sgr A*. I investigate whether stellar feedback in the CMZ alone can drive winds capable of producing these features, using high-resolution MHD simulations of the Galactic Center with the PIERNIK code. The simulations achieve parsec-scale resolution, capturing both the CMZ and the outflows that arise from it. I examine the morphology, kinematics, and multiphase structure of the resulting winds, focusing on cold HI clouds launched from the CMZ at velocities of a few hundred km/s and comparing them directly to observations.

To investigate high-energy astrophysical phenomena around black holes, we examine the motion of charged particles in a black hole magnetosphere. The magnetosphere is assumed to be a vacuum, with its magnetic field generated by a geometrically thin disk located on the equatorial plane. The spacetime dragging effect of a spinning black hole induces an electric field within the magnetosphere. We identify a region of negative potential near the rotation axis and above the disk surface. We also demonstrate that energy extraction from the black hole magnetosphere is possible via the magnetic Penrose process. Consequently, the generation of ultra–high-energy particles can be expected in such magnetospheric environments.

We propose a novel observable quantity which depends only on the mass and spin of BH but NOT on parameters of gasses/matters surrounding BH. The key point of the observable is the gravitational redshift which the photon/radio-wave experiences during propagating from the vicinity of BH horizon to far observer. The gravitational redshift due to BH stretches the wavelength of photon exponentially, and its exponent index is determined by only the mass and spin of BH. We expect this observable, the exponent index, provides with a new approach to the vicinity of BH horizon.

We conducted a reanalysis of the EHT archive data of Sgr A* in 2017. Since 2024, we have developed a methodology that constructs image models from CLEAN components and evaluates them using closure-phase residuals. Because closure phase is independent of antenna-based errors and depends solely on the source structure, it provides an objective criterion for assessing image reliability. Miyoshi et al. (2024, MN) identified an east–west elongated and asymmetric brightness distribution in Sgr A*, interpreted as an accretion disk viewed nearly edge-on. We extended this analysis by comparing roughly 10⁹ image models through closure-phase residual criteria, enabling a comprehensive exploration of the allowed image space. This large-scale evaluation produced models with reduced residuals, offering strengthened support for the interpretation proposed by Miyoshi et al. (2024, MN). The selected images exhibit a morphology that appears to represent the shape of a black-hole shadow.

In the galactic center, stars orbiting the supermassive black hole follow a mass segregated distribution in the inclination angle of the orbital planes. This distribution may represent the equilibrium state of vector resonant relaxation (VRR). In this talk, I will present simple statistical physics models to understand the equilibrium distribution. Using the method of maximising the total entropy and mean-field approximation, we determine the equilibrium distribution of axisymmetric two-component gravitating systems with distinct masses and semi-major axes. We explore the parameter space and find evidence of vertical mass segregation. When the two components have small inter-component interaction energy, phase transitions could occur: the change in one component can induce a discontinuous change in the other component between a disk state and an isotropic state. N-body VRR dynamical simulation results are largely consistent with the predictions of the thermal model.

We present a Machine Learning framework on synthetic spectra of objects inhabiting the Galactic Center. Initially, Be stars are modeled using HDUST in the IR/Visible. These massive stars possess circumstellar decretion disks that are strong infrared emitters. We generate clusters based on flux ratios to distinguish distinct disk geometries, densities, and evolutionary phases, aiding in identifying young stellar populations. Furthermore, we classify predictions of physical parameters from N2H+ spectra generated by the LOC code. As a robust tracer of dense, cold gas resistant to depletion, N2H+ is vital for probing initial star formation conditions, for example, in the protocluster G327.29. We apply classification models to constrain properties like column density and velocity dispersion. Finally, we analyze how this automated approach serves as a tool to potentially study the complex kinematics and environment of the Central Molecular Zone from these tracers.

In the past, researchers have identified several peculiar environments in the inner parsec of the Milky Way, the most well-known of which is the black hole Sagittarius A*. Notable structures in the infrared L band are the Northern Arm, portions of the Western and Eastern Arms, the Minicavity, and IRS 13. Following these studies, ALMA observations of the 343 GHz CO transition line revealed increased radio emission surrounding the stars IRS 6E and IRS 6W. A polychromatic analysis of this „IRS 6“ region using radio and four infrared wavelengths resulted in a catalogue of over 400 sources and includes their proper motions, magnitudes, fluxes, and velocity dispersion. Keplerian orbit and spectral energy distribution fits to a subset of sources suggest a common origin as well as two generations of stars. Thus, IRS 6 can be classified as a potential stellar association that may be further evolved compared to literature examples.

