(Abridged) We have analyzed Chandra LETG and XMM-Newton RGS spectra towards the z=0.177 quasar PG 1116+215, a sightline that is rendered particularly interesting by the HST detection of several OVI and HI broad Lyman-alpha absorption lines that may be associated with the warm-hot intergalactic medium. We performed a search for resonance K-alpha absorption lines from OVII and OVIII at the redshifts of the detected far-ultraviolet lines. We detected an absorption line in the Chandra spectra at 5.2 sigma confidence level at wavelengths corresponding to OVIII K-alpha at z=0.0911+-0.0004+-0.0005 (statistical followed by systematic error). This redshift is within 3 sigma of that of a HI broad Lyman-alpha of b=130 km/s at z=0.09279+-0.00005. We have also analyzed the available XMM-Newton RGS data towards PG 1116+215. Unfortunately, the XMM-Newton data are not suitable to investigate this line because of instrumental features at the wavelengths of interest. At the same redshift, the Chandra and XMM-Newton spectra have OVII K-alpha absorption line features of significance 1.5 sigma and 1.8 sigma, respectively. We also analyzed the available SDSS spectroscopic galaxy survey data towards PG 1116+215 in the redshift range of interest. We found evidence for a galaxy filament that intersects the PG 1116+215 sightline and additional galaxy structures that may host WHIM. The combination of HST, Chandra, XMM-Newton and SDSS data indicates that we have likely detected a multi-temperature WHIM at z=0.091-0.093 towards PG 1116+215.
We report the $a~posteriori$ confirmation of two large-scale filaments along the sight-line of the blazar 1ES~1553+113, which correspond to Warm-Hot Intergalactic Medium (WHIM) absorption features in the X-ray and far ultraviolet. We use the WISE-SuperCOSMOS photometric catalog to map the cosmic-web in the direction of the blazar, and find significant filaments at redshifts of $z=0.23\pm0.02$ and $z=0.31\pm0.02$, which roughly align with the absorption redshifts. A third X-ray absorption feature at $z_X=0.133$ did not have any corresponding structures in the photometric catalog.
我们提出了XMM RGS和钱德拉LETG观测的耀变体，H 2356 - 309，位于后面的雕塑家墙，一个大规模的星系结构，预计港口高密度的温热星系际介质（WHIM）。我们对RGS和LETG光谱的同时分析产生了对关键的红移O vii K-α线的3-sigma检测，其柱密度（>~10 ^{16} cm ^{-2}）与宇宙学模拟中产生的类似大尺度结构一致。这代表了第一次检测到非本地WHIM从X射线吸收研究，XMM和钱德拉数据进行了分析，同时吸收体红移是已知的，从而提供了强大的证据，预期的存储库的"失踪重子"。
We explore the high spectral resolution X-ray data towards the quasar 3C273 to search for signals of hot ($\sim10^{6-7}$ K) X-ray-absorbing gas co-located with two established intergalactic FUV OVI absorbers. We analyze the soft X-ray band grating data of all XMM-Newton and Chandra instruments to search for the hot phase absorption lines at the FUV predicted redshifts. The viability of potential line detections is examined by adopting the constraints of a physically justified absorption model. The WHIM hypothesis is investigated with a complementary 3D galaxy distribution analysis, and by comp…
Known as the "Missing Baryon Problem", about one-third of baryons in the local universe remain unaccounted for. The missing baryons are thought to reside in the warm-hot intergalactic medium (WHIM) of the cosmic web filaments, which are challenging to detect. Recent Chandra X-ray observations used a novel stacking analysis and detected an OVII absorption line toward the sightline of a luminous quasar, hinting that the missing baryons may reside in the WHIM. To explore how the properties of the OVII absorption line depend on feedback physics, we compare the observational results with prediction…
As the Universe evolves, it develops a web of filamentary structure of matter. This cosmic web is filled with gas, with the most diffuse gas lying in the intergalactic regions. At low redshift, the gas is predominantly warm-hot, and one of its best tracers is X-ray absorption in sightlines to background quasars. In this Chapter, we present the theoretical background for the formation of the warm-hot intergalactic medium (WHIM) and present the physical properties of the WHIM from cosmological hydro-dynamical simulations. We discuss the feasibility of detecting the WHIM with X-ray absorption lin…
The problem of missing baryons in the local universe remains an open question. One propose alternative is that at low redshift missing baryons are in the form of the Warm Hot Intergalactic Medium (WHIM). In order to test this idea, we present a detailed analysis of X-ray high-resolution spectra of six extragalactic sources, Mrk 421, 1ES 1028+511, 1ES 1553+113, H2356-309, PKS 0558-504 and PG 1116+215, obtained with the XMM-Newton Reflection Grating Spectrometer to search for signals of WHIM and/or circumgalactic medium (CGM) X-ray absorbing gas. We fit the X-ray absorption with the IONeq model,…
Based on constraints from Big Bang nucleosynthesis and the cosmic microwave background, the baryon content of the high-redshift Universe can be precisely determined. However, at low redshift, about one-third of the baryons remain unaccounted for, which poses the long-standing missing baryon problem. The missing baryons are believed to reside in large-scale filaments in the form of warm-hot intergalactic medium (WHIM). In this work, we employ a novel stacking approach to explore the hot phases of the WHIM. Specifically, we utilize the 470 ks Chandra LETG data of the luminous quasar, H1821+643, …
We have analyzed all available archival XMM-Newton observations of X Comae, a bright X-ray quasar behind the Coma cluster, to study the properties of the warm-hot intergalactic medium in the vicinity of the nearest massive galaxy cluster. The RGS observations confirm the possible presence of a Ne IX K-alpha absorption line at the redshift of Coma, although with a limited statistical significance. This analysis is therefore in line with the earlier analysis by Takei et al. (2007) based on a sub-set of these data. Its large column density and optical depth, however, point to implausible conditio…
