Relics of structure formation: extra-planar gas and high-velocity clouds around the Andromeda Galaxy

Abstract

Using the 100-m radio telescope at Effelsberg, we mapped a large area around the Andromeda Galaxy in the 21-cm line emission of neutral hydrogen to search for high-velocity clouds (HVCs) out to large projected distances in excess of 100 kpc. Our 3-sigma HI mass sensitivity for the warm neutral medium is 8x10^4 solar masses. We can confirm the existence of a population of HVCs with typical HI masses of a few times 10^5 solar masses near the disc of M31. However, we did not detect any HVCs beyond a projected distance of about 50 kpc from M31, suggesting that HVCs are generally found in proximity of large spiral galaxies at typical distances of a few 10 kpc. Comparison with CDM-based models and simulations suggests that only a few of the detected HVCs could be associated with primordial dark-matter satellites, whereas others are most likely the result of tidal stripping. The lack of clouds beyond a projected distance of 50 kpc from M31 is also in conflict with the predictions of recent CDM structure formation simulations. A possible solution to this problem could be ionisation of the HVCs as a result of decreasing pressure of the ambient coronal gas at larger distances from M31. A consequence of this scenario would be the presence of hundreds of mainly ionised or pure dark-matter satellites around large spiral galaxies like the Milky Way and M31.

arXiv comment21 pages, 15 figures, accepted for publication in MNRAS

References in corpus (62)

• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• Dark Matter Substructure in Galactic Halos
• Where are the missing galactic satellites?
• The Structure of Dark Matter Haloes in Dwarf Galaxies
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: I. Morphology of the Sagittarius Core and Tidal Arms
• The tumultuous lives of galactic dwarfs and the missing satellites problem
• A giant stream of metal-rich stars in the halo of the galaxy M31
• Highly-Ionized High-Velocity Gas in the Vicinity of the Galaxy
• High Velocity Clouds: Building Blocks of the Local Group
• The great disk of Milky-Way satellites and cosmological sub-structures
• Distance to M31 With the HST and Hipparcos Red Clump Stars
• Distances and Metallicities of High- and Intermediate-Velocity Clouds
• The Anisotropic Distribution of Galactic Satellites
• The Magellanic Stream, High-Velocity Clouds and the Sculptor Group
• The Distribution of Satellite Galaxies: The Great Pancake
• On the Continuing Formation of the Andromeda Galaxy: Detection of HI Clouds in the M31 Halo
• Distances to Galactic high-velocity clouds. I. Cohen Stream, complex GCP, cloud g1
• The spatial distribution of the Milky Way and Andromeda satellite galaxies
• Discovery and analysis of three faint dwarf galaxies and a globular cluster in the outer halo of the Andromeda galaxy
• HIPASS High-Velocity Clouds: Properties of the Compact and Extended Populations
• H_alpha Emission from High-Velocity Clouds and their Distances
• The Kinematics and Metallicity of the M31 Globular Cluster System
• Andromeda IX: A New Dwarf Spheroidal Satellite of M31
• Distances to Galactic high-velocity clouds. Complex C
• The WSRT wide-field HI survey: II. Local Group features
• N-body simulations of the Magellanic Stream
• An Accurate Distance to High-Velocity Cloud Complex C
• Investigating the Andromeda Stream: III. A Young Shell System in M31
• Atomic Hydrogen Gas in Dark-Matter Minihalos and the Compact High Velocity Clouds
• The Mass of the Andromeda Galaxy
• The Anisotropic Distribution of M 31 Satellite Galaxies: A Polar Great Plane of Early-Type Companions
• The satellite distribution of M31
• Andromeda X, A New Dwarf Spheroidal Satellite of M31: Photometry
• Investigating the Andromeda Stream: II. Orbital Fits and Properties of the Progenitor
• X-Ray IGM in the Local Group
• A confirmed location in the Galactic halo for the high-velocity cloud 'chain A'
• FUSE Observations of Atomic Abundances and Molecular Hydrogen in the Leading Arm of the Magellanic Stream
• Westerbork HI observations of high-velocity clouds near M31 and M33
• Discovery of a Population of HI Clouds in the Galactic Halo
• Where are the high velocity clouds?
• The Galactic Nature of High Velocity Cloud Complex WB
• An all-sky study of compact, isolated high-velocity clouds
• A Targeted Survey for HI Clouds in Galaxy Groups
• The Once and Future Andromeda Stream
• The origin of globular cluster systems from cosmological simulations
• The many streams of the Magellanic Stream
• Deep H I observations of the compact high-velocity cloud HVC125+41-207
• Where are the High Velocity Clouds in Local Group Analogs?
• WHAM Observations of H-alpha from High-Velocity Clouds: Are They Galactic or Extragalactic?
• Low-column density gas clumps in the halo of the Milky Way
• High-resolution imaging of compact high-velocity clouds (II)
• Are Compact High-Velocity Clouds Extragalactic Objects?
• Dynamical evolution of high velocity clouds in the intergalactic medium
• Arecibo imaging of compact high-velocity clouds
• Effelsberg HI observations of compact high-velocity clouds
• The Gaseous Trail of the Sagittarius Dwarf Galaxy
• The scattered debris of the Magellanic Stream
• HI Observations of an Ultra-Compact High-Velocity Cloud
• Physical properties of two compact high-velocity clouds possibly associated with the Leading Arm of the Magellanic System
• Status of HI searches for CHVCs beyond the Local Group
• Neutral hydrogen in galactic fountains
• Mini High Velocity Clouds

