摘要：Aims.We explore the high spectral resolution X-ray data towards the quasar 3C 273 to search for signals of hot (∼106−7K) X-ray-absorbing gas co-located with two established intergalactic far-ultraviolet (FUV) O VIabsorbers.Methods.We analyze the soft X-ray band grating data of allXMM-NewtonandChandrainstruments 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 detailed comparison of the measurement results to the WHIM properties in theEAGLEcosmological, hydrodynamical simulation.Results.At one of the examined FUV redshifts,z = 0.09017 ± 0.00003, we measured signals of two hot ion species, O VIIIand Ne IX, with a 3.9σcombined significance level. While the absorption signal is only marginally detected in individual co-added spectra, considering the line features in all instruments collectively and assuming collisional equilibrium for absorbing gas, we were able to constrain the temperature (kT = 0.26 ± 0.03 keV) and the column density (NH×Z⊙/Z= 1.3−0.5+0.6× 1019cm−2) of the absorber. Thermal analysis indicates that FUV and X-ray absorption relate to different phases, with estimated temperatures,TFUV ≈ 3 × 105, and,TX − ray ≈ 3 × 106K. These temperatures match theEAGLEpredictions for WHIM at the FUV/X-ray measuredNion-ranges. We detected a large scale galactic filament crossing the sight-line at the redshift of the absorption, linking the absorption to this structure.Conclusions.This study provides observational insights into co-existing warm and hot gas within a WHIM filament and estimates the ratio of the hot and warm phases. Because the hot phase is thermally distinct from the O VIgas, the estimated baryon content of the absorber is increased, conveying the promise of X-ray follow-up studies of FUV detected WHIM in refining the picture of the missing baryons.
关键词：enX-rays: individuals: 3C 273intergalactic mediumlarge-scale structure of Universe