The chemical abundance of active galaxies with active galactic nuclei (AGN) is under-studied due to challenges in metallicity measurements. Specifically, the abundance in various environments, including clusters and groups, remains unknown. We utilize the HCm code (HII-CHI-mistry) to measure the chemical abundance of type-2 AGN, focusing on oxygen (12 + log(O/H)), nitrogen (log(N/O)), and ionization parameter (logU) for ~12,000 type-2 AGN from the SDSS survey. We analyze metallicity properties in relation to AGN host characteristics like morphology, stellar mass, and star formation rate (SFR). Our findings indicate that in clusters, 12 + log(O/H) is higher with increased stellar mass, while abundance decreases with higher SFR in all environments. Notably, we find no strong mass-metallicity relation, suggesting complex dynamics involving stellar mass, SFR, and metallicity in AGNs. This study provides the largest catalogue of chemical abundances for type-2 AGN to date.

We have carried out high-resolution NIR spectroscopy of stars in the central pc from Sgr A* using the Subaru telescope. We determined metal abundances ([Fe/H], [alpha/Fe], etc.) for more than ten late-type stars. These stars lie almost exactly on the sequence of the NSC stars in the [M/H]-[alpha/Fe] plane, suggesting a common origin for the NSC metal-rich population. However, one of the stars, S0-6/S10, shows low metal abundances of [Fe/H] = -0.40, [alpha/Fe] = -0.20, [Mg/Fe] = -0.30, and so on. This star may have a different origin from the other stars. We also performed spectroscopy of early-type stars. Spectra of two supergiants were used to determine their stellar parameters such as temperatures, initial masses, and ages. Despite their different dynamical properties, the stars show very similar ages of 4 to 5 Myr, suggesting that they share a common origin.

Magneto-rotational instability is the key mechanism for driving turbulence in accretion disks, which disrupts the axial symmetry of the system and can excite the quasi-normal ringing of black holes (BHs), potentially emitting gravitational waves (GWs). Motivated by this, we investigate stochastic GW signals from turbulent, magnetized disks around BHs. In doing so, we conduct three global GRMHD simulations of (i) standard and normal evolution (SANE), (ii) sub-SANE, and (iii) magnetically arrested disk models. The results from these simulations serve as a source in the Teukolsky equation to calculate the emitted GW energy. We compare the GW signals from these models and identify the aspects of gas physics, including turbulence and magnetic fields, that effectively excite BH quasi-normal modes. We assess whether the stochastic GW generated in each scenario approaches the sensitivity curves of future gravitational wave detectors, offering new insights into multimessenger astrophysics.

Investigation of unknown matter distribution near the Galactic Center black hole holds the key to understanding the black hole’s formation history. In this work we use recent bound on dark mass near the Galactic Center, to constrain the parameters of several dark matter distributions. The precession of stellar orbits in presence of such mass distributions is calculated. We identify regimes where dark matter dominates general relativistic effect. 13 S-stars have been used to assess prospects for detecting these effects with current and upcoming astronomical facilities. For S2 star, we find the orbit to be largely insensitive to dark matter but is a strong probe of modified gravity. Stars of low eccentricity and wide orbits show higher sensitivity. Finally, we construct dark matter induced metrics and highlight prospects for black hole shadow measurements.

The extreme phenomena in the Galactic Center such as large-scale shocks and enhanced cosmic-ray ionization rates, drive a very rich chemistry in carbon chains, complex organic molecules and metal-bearing species. Specifically, the Galactic Center molecular cloud G+0.693-0.027 is distinguished by its chemical richness where a wide range of molecules have been discovered. Recently, we have reported in this cloud the first detection of the metal-sulfide molecules MgS and NaS in the interstellar medium (Rey-Montejo et al. 2024). This detection suggests that these species may represent important reservoir of sulfur, known to be heavily depleted in dense molecular clouds. In this contribution, we present the results from a new chemical model that includes the chemistry of metal-sulfides. The comparison of the observations with the models provide essential information about the formation and destruction routes of these species and it constrains the amount of sulfur locked into dust grains.