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• Gaseous Galaxy Halos
• An Empirical Characterization of Extended Cool Gas Around Galaxies Using MgII Absorption Features
• Evidence for a Massive, Extended Circumgalactic Medium Around the Andromeda Galaxy
• Gas and dark matter in the Sculptor group: NGC 300
• Discrete clouds of neutral gas between the galaxies M31 and M33
• The Origin and Distribution of Cold Gas in the Halo of a Milky Way-Mass Galaxy
• Shaken, Not Stirred: The Disrupted Disk of the Starburst Galaxy NGC 253
• The Neutral Hydrogen Bridge between M31 and M33
• Molecular gas in the inner 0.7kpc-radius ring of M31
• The Smith Cloud and its dark matter halo: Survival of a Galactic disc passage
• Formation of the Andromeda Giant Stream: Asymmetric Structure and Disc Progenitor
• Sensitive 21cm Observations of Neutral Hydrogen in the Local Group near M31
• Collisions between Dark Matter Confined High Velocity Clouds and Magnetized Galactic Disks: The Smith Cloud
• Project AMIGA: A Minimal Covering Factor for Optically Thick Circumgalactic Gas Around the Andromeda Galaxy
• Possible detection of the M31 rotation in WMAP data
• Outskirts of Distant Galaxies In Absorption
• The HI Chronicles of LITTLE THINGS BCDS III: Gas Clouds in and around Mrk 178, VII Zw 403, AND NGC 3738
• A survey of HI gas toward the Andromeda Galaxy
• Searching for Dark Matter Annihilation in the Smith High-Velocity Cloud
• The effect of rotation on the thermal instability of stratified galactic atmospheres - II. The formation of High Velocity Clouds
• The Origin of Neutral Hydrogen Clouds in Nearby Galaxy Groups: Exploring the Range Of Galaxy Interactions
• Large and small-scale structure of the Intermediate and High Velocity Clouds towards the LMC and SMC
• Synchrotron Emission from Dark Matter in Galactic Subhalos. A Look into the Smith Cloud
• A 5deg x 5deg deep HI survey of the M81 group: II. HI distribution and kinematics of IC 2574 and HIJASS J1021+68
• Evidence for a hot galactic halo around the Andromeda Galaxy using fast radio bursts along two sightlines
• A Component of the Smith High Velocity Cloud Now Crossing the Galactic Plane
• Solar-Metallicity Gas in the Extended Halo of a Galaxy at $z\sim 0.12$
• Neutral Gas Accretion onto Nearby Galaxies
• Accretion Onto the Milky Way: The Smith Cloud
• Cosmic Rays and Non-thermal Emission Induced by Accretion of Cool Gas onto the Galactic Disk
• On the origin of gaseous galaxy halos - Low-column density gas in the Milky Way halo