Virial shocks in galactic haloes

By Y. Birnboim, A. D. O. Physics, The Hebrew University, Jerusalem Israel. 2003

876 citations recorded by the source corpus.

We investigate the conditions for the existence of an expanding virial shock in the gas falling within a spherical dark matter halo. The shock relies on pressure support by the shock-heated gas behind it. When the radiative cooling is efficient compared with the infall rate, the post-shock gas becomes unstable; it collapses inwards and cannot support the shock. We find for a monatomic gas that the shock is stable when the post-shock pressure and density obey γ e f f ≡ (d In P/dt)/(d In p/dt) > 10/7. When expressed in terms of the pre-shock gas properties at radius r it reads as ρrΛ(T)/u 3 < 0.0126, where p is the gas density, u is the infall velocity and A(T) is the cooling function, with the post-shock temperature T u 2 . This result is confirmed by hydrodynamical simulations, using an accurate spheri-symmetric Lagrangian code. When the stability analysis is applied in cosmology, we find that a virial shock does not develop in most haloes that form before z ∼ 2, and it never forms in haloes less massive than a few 10 1 1 M O .. In such haloes, the infalling gas is not heated to the virial temperature until it hits the disc, thus avoiding the cooling-dominated quasi-static contraction phase. The direct collapse of the cold gas into the disc should have non-trivial effects on the star formation rate and on outflows. The soft X-ray produced by the shock-heated gas in the disc is expected to ionize the dense disc environment, and the subsequent recombination would result in a high flux of La emission. This may explain both the puzzling low flux of soft X-ray background and the La emitters observed at high redshift.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/64d27e9ec98295d8f8379de58c6f0a661dd402e7