The Galactic Center provides one of the most extreme astrophysical environments for testing physics beyond the Standard Model. In this study, I investigate potential variations of fundamental constants, focusing on the fine-structure constant α and the gravitational constant G, using high-precision spectroscopic and gravitational-redshift measurements of compact stellar systems. By applying GUT-motivated relations connecting α, μ, and G, I derive updated constraints on possible spatial variations under strong-gravity and high-density conditions. Current results provide stringent limits on fundamental-constant variations, contributing to our understanding of cosmological evolution and reinforcing the Galactic Center as a powerful natural laboratory for probing new physics.

Integrable two-dimensional gravitational potentials with fourth-order integrals of motion provide powerful analytical tools for studying the orbital structure of the Galactic Center (GC). We present a classification of such potentials and show their relevance for modeling regular and resonant orbits in the central few hundred parsecs. The resulting integrable families reproduce key GC components, including bar-related x1/x2 trajectories, elongated paths in the Central Molecular Zone, and near-regular stellar orbits in the nuclear cluster. These models allow systematic exploration of transitions between regular and chaotic motion, the emergence of higher-order resonances, and the behavior of approximate third integrals in GC-like potentials. Our results establish an analytical framework for interpreting GC dynamical architecture and for constructing controlled models to study secular evolution, orbital transport, and the interplay between regular and stochastic components around Sgr A*.

Massive young stars emit thermal radio emission from their ionised winds and non-thermal radio emission from colliding winds in binary or multiple systems. We have carried out radio continuum observations of the Arches and Quintuplet clusters with the JVLA over a timespan of six years. With these data we present the most detailed radio-stellar catalogue of both clusters to date. In our study, we constrain mass-loss rates of thermal emitters and radio-stellar variability. We show that radio-continuum observations are complementary to radial-velocity campaigns to infer massive stellar multiplicity. Furthermore, our data enable us to constrain global cluster parameters. In particular, we find evidence for a top-heavy initial mass function for the Arches cluster, that is independent from, but coincides very well with near infrared observations.

I will present our recent results on the central parsec of the Galactic Center based on JWST/MIRI Medium Resolution Spectrometer (MRS) observations. By fitting the spectra with an extensive grid of CLOUDY photoionization models, we identify the dominant gas phases and constrain the abundances of the three major elemental groups.

Quasi-periodic eruptions (QPEs) are newly discovered transients of unknown nature occurring near supermassive black holes, which feature bright X-ray bursts separated by approximately 10 hours. A promising model for QPEs is the star-disc model, where a star interacts periodically with a black hole’s pre-existing accretion disc, creating shocks that expel dense gas clouds from which radiation emerges. We performed the first 3D radiation-hydrodynamics simulations to investigate the dynamics of the star-disc collisions, the properties of the ejected gas clouds, and the resulting radiation signatures. We found that star-disc collisions generate a nearly paraboloidal bow shock. The collision drives an outflow of gas both in the forward and backward directions relative to the star’s motion. These outflows are asymmetric, with the forward outflow carrying more mass and producing a brighter luminosity than the backward component.

The Galactic Center offers a unique laboratory to study a complex interstellar medium. This work investigates thermal and nonthermal processes within 7 pc of Sgr A⋆. Using MeerKAT 1.3 GHz data and ALMA H40α line emission from the ACES survey, we separate free-free and synchrotron components at ∼0.2 pc resolution. Comparison with Herschel data reveals a correlation between nonthermal and far-infrared emission, suggesting a balance among magnetic field, cosmic ray, and molecular gas pressures. The mean of the equipartition magnetic field is 418 ± 2 µG. We find that nonthermal pressure from turbulent gas nearly balances the magnetic and cosmic-ray pressures and exceeds thermal pressure. This indicates the region is filled with low-β and an Alfvén Mach number ≳ 4. The mass-to-magnetic flux ratio suggests the region is subcritical. Hence, the magnetic field is a prominent parameter that can help stabilize gas clouds against gravitational collapse.

