Contraction of dark matter galactic halos due to baryonic infall

“…Sancisi 1986; de Blok & McGaugh 1997; Bosma 1999; Gavazzi et al. 2007; Conroy et al. 2007; Dutton et al. 2011; Ruff et al. 2011; Suyu et al. 2012) and its interactions with baryonic matter (e.g., Blumenthal et al. 1986; Gnedin et al. 2004; Auger et al. 2010; Schulz, Mandelbaum, & Padmanabhan 2010).”

“Mechanisms such as dark matter contraction (e.g. Barnes & White 1984; Blumenthal et al. 1986; Gnedin et al. 2004) can drag dark matter towards the centre, steepening the profile.”

“In addition, baryonic effects may cause halo profiles to differ from the NFW form that we assume (e.g. Blumenthal et al. 1986; Governato et al. 2010; Pontzen & Governato 2012).”

“Here we consider two variants of AC—classic “strong” AC as originally proposed by Blumenthal et al. (1986), and a “weak” AC model proposed by Dutton et al. (2015), which they call “forced quenched.””

“The steeper profiles are likely due to baryonic effects such as adiabatic contraction (Blumenthal et al. 1986; Dutton et al. 2016), but it is notable because any theory put forth to explain the presence of shallow or cored dark matter profiles must also be able to account for steeper profiles in…”

“The dissipation of gas to the center of haloes is thought to only make the dark matter halo contract (Blumenthal et al. 1986; ⋆ dutton@nyu.edu Gnedin et al. 2004).”

“…the velocity dispersion profile in groups and clusters both due to the contraction and deepening of cluster potential (e.g., Zeldovich et al. 1980; Blumenthal et al. 1986; Gnedin et al. 2004; Sellwood & McGaugh 2005) and due to the overall redistribution of baryonic mass (e.g., Rudd et al. 2008).”

“Models can be constructed that reproduce these properties (Dutton & van den Bosch 2009), but they require efficient mass outflows (a.k.a. feedback), and the absence of dark halo adiabatic contraction (Blumenthal et al. 1986).”

“The radial scale length of the halo is 52kpc prior to applying adiabatic contraction according to (Blumenthal et al. 1986).”

“The overall impact of adiabatic contraction can be calculated iteratively using (Blumenthal et al. 1986): r[Mb(r) + MDM(r)] = riMi(ri), (6) where Mb(r) is the final baryon mass distribution, MDM(r) is the final dark matter distribution and Mi(ri) is the initial total mass distribution at an initial…”

“Although the deposition of the cold gas in the halo center may make the the halo contract (Blumenthal et al. 1986; Choi et al. 2006), our test with the same 1-”

“Thus it provides a complementary site to testing DM properties.”

“We have checked that such a profile is consistent with the expectation that the dark matter halo undergoes adiabatic contraction [33] due to the formation of the disk and bulge of stars.”

“Halos of sufficient mass are the natural sites of galaxy formation, with baryons cooling and condensing towards potential well minima (White & Rees 1978; Blumenthal et al. 1986).”

“A theoretical modification to the DM profile is expected to arise from adiabatic contraction (Blumenthal et al. 1986; Gnedin et al. 2007; Abadi et al. 2010), which causes the halo to become cuspier due to the gravitational influence of the baryons.”

“We renormalized the dark matter particle mass and adiabatically contracted the particle distribution to account for this extra contribution to the potential (e.g. Barnes & White 1984; Blumenthal et al. 1986; Mo, Mao & White 1998; Gnedin et al. 2004).”

“The parameter Γ = r f /ri is the contraction factor (Blumenthal et al. 1986), which can be numerically calculated via the conservation equation Mi(ri)ri = M f (r f )r f , (4) with Mi the initial (baryonic plus dark matter) mass distribution, and M f (r f ) = Mstar(r f ) + (1 − fgal)Mi(ri) (5) the…”

“[28] AC approach via more sophisticated analyses [29].”

“If so, the steeper cusps would reduce the strength of the actual AC recipe with respect to the classical prescriptions (Blumenthal et al. 1986; Gnedin et al. 2004) as reported elsewhere.”

“However, it is expected that baryonic condensation at the centers of dark matter haloes may modify the inner profiles significantly, particularly on the galaxy scale (White & Rees 1978; Blumenthal et al. 1986).”

