相关论文: The Search for the Missing Baryons at Low Redshift

Recent Cosmological measurements indicate that baryons comprise about four percent of the total mass-energy density of the Universe, which is in accord with the predictions arising from studies of the production of the lightest elements. It…

Motivated by recent observation of Lanzetta et al. that most luminous galaxies at low redshifts produce $\lya$ absorption at impact parameter $l\lsim 160 \kpch$, we propose that these absorbers are clouds confined by the pressure of ambient…

We explore the evolution of the ~107 degree hot gas in normal galaxies out to redshift = 0.5 (lookback time = 5 Gyr), using X-ray luminosity functions (XLF) built from a sample of 575 normal galaxies with z < 0.6 detected in five high…

Most of the baryons in L* galaxies are unaccounted for and are predicted to lie in hot gaseous halos (T ~ 3E6 K) that may extend beyond R200. A hot gaseous halo will produce a thermal Sunyaev-Zeldovich signal that is proportional to the…

One of the biggest mysteries in the modern cosmology and galaxy formation is the hideout of the "missing baryons". The leading theory of galaxy formation predicts that a huge amount of baryons resides around galaxies extending out to their…

Francis & Hewett (1993) identified two 10-Mpc scale regions of the high redshift universe that were seemingly very overdense in neutral hydrogen. Subsequent observations showed that at least one of these gas-rich regions enveloped a cluster…

Disc galaxies like the Milky Way are expected to be surrounded by massive coronae of hot plasma that may contain a significant fraction of the so-called missing baryons. We investigate whether the local (|vLSR|<400 km/s) warm-hot absorption…

Based on 19 high-resolution N-body/gas-dynamical galaxy formation simulations in the LCDM cosmology it is shown, that for a galaxy like the Milky Way, in addition to the baryonic mass of the galaxy itself, about 70% extra baryonic mass…

We report new observations of circumgalactic gas in the halos of early type galaxies obtained by the COS-Halos Survey with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope. We find that detections of HI surrounding early…

We report the first detection of an OVIII Ly-alpha absorption line associated with an overdense region in the intergalactic medium (IGM) along the sightline towards PKS 2155-304 with the Chandra Low Energy Transmission Grating Spectrometer…

Halo gas in low-z (z<0.5) >0.1L* galaxies in high-resolution, large-scale cosmological hydrodynamic simulations is examined with respect to three components: (cold, warm, hot) with temperatures equal to (<10^5, 10^{5-6}, >10^6)K,…

Early-type galaxies often contain a hot X-ray emitting interstellar medium (3-8E6 K) with an apparent radiative cooling time much less than a Hubble time. If unopposed by a heating mechanism, the gas will radiatively cool to temperatures <=…

Recent surveys have discovered hundreds of low surface brightness galaxies in the local (z < 0.1) Universe. Plots of the surface brightness distribution (the space density of galaxies plotted against central surface brightness) show a flat…

Today, the majority of the cosmic baryons in the Universe are not observed directly, leading to an issue of "missing baryons" at low redshift. Cosmological hydrodynamical simulations have indicated that a significant portion of them will be…

A small survey of the UV-absorbing gas in 12 low-$z$ galaxy groups has been conducted using the Cosmic Origins Spectrograph (COS) on-board the Hubble Space Telescope (HST). Targets were selected from a large, homogeneously-selected sample…

We show that a global relation between baryonic mass and virial velocity can be constructed from the scale of dwarf galaxies up to that of rich galaxy clusters. The slope of this relation is close to that expected if dark matter halos form…

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…

With the Chandra X-ray Telescope we have detected a zero-redshift OVII He-alpha absorption line along the sight line toward 3C 273. This line detection is highly significant, with a signal-to-noise ratio (S/N) of 6.4. We explore two models,…

Elliptical galaxies and their groups having the largest L_x/L_B lie close to the locus in the L_x,L_B diagram expected for closed systems with baryon fractions equal to the cosmic mean value, f_b = 0.16. The estimated baryon fractions for…

Context. A significant fraction of the predicted baryons remains undetected in the local universe. We adopted the common assumption that a large fraction of the missing baryons corresponds to the hot (log T(K) = 5.5-7) phase of the Warm Hot…