Andromeda XXXV: The Faintest Dwarf Satellite of the Andromeda Galaxy

Abstract

We present the discovery of Andromeda XXXV, the faintest Andromeda satellite galaxy discovered to date, identified as an overdensity of stars in the Pan-Andromeda Archaeological Survey and confirmed via Hubble Space Telescope imaging. Located at a heliocentric distance of $927_{-63}^{+76}$ kpc and $158_{-45}^{+57}$ kpc from Andromeda, Andromeda XXXV is an extended ($r_h=53{}_{-11}^{+13}$ pc), elliptical ($\epsilon =0.4\pm 0.2$), metal-poor ($[\text{Fe}/\text{H}]\sim -1.9$) system, and the least luminous ($M_V=-5.2\pm 0.3$) of Andromeda's dwarf satellites discovered so far. Andromeda XXXV's properties are consistent with the known population of dwarf galaxies around the Local Group, bearing close structural resemblance to the Canes Venatici II and Hydra II Milky Way (MW) dwarf satellite galaxies. Its stellar population, characterized by a red horizontal branch or a red clump feature, mirrors that of other Andromeda satellite galaxies in showing evidence for a spread in age and metallicity, with no signs of younger stellar generations. This age-metallicity spread is not observed in MW satellites of comparable stellar mass, and highlights the persistent differences between the satellite systems of Andromeda and the MW, extending even into the ultrafaint regime.

arXiv comment13 pages, 5 figures, 1 Table, accepted to ApJL

References in corpus (74)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Astropy: A Community Python Package for Astronomy
• emcee: The MCMC Hammer
• The NumPy array: a structure for efficient numerical computation
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• scikit-image: Image processing in Python
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• The observed properties of dwarf galaxies in and around the Local Group
• The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems
• Small-Scale Challenges to the $\Lambda$CDM Paradigm
• The Photometric Performance and Calibration of the HST Advanced Camera For Surveys
• WFPC2 Stellar Photometry with HSTphot
• Cats and Dogs, Hair and A Hero: A Quintet of New Milky Way Companions
• Reddening and Extinction Toward the Galactic Bulge from OGLE-III: The Inner Milky Way's Rv ~ 2.5 Extinction Curve
• Eight New Milky Way Companions Discovered in First-Year Dark Energy Survey Data
• The Faintest Dwarf Galaxies
• Eight Ultra-faint Galaxy Candidates Discovered in Year Two of the Dark Energy Survey
• A comprehensive Maximum Likelihood analysis of the structural properties of faint Milky Way satellites
• A Vast Thin Plane of Co-rotating Dwarf Galaxies Orbiting the Andromeda Galaxy
• The Haunted Halos of Andromeda and Triangulum: A panorama of galaxy formation in action
• The Luminosity Function of the Milky Way Satellites
• The Quenching of the Ultra-Faint Dwarf Galaxies in the Reionization Era
• Population effects on the Red Giant Clump absolute magnitude, and distance determinations to nearby galaxies
• "Galaxy," Defined
• Pre-reionization Fossils, Ultra-faint Dwarfs and the Missing Galactic Satellite Problem
• A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters
• Population effects on the red giant clump absolute magnitude: The K-band
• Discovery and analysis of three faint dwarf galaxies and a globular cluster in the outer halo of the Andromeda galaxy
• A kinematic study of the Andromeda dwarf spheroidal system
• Small Dwarf Galaxies Within Larger Dwarfs: Why Some Are Luminous While Most Go Dark
• PAndAS' progeny: extending the M31 dwarf galaxy cabal
• The large-scale structure of the halo of the Andromeda galaxy II. Hierarchical structure in the Pan-Andromeda Archaeological Survey
• The Star Formation Histories of Local Group Dwarf Galaxies II. Searching For Signatures of Reionization
• A wide-field HI mosaic of Messier 31. II.The disk warp, rotation and the dark matter halo
• The Orbital Histories of Magellanic Satellites Using Gaia DR2 Proper Motions
• Milky Way Satellite Census. I. The Observational Selection Function for Milky Way Satellites in DES Y3 and Pan-STARRS DR1
• The PAndAS view of the Andromeda satellite system - II. Detailed properties of 23 M31 dwarf spheroidal galaxies
• A trio of new Local Group galaxies with extreme properties
• PAndAS' cubs: discovery of two new dwarf galaxies in the surroundings of the Andromeda and Triangulum galaxies
• Inferring the Andromeda Galaxy's mass from its giant southern stream with Bayesian simulation sampling
• The Missing Satellites of the Magellanic Clouds? Gaia Proper Motions of the Recently Discovered Ultra-Faint Galaxies
• Spectroscopic Confirmation of the Dwarf Galaxies Hydra II and Pisces II and the Globular Cluster Laevens 1
• The outer halo globular cluster system of M31 - I. The final PAndAS catalogue
• The GHOSTS survey. II. The diversity of Halo Color and Metallicity Profiles of Massive Disk Galaxies
• The PAndAS view of the Andromeda satellite system - I. A Bayesian search for dwarf galaxies using spatial and color-magnitude information
• The ISLAndS project II: The Lifetime Star Formation Histories of Six Andromeda dSphs
• The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda I
• K-Band Red Clump Distance to the Large Magellanic Cloud
• The Hubble Space Telescope Survey of M31 Satellite Galaxies I. RR Lyrae-based Distances and Refined 3D Geometric Structure
• The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda II
• The Carnegie-Chicago Hubble Program. IX. Calibration of the Tip of the Red Giant Branch Method in the Mega-Maser Host Galaxy, NGC4258 (M106)
• The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda III
• Comparing the Quenching Times of Faint M31 and Milky Way Satellite Galaxies
• Comparing M31 and Milky Way Satellites: The Extended Star Formation Histories of Andromeda II and Andromeda XVI
• Deconstructing dwarf galaxies: a Suprime-Cam survey of Andromeda II
• Hubble Space Telescope Observations of NGC 253 Dwarf Satellites: Discovery of Three Ultra-faint Dwarf Galaxies
• Metallicity Distribution Functions of 13 Ultra-Faint Dwarf Galaxy Candidates from Hubble Space Telescope Narrowband Imaging
• The Deepest HST Color-Magnitude Diagram of M32: Evidence for Intermediate-Age Populations
• The Pristine Dwarf-Galaxy survey -- III. Revealing the nature of the Milky Way globular cluster Sagittarius II
• Pegasus W: An Ultra-Faint Dwarf Galaxy Outside the Halo of M31 Not Quenched by Reionization
• Stellar mass segregation as separating classifier between globular clusters and ultra-faint dwarf galaxies
• On the relation between metallicity and RGB color in HST/ACS data
• Pegasus V -- a newly discovered ultra-faint dwarf galaxy on the outskirts of Andromeda
• Stellar population and structural properties of dwarf galaxies and young stellar systems in the M81 group
• A rogues gallery of Andromeda's dwarf galaxies I. A predominance of red horizontal branches
• The Araucaria Project. Population effects on the V and I band magnitudes of red clump stars
• The PAndAS View of the Andromeda Satellite System. III. Dwarf galaxy detection limits
• Project AMIGA: Distance and Metallicity Gradients Along Andromeda's Giant Southern Stream from the Red Clump
• Ultrafaint Dwarf Galaxy Candidates in the M81 Group: Signatures of Group Accretion
• Metallicity Distribution Function of the Eridanus~II Ultra-Faint Dwarf Galaxy from Hubble Space Telescope Narrow-band Imaging
• Tests of photometry: the case of the NGC 3370 ACS field

Cited by in corpus (1)

• DELVE-DEEP Survey: The Faint Satellite System of NGC 55