“The distribution of stars, dark matter, and gas depends on processes such as gas cooling, which allows baryons to condense toward the center (e.g., Blumenthal et al. 1986; Gnedin et al. 2004; Sellwood & McGaugh 2005; Gustafsson et al. 2006; Pedrosa et al. 2009; Abadi et al. 2010; Sommer-Larsen &…”

“Blumenthal et al. (1986) estimated how dm would respond to adiabatic compression by considering the trivially computed case in which all particles are on circular orbits.”

“…all the previous quoted analysis do not study the possible effects produced by the presence of baryons on ρ/σ(r)3, whose effect is to shallow (El-Zant et al. 2001, 2004; Romano-Diaz et al. 2008) and to steepen (Blumenthal et al. 1986; Gnedin et al. 2004; Klypin et al. 2002) the dark matter profile.”

“E-mail: maccio@nyu.edu † E-mail: sc6459@nyu.edu (DM) that then tends to contract towards the center (e.g. Blumenthal et al. 1986; Gnedin et al. 2004; Abadi et al. 2010; Schaller et al. 2015), on the other hand vigorous gas outflows generate rapid change of the total gravitational potential and…”

“2012; Hilz et al. 2013), the interplay between luminous and dark components over different timescales (Blumenthal et al. 1986; Abadi et al. 2010; Zubovas & King 2012), as well as the initial conditions (Stiavelli & Bertin 1987; Nipoti et al. 2012; Remus et al. 2013) all leave imprints on the final…”

“…of stars is likely due to radiative cooling, which causes gas particles to lose energy, fall to the centre of the halo where the densities are high enough for star formation, adiabatically contract the DM and deepen the potential, a result that has been know since at least Blumenthal et al. (1986).”

“One formalism for analysing how a stellar component affects a dark matter profile is called adiabatic contraction (AC: Young 1980; Blumenthal et al. 1986; Gnedin et al. 2004; Sellwood & McGaugh 2005).”

“Whether originating from adiabatic compression (Blumenthal et al. 1986), supernovae winds (Navarro et al. 1996a), or ram-pressure stripping (Arraki et al. 2012), baryonic feedback has been shown to affect the dark matter profiles of galaxies by perturbing their baryons in a highly nonlinear way.”

“These relations have been used to constrain aspects of galaxy formation such as the growth of disks within dark matter halos (e.g. Fall & Efstathiou 1980; Blumenthal et al. 1986; Mo et al. 1998) and variations in the global massto-light ratios of elliptical galaxies (e.g. Faber 1987).”

“If the condensation process is slow comparing to the local dynamical time-scale of the dark matter halo, then the response of the dark matter halo can be described by an adiabatic contraction effect (e.g. Blumenthal et al. 1986; Gnedin et al. 2004; Gustafsson, Fairbairn & Sommer-Larsen 2006).”

“…disc should be Rd λ√ 2 fcfRfjRh. (1) Here fc and fR are factors of order unity that provide minor corrections that account for adiabatic contraction (Blumenthal et al. 1986; Shankar et al. 2017) and disc self-gravity, and Rh is the dark matter halo radius Rh = ( 3Mh 4π ρ ) 1 3 , (2) where is the…”

“However, if the timescale for galaxy formation is long compared to the halo dynamical time then the halo is expected to contract adiabatically as a result of baryonic collapse (e.g. Blumenthal et al. 1986; Gnedin et al. 2004).”

“…2004) – may have altered the inner density profile in some complicated way not taken into account in the simple scenario of adiabatic contraction (Blumenthal et al. 1986; Gnedin et al. 2004; Sellwood & McGaugh 2005), which is often advocated to argue that baryons should increase – and not…”

“Following Blumenthal et al. (1986), we model this compression by assuming that dark matter particles conserve the adiabatic invariant quantity j during the process of baryonic collapse and that there is no shell crossing [dM(j)/dt = 0].”

“…work focused on galaxy clusters, while the latter study used only the de Vaucouleurs stellar mass profile and the NFW DM profile without taking into account halo contraction effects by baryonic physics (e.g., Blumenthal et al. 1986; Gnedin et al. 2004; Sellwood & McGaugh 2005; Gnedin et al. 2011).”

