New constraints on the structure of the nuclear stellar cluster of the Milky Way from star counts and MIR imaging

Abstract

The Milky Way nuclear star cluster (MWNSC) is a crucial laboratory for studying the galactic nuclei of other galaxies, but its properties have not been determined unambiguously until now. Aims. We aim to study the size and spatial structure of the MWNSC. Methods. This study uses data and methods that address potential shortcomings of previous studies on the topic. We use $0.2^{\prime \prime }$ angular resolution $K_s$ data to create a stellar density map in the central $86.4$pc x $21$pc at the Galactic center. We include data from selected adaptive-optics-assisted images obtained for the inner parsecs. In addition, we use IRAC/Spitzer mid-infrared (MIR) images. We model the Galactic bulge and the nuclear stellar disk in order to subtract them from the MWNSC. Finally, we fit a Sérsic model to the MWNSC and investigate its symmetry. Results. Our results are consistent with previous work. The MWNSC is flattened with an axis ratio of $q=0.71\pm 0.10$, an effective radius of $R_e=(5.1\pm 1.0)$ pc, and a Sérsic index of $n=2.2\pm 0.7$. Its major axis may be tilted out of the Galactic plane by up to $-10$ degrees. The distribution of the giants brighter than the Red Clump (RC) is found to be significantly flatter than the distribution of the faint stars. We investigate the 3D structure of the central stellar cusp using our results on the MWNSC structure on large scales to constrain the deprojection of the measured stellar surface number density, obtaining a value of the 3D inner power law of $\gamma =1.38\pm 0.06_{sys}\pm 0.01_{stat}$. Conclusions. The MWNSC shares its main properties with other extragalactic NSCs found in spiral galaxies. The differences in the structure between bright giants and RC stars might be related to the existence of not completely mixed populations of different ages. This may hint at recent growth of the MWNSC through star formation or cluster accretion.

arXiv comment20 pages

References in corpus (57)