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Citations in the corpus

High-redshift clumpy discs and bulges in cosmological simulations (2009, background): “The common low-redshift discs are expected to form predominantly in haloes below the threshold mass of ∼1012 M , and not necessarily by narrow streams (Birnboim & Dekel 2003; Binney 2004; Kereš et al. 2005; Dekel & Birnboim 2006; Birnboim, Dekel & Neistein 2007).”
METALLICITY-DEPENDENT QUENCHING OF STAR FORMATION AT HIGH REDSHIFT IN SMALL GALAXIES (2011, methodology): “…estimated the fraction of gas inflow from outside the virial radius that actually reaches the galaxy at the halo center, in, using analytic arguments and hydro cosmological simulations (Birnboim & Dekel 2003; Kereš et al. 2005, 2009b; Dekel & Birnboim 2006; Ocvirk et al. 2008; Dekel et al. 2009).”
The environmental dependence of the relations between stellar mass, structure, star formation and nuclear activity in galaxies (2004, background): “In high mass halos, collapsing gas is first heated to the halo virial temperature by shocks; it then remains pressure-supported and in quasi-static equilibrium while it cools by radiative processes (White & Frenk 1991; Birnboim & Dekel 2003).”
Erratum: From dwarf spheroidals to cD galaxies: simulating the galaxy population in a ΛCDM cosmology (2010, background): “…massive halos, post-shock cooling times exceed halo sound crossing times, the accretion shock moves away from the galaxy, and infalling gas forms a quasi-static hot atmosphere from which it condenses onto the central galaxy through a cooling flow (Forcada-Miro & White 1997; Birnboim & Dekel 2003).”
How do galaxies get their gas (2002, background): “Birnboim & Dekel (2003) show that the cooling time condition corresponds approximately to a threshold in the halo mass of the galaxy, with little dependence on redshift.”
Constraining the galaxy–halo connection over the last 13.3 Gyr: star formation histories, galaxy mergers and structural properties (2017, background): “The conception of a transition halo mass above which the star formation becomes strongly inefficient has been introduced by a number of theoretical studies (e.g., White & Frenk 1991; Birnboim & Dekel 2003; Kereš et al. 2005; Dekel & Birnboim 2006; Cattaneo et al. 2007).”
The dark nemesis of galaxy formation : why hot haloes trigger black hole growth and bring star formation to an end (2016, background): “As the halo mass increases, and the characteristic cooling time of the halo becomes longer, the density of the corona increases (White & Frenk 1991; Birnboim & Dekel 2003).”
Extended Lyman-alpha emission from cold accretion streams (2011, background): “…relatively dense, cold (104 K) and pristine gas which penetrates in the form of streams through the diffuse shock-heated medium (Fardal et al. 2001; Birnboim & Dekel 2003; Kereš et al. 2005; Dekel & Birnboim 2006; Birnboim et al. 2007; Ocvirk et al. 2008; Dekel et al. 2009; Brooks et al. 2009;…”
Jet-regulated cooling catastrophe (2010, background): “We know (Birnboim & Dekel 2003; Kereš et al. 2005; Dekel & Birnboim 2006; Ocvirk et al. 2008) that for the most massive haloes [those with masses Mstream ≥ 6 × 107 (1 + z)8 M at z ≥ 2], cold accretion of gas from the IGM is efficiently thermalized at a few virial radii by an accretion shock, and…”
The Giant Gemini GMOS survey of zem > 4.4 quasars – I. Measuring the mean free path across cosmic time (2014, background): “…of galaxy formation do predict a significant reservoir of cool, dense gas accreting on to galaxies via ‘cold streams’ that span the dark matter haloes (Birnboim & Dekel 2003; Dekel & Birnboim 2006; Ocvirk, Pichon & Teyssier 2008; Dekel et al. 2009; Kereš et al. 2009; van de Voort et al. 2011).”
CANDELS: THE PROGENITORS OF COMPACT QUIESCENT GALAXIES AT z ∼ 2 (2012, background): “This slow track (left region) is likely associated with the fading of normal disk galaxies to become S0s, due to halo quenching (Birnboim & Dekel 2003) or morphological quenching (Martig et al. 2009).”
THE DEPENDENCE OF QUENCHING UPON THE INNER STRUCTURE OF GALAXIES AT 0.5 ⩽ z < 0.8 IN THE DEEP2/AEGIS SURVEY (2012, background): “The main external process is halo mass quenching (Silk 1977; Rees & Ostriker 1977; Blumenthal et al. 1984; Birnboim & Dekel 2003; Kereš et al. 2005; Dekel & Birnboim 2006; Cattaneo et al. 2006); this posits that dark matter halos above a critical halo mass establish virial shocks that stop the flow…”
Galaxy bimodality due to cold flows and shock heating (2004, methodology): “In §2 we provide an improved presentation of the original analysis of spherical shock stability (Birnboim & Dekel 2003, hereafter BD03).”
ON THE LACK OF EVOLUTION IN GALAXY STAR FORMATION EFFICIENCY (2012, background): “More recently, hydrodynamical simulations have indicated that the host dark matter halo mass strongly influences gas accretion onto galaxies (Birnboim & Dekel 2003; Kereš et al. 2005; Dekel & Birnboim 2006).”
Modelling the galaxy bimodality: shutdown above a critical halo mass (2006, background): “…u−r ≃ 0.2 at Mr <∼ − 22 as seen in the SDSS. Part of this failure arises from the gradual dependence of cooling on mass. Analyses in spherical symmetry (Birnboim & Dekel 2003, BD03) and cosmological simulations (Kereš et al. 2005, K05) have shown that in haloes below a critical shockheating…”
Systematic variation of the stellar initial mass function with velocity dispersion in early-type galaxies (2012, background): “…formation, whereby massive galaxies are supposed to grow mainly through the merging of smaller systems, with the growth ratelimited by cosmology (see, e.g., De Lucia et al. 2006), requiring alternative channels of massive galaxy formation, such as cold accretion (see, e.g. Birnboim & Dekel 2003).”
NEW CONSTRAINTS ON THE EVOLUTION OF THE STELLAR-TO-DARK MATTER CONNECTION: A COMBINED ANALYSIS OF GALAXY–GALAXY LENSING, CLUSTERING, AND STELLAR MASS FUNCTIONS FROM z = 0.2 to z = 1 (2011, background): “…times has been invoked by modelers for some time to help explain why cooling and star formation shut down at the highest masses, with some refinement due to the presence of so-called cold-mode accretion (Birnboim & Dekel 2003; Kereš et al. 2005; Birnboim et al. 2007; Cattaneo et al. 2006).”
The DEEP2 Galaxy Redshift Survey: the relationship between galaxy properties and environment at z∼ 1 (2006, positive): “As shown by Birnboim & Dekel (2003), Kereš et al. (2005) and Croton et al. (2006), models of gas infall on to dark matter haloes produce a natural bimodal distribution in gas temperature, dividing cold infalling gas from that which remains at the virial temperature to form a static hot halo.”