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The intracluster medium (ICM) in the far outskirts (r $>$ 2-3 R$_{200}$) of galaxy clusters interfaces with the intergalactic medium (IGM) and is theorized to comprise diffuse, multiphase gas. This medium may hold vital clues to clusters'…

Observations of the QSO HE 0153-4520 (z-em = 0.450) with the Cosmic Origins Spectrograph (COS) from 1134 to 1796 A with a resolution of ~17 km/s and signal-to- noise per resolution element of 20 to 40 are used to study a multi-phase partial…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 B. D. Savage , A. Narayanan , N. Lehner , B. P. Wakker

We have obtained moderate resolution spectra of the bright QSO H1821+643 (z=0.297) in the wavelength interval 990-1185A with FUSE. Strong, complex OVI 1032 and FeII 1145 absorption arising in gas above several spiral arms and the outer warp…

Ultraviolet observations of the QSO 3C 263 (zem = 0.652) with COS and FUSE reveal O VI absorption systems at z = 0.06342 and 0.14072 . WIYN multi-object spectrograph observations provide information about the galaxies associated with the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 B. Savage , T. -S. Kim , B. Keeney , A. Narayanan , J. Stocke , B. Wakker

FUV observations have revealed the transition temperature gas (TTG; $\log{T({\mathrm{K}})}$ ~ 5), located in the lower Galactic halo and in the High Velocity Clouds. However, the corresponding X-ray absorption has so far remained mostly…

Astrophysics of Galaxies · Physics 2017-09-13 J. Nevalainen , B. Wakker , J. Kaastra , M. Bonamente , S. Snowden , F. Paerels , C. de Vries

We report a ~3 sigma detection of a 21.82 A absorption feature in the direction of the BL Lac MRK 421 which is interpreted as OVII K(alpha) at z~0.01. This corresponds to the redshift of a H absorber in a cosmic void detected by HST along…

Astrophysics · Physics 2007-05-23 Ilaria Cagnoni

We present the high resolution X-ray spectrum of the BL Lac object PKS 2155-304 taken with the RGS units onboard XMM-Newton in November 2000. We detect a OVII Kalpha resonant absorption line from warm/hot local gas at 21.59A (~4.5 sigma…

Astrophysics · Physics 2009-11-10 I. Cagnoni , F. Nicastro , L. Maraschi , A. Treves , F. Tavecchio

The cosmological missing baryons at z<1 most likely hide in the hot (T$\gtrsim10^{5.5}$ K) phase of the Warm Hot Intergalactic Medium (WHIM). While the hot WHIM is hard to detect due to its high ionisation level, the warm…

Cosmology and Nongalactic Astrophysics · Physics 2019-01-16 J. Nevalainen , E. Tempel , J. Ahoranta , L. J. Liivamagi , M. Bonamente , E. Tilton , J. Kaastra , T. Fang , P. Heinamaki , E. Saar , A. Finoguenov

Hydrodynamic simulations of growth of cosmic structure suggest that 30-50% of the total baryons at z=0 may be in a warm-hot intergalactic medium (WHIM) with temperatures ~10^5-10^7K. The O VI \lambda \lambda 1032, 1038 absorption line…

Astrophysics · Physics 2009-11-06 Renyue Cen , Todd M. Tripp , Jeremiah P. Ostriker , Edward B. Jenkins

We report the first detection of multiphase gas within a quiescent galaxy beyond $z\approx0$. The observations use the brighter image of doubly lensed QSO HE 0047$-$1756 to probe the ISM of the massive ($M_{\rm star}\approx 10^{11}…

Astrophysics of Galaxies · Physics 2020-11-25 Fakhri S. Zahedy , Hsiao-Wen Chen , Erin Boettcher , Michael Rauch , K. Decker French , Ann Zabludoff

Observations of the QSO HE 0226-4110 (zem = 0.495) with the Cosmic Origins Spectrograph (COS) from 1134 to 1796 {\AA} with a resolution of ~17 km s-1 and signal-to- noise (S/N) per resolution element of 20 to 40 are used to study the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 B. Savage , N. Lehner , A. Narayanan

We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the molecular, neutral atomic, weakly ionized, and highly ionized components of the interstellar and intergalactic material toward the quasar 3C 273. We identify…

Astrophysics · Physics 2009-11-07 K. R. Sembach , J. C. Howk , B. D. Savage , J. M. Shull , W. R. Oegerle

X-ray absorption lines of highly-ionized species such as OVII at about zero redshift have been firmly detected in the spectra of several active galactic nuclei. However, the location of the absorbing gas remains a subject of debate. To…

Astrophysics · Physics 2009-11-13 Q. D. Wang , Y. Yao , T. M. Tripp , T. -T. Fang , W. Cui , F. Nicastro , S. Mathur , R. J. Williams , L. Song , R. Croft

The low-redshift Ly-alpha forest of absorption lines provides a probe of large-scale baryonic structures in the intergalactic medium, some of which may be remnants of physical conditions set up during the epoch of galaxy formation. We…

Astrophysics · Physics 2019-08-17 J. Michael Shull , Steven V. Penton , John T. Stocke

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…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Anand Narayanan , Blair D. Savage , Bart P. Wakker

High signal-to-noise (S/N) observations of the QSO PKS 0405-123 (zem = 0.572) with the Cosmic Origins Spectrograph from 1134 to 1796 A with a resolution of 17 km s-1 are used to study the multi-phase partial Lyman limit system (LLS) at z =…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 B. D. Savage , A. Narayanan , B. P. Wakker , J. T. Stocke , B. A. Keeney , J. M. Shull , K. R. Sembach , Y. Yao , C. , J. Green

The hot gas in galaxy halos may account for a significant fraction of missing baryons in galaxies, and some of these gases can be traced by high ionization absorption systems in QSO UV spectra. Using high S/N ratio $ HST$/COS spectra, we…

Astrophysics of Galaxies · Physics 2016-12-14 Zhijie Qu , Joel N. Bregman

(abridged) We searched for evidence of soft X-ray absorption by hot gas in the vicinity of the Galaxy in a small sample of fifteen type I AGN observed with the high resolution X-ray gratings on board Chandra. We find that around half of the…

Astrophysics · Physics 2009-11-10 B. McKernan , T. Yaqoob , C. S. Reynolds

We analyze the intracluster medium (ICM) and circumgalactic medium (CGM) in 7 X-ray detected galaxy clusters using spectra of background QSOs (HST-COS/STIS), optical spectroscopy of the cluster galaxies (MMT/Hectospec and SDSS), and X-ray…

We present a structural study of the hot ISM in the Galactic halo along the sight line toward the bright active galactic nucleus Mkn 421. The OVII and OVIII absorption lines were measured with the Low Energy Transmission Grating…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Kazuhiro Sakai , Yangsen Yao , Kazuhisa Mitsuda , Noriko Yamasaki , Q. Daniel Wang , Yoh Takei , Dan McCammon