The Hot, Accreted Halo of NGC 891

Abstract

Galaxies are surrounded by halos of hot gas whose mass and origin remain unknown. One of the most challenging properties to measure is the metallicity, which constrains both of these. We present a measurement of the metallicity around NGC 891, a nearby, edge-on, Milky Way analog. We find that the hot gas is dominated by low metallicity gas near the virial temperature at $kT=0.20\pm 0.01$ keV and $Z/Z_{\odot }=0.14\pm 0.03$(stat)${}_{-0.02}^{+0.08}$(sys), and that this gas co-exists with hotter ($kT=0.71\pm 0.04$ keV) gas that is concentrated near the star-forming regions in the disk. Model choices lead to differences of $\Delta Z/Z_{\odot }\sim 0.05$, and higher $S/N$ observations would be limited by systematic error and plasma emission model or abundance ratio choices. The low metallicity gas is consistent with the inner part of an extended halo accreted from the intergalactic medium, which has been modulated by star formation. However, there is much more cold gas than hot gas around NGC 891, which is difficult to explain in either the accretion or supernova-driven outflow scenarios. We also find a diffuse nonthermal excess centered on the galactic center and extending to 5 kpc above the disk with a 0.3-10 keV $L_X=3.1\times 10^{39}$ erg s${}^{-1}$. This emission is inconsistent with inverse Compton scattering or single-population synchrotron emission, and its origin remains unclear.

23 pages, 13 figures, 6 tables. Accepted to ApJ

References in corpus (25)

• The Quiescent Intracluster Medium in the Core of the Perseus Cluster
• The cold gaseous halo of NGC 891
• Constraining the Milky Way's Hot Gas Halo with OVII and OVII Emission Lines
• X-ray coronae in simulations of disc galaxy formation
• The oxygen abundance in the inner HII regions of M101. Implications for the calibration of strong-line metallicity indicators
• The Extended Distribution of Baryons Around Galaxies
• Efficiency of gas cooling and accretion at the disc-corona interface
• Metallicity of the intergalactic medium using pixel statistics: IV. Oxygen
• Gas Accretion via Condensation and Fountains
• Identifying XMM-Newton observations affected by solar wind charge exchange - Part I
• The Circum-Galactic Medium of MASsive Spirals II: Probing the Nature of Hot Gaseous Halo around the Most Massive Isolated Spiral Galaxies
• The distribution of gas in the Local Group from constrained cosmological simulations: the case for Andromeda and the Milky Way galaxies
• Probing the Hot X-ray Corona around the Massive Spiral Galaxy, NGC 6753, Using Deep XMM-Newton observations
• The chemical evolution of local star forming galaxies: Radial profiles of ISM metallicity, gas mass, and stellar mass and constraints on galactic accretion and winds
• Chandra Survey of Nearby Galaxies: A Significant Population of Candidate Central Black Holes in Late-type Galaxies
• Spectral Modeling of the Charge-Exchange X-ray Emission from M82
• The Properties of the Galactic Hot Gaseous Halo from X-ray Emission
• Investigation of the cosmic ray population and magnetic field strength in the halo of NGC 891
• Radiation Hydrodynamic Simulations of Dust-Driven Winds
• Testing a Dynamical Equilibrium Model of the Extraplanar Diffuse Ionized Gas in NGC 891
• Ultraviolet Halos Around Spiral Galaxies. I. Morphology
• X-Ray Emission from Star-Forming Galaxies - Signatures of Cosmic Rays and Magnetic Fields
• Monte Carlo simulations of soft proton flares: testing the physics with XMM-Newton
• A systematic analysis of the XMM-Newton background: IV. Origin of the unfocused and focused components
• Cosmic Ray Driven Outflows in an Ultraluminous Galaxy

Cited by in corpus (27)

• Hot Extended Galaxy Halos Around Local L* Galaxies From Sunyaev-Zeldovich Measurements
• Widespread Detection of Two Components in the Hot Circumgalactic Medium of the Milky Way
• The Magellanic System: the puzzle of the leading gas stream
• CHANG-ES XX. High Resolution Radio Continuum Images of Edge-on Galaxies and their AGNs -- Data Release 3
• The warm-hot circumgalactic medium of the Milky Way as seen by eROSITA
• Detection of non-thermal hard X-ray emission from the "Fermi bubble" in an external galaxy
• The warm-hot, extended, massive circumgalactic medium of NGC 3221: an XMM-Newton discovery
• Detection of the diffuse HI emission in the Circumgalactic Medium of NGC 891 and NGC 4565
• Efficiency of Thermal Conduction in a Magnetised Circumgalactic Medium
• The origin of X-ray coronae around simulated disc galaxies
• Exploring the Dust Content of Galactic Halos with Herschel III. NGC 891
• {\it HST}/COS Observations of the Warm Ionized Gaseous Halo of NGC 891
• JWST MIRI and NIRCam observations of NGC 891 and its circumgalactic medium
• The role of the halo magnetic field on accretion through High-Velocity Clouds
• Launching of hot gas outflow by disc-wide supernova explosions
• The stratification of ISM properties in the edge-on galaxy NGC 891 revealed by NIKA2
• Revisiting FUSE O VI Emission in Galaxy Halos
• An X-ray View of the Hot Circum-Galactic Medium
• Radio halos of star forming galaxies
• Observing the Earliest Stages of Star Formation in Galaxies: 8 micron Cores in Three Edge-on Disks
• Disc-halo gas outflows driven by stellar clusters as seen in multiwavelength tracers
• Ultraluminous X-ray Sources in Seven Edge-On Spiral Galaxies
• X-ray Spectroscopic Evidence of Charge Exchange Emission in the Disk of M51
• A Long-term Study of Ultraluminous X-ray Sources in NGC 891
• Multi-wavelength emission from leptonic processes in ageing galaxy bubbles
• Predictions for the X-ray circumgalactic medium of edge-on discs and spheroids
• Exploring the interstellar medium of NGC 891 at millimeter wavelengths using the NIKA2 camera