The<i>β</i>-model of the intracluster medium

Arnaud, M.

doi:10.1051/0004-6361/200912150

Cited by 27 publications

(27 citation statements)

References 23 publications

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“…We now introduce the common β notation used in the presence of complex multiphase gases (Cavaliere & Fusco-Femiano 1976;Arnaud 2009). An initial (quasi) hydrostatic gas distribution depends on an effective temperature T eff = T gas + T turb ∼ T init arising from a combination of thermal and turbulent support (plus other terms due to magnetic fields which we neglect at present).…”

Section: Simulationsmentioning

confidence: 99%

Ultrafaint Dwarf Galaxies—the Lowest-Mass Relics From Before Reionization

Bland-Hawthorn

Sutherland

Webster

2015

ApJ

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New observations suggest that ultrafaint dwarf galaxies (UFD) -the least luminous systems bound by dark matter halos ( 10 5 L ) -may have formed before reionization. The extrapolated virial masses today are uncertain with estimates ranging from 10 8 M to as high as 10 9 M depending on the assumed form of the underlying potential. We show that the progenitor halo masses of UFDs can, in principle, be as low as M vir ≈ 10 7 M . Under the right conditions, such a halo can survive the energy input of a supernova (SN) and its radiative progenitor. A clumpy (fractal) medium is much less susceptible to both internal and external injections of energy. It is less prone to SN sweeping (particularly if it is off-centred) because the coupling efficiency of the explosive energy is much lower than for a diffuse interstellar medium. With the aid of the 3D hydro/ionization code Fyris, we show that sufficient baryons are retained to form stars following a single supernova event in dark matter halos down to M vir ≈ 10 7 M in the presence of radiative cooling. In these models, the gas survives the SN explosion, is enriched with the specific abundance yields of the discrete events, and reaches surface densities where low mass stars can form. Our highest resolution simulations reveal why cooling is so effective in retaining gas compared to any other factor. In the early stages, the super-hot metal-enriched SN ejecta exhibit strong cooling, leading to much of the explosive energy being lost. Consistent with earlier work, the baryons do not survive in smooth or adiabatic models in the event of a supernova. The smallest galaxies may not contribute a large fraction of matter to the formation of galaxies, but they carry signatures of the earliest epochs of star formation, as we show. These signatures may allow us to distinguish a small primordial galaxy from one that was stripped down to its present size through tidal interaction. We discuss these results in the context of local ultra-faint dwarfs and damped Lyα systems (z ∼ 2) at very low metallicity ([Fe/H] ∼ −3). We show that both classes of objects are consistent with primordial low-mass systems that have experienced only a few enrichment events.

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Section: Simulationsmentioning

confidence: 99%

Ultrafaint Dwarf Galaxies—the Lowest-Mass Relics From Before Reionization

Bland-Hawthorn

Sutherland

Webster

2015

ApJ

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“…We consider three different gas models in this study: the Komatsu-Seljak (KS) profile [23]; the universal pressure (UP) profile [24]; and the isothermal β-model [25][26][27][28]. For the KS model, we use equations (D4)-(D13) in [29] to implement the pressure profile.…”

Section: Pressure Profile 41 Models For Gas Pressurementioning

confidence: 99%

Probing the diffuse baryon distribution with the lensing-tSZ cross-correlation

Waerbeke

Hinshaw

et al. 2015

J. Cosmol. Astropart. Phys.

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Approximately half of the Universe's baryons are in a form that has been hard to detect directly. However, the missing component can be traced through the cross-correlation of the thermal Sunyaev-Zeldovich (tSZ) effect with weak gravitational lensing. We build a model for this correlation and use it to constrain the extended baryon component, employing data from the Canada France Hawaii Lensing Survey and the Planck satellite. The measured correlation function is consistent with an isothermal β-model for the halo gas pressure profile, and the 1-and 2-halo terms are both detected at the 4σ level. In addition, we measure the hydrostatic mass bias (1 − b) = 0.79 +0.07 −0.10 , which is consistent with numerical simulation results and the constraints from X-ray observations. The effective temperature of the gas is found to be in the range (7 × 10 5 -3 × 10 8 ) K, with approximately 50% of the baryons appearing to lie beyond the virial radius of the halos, consistent with current expectations for the warm-hot intergalactic medium.

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“…Arnaud 2009). One of the most important issues related to the study of galaxy clusters is the evolution of their star formation (SF) activity.…”

Section: Introductionmentioning

confidence: 99%

A gas-rich AGN near the centre of a galaxy cluster atz~ 1.4

Casasola¹,

Magrini²,

Combes³

et al. 2013

A&A

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Context. The formation of the first virialized structures in overdensities dates back to ∼9 Gyr ago, i.e. in the redshift range z ∼ 1.4−1.6. Some models of structure formation predict that the star formation activity in clusters was high at that epoch, implying large reservoirs of cold molecular gas. Aims. Aiming at finding a trace of this expected high molecular gas content in primeval clusters, we searched for the 12 CO(2-1) line emission in the most luminous active galactic nucleus (AGN) of the cluster around the radio galaxy 7C 1756+6520 at z ∼ 1.4, one of the farthest spectroscopic confirmed clusters. This AGN, called AGN.1317, is located in the neighbourhood of the central radio galaxy at a projected distance of ∼780 kpc. Methods. The IRAM Plateau de Bure Interferometer was used to investigate the molecular gas quantity in AGN.1317, observing the 12 CO(2−1) emission line. Results. We detect CO emission in an AGN belonging to a galaxy cluster at z ∼ 1.4. We measured a molecular gas mass of 1.1 × 10 10 M , comparable to that found in submillimeter galaxies. In optical images, AGN.1317 does not seem to be part of a galaxy interaction or merger. We also derived the nearly instantaneous star formation rate (SFR) from Hα flux obtaining a SFR ∼ 65 M yr −1 . This suggests that AGN.1317 is actively forming stars and will exhaust its reservoir of cold gas in ∼0.2−1.0 Gyr.

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Theβ-model of the intracluster medium

Cited by 27 publications

References 23 publications

Ultrafaint Dwarf Galaxies—the Lowest-Mass Relics From Before Reionization

Ultrafaint Dwarf Galaxies—the Lowest-Mass Relics From Before Reionization

Probing the diffuse baryon distribution with the lensing-tSZ cross-correlation

A gas-rich AGN near the centre of a galaxy cluster atz~ 1.4

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