DO HOT HALOS AROUND GALAXIES CONTAIN THE MISSING BARYONS?

By Michael E. Anderson, J. Bregman. 2010

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Galaxies are missing most of their baryons, and many models predict these baryons lie in a hot halo around galaxies. We establish observationally motivated constraints on the mass and radii of these halos using a variety of independent arguments. First, the observed dispersion measure of pulsars in the Large Magellanic Cloud allows us to constrain the hot halo around the Milky Way: if it obeys the standard Navarro, Frenk, and White (NFW) profile, it must contain less than 4%–5% of the missing baryons from the Galaxy. This is similar to other upper limits on the Galactic hot halo, such as the soft X-ray background and the pressure around high-velocity clouds. Second, we note that the X-ray surface brightness of hot halos with NFW profiles around large isolated galaxies is high enough that such emission should be observed, unless their halos contain less than 10%–25% of their missing baryons. Third, we place constraints on the column density of hot halos using nondetections of O vii absorption along active galactic nucleus (AGN) sightlines: in general they must contain less than 70% of the missing baryons or extend to no more than 40 kpc. Flattening the density profile of galactic hot halos weakens the surface brightness constraint so that a typical L* galaxy may hold half its missing baryons in its halo, but the O vii constraint remains unchanged, and around the Milky Way a flattened profile may only hold 6%–13% of the missing baryons from the Galaxy ((2–4) × 1010 M☉). We also show that AGN and supernovae at low to moderate redshift—the theoretical sources of winds responsible for driving out the missing baryons—do not produce the expected correlations with the baryonic Tully–Fisher relationship and, therefore, are insufficient to explain the missing baryons from galaxies. We conclude that most of missing baryons from galaxies do not lie in hot halos around the galaxies, and that the missing baryons never fell into the potential wells of protogalaxies in the first place. They may have been expelled from the galaxies as part of the process of galaxy formation.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/2d9603e2f1755a0ef0e177cb81babd7f72551ff7