• Monitoring stellar orbits around the Massive Black Hole in the Galactic Center
• Measuring Distance and Properties of the Milky Way's Central Supermassive Black Hole with Stellar Orbits
• The Galactic Center Massive Black Hole and Nuclear Star Cluster
• Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole
• Formation of Galactic Nuclei
• The ACS Virgo Cluster Survey. VIII. The Nuclei of Early-Type Galaxies
• An Update on Monitoring Stellar Orbits in the Galactic Center
• The Nuclear Bulge of the Galaxy. III. Large-Scale Physical Characteristics of Stars and Interstellar Matter
• An Extremely Top-Heavy IMF in the Galactic Center Stellar Disks
• A 100-parsec elliptical and twisted ring of cold and dense molecular clouds revealed by Herschel around the Galactic Center
• An HST Census of Nuclear Star Clusters in Late-Type Spiral Galaxies: I. Observations and Image Analysis
• Interstellar Extinction Law toward the Galactic Center III: J, H, Ks bands in the 2MASS and the MKO systems, and 3.6, 4.5, 5.8, 8.0 micron in the Spitzer/IRAC system
• COBE's Galactic Bar and Disk
• Stellar Populations in the Central 0.5 pc of the Galaxy II: The Initial Mass Function
• An Improved Distance and Mass Estimate for Sgr A* from a Multistar Orbit Analysis
• Line derived infrared extinction towards the Galactic Center
• Masses of star clusters in the nuclei of bulge-less spiral galaxies
• The effect of mass-segregation on gravitational wave sources near massive black holes
• Modelling the Galactic Bar Using Red Clump Giants
• Stellar remnants in galactic nuclei: mass segregation
• Quantifying the Coexistence of Massive Black Holes and Dense Nuclear Star Clusters
• A HST Census of Nuclear Star Clusters in Late-Type Spiral Galaxies: II. Cluster Sizes and Structural Parameter Correlations
• The Shortest Known Period Star Orbiting our Galaxy's Supermassive Black Hole
• An investigation into the prominence of spiral galaxy bulges
• Surface Brightness Profile of the Milky Way's Nuclear Star Cluster
• The old nuclear star cluster in the Milky Way: dynamics, mass, statistical parallax, and black hole mass
• HST Proper Motions and Stellar Dynamics in the Core of the Globular Cluster 47 Tucanae
• Nuclear star clusters in 228 spiral galaxies in the HST/WFPC2 archive: catalogue and comparison to other stellar systems
• High angular resolution integral-field spectroscopy of the Galaxy's nuclear cluster: a missing stellar cusp?
• Clues to Nuclear Star Cluster Formation from Edge-on Spirals
• Interstellar Extinction Law toward the Galactic Center II: V, J, H, and Ks Bands
• Stellar Dynamics and Stellar Phenomena Near A Massive Black Hole
• The star formation history of the Milky Way's Nuclear Star Cluster
• Origin and growth of nuclear star clusters around massive black holes
• Large scale kinematics and dynamical modelling of the Milky Way nuclear star cluster
• JHKL Photometry and the K-band Luminosity Function at the Galactic Center
• Stellar Populations in the Central 0.5 pc of the Galaxy I: A New Method for Constructing Luminosity Functions and Surface-Density Profiles
• Source-intrinsic near-infrared properties of Sgr A*: Total intensity measurements
• HST Paschen-alpha Survey of the Galactic Center: Data Reduction and Products
• The distribution of old stars around the Milky Way's central black hole I: Star counts
• The nuclear cluster of the Milky Way: Our primary testbed for the interaction of a dense star cluster with a massive black hole
• The Nuclear Cluster of the Milky Way: Total Mass and Luminosity (long version)
• Discovery of low-metallicity stars in the central parsec of the Milky Way
• KMOS view of the Galactic Centre I. Young stars are centrally concentrated
• On the distribution of stellar remnants around massive black holes: slow mass segregation, star cluster inspirals and correlated orbits
• GALACTICNUCLEUS: A high angular resolution $JH{K}_s$ imaging survey of the Galactic Centre. I. Methodology, performance, and near-infrared extinction towards the Galactic Centre
• The distribution of stars around the Milky Way's black hole III: Comparison with simulations
• The Structure of Nuclear Star Clusters in Nearby Late-type Spiral Galaxies from Hubble Space Telescope Wide Field Camera 3 Imaging
• GALACTICNUCLEUS: A high-angular-resolution JHKs imaging survey of the Galactic centre II. First data release of the catalogue and the most detailed CMDs of the GC
• Magnetically Confined Interstellar Hot Plasma in the Nuclear Bulge of our Galaxy
• Dynamical friction in cuspy galaxies
• Mapping the Outer Edge of the Young Stellar Cluster in the Galactic Center
• Star formation history and metallicity in the Galactic inner bulge revealed by the red giant branch bump
• Variability of the near-infrared extinction curve towards the Galactic centre
• HST Observations of the Stellar Distribution Near Sgr A*
• Nuclear Star Clusters in Cosmological Simulations
• The Nuclear Cluster of the Milky Way: Total Mass and Luminosity

Cited by in corpus (45)