We study the physical conditions toward eight positions in the Sgr C region of the Galactic Center using molecular line observations that trace different heating sources and physical parameters. We derive kinetic temperatures ranging from ~40 to 80 K for five positions, with the highest value for a structure known as the molecular shell (MS). Furthermore, a non-LTE analysis yields H2 densities of ~10^3 1/cm3 in four regions. At one position, an HII region is powered by an O9.5 star. HNCO and SiO abundances are highest in the HII region and MS, where high gas velocities and broad line widths indicate expanding gas, likely enhancing grain sputtering. To extend our study, we also analyze X-ray data. Although Sgr C is exposed to diffuse X-rays from Sgr A*, our measured HCO+/HOC+ ratio and X-ray ionization rates - at least an order of magnitude lower than the cosmic-ray ionization rate - indicate that X-rays are not a dominant heating source in this region.

The central regions of the Galaxy has experienced recent rich star-forming activity, which created numerous young star clusters dominated by Red Supergiants (RSGs) and can be traced by the chemical abundances of these young objects. It was only in the last ~ 20 years that the dust extinction in the inner Milky Way was penetrated and the presence of such objects was revealed. Their detailed properties have still not been fully studied. Using X-shooter at the Very Large Telescope (VLT) infrared (IR) data, we present the spectral analysis of a sample of 39 RSGs in the inner Galaxy revealing their radial velocity, spectral type, metallicity, surface temperature and log (g). We use these parameters to estimate the age, distance and metallicity of the star clusters they belong to and infer clues on the origin of the recent rich star forming activity that the central region has experienced.

The Time-Resolving Explorer (T-REX) is a proposed satellite mission which will capture the first video of a black hole. T-REX will achieve the finest temporal resolution in the history of astronomy, by leveraging a Low-Earth Orbit Very-Long-Baseline-Interferometry (VLBI) SmallSat platform. This will be enabled by laser downlink communications, ultra-stable oscillators and extensive ground-based supporting infrastructure. T-REX will constrain Sgr A∗’s spin to ≤ 10% ground truth by capturing time-resolved videos of Sgr A∗ at 86 GHz. T-REX will operate at λ ∼ 3.5mm with a d ∼ 2.5m antenna and a primary receiver temperature of ∼ 20K. By virtue of its sub-ISCO 22 minute temporal resolution, T-REX will also enable parameter estimation on transient astrophysical phenomena by capturing time-resolved videos of black hole accretion disks, quasi-periodic outbursts, relativistic jets from AGN, and tidal-disruption events.

The formation conditions of globular clusters (GCs) in the early Universe have been an active topic of discussion in the last decades. Of particular interest is the understanding of the GC initial mass function (GCIMF), which poses theoretical and observation challenges. In this work we revisit the problem of the GCIMF by testing the ability of cluster disruption mechanisms in shaping the GCIMF into its present state, which according to observational constraints displays a peaked shape in most galaxies. We find that, since cluster disruption correlates with the mass and density of the galaxy, the efficiency of the disruption mechanisms in modifying the shape of the GCMF is galaxy-dependent. Our results show the difficulties in trying to reconcile a universal GCIMF and a near-universal peak mass with cluster disruption efficiencies that are environment-dependent.

The cosmic microwave background (CMB) provides a unique radiative field permeating the interstellar medium, and its temperature (T_CMB) evolution with redshift offers a fundamental cosmological test. We present high-precision T_CMB measurements using molecular absorption toward the gravitationally lensed quasars B0218+357 and PKS1830–211. Using ALMA, we detect multiple transitions of highly polar molecules (HCN, HCO+, HNC, and isotopologues) at z=0.68 and z=0.89, whose excitation in diffuse gas is dominated by radiative coupling to the CMB rather than by collisions. We account for uncertainties in the continuum covering factor, cloud inhomogeneity using a lognormal column-density distribution, and time variability in absorption driven by background AGN structure. We derive T_CMB=4.50±0.17 K at z=0.68 and 5.13±0.06 K at z=0.89. These results demonstrate that ALMA absorption studies of diffuse molecular gas provide a powerful link between detailed ISM physics and precision cosmology.

This poster reports the results of a dynamical analysis of SiO maser sources located within the galactic centre region, where |l| < 4° and |b| < 2°. We cross-matched known SiO maser sources with currently available variable star and proper motion catalogues, integrating information on radial velocity, variability period, and proper motion. As many objects are likely Mira-type stars, we estimated the six-dimensional position-velocity information for each object using the period–luminosity relation. Furthermore, combining this six-dimensional information with the period–age relation for Mira-type stars enables discussion of the temporal evolution of the dynamical structure in the galactic centre. Considering these points, this study presents the motion characteristics of SiO maser sources distributed towards the galactic centre, examines the possibility of separating the disc and bulge components, and investigates the formation and evolution of the dynamical structure in this region.

