Probing the Warm-Hot Circumgalactic Medium with broad OVI and X-rays

Abstract

Most of the baryonic mass in the circumgalactic medium (CGM) of a spiral galaxy is believed to be warm-hot, with temperature around $10^6$K. The narrow OVI absorption lines probe a somewhat cooler component at $\log \mathrm{T}(\mathrm{K})=5.5$, but broad OVI absorbers have the potential to probe the hotter CGM. Here we present 376 ks Chandra LETG observations of a carefully selected galaxy in which the presence of broad OVI together with the non-detection of Lya was indicative of warm-hot gas. The strongest line expected to be present at $\approx 10^6$K is OVII $\lambda 21.602$. There is a hint of an absorption line at the redshifted wavelength, but the line is not detected with better than $2\sigma$ significance. A physical model, taking into account strengths of several other lines, provides better constraints. Our best-fit absorber model has $\log \mathrm{T}(\mathrm{K})=6.3\pm 0.2$ and $\log {\mathrm{N}}_{\mathrm{H}}(\mathrm{c}{\mathrm{m}}^{-2})=20.7_{-0.5}^{+0.3}$. These parameters are consistent with the warm-hot plasma model based on UV observations; other OVI models of cooler gas phases are ruled out at better than $99$% confidence. Thus we have suggestive, but not conclusive evidence for the broad OVI absorber probing the warm-hot gas from the shallow observations of this pilot program. About 800ks of XMM-Newton observations will detect the expected absorption lines of OVII and OVIII unequivocally. Future missions like XRISM, Arcus and Athena will revolutionize the CGM science.

Submitted to ApJ

References in corpus (35)

• The chemical composition of the Sun
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• The Circumgalactic Medium
• Where are the Baryons?
• A huge reservoir of ionized gas around the Milky Way: Accounting for the Missing Mass?
• Chandra Discovery of a Tree in the X-ray Forest towards PKS 2155-304: the Local Filament?
• Bimodality of low-redshift circumgalactic O VI in non-equilibrium EAGLE zoom simulations
• Toward a Self Consistent Model of the Ionized Absorber in NGC 3783
• X-Ray Absorption from the Milky Way Halo and the Local Group
• Physical Properties, Baryon Content, and Evolution of the LyαForest: New Insights from High Resolution Observations at z < 0.4
• The Properties of Low Redshift Intergalactic O VI Absorbers Determined from High S/N Observations of 14 QSOs with the Cosmic Origins Spectrograph
• Tracing the Warm-Hot Intergalactic Medium at Low Redshift: X-ray Forest Observations Towards H1821+643
• A Deep XMM-Newton Study of the Hot Gaseous Halo Around NGC 1961
• Warm-Hot Gas in and around the Milky Way: Detection and Implications of OVII Absorption toward LMC X-3
• Suzaku Observations of the Local and Distant Hot ISM
• Probing the Local Group Medium Toward Mkn 421 with Chandra and FUSE
• A Galactic Origin for the Local Ionized X-ray Absorbers
• Absorption-Line Detections of $10^{5-6}$ K Gas in Spiral-Rich Groups of Galaxies
• Xmm-Newton Observations of the Diffuse X-ray Background
• Comparing Suzaku and XMM-Newton Observations of the Soft X-ray Background: Evidence for Solar Wind Charge Exchange Emission
• Probing the IGM-galaxy connection at z<0.5 II. New insights into the galaxy environments of OVI absorbers in PKS 0405-123
• Discovery of a very hot phase of the Milky Way CGM with non-solar abundance ratios
• Detection of the Missing Baryons toward the Sightline of H1821+643
• O VI Absorbers Tracing Hot Gas Associated with a Pair of Galaxies at z = 0.167
• An XMM-Newton Observation of the Local Bubble Using a Shadowing Filament in the Southern Galactic Hemisphere
• Multiple temperature components of the hot circumgalactic medium of the Milky Way
• Properties of the Diffuse X-ray Background toward MBM20 with Suzaku
• Chandra and Far Ultraviolet Spectroscopic Explorer Observations of z~0 Warm-Hot Gas Toward PKS 2155-304
• Probing the anisotropy of the Milky Way gaseous halo: Sight-lines toward Mrk 421 and PKS2155-304
• Chandra Detection of Local Warm-Hot Gas Toward Markarian 279
• Probing the Anisotropy of the Milky Way Gaseous Halo-II: sightline toward Mrk509
• Evidence for massive warm-hot circumgalactic medium around NGC 3221
• The warm-hot, extended, massive circumgalactic medium of NGC 3221: an XMM-Newton discovery
• Agnostic Stacking of Intergalactic Doublet Absorption: Measuring the NeVIII Population
• The baryon density at z=0.9-1.9 - Tracing the warm-hot intergalactic medium with broad Lyman alpha absorption

Cited by in corpus (5)

• Detection of thermal Sunyaev-Zel'dovich Effect in the circumgalactic medium of low-mass galaxies -- a surprising pattern in self-similarity and baryon sufficiency
• Probing the hot circumgalactic medium of external galaxies in X-ray absorption II: a luminous spiral galaxy at $z\approx 0.225$
• Searching for cold gas traced by MgII quasar absorbers in massive X-ray-selected galaxy clusters
• A Sub-solar Fe/O, logT~7.5 Gas Component Permeating the Milky Way's CGM
• MUSE-ALMA Haloes XIV: The ALMA Large Programme Data Release