• Simulations of the Milky Way's central molecular zone -- II. Star formation
• Gas Dynamics in the Galaxy: Total Mass Distribution and the Bar Pattern Speed
• The Milky Way's nuclear stellar disc: A dynamically cool and metal-rich component formed from the Central Molecular Zone?
• Jeans modelling of the Milky Way's nuclear stellar disc
• Detailed abundances in the Galactic center: Evidence of a metal-rich alpha-enhanced stellar population
• The Star Formation History of the Milky Way's Nuclear Star Cluster
• On the origin of a rotating metal-poor stellar population in the Milky Way Nuclear Cluster
• GALACTICNUCLEUS: A high-angular-resolution $JH{K}_s$ imaging survey of the Galactic centre. IV. Extinction maps and de-reddened photometry
• GALACTICNUCLEUS: A high-angular-resolution JHKs imaging survey of the Galactic centre III. Evidence for wavelength dependence of the extinction curve in the near-infrared
• On Socially Distant Neighbors: Using Binaries to Constrain the Density of Objects in the Galactic Center
• The nuclear star cluster and nuclear stellar disc of the Milky Way: Different stellar population and star formation history
• A KMOS survey of the nuclear disk of the Milky Way I: Survey design and metallicities
• Mira variables in the Milky Way's nuclear stellar disc: discovery and classification
• Composite Bulges -- II. Classical Bulges and Nuclear Discs in Barred Galaxies: The Contrasting Cases of NGC 4608 and NGC 4643
• The extinction law in the inner $3\times 3$ deg${}^2$ of the Milky Way and the red clump absolute magnitude in the inner bar-bulge
• A proper motion catalogue for the Milky Way's nuclear stellar disc
• Study of the excess Fe XXV line emission in the central degrees of the Galactic centre using XMM-Newton data
• Evidence of an age gradient along the line of sight in the nuclear stellar disc of the Milky Way
• Stellar Populations in the Transition Region of Nuclear Star Cluster and Nuclear Stellar Disc
• Kinematic data rebuild the Nuclear star cluster as the most metal rich region of the Galaxy
• Can ultralight dark matter explain the age-velocity dispersion relation of the Milky Way disc: A revised and improved treatment
• PHANGS-JWST First Results: A combined HST and JWST analysis of the nuclear star cluster in NGC 628
• The Inner 2 pc of Sagittarius A*: Simulations of the Circumnuclear Disk and Multiphase Gas Accretion in the Galactic Center
• Measuring the Orbits of the Arches and Quintuplet Clusters using HST and Gaia: Exploring Scenarios for Star Formation Near the Galactic Center
• A first glimpse at the line-of-sight structure of the Milky Way's nuclear stellar disc
• Distance to the Brick cloud using stellar kinematics
• Smooth kinematic and metallicity gradients reveal that the Milky Way's nuclear star cluster and disc might be part of the same structure
• On the Tidal Capture of White Dwarfs by Intermediate-mass Black Holes in Dense Stellar Environments
• Evidence of Deep Mixing in IRS 7, a Cool Massive Supergiant Member of the Galactic Nuclear Star Cluster
• Black Hole Discs and Spheres in Galactic Nuclei -- Exploring the Landscape of Vector Resonant Relaxation Equilibria
• Forming Young and Hypervelocity Stars in the Galactic Centre via Tidal Disruption of a Molecular Cloud
• Photometric Classification of Stars Around the Milky Way's Central Black Hole: I. Central Parsec
• A spectroscopic map of the Galactic centre -- Observations and resolved stars
• Dynamical mass distribution and velocity structure of the Galactic centre
• Constraining Ultra Light Dark Matter with the Galactic Nuclear Star Cluster
• Detecting hot stars in the Galactic centre with combined near- and mid-infrared photometry
• Metallicity-dependent kinematics and orbits in the Milky Way's nuclear stellar disc
• The Near-Infrared Spectrum of the Nuclear Star Cluster: Looking Below the Tip of the Iceberg and Comparisons with Extragalactic Nuclei
• Age and metallicity of the Milky Way's nuclear star cluster studied at 3 pc from Sagittarius A*
• Chemical analysis of the Milky Way's Nuclear Star Cluster: Evidence for a metallicity gradient
• Self-consistent modelling of the Milky Way's Nuclear Stellar Disc
• 3D CMZ V: A new orbital model of our Galaxy's Center, informed by data across the electromagnetic spectrum
• Supergiant GCIRS 22 in the Milky Way Nuclear Star Cluster: Revised alpha abundances
• On the possible orbital motion of Sgr A* in the smooth potential of the Milky Way
• X-ray emission of the Nuclear Stellar Disk as seen by SRG/ART-XC