Absorption-based Circumgalactic Medium Line Emission Estimates

Abstract

Motivated by integral field units (IFUs) on large ground telescopes and proposals for ultraviolet-sensitive space telescopes to probe circumgalactic medium (CGM) emission, we survey the most promising emission lines and how such observations can inform our understanding of the CGM and its relation to galaxy formation. We tie our emission estimates to both HST/COS absorption measurements of ions around $z\approx 0.2$ Milky Way mass halos and models for the density and temperature of gas. We also provide formulas that simplify extending our estimates to other samples and physical scenarios. We find that OIII 5007 A and NII 6583 A, which at fixed ionic column density are primarily sensitive to the thermal pressure of the gas they inhabit, may be detectable with KCWI and especially IFUs on 30 m telescopes out to half a virial radius. OV 630 A and OVI $1032,1038$ A are perhaps the most promising ultraviolet lines, with models predicting intensities $>100\gamma$ cm${}^{-2}$ s${}^{-1}$ sr${}^{-1}$ in the inner 100 kpc of Milky Way-like systems. A detection of OVI would confirm the collisionally ionized picture and constrain the density profile of the CGM. Other ultraviolet metal lines constrain the amount of gas that is actively cooling and mixing. We find that CIII 978 A and CIV 1548 A may be detectable if an appreciable fraction of the observed OVI column is associated with mixing or cooling gas. H$\alpha$ emission within $100$kpc of Milky Way-like galaxies is within reach of current IFUs even for the minimum signal from ionizing background fluorescence, while Hydrogen $n>2$ Lyman-series lines are too weak to be detectable.

22 pages; accepted to MNRAS; comments welcome; line emission data used to make Fig.1 is included in the source files

References in corpus (25)

• The Circumgalactic Medium
• The COS-Halos Survey: Physical Conditions and Baryonic Mass in the Low-Redshift Circumgalactic Medium
• CHIANTI -- an atomic database for emission lines -- Paper XVI: Version 10, further extensions
• The COS-Halos Survey: Metallicities in the Low-Redshift Circumgalactic Medium
• HeII Reionization and its Effect on the IGM
• Constraining the Milky Way's Hot Gas Halo with OVII and OVII Emission Lines
• The COS-Halos Survey: Origins of the Highly Ionized Circumgalactic Medium of Star-Forming Galaxies
• Multiphase Gas and the Fractal Nature of Radiative Turbulent Mixing Layers
• X-Ray Absorption from the Milky Way Halo and the Local Group
• A 100-kiloparsec wind feeding the circumgalactic medium of a massive compact galaxy
• Cooling flow solutions for the circumgalactic medium
• Radiative Mixing Layers: Insights from Turbulent Combustion
• The extent of chemically enriched gas around star-forming dwarf galaxies
• Sizes and Kinematics of Extended Narrow-Line Regions in Luminous Obscured AGN Selected by Broadband Images
• MUSE Analysis of Gas around Galaxies (MAGG) -- III: The gas and galaxy environment of z = 3-4.5 quasars
• The Efficiency of Stellar Reionization: Effects of Rotation, Metallicity, and Initial Mass Function
• Circumgalactic Mg II Emission from an Isotropic Starburst Galaxy Outflow Mapped by KCWI
• MusE GAs FLOw and Wind (MEGAFLOW) VIII. Discovery of a MgII emission halo probed by a quasar sightline
• The physical origins and dominant emission mechanisms of Lyman-alpha halos: results from the TNG50 simulation in comparison to MUSE observations
• A measurement of the z = 0 UV background from H$\alpha$ fluorescence
• The cold circumgalactic medium in emission: MgII halos in TNG50
• Empirically Constrained Predictions for Metal-Line Emission from the Circumgalactic Medium
• A Model for Line Absorption and Emission from Turbulent Mixing Layers
• On the detectability of visible-wavelength line emission from the local circumgalactic and intergalactic medium
• Characterising the turbulent multiphase halos with periodic box simulations

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• Metal line emission from galaxy haloes at z~1
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• The Cosmic Evolution of CIV Absorbers at $1.4<z<4.5$: Insights from $100,000$ Systems in DESI Quasars
• Modeling Emission-Line Surface Brightness in a Multiphase Galactic Wind: An O VI Case Study