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Citations in the corpus

The current status of galaxy formation (2012, background): “These baryons are not in hot gaseous halos (Anderson & Bregman, 2010).”
CHARACTERIZING THE CIRCUMGALACTIC MEDIUM OF NEARBY GALAXIES WITH HST/COS AND HST/STIS ABSORPTION-LINE SPECTROSCOPY (2012, background): “…the limit on the percentage of very hot (T & 107 K) coronal gas around spirals set by the failure to detect hot (kT ∼ 300 eV) gas around the Milky Way or other nearby galaxies (Bregman 2007; Anderson & Bregman 2010); but see Anderson & Bregman (2011) and the discussion of Gupta et al. (2012) below.”
The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, unknown): “…Sembach et al. (2003) ≈70 1–10 >1 − OVI absorption (100 LOS) Bregman & Lloyd-Davies (2007) <20 90d 2c 0.04e OVII absorption (25 LOS) Uniform spherical halo Anderson & Bregman (2010) 50f 50a,d 3.5 1.2–1.5 LMC pulsar dispersion measures Gatto et al. (2013) 50–90 36–13a 1.8c 3.4–4.8 Ram-pressure…”
The Dark Matter Crisis: Falsification of the Current Standard Model of Cosmology (2012, background): “An important problem related to Hypothesis 0ii which plagues all known BB-based cosmological models are the two missing baryon problems (e.g. Anderson & Bregman 2010; McGaugh et al. 2010): (i) From BB-nucleosynthesis and CMB observations the cosmic average baryon-to-DMmass-density fraction is fb,…”
Gaseous Galaxy Halos (2012, background): “Mass estimates for the hot halo medium are < 1010 M within 100 kpc of the 10 disk (e.g., Collins et al., 2005; Anderson & Bregman, 2010; Yao et al., 2008), and the covering fraction is estimated to be > 60% (Fang et al., 2006; Sembach et al., 2003).”
A HUGE RESERVOIR OF IONIZED GAS AROUND THE MILKY WAY: ACCOUNTING FOR THE MISSING MASS? (2012, background): “The baryonic fraction fb of this warm-hot gas varies from 0.09−0.23 depending on the estimates of the virial mass of the Milky Way, from 1012M⊙ to 2.5×10 12M⊙ ((Anderson & Bregman 2010) and references therein), bracketing the Universal value of fb = 0.17.”
A BUDGET AND ACCOUNTING OF METALS AT z ∼ 0: RESULTS FROM THE COS-HALOS SURVEY (2013, background): “…measure toward pulsars in the Large Magellanic Cloud, the pressure confinement of HVCs in the Milky Way’s halo, the (lack of) O VII absorption in the halos of other galaxies, and X-ray surface brightness limits from individual galaxies (Anderson & Bregman 2010, though see also Fang et al. 2013).”
Gusty, gaseous flows of FIRE: Galactic winds in cosmological simulations with explicit stellar feedback (2015, background): “…the entire budget of ‘missing baryons’ in the CGM and IGM have generally come up short, particularly if it is required that the gas would be at least as hot as the virial temperature of L* galaxies (Bregman 2007; Anderson & Bregman 2010; Shull, Smith & Danforth 2012; Anderson, Bregman & Dai 2013).”
The COS-Halos Survey: Metallicities in the Low-redshift Circumgalactic Medium (2017, background): “…number abundance of 8.69 and that oxygen represents 70% of the mass in metals. virialized gas (T & 106 K) suggested that MhotCGM M bhalo (e.g. Anderson & Bregman 2010), researchers proposed that the halos hosting L∗ galaxies were deficient in baryons yielding the so-called galactic “missing…”
Probing Galactic Halos with Fast Radio Bursts (2019, background): “Standard treatment has been to assume that the total DM from Earth to the LMC DMLMC = 70pc cm−3 based on several of the pulsars showing approximately this value (e.g. Anderson & Bregman 2010).”
THE STRUCTURE OF THE MILKY WAY'S HOT GAS HALO (2013, methodology): “We are able to place a constraint on the metallicity of the gas between the Sun and the LMC based on the observed pulsar dispersion measure (Anderson & Bregman 2010).”
THE COS-HALOS SURVEY: PHYSICAL CONDITIONS AND BARYONIC MASS IN THE LOW-REDSHIFT CIRCUMGALACTIC MEDIUM (2014, background): “Traditionally, baryon counting in this regime has focused on a galaxy’s stars, cold ISM, and its hot X-ray halo gas (Bell et al. 2003; Klypin et al. 2011; Baldry et al. 2008; Yang et al. 2009; McGaugh et al. 2010; Anderson & Bregman 2010; Papastergis et al. 2012; Gupta et al. 2012).”
Introducing the Illustris Project: the evolution of galaxy populations across cosmic time (2014, background): “The observed limits are quite sensitive to model assumptions (Anderson & Bregman 2010), such that a far more detailed modelling of the exact conditions of this predicted gas is needed in order to give faithful predictions for its observability.”
CONSTRAINING THE MILKY WAY'S HOT GAS HALO WITH O vii AND O viii EMISSION LINES (2014, background): “This means that we match the hot halo DM estimate from Anderson & Bregman (2010) if we assume a halo gas metallicity of Z = 0.3 Z⊙.”
FORMING REALISTIC LATE-TYPE SPIRALS IN A ΛCDM UNIVERSE: THE ERIS SIMULATION (2011, background): “This leads to an estimate for the dispersion measure introduced by Galactic free electrons towards the LMC of DM ≈ 70 cm−3 pc (Anderson & Bregman 2010).”
The Circumgalactic Medium (2017, background): “Anderson & Bregman (2010) addressed directly the problem of whether hot gas could close the baryon budget for the Milky Way.”
THE BARYONIC TULLY–FISHER RELATION OF GAS-RICH GALAXIES AS A TEST OF ΛCDM AND MOND (2011, background): “While some hot gas is certainly present, it appears that its density is too low to make a substantial contribution here (Anderson & Bregman 2010).”
First results from the IllustrisTNG simulations: radio haloes and magnetic fields (2017, methodology): “We convert it to a background surface brightness by dividing by the effective telescope area, which we assume MNRAS 000, 1–26 (2017) to be 200 cm2 (see again Anderson & Bregman 2010).”