Related papers: Where are the ``Missing'' Galactic Baryons?
Milky Way's hot gaseous halo extends up to the Galactic virial radius ($\sim 200$ kpc) and contains a significant component of baryon mass of the Galaxy. The halo properties can be constrained from X-ray spectroscopic observations and from…
The circumgalactic medium (CGM) of the Milky Way is composed of a tenuous atmosphere filled with multi-phase plasma, including a warm-hot virialised component. Recent studies suggest a much hotter (~0.7 keV) super-virial component detected…
Recent observations show that spiral galaxies are surrounded by extended gaseous halos as predicted by the hierarchical structure formation scenario. The origin and nature of extraplanar gas is often unclear since the halo is continuously…
The Milky Way and all other galaxies are missing most of their baryons in that the ratio of the known baryonic mass to the gravitating mass (within the virial radius), is several times less than the cosmic ratio determined from WMAP. This…
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…
Although only about 5 percent of the total baryonic mass in luminous elliptical galaxies is in the form of cooled interstellar gas, it is concentrated within the optical effective radius r_e where it influences the local dynamical mass. The…
Galactic halo gas traces inflowing star formation fuel and feedback from a galaxy's disk and is therefore crucial to our understanding of galaxy evolution. In this review, we summarize the multi-wavelength observational properties and…
Models of disk galaxy formation commonly predict the existence of an extended reservoir of hot gas surrounding massive spirals at low redshift. As a test of these models, we have obtained X-ray and optical data of the two massive edge-on…
Observations of clusters of galaxies suggest that they contain significantly fewer baryons (gas plus stars) than the cosmic baryon fraction. This `missing baryon' puzzle is especially surprising for the most massive clusters which are…
Vertically extended, high velocity dispersion stellar distributions appear to be a ubiquitous feature of disc galaxies, and both internal and external mechanisms have been proposed to be the major driver of their formation. However, it is…
Most spiral galaxies are found in galaxy groups with low velocity dispersions; most E/S0 galaxies are found in galaxy groups with relatively high velocity dispersions. The mass of the hot gas we can observe in the E/S0 groups via their…
In a $\Lambda$CDM cosmology, galaxy formation is a globally inefficient process: it is often the case that far fewer baryons are observed in galaxy disks than expected from the cosmic baryon fraction. The location of these "missing baryons"…
We present one-dimensional models of the hot gas in dark-matter halos, which both predict the existence of cool cores and explain their structure. Our models are directly applicable to semi-analytic models (SAMs) of galaxy formation. We…
The presence of the $\approx 10^6$ K gas in the circumgalactic medium of the Milky Way has been well established. However, the location and the origin of the newly discovered hot gas at `super-virial' temperatures of $\approx 10^7$ K have…
The High-Velocity Clouds (HVCs) observed in the Galactic neighbourhood, have been proposed to be remnants of the formation of the galaxies in the Local Group, having distances, and thus masses, predominantly of dark matter, considerably…
Observational evidence shows that low-redshift galaxies are surrounded by extended haloes of multiphase gas, the so-called 'circumgalactic medium' (CGM). To study the survival of relatively cool gas (T < 10^5 K) in the CGM, we performed a…
We continue our empirical study of the emission line flux originating in the cool ($T\sim10^4$ K) gas that populates the halos of galaxies and their environments. Specifically, we present results obtained for a sample of nearly half a…
Ongoing accretion onto galactic disks has been recently theorized to progress via the unstable cooling of the baryonic halo into condensed clouds. These clouds have been identified as analogous to the High-Velocity Clouds (HVCs) observed in…
Within a sufficiently large cosmic volume, conservation of baryons implies a simple `closed box' view in which the sum of the baryonic components must equal a constant fraction of the total enclosed mass. We present evidence from Rhapsody-G…
Hot ionized gas is important in the baryon cycle of galaxies and contributes the majority of their ``missing baryons''. Until now, most semi-analytic models of galaxy formation have paid little attention to hot gaseous haloes and their…