Missing baryons and the soft X-ray background

Sołtan, A.; Freyberg, M. J.; Hasinger, G.

doi:10.1051/0004-6361:20021291

Cited by 33 publications

(48 citation statements)

References 19 publications

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“…• 3 (Sołtan et al 2002; references to earlier work on this subject therein). Our investigation was also impeded by the narrow useful energy range and the low energy resolution of the RASS maps.…”

Section: Warm-hot Intergalactic Mediummentioning

confidence: 95%

“…These data were then used to construct the X-ray "colour-colour" diagram shown in Fig. 2 in the same way as the diagrams for the RASS maps in Sołtan et al (2002). A large solid dot indicates the position of excess emission.…”

Section: Pspcmentioning

confidence: 99%

“…Labels give temperatures in keV. The X-ray colours of the enhancements found by Sołtan et al (2002) limits), and open circles denote the colours around galaxies. The enhancements are integrated between 0.…”

Section: Pspcmentioning

confidence: 99%

“…In Fig. 3 we plotted also the CCF of the RASS with the galaxy distribution of the Lick counts (see Sołtan et al (2002) for the details of the calculations). Error bars represent 1σ uncertainties based on the simulations.…”

Section: Pspcmentioning

confidence: 99%

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Signs of warm-hot intergalactic medium in the soft X-ray background

Sołtan¹,

Freyberg

Hasinger

2005

A&A

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Abstract. Small angular scale structure of the soft X-ray background correlated with the galaxy distribution is investigated. An extensive data sample from the ROSAT and XMM-Newton archives are used. Excess emission below ∼1 keV extending up to at least several hundred kpc around galaxies is detected. The relative amplitude of the excess emission in the 0.3−0.5 keV band amounts to 1.3 ± 0.2% of the total background flux. A steep spectrum of the emission at higher energies is indicated by a conspicuous decline of the signal above 1 keV. The XMM-Newton EPIC/MOS data covering wider energy range than the ROSAT PSPC are consistent with a thermal bremsstrahlung spectrum with kT < ∼ 0.5 keV. This value is consistent with temperatures of the Warm-Hot Intergalactic Medium (WHIM) derived by several groups from hydrodynamic simulations. Correlation analysis allows for estimate of the average excess emission associated with galaxies but the data are insufficient to constrain physical parameters of the WHIM and to determine the contribution of WHIM to the total baryonic mass density.Key words. X-rays: diffuse background -intergalactic medium Warm-hot intergalactic mediumX-ray telescopes on board the satellites EINSTEIN, ROSAT and Chandra have firmly established the discrete nature of the extragalactic X-ray background (XRB). High angular resolution provided by the imaging optics allowed for isolation of various classes of point-like X-ray sources, leaving unresolved only a small fraction of the total XRB flux.While the observational evidences are dominated by the discrete sources, theoretical considerations indicate that in the soft X-rays a still non-negligible fraction of the XRB should remain in the form of the diffuse component. Apart from clusters of galaxies that have been recognized sources of extended emission since the beginning of X-ray astronomy, a substantial amount of plasma residing in the intergalactic space might be hot enough to emit a noticeable amount of X-ray flux. Following Cen & Ostriker (1999), several groups performed hydrodynamical simulations that have demonstrated that a significant fraction of baryons in the Universe has not yet accumulated in stars and galaxies. It is estimated that 30−40% of the baryonic matter fills the intergalactic space (e.g. Davé et al. 2000). This gas slowly falls toward potential wells created by the (non-baryonic) dark matter. The density and temperature of the infalling material increase. Eventually, halos of hot plasma arise around mass concentrations. The spatial distribution and physical parameters of the diffuse gas in the local Universe (z < ∼ 0.4) are distinctly different from both the matter in galaxies and plasma in clusters of galaxies. This constituent of the baryonic matter is known as WHIM -Warm-Hot Intergalactic Medium (Davé et al. 2000).The quantitative characteristics of the WHIM as a function of redshift depend on the rate at which the gas is accumulating. The process is determined by the evolution of the gravitational potential and by the non-gravitatio...

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Section: Warm-hot Intergalactic Mediummentioning

confidence: 95%

Section: Pspcmentioning

confidence: 99%

Section: Pspcmentioning

confidence: 99%

Section: Pspcmentioning

confidence: 99%

See 2 more Smart Citations

Signs of warm-hot intergalactic medium in the soft X-ray background

Sołtan¹,

Freyberg

Hasinger

2005

A&A

Self Cite

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“…The ROSAT results, based on deep pointings (Carrera et al 1998), show a much smaller amplitude of correlation than predicted from optical samples, while an analysis of the ROSAT north ecliptic pole sample, which is shallower but covers a wider solid angle (Mullis 2002), comes to the opposite conclusion. It has been claimed that at a flux level below 1.5 # ergs cm Ϫ2 s Ϫ1 (0.5-2 keV), the XRB exhibits no clustering (Soltan & Hasinger 1994). This contradicts the observed cosmic variance in the ultradeep surveys by Chandra and XMM.…”

Section: Introductionmentioning

confidence: 93%

Imaging Large-Scale Structure in the X-Ray Sky

Yang

Mushotzky

Barger

et al. 2003

The Astrophysical Journal

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We present the first results from a wide solid angle, moderately deep Chandra survey of the Lockman Hole North-West region. Our nine ACIS-I fields cover an effective solid angle of 0.4 deg 2 and reach a depth of 3 # ergs cm Ϫ2 s Ϫ1 in the 0.4-2 keV band and ergs cm Ϫ2 s Ϫ1 in the 2-8 keV band. The best-fit log N-Ϫ16 Ϫ15 10 3 # 10 log S for the entire field matches well onto that of the Chandra Deep Field-North. We show that the full range of the "cosmic variance" previously seen in different Chandra fields is reproduced in this small region of the sky. A counts-in-cells analysis shows that the hard-band sources are more strongly correlated than the soft-band sources. Subject headings: cosmology: observations -galaxies: nuclei -large-scale structure of universe -X-rays: diffuse background

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Whim Emission and the Cluster Soft Excess: A Model Comparison

Mittaz¹,

Lieu²,

Cen³

et al. 2004

Soft X-Ray Emission From Clusters of Galaxies and Related Phenomena

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The confirmation of the cluster soft excess (CSE) by XMM-Newton has rekindled interest as to its origin. The recent detections of CSE emission at large cluster radii together with reports of O VII line emission associated with the CSE has led many authors to conjecture that the CSE is, in fact, a signature of the warm-hot intergalactic medium (WHIM). In this paper we test the scenario by comparing the observed properties of the CSE with predictions based on models of the WHIM. We find that emission from the WHIM in current models is 3 to 4 orders of magnitude too faint to explain the CSE. We discuss different possibilities for this discrepancy including issues of simulation resolution and scale, and the role of small density enhancements or galaxy groups. Our final conclusion is that the WHIM alone is unlikely to be able to accout for the observed flux of the CSE.

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Missing baryons and the soft X-ray background

Cited by 33 publications

References 19 publications

Signs of warm-hot intergalactic medium in the soft X-ray background

Signs of warm-hot intergalactic medium in the soft X-ray background

Imaging Large-Scale Structure in the X-Ray Sky

Whim Emission and the Cluster Soft Excess: A Model Comparison

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