Excluding Light Asymmetric Bosonic Dark Matter

Abstract

We argue that current neutron star observations exclude asymmetric bosonic non-interacting dark matter in the range from 2 keV to 16 GeV, including the 5-15 GeV range favored by DAMA and CoGeNT. If bosonic WIMPs are composite of fermions, the same limits apply provided the compositeness scale is higher than ∼ 10 12 GeV (for WIMP mass ∼ 1 GeV). In case of repulsive self-interactions, we exclude large range of WIMP masses and interaction cross sections which complements the constraints imposed by observations of the Bullet Cluster. Apart from direct searches, constraints on WIMPs can be set by observations of compact objects such as white dwarfs and neutron stars [4][5][6][7][8][9][10][11][12]. These constraints can be grouped in two types. The first type targets WIMPs that can annihilate inside the star producing heat that can change the thermal evolution of the star [5]. WIMPs of this type can arise in supersymmetric extensions of the SM (see [13] and references therein), or in Technicolor models [14]. Constraints of the second type target asymmetric DM models. In these models the annihilation of DM in the present-day Universe is impossible because only particles, and no anti-particles (hence the term "asymmetric") remain [15][16][17][18][19]. An additional bonus in these models is that the asymmetry of WIMPs might be linked through sphalerons with the baryon asymmetry [16,18], which can explain the today's ratio Ω DM /Ω B ∼ 5 provided the WIMP has a mass around 5 GeV. Note that this value is not far from the one suggested by DAMA and CoGeNT. In view of this coincidence, the models with WIMP masses in the GeV range have become quite popular.Since in the asymmetric DM models WIMPs cannot annihilate, if a large number of them is accreted during the lifetime of a neutron star, they may collapse forming a small black hole inside the star that eventually destroy the latter. Therefore the existence of old neutron stars can impose constraints on the properties of asymmetric WIMPs. In fact, in the case of fermionic asymmet-

Asymmetric inelastic inert doublet dark matter from triplet scalar leptogenesis

“…Over the years a large number of possibilities for asymmetric DM have been proposed . The most stringent constraint on asymmetric DM candidate comes from neutron stars and white dwarfs in globular cluster, which exclude asymmetric scalar DM below 16 GeV [39,40]. In this paper we consider a relatively heavy asymmetric scalar doublet DM (SDDM) whose stability is provided by a remnant Z 2 flavour symmetry inspired by the Inert Doublet Model [41][42][43][44][45].…”

Composite millicharged dark matter

“…The value is sufficiently small to enable the dark pion to evade constraints on dark matter self-interactions imposed by the bullet cluster [36], or galaxy ellipticity [37,38], or old neutron stars [39][40][41]. However, the cross section being of the order of picopbarn or even higher (if one selects a smaller f π and/or larger m π0 ), can potentially have an effect on how warm the dark matter candidate is, and on the inner dark matter halo profile.…”

(Not)-constraining heavy asymmetric bosonic dark matter

“…(1) This amount of WIMPs can be easily accumulated even by nearby known old neutron stars with the standard assumption about dark matter density near the Earth. As it was pointed out in [23], once ∼ 10 36 WIMPs have been accreted and thermalized within the neutron star, a Bose-Einstein condensate (BEC) forms and all newly accreted WIMPs fall into the ground state. This state is very compact, so the WIMPs in the condensate start to self-gravitate way before the condition of Eq.…”

“…In this case, annihilation of trapped weