Dark matter protohalos in a nine parameter MSSM and implications for direct and indirect detection

Abstract

Dark matter protohalos in a nine parameter MSSM and implications for direct and indirect detection Diamanti, R.; Cabrera Catalan, M.E.; Ando, S. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 24 Mar 2019Dark matter protohalos in a nine parameter MSSM and implications for direct and indirect detection We study how the kinetic decoupling of dark matter within a minimal supersymmetric extension of the standard model, by adopting nine independent parameters (MSSM-9), could improve our knowledge of the properties of the dark matter protohalos. We show that the most probable neutralino mass regions, which satisfy the relic density and the Higgs mass constraints, are those with the lightest supersymmetric neutralino mass around 1 TeV and 3 TeV, corresponding to Higgsino-like and winolike neutralino, respectively. The kinetic decoupling temperature in the MSSM-9 scenario leads to a most probable protohalo mass in a range of M ph ∼ 10 −12 -10 −7 M ⊙ . The part of the region closer to ∼2 TeV gives also important contributions from the neutralino-stau coannihilation, reducing the effective annihilation rate in the early Universe. We also study how the size of the smallest dark matter substructures correlates to experimental signatures, such as the spin-dependent and spin-independent scattering cross sections, relevant for direct detection of dark matter. Improvements on the spin-independent sensitivity might reduce the most probable range of the protohalo mass between ∼10 −9 M ⊙ and ∼10 −7 M ⊙ , while the expected spindependent sensitivity provides weaker constraints. We show how the boost of the luminosity due to dark matter annihilation increases, depending on the protohalo mass. In the Higgsino case, the protohalo mass is lower than the canonical value often used in the literature (∼10 −6 M ⊙ ), while hσvi does not deviate from hσvi ∼ 10 −26 cm 3 s −1 ; there is no significant enhancement of the luminosity. On the contrary, in the wino case, the protohalo mass is even lighter, and hσvi is two orders of magnitude larger; as its consequence, we see a substantial enhancement of the luminosity.

Smallest halos in thermal wino dark matter

“…[95] by the present dark matter mass density ρ χ;0 since the baryon does not collapse into such a small halo even with cold dark matter due to gas pressure. Our naïve estimate is already different from an estimate in the previous literature [77] only considering elastic processes, where T kd ∼ 1 GeV and M kd ∼ 10 −11 M ⊙ . However, as we see in the next section, the true evolution of the density contrast is more complicated than naïvely expected due to the overshooting phenomenon.…”

“…There have been attempts to determine the smallest halos in supersymmetric dark matter [71][72][73][74][75][76] and even particularly in wino dark matter [77]. However, previous literatures did not appreciate the fact that what keeps wino dark matter in kinetic equilibrium with primordial plasma is not elastic processes but inelastic ones unlike typical bino dark matter.…”

Characterization of subhalo structural properties and implications for dark matter annihilation signals

“…The minimum halo mass depends on the free-streaming of DM particles from high to low density regions (Zybin et al 1999;Hofmann et al 2001;Berezinsky et al 2003;Green et al 2005) and on the effect of acoustic oscillations (Loeb & Zaldarriaga 2005;Bertschinger 2006). These processes depend on the particle physics and cosmological models (Profumo et al 2006;Bringmann & Hofmann 2007;Bringmann 2009;van den Aarssen et al 2012;Cornell & Profumo 2012;Gondolo et al 2012;Cornell et al 2013;Shoemaker 2013;Diamanti et al 2015) and hence, the minimum mass is very uncertain, 8 with possible values within Mmin = 10 −12 − 10 −4 M . In what follows, we set it to Mmin = 10 −6 M .…”

The 21 cm signal and the interplay between dark matter annihilations and astrophysical processes

“…where dn/dM , as in the previous sections, is the comoving halo mass function, ρ(r) is the DM halo density profile, which also depends on the halo mass and redshift, and R vir is the halo virial radius. The value of the minimum halo mass, M min , depends on the DM particle properties and on the cosmological model [147][148][149][150][151][152][153][154][155][156][157][158][159][160][161][162][163][164][165][166] and thus, it can lie within a wide range. Here we consider three representative values, M min = 10 −12 M , 10 −6 M and 10 −3 M .…”