“In particular, in elliptical galaxies baryonic feedback (Dubois et al. 2013) and virialisation of the infalling material (Lackner & Ostriker 2010) can produce a shallower density profile, whereas a slow mass build-up tends to steepen it (Blumenthal et al. 1986; Lackner & Ostriker 2010).”

“The density profile of the dark matter halo is adiabatically contracted in response to baryonic infall (Blumenthal et al. 1986).”

“The effects of the baryonic infall are treated here following the approach of the adiabatic compression (Blumenthal et al. 1986; Flores et al. 1993; Mo et al. 1998).”

“Let me start by describing the standard adiabatic contraction model by Blumenthal et al. (1986); Ryden & Gunn (1987), which assumes any structure as made of concentric spherical shells which contract isotropically by conserving angular momentum.”

“The baryonic mass distribution affects a galaxy’s circular velocity profile significantly, while also changing the equilibrium configuration of the host dark matter halo through adiabatic contraction (Blumenthal et al. 1986).”

“The latter effect is generally modelled as adiabatic contraction (Blumenthal et al. 1986; Gnedin et al. 2004).”

“The extreme DM densities shown in Figure 4 may be present within the inner parsec of our Galaxy, according to models that account for the effect of the baryons on the DM halo via adiabatic contraction (Blumenthal et al. 1986; Gnedin et al. 2004).”

“What is more, studies (e.g., Blumenthal et al., 1986; Kochanek et al., 2001) of the effect of baryonic infall on the dark matter distribution conclude that the dark matter is adiabatically compressed by the cooled baryons during the formation of the central galaxy and is drawn towards the center;…”

“The original specific and comprehensive work on this matter is by Blumenthal et al. (1986).”

“However, the baryons themselves can modify the mass profile as a result of adiabatic contraction (Blumenthal et al. 1986), which raises the peak velocity – an effect that must be taken into account when comparing theory with observations.”

“6Note that our analytic model for the SIDM density profile does not account for adiabatic contraction of the halo [64, 65], which can have an effect for log10 M?/Mvir & −2 and increase the inner density of the DM profile.”

“The dark halos of both systems followed the Navarro et al. (1997) density profile and have been adiabatically contracted to account for the presence of the stellar component (see e.g., Blumenthal et al. 1986; Mo et al. 1998).”

“Indeed it has been claimed [20, 21] that when baryonic gas is taken into account, it falls to the central region, modifying the gravitational potential.”

“A non-exhaustive list of ways by which baryons can change the distribution of dark matter includes: adiabaticcontraction (Blumenthal et al. 1986, Gnedin et al. 2004, Sellwood & Mc- Gaugh 2005), the influence of bars (e.g., Weinberg & Katz 2002, McMillan & Dehnen 2005, Sellwood 2008), or the…”

“For a standard NFW profile we take γ = 1, however when including significant baryonic matter, such as in the central regions of galaxies, the DM distribution is expected to have a more centrally peaked profile [49, 50].”

“This process is called ’adiabatic contraction’ (Blumenthal et al., 1986), and it can lead to a density increase of several orders of magnitude in the very center of the halo. As the annihilation rate scales quadratically with the density the corresponding energy input and ionization rate may become large enough to inf…”

“When processes other than gravitational are involved in mass assembly (for example, cooling or heating), the dark matter density profiles could be modified (see Blumenthal et al. 1986; Dalcanton et al. 1997; Tissera & Domı́nguezTenreiro 1998; Gnedin et al. 2004).”

“…with dark matter only or non-radiative gas, predominantly due to the more spherical shape of the clusters resulting from the condensing of baryons and the subsequent response from the dark matter component (Blumenthal et al. 1986; Gnedin et al. 2004; Kazantzidis et al. 2004; Bryan et al. 2012).”

“The shape of dark matter halos can be affected by baryons by either adiabatic contraction (Blumenthal et al. 1986), or expansion (see Pontzen & Governato 2014, for a review).”

“Genzel et al. (2020) performed fits with and without adiabatic contraction being effective (see Blumenthal et al. 1986).”

“The density profile of the halo, however, is modified to account for the gravitational response to galaxy formation (most often modelled as adiabatic contraction, see Blumenthal et al. 1986).”

“The Blumenthal model treats a halo as spherically symmetric, which undergoes homologous contraction – spherical shells that contact in radius but do not cross each other, with particle Figure A1.”

“G A ] contraction (Blumenthal et al. 1986) and the self gravitational effects of the disk.”