Contraction of dark matter galactic halos due to baryonic infall

“…qualitative understanding of how profile characteristics may affect galactic disc formation, we may assume that an exponential disc forms by the adiabatic contraction of gas inside the dark-matter halo (Blumenthal et al. 1986; Flores et al. 1993; Dalcanton, Spergel, & Summers 1997; Mo et al. 1998).”

“This adiabatic invariance method for calculating the response of a halo or spheroid to the disk was originally developed and applied by Barnes & White (1984), Blumenthal et al. (1986) and Ryden & Gunn (1987).”

“The simplest model for this effect assumes adiabatic contraction within a spherical halo (e.g. Barnes 1984; Blumenthal et al. 1986) and has often been adopted in galaxy formation models (e.g. Mo et al. 1998; Cole et al. 2000).”

“Our approach is based on work by Blumenthal et al. (1986), Flores et al. (1993) and Mo, Mao & White (1998, hereafter MMW98), and is described in detail in Somerville et al. (2008, hereafter S08).”

“We neglect the modification of the inner profile of the dark matter due to the infall of the baryons, which will tend to lead to smaller disks (Blumenthal et al. 1986; Flores et al. 1993; Mo, Mao, & White 1998).”

“Blumenthal et al. (1986) addressed the rotation curves of disk galaxies in the context of the CDM hierarchical formation scenario, assuming ∼ 10% of the mass in the gas component (Blumenthal et al. 1984).”

“The standard modelf suchadiabatic contraction assumes that DM particles are predominantly on circular orbits, and for each shell of DM at radiusr the product of the radius and the enclosed massrM (r) is conserved (Blumenthal et al. 1986).”

“…expected from the effect of adiabatic contraction galaxies with significant in-situ star formation, i.e. more dissipation, live in more concentrated halos (Blumenthal et al. 1986; Dubinski 1994; Jesseit et al. 2002; Debattista et al. 2008; Gnedin et al. 2004; Abadi et al. 2010; Auger et al. 2010).”

“Usually this is thought to take place in the form of a process called “adiabatic contraction” (Blumenthal et al. 1986), which has the effect of contracting the inner dark matter distribution (increasing the density).”

“It should be noted that Vmax used here will not correspond directly to Vmax observed in, for example, the Tully-Fisher relation because dissipationless simulations do not take into account the effect of baryon condensation on Vmax (e.g., Blumenthal et al. 1986).”

“If we fit an adiabatically contracted NFW profile (using the prescription of Blumenthal et al. 1986 and Mo et al. 1998) and the same disk and bulge as in Eqn 11 and Eqn 12, taking the concentration parameter (c) and virial mass (Mvir) of the NFW profile as independent parameters (i.e., we do not…”

“These simulations show that galaxy condensation leads to a compression of the inner dark halo which is similar to but somewhat weaker than that predicted by simple adiabatic contraction models (Barnes & White 1984; Blumenthal et al. 1986; Gnedin et al. 2004).”

“Another possibility is that halo contraction due to the condensation of baryons at the center of the halo (Blumenthal et al. 1986) has played an important role.”

“The effects of baryonic infall are treated following same approach as that of Blumenthal et al. (1986), Flores et al. (1993), and Mo, Mao, & White (1998).”

“…of Cambridge, Madingley Road, Cambridge CB30HA 3 Hubble Fellow volving baryons might alter the original structure of a dark matter halo (e.g., Blumenthal et al. 1986; Navarro et al. 1996; El-Zant et al. 2001; Gnedin et al. 2004; Tonini et al. 2006; Governato et al. 2010; Pontzen &…”

“…matter halo, because of the contribution of the baryons to the total circular velocity and the contraction of the dark matter halo during the formation of the disk (see e.g., Barnes & White 1984; Blumenthal et al. 1986; Flores et al. 1993; Mo, Mao & White 1998; Mo & Mao 2000; van den Bosch 2002).”

“Early models of galaxy formation assumed halo adiabatic contraction due to the infall of baryons into the halo center (Blumenthal et al. 1986; Mo et al. 1998), which gives typically Vmax ≃ 1.6–1.8Vh for a wide range of halo concentrations c = [5, 30] and disk mass fractions md = [0.02, 0.2].”

“We use only the Blumenthal et al. (1986) algorithm for simplicity: as we demonstrate in x 4.3.1, the model parameters do not substantially change our results.”

“While some progresshas been made toward understanding these e ects (e.g., Blumenthal et al. 1986), our understanding of the77 physical basis of the TF relation remains schematic at best.”