In our Galaxy, the mechanisms that transport gas from scales of hundreds of parsecs, the central molecular zone (CMZ), down to Sgr A*, remain unclear. We investigate whether gravitational perturbations from globular clusters and other massive perturbers that may have occurred in the past can drive episodic gas inflow toward the Galactic centre. We perform isothermal hydrodynamic simulations of the Milky Way CMZ gas disk in an external gravitational potential that includes Plummer-sphere satellites as perturbers. We find that the known Galactic globular clusters are inefficient at disturbing the gas at R<100pc. Exploring the parameter space of higher mass perturbers, we find that a 10^7 Msun satellite with orbital pericenter at ~140 pc drives non-negligible perturbations of the gas in the CMZ. Finally, in a more massive scenario with a 10^8 Msun satellite, we find strong perturbations that efficiently mix the gas at R<100 pc and drive inflow toward the Galactic centre.

The role of relativistic frame dragging, caused by the spin of a rotating black hole, is particularly prominent near the event horizon, and it becomes insurmountable within the ergosphere. It acts on massive particles as well as fields, in particular the magnetic field to which astrophysical black holes are embedded due to external currents flowing in the accreting medium. In a steady-state situation, a relatively small but non-vanishing electric charge is established on the black hole, which helps to accelerate particles in the black hole vicinity. Assuming the background of a weakly charged, weakly magnetized Kerr metric, we explore the terminal velocity and directionality of different species of accelerated particles. We find that the charge induced on the black hole may significantly increase the effectivity of the acceleration process.

The coevolution of supermassive black holes and nuclear star clusters (NSCs) relies on the transport of angular momentum in galactic centers, yet the driving mechanisms remain debated. We investigate the hypothesis that supernova feedback drives stochastic turbulence, creating an effective viscosity in the region covering the central molecular zone and the circumnuclear disk. Using the Kramers–Moyal expansion of the master equation for the angular momentum density, we analytically derive this viscosity for both spherical and cylindrical geometries. We explore the implications of these coefficients and investigate how varying density gradients might drive advective mass flows alongside standard diffusive behavior. Furthermore, we outline strategies for implementing and testing these analytical prescriptions in future hydrodynamic simulations. Ultimately, this approach provides a physically consistent foundation for modeling the coevolution of NSCs and their host galactic nuclei.

As data volumes increased dramatically, following LIGO–Virgo–KAGRA observation runs produced hundreds of occurrences. Machine learning (ML), and artificial intelligence (AI) approaches are becoming more and more popular as a result of traditional analytic techniques like matched filtering struggling with computing demands and non-Gaussian noise. tThis topical review summarises significant developments in GW data analysis from 2024–2025.

The presence of a strong relativistic jet in the Galactic center remains debated, although several arguments suggest that some form of jet outflow should exist. The flat-to-inverted radio spectrum of Sagittarius A* can be explained by analytical jet models, and all GRMHD models used by the Event Horizon Telescope to interpret horizon-scale emission develop magnetically driven polar outflows. These simulations are scale-free and can be rescaled to different black hole masses and accretion rates. We investigate whether GRMHD models that best fit Sgr A* are applicable to the broader population of radio-loud AGN, requiring consistency with both the 230 GHz horizon-scale emission and large-scale radio jet spectra. We find that most magnetically arrested disk (MAD) models fail to reproduce the typically flat AGN radio spectra, while standard and normal evolution (SANE) models perform significantly better. We further assess how GRMHD setup choices affect the resulting jet spectra.

Radio-loud and radio-quiet active galactic nuclei (AGN) may reflect different accretion states rather than an intrinsic bimodality in jet production. In X-ray binaries, spectral state transitions regulate the coupling between the accretion disc, corona, and relativistic jets. If similar state behaviour operates across black hole mass scales, AGN radio properties should be governed primarily by accretion regime. We analyse more than 3500 AGN with simultaneous UV and X-ray observations from XMM-Newton and Swift, complemented by radio data. Constructing an AGN analogue of the hardness–intensity diagram, we identify distinct accretion states that mirror those observed in X-ray binaries. Jet-dominated systems preferentially occupy hard, low-accretion states. Within this framework, Sgr A* can be interpreted as a nearby example of a radiatively inefficient accretion state.