Soft X-ray and ultra-violet metal-line emission from the gas around galaxies

Abstract

(Abridged) A large fraction of the gas in galactic haloes has temperatures between 10^4.5 and 10^7 K. At these temperatures, cooling is dominated by metal-line emission if the metallicity Z>~0.1 Zsun. We explore the detectability of several lines using large cosmological, hydrodynamical simulations. We stack surface brightness maps centred on galaxies to calculate the expected mean surface brightness profiles for different halo masses. Assuming a detection limit of 10^-1 photon s^-1 cm^-2 sr^-1, proposed X-ray telescopes can detect O VIII emission from z=0.125 out to 80% of the virial radius (Rvir) of groups and clusters and out to 0.4Rvir for haloes with masses Mhalo=10^12-13 Msun. Emission lines from C VI, N VII, O VII, and Ne X can be detected out to smaller radii, 0.1-0.5Rvir. With a detection limit of 10^-20 erg s^-1 cm^-2 arcsec^-2, future UV telescopes can detect C III emission out to 0.2-0.6Rvir at z=0.25. C IV, O VI, Si III, and Si IV can be seen out to 0.1-0.2Rvir for Mhalo>10^12 Msun. Optical HI H-alpha emission is comparable in strength to C III emission. At z=3 it may be possible to observe C III out to 0.2-0.3Rvir and other rest-frame UV lines out to ~0.1Rvir for Mhalo>10^11 Msun with upcoming optical instruments. Metal-line emission is typically biased towards high density and metallicity and towards the temperature at which the emissivity curve of the corresponding metal line peaks. The bias is similar for the different soft X-ray lines considered, whereas it varies strongly between different UV lines. Active galactic nucleus (AGN) feedback can change the inner surface brightness profiles significantly, but it generally does not change the radius out to which the emission can be observed. Metal-line emission is a promising probe of the warm and hot, enriched gas around galaxies and provides a unique window into the interactions between galaxies and their gaseous haloes.

17 pages, 8 figures. Accepted for publication in MNRAS. Revised version: minor changes

References in corpus (14)

• The effect of photo-ionization on the cooling rates of enriched, astrophysical plasmas
• The MUSE second-generation VLT instrument
• Chemical enrichment in cosmological, smoothed particle hydrodynamics simulations
• Baryons at the Edge of the X-ray Brightest Galaxy Cluster
• Detection of hot gas in the filament connecting the clusters of galaxies Abell 222 and Abell 223
• X-ray coronae in simulations of disc galaxy formation
• Through Thick and Thin - HI Absorption in Cosmological Simulations
• Chandra Survey of Nearby Highly-Inclined Disk Galaxies I: X-ray Measurements of Galactic Coronae
• The Nature and Origin of Low-Redshift O VI Absorbers
• Thermal radiation processes
• Absorption signatures of warm-hot gas at low redshift: OVI
• Warm-Hot Intergalactic Medium Associated with the Coma Cluster
• Can Chandra resolve the remaining cosmic X-ray background?
• Warm-hot gas in groups and galaxies toward H2356-309

Cited by in corpus (30)

• Predictions for the Angular Dependence of Gas Mass Flow Rate and Metallicity in the Circumgalactic Medium
• Deep HeII and CIV Spectroscopy of a Giant Lyman alpha Nebula: Dense Compact Gas Clumps in the Circumgalactic Medium of a z~2 Quasar
• MUSE Analysis of Gas around Galaxies (MAGG) -- III: The gas and galaxy environment of z = 3-4.5 quasars
• Circumgalactic Mg II Emission from an Isotropic Starburst Galaxy Outflow Mapped by KCWI
• The impact of stellar feedback on hot gas in galaxy haloes: the Sunyaev-Zel'dovich effect and soft X-ray emission
• Enriching the hot circumgalactic medium
• Figuring Out Gas & Galaxies in Enzo (FOGGIE). II. Emission from the z=3 Circumgalactic Medium
• Metal enrichment in the circumgalactic medium and Lyα haloes around quasars at z $\sim$3
• The cold circumgalactic medium in emission: MgII halos in TNG50
• Stacking the Cosmic Web in Fluorescent Lyman alpha Emission with MUSE
• Empirically Constrained Predictions for Metal-Line Emission from the Circumgalactic Medium
• Metal line emission from galaxy haloes at z~1
• The Sources of Extreme Ultraviolet and Soft X-ray Backgrounds
• X-ray metal line emission from the hot circumgalactic medium: probing the effects of supermassive black hole feedback
• Virial shocks are suppressed in cosmic ray-dominated galaxy halos
• On the detectability of visible-wavelength line emission from the local circumgalactic and intergalactic medium
• How the diffuse Universe cools
• The warm-hot circumgalactic medium around EAGLE-simulation galaxies and its detection prospects with X-ray line emission
• The large-scale environment from cosmological simulations II: The redshift evolution and distributions of baryons
• Multi-wavelength scaling relations in galaxy groups: a detailed comparison of GAMA and KiDS observations to BAHAMAS simulations
• Strongly Time-Variable Ultra-Violet Metal Line Emission from the Circum-Galactic Medium of High-Redshift Galaxies
• Soft X-ray emission from warm gas in IllustrisTNG circum-cluster environments
• Metal content of the circumgalactic medium around star-forming galaxies at z $\sim$ 2.6 as revealed by the VIMOS Ultra-Deep Survey
• The Hot and Energetic Universe: The missing baryons and the warm-hot intergalactic medium
• Quantifying Observational Projection Effects with a Simulation-based hot CGM model
• Absorption-based Circumgalactic Medium Line Emission Estimates
• Observational Diagnostics of Gas Flows: Insights from Cosmological Simulations
• Retrieving the hot circumgalactic medium physics from the X-ray radial profile from eROSITA with an IlustrisTNG-based forward model
• Prospects for detecting the circum- and intergalactic medium in X-ray absorption using the extended intracluster medium as a backlight
• Soft X-ray line emission from hot gas in intervening galaxy halos and diffuse gas in the cosmic web