“…inner regions of massive ellipticals can contract into an increasingly denser structure, if significant mass in dissipational gas is accreted (e.g. Blumenthal et al. 1986; Ryden & Gunn 1987; Navarro & Benz 1991; Dubinski 1994; Jesseit, Naab & Burkert 2002; Gnedin et al. 2004; Kazantzidis et al.…”

“On the other hand, adiabatic contraction (e.g. Blumenthal et al. 1986) thought to be associated with the formation of disc galaxies, actually tends to increase the halo concentration, and it remains to be seen whether the above mentioned processes are strong enough to undo this contraction and…”

“…theory (Peebles 1969), and by incorporating these results subsequent work explained the flat rotation curves and sizes of disk galaxies through the combination of gas dissipation, halo spin, and the adiabatic response of dark matter to baryonic infall (Blumenthal et al. 1986; Mo et al. 1998).”

“, if all particles are placed initially on circular orbits), the adiabatic invariants drive a rather sharp enhancement of the dark matter concentration in the central region of the Galaxy [50].”

“For example, as gas cools to the central region of galaxy haloes, it adiabatically contracts dark matter to the centre (e.g. Blumenthal et al. 1986; Gnedin et al. 2004).”

“Solutions in Baryonic Physics? When the cusp-core problem was first identified, the conventional lore was that including baryonic physics would only exacerbate the problem by adiabatically contracting the dark matter density distribution (6, 40).”

“For instance, a steeper profile (ρDM ∝ r −α with α > 1) could possibly arise from the adiabatic contraction (Blumenthal et al. 1986; Gnedin et al. 2004) of a NFW halo which is found in pure dark matter N-body cosmological simulations made without taking into account the complex physics of baryons.”

“Dark matter can contract in response to gas condensation (Young, 1980; Blumenthal et al., 1986), or even expand if energetic supernovae, or active galactic nuclei eject a significant amount of mass (Navarro et al., 1996a).”

“We note that the dark mass distribution responds sensitively to the concentration of luminous material (Barnes & White 1984; Blumenthal et al. 1986), so it is possible that a less massive (or less concentrated) luminous component would result in a less concentrated dark matter component, in better…”

“(c) The DM halo is assumed to initially have an NFW profile, but then to def rm adiabatically in response to the gravity of the disk and spheroid, assuming that each spherical shell adiabatically conserves its value of rVc(r) (Barnes & White 1984; Blumenthal et al. 1986).”

“We assume that the collapse of the baryons within the dark halo is slow, and correct for adiabatic contraction of the halo following the procedure outlined in Barnes & White (1984), Blumenthal et al. (1986) and Flores et al. (1993).”

“As a result the half-mass radius of the galaxy decreases similar to adiabatic contraction (Blumenthal et al. 1986; Jesseit et al. 2002).”

“The presence of the super-massive black hole [57] or adiabatic contraction [58–61] can steepen the inner profile, which is here effectively taken into account by allowing that α > 1.”

“This is done by assuming the disk is assembled slowly and the angular momentum of dark matter particles is an adiabatic invariant (Blumenthal et al. 1986; Flores et al. 1993).”

“In addition, since the inner part of dark matter halos is actually populated by baryons that collapse through dissipative processes, dark halos should contract, thus exacerbating any preexisting cusp (Blumenthal et al. 1986; Gnedin et al. 2004; Abadi et al. 2010).”

“One of the early models of the effects of baryon collapse on the structure of a halo, making use of adiabatic invariants, concluded that haloes would become denser in their centres (Blumenthal et al. 1986).”

“In order to estimate the effect of baryonic contraction on the dark matter profiles, we follow Blumenthal et al. (1986) to calculate the final dark matter mass distribution Mx, given the final baryon mass distribution mb and the initial total mass distribution Mi: r[mb(r) +Mx(r)] = riMi(ri) =…”

“…by the tidal field of the central object, and their gas is likely to shock against the gas in and around 9 This picture was further developed by Blumenthal et al. (1986), Flores et al. (1993), Mao, Mo, & White (1998), and Mo, Mao, & White (1998), who took into account the response of the dark…”

“The original formulation of this argument for galaxies was given by Blumenthal et al. (1986) and has been used extensively ever since.”

“If the radial mass profiles of baryons and dark matter were initially the same, then adiabatic invariance in the simplest approximation (Blumenthal et al. 1986) relates the initial and final radii of the mass shells ri and rf , respectively, by rf [ M⋆(rf) +MDM(rf) ] = riMi(ri).”

“Other simpler adiabatic contraction approximations, such as those used by Blumenthal et al. (1986) and Gnedin et al. (2004), tend systematically to under- or overpredict the halo contraction (e.g. Abadi et al. 2010; Duffy et al. 2010; Pedrosa et al. 2010; Dutton et al. 2016; Artale et al. 2019).”

“We initialize the size of the disk according to the Mo et al. (1998) formalism for dissipational disk galaxy formation (see also Fall&Efstathiou 1980;Blumenthal et al. 1986) assuming the disk contains a fraction of the total galaxy angular momentum equal to its mass fraction, which we set to md…”

“The dark halo is adiabatically contracted in response to the formation of a stellar disk in its central part (Blumenthal et al. 1986; Mo et al. 1998).”

“Unlike individual galaxies, massive clusters are not expected to be significantly affected by baryonic gas cooling (Blumenthal et al. 1986; Mead et al. 2010; Duffy et al. 2010; Lau et al. 2011; Blanchard et al. 2013) because the majority (∼ 80”

“…742:16 (23pp), 2011 November 20 Trujillo-Gomez et al. (A color version of this figure is available in the online journal.) compression model of Blumenthal et al. (1986) which produces the largest increase in the density of the DM. (The full and dashed curves were already shown in Figure 4.)”

“[67] would give rise to even larger values of α, see e.”

“One possible situation, known as adiabatic contraction, is that as baryons sink dissipatively into the bottom of the total matter potential they are likely to steepen the underlying DM distribution simply through gravitational processes (Blumenthal et al. 1986).”

“Based on the local density and temperature estimated from the pair separation and relative velocity, the colliding pair may be merged together (Blumenthal et al 1986).”

“In real galaxies, it is thought that the dark matter halo willadiabatically compress in response to the dissipational formation of the disk (e.g., Blumenthal et al. 1986).”

“It is well established that baryons affect DM density profiles of haloes in galaxies (e.g. Blumenthal et al. 1986; Navarro et al. 1996a; El-Zant et al. 2001; Gnedin et al. 2004; Read & Gilmore 2005; Goerdt et al. 2006, 2010; Mashchenko et al. 2006; Read et al. 2006; Tonini et al. 2006; Romano-D´ıaz…”

“Including interactions of dark matter with baryons (Blumenthal et al., 1986) or with a central black hole (Gondolo and Silk, 1999) generically tend to enhance the cusp (e.g. Sellwood and McGaugh, 2005).”

“If the potential variations due to the dissipating baryons occur slowly compared to the orbital period of a dark matter particle in circular orbit, then the end state of the system is independent of the path taken (Blumenthal et al. 1986; Gnedin et al. 2004; Abadi et al. 2010).”

“…of isothermal cluster mass distributions in these early Ñow studies was motivated largely by analogy to the Milky Way and the evidence that cluster mass-tolight ratios increase outward from the core (e.g., Faber & Gallagher 1979), as well as by theoretical modeling (e.g., Blumenthal et al. 1986).”

“…monolithic collapse (Eggen, Lyndon-Bell & Sandage 1962; Sandage 1990), hierarchical merging (White & Rees 1978; Fall & Efstathiou 1980), gas infall (Blumenthal et al. 1986), satellite accretion (Searle & Zinn 1978), secular evolution (see review by Kormendy & Kennicutt 2004) and splashback…”

“Within this radius, the dark matter profile steepens, presumably as a result of contraction of the dark matter halo due to the condensation of baryons (e.g., Blumenthal et al. 1986; Gnedin et al. 2004; Duffy et al. 2010).”

“In assessing the role of baryons on their host halos, much of the focus of the theoretical literature has been on the halo contraction (e.g., Blumenthal et al. 1986; Gnedin et al. 2004, 2011) expected to result from a central dissipative buildup of baryons.”

“…2006; Peirani, Kay & Silk 2008; Pontzen & Governato 2012; Teyssier et al. 2013), in conjunction with the adiabatic expansion of DM and stars (Blumenthal et al. 1986; Gnedin & Zhao 2002; Gnedin et al. 2004) produced by the decrease of the gas density due to AGN feedback in the centre of DM…”

“It appears that compression of the central dark matter due to baryonic infall (e.g., Blumenthal et al. 1986; Gnedin et al. 2004, 2011) is an important effect in early-type galaxies, but this is apparently largely offset by other effects in late-type galaxies (e.g., Dutton et al. 2007;…”

“In contrast, a major focus in the theoretical literature has been the “adiabatic contraction” (AC) formalism (Blumenthal et al. 1986) and its modified versions (e.g., Gnedin et al. 2004, 2011), which predict the steepening of the inner DM profile resulting from the slow cooling and central…”

“The relation using the standard (Blumenthal et al. 1986) adiabatic invariant, rM(r), is given by the blue solid line.”

“We make the assumption that the baryonic collapse is slow, and take this adiabatic contraction of the dark halo into account following the procedure in Barnes & White (1984), Blumenthal et al. (1986) and Flores et al. (1993).”

“(18), using the standard prescription of Blumenthal et al. (1986).”