Highly Ionized Plasma in the Halo of a Luminous Spiral Galaxy Near z=0.225

Abstract

We present analyses of the physical conditions in the z=0.22496 and z=0.22638 multi-phase O VI absorption systems detected in the ultraviolet HST/STIS and FUSE spectra of the quasar H1821+643. Both absorbers are likely associated with the extended halo of a ~2L* Sbc-Sc galaxy situated at a projected distance of ~116 kpc from the sight line. The z=0.22496 absorber is detected in C II, C III, C IV, O III, O VI, Si II, Si III and H I at > 3 sigma significance. The low and intermediate ions in this absorber are consistent with an origin in photoionized gas with [Si/H] and [C/H] of -0.6 dex. In contrast, the broader O VI absorption is likely produced in collisionally ionized plasma under nonequilibrium conditions. The z=0.22638 system has broad-Lya (BLA) and C III absorption offset by v = -53 km/s from O VI. The H I and C III line widths for the BLA imply T = 1.1 x 10^5 K. For non-equilibrium cooling we obtain [C/H] of -1.5 dex and a total hydrogen column of N(H) = 3.2 x 10^{18} cm^-2 in the BLA. The O VI, offset from the BLA with no detected H I or C III, is likely collisionally ionized at T ~ 3 x 10^5 K. From the observed multiphase properties and the proximity to a luminous galaxy, we propose that the z=0.22496 absorber is an extragalactic analog of a highly ionized Galactic HVC, in which the O VI is produced in transition temperature plasma (T ~ 10^5 K) at the interface layers between the warm HVC gas phase and the hot coronal halo of the galaxy. The z=0.22638 O VI - BLA absorber could be tracing a cooling condensing fragment in the nearby galaxy's hot gaseous halo.

The Astrophysical Journal accepted

References in corpus (11)

• Time-Dependent Ionization in Radiatively Cooling Gas
• A High-Resolution Survey of Low-Redshift QSO Absorption Lines: Statistics and Physical Conditions of O VI Absorbers
• The Low-z Intergalactic Medium. III. HI and Metal Absorbers at z<0.4
• The Nature and Origin of Low-Redshift O VI Absorbers
• The Relationship Between Intergalactic HI/OVI and Nearby (z<0.017) Galaxies
• Probing the IGM-Galaxy Connection at z < 0.5 I: A Galaxy Survey in QSO Fields and a Galaxy-Absorber Cross-Correlation Study
• A Survey of O VI, C III, and H I in Highly Ionized High-Velocity Clouds
• The H alpha Galaxy Survey. VIII. Close companions and interactions, and the definition of starbursts
• A STIS Survey for OVI Absorption Systems at 0.12 < z < 0.5 II.: Physical Conditions of the Ionised Gas
• The O VI Absorbers Toward PG0953+415: High Metallicity, Cosmic-Web Gas Far From Luminous Galaxies
• Low Redshift Intergalactic Absorption Lines in the Spectrum of HE0226-4110

Cited by in corpus (23)

• The Properties of Low Redshift Intergalactic O VI Absorbers Determined from High S/N Observations of 14 QSOs with the Cosmic Origins Spectrograph
• A Universal Density Structure for Circum-Galactic Gas
• Multiphase Gas In Galaxy Halos: The OVI Lyman-limit System toward J1009+0713
• An Extreme Metallicity, Large-Scale Outflow from a Star-Forming Galaxy at z ~ 0.4
• O VI Absorbers Tracing Hot Gas Associated with a Pair of Galaxies at z = 0.167
• A Multiphase Absorber Containing O VI and Broad H I Directly Tracing 10^6 K Plasma at Low-Redshift Toward HE 0153-4520
• Cosmic Origins Spectrograph Detection of Ne VIII Tracing Warm - Hot Gas Towards PKS 0405-123
• Cos observations of metal line and broad lyman alpha absorption in the multi-phase o vi and ne viii system toward he 02226-4110
• Cosmic Origins Spectrograph and FUSE Observations of T ~ 10^5 K Gas In A Nearby Galaxy Filament
• COS-Weak: Probing the CGM using analogs of weak Mg II absorbers at z < 0.3
• Probing the large and massive CGM of a galaxy at z ~ 0.2 using a pair of quasars
• Molecular Hydrogen Absorption from the Halo of a z ~ 0.4 Galaxy
• Cosmic Origins Spectrograph Observations of Warm Intervening Gas Towards 3C263
• A Pair of O VI and Broad Ly-alpha Absorbers Probing Warm Gas in a Galaxy Group Environment at z ~ 0.4
• Search for X-Ray Emission Associated with the Shapley Supercluster with Suzaku
• The Surprisingly Constant Strength of O VI Absorbers over Cosmic Time
• The 21cm "Outer Arm" and the Outer-Galaxy High-Velocity Clouds: Connected by Kinematics, Metallicity, and Distance
• Studying the Warm-Hot Intergalactic Medium in Emission
• Detection of Two Intervening Ne VIII Absorbers Probing Warm Gas at z~0.6
• Probing the hot circumgalactic medium of external galaxies in X-ray absorption II: a luminous spiral galaxy at $z\approx 0.225$
• Hot gas in galaxy halos traced by coronal broad Lyman alpha absorbers
• Solar-Metallicity Gas in the Extended Halo of a Galaxy at $z\sim 0.12$
• Multiple Absorption-Line Spectroscopy of the Intergalactic Medium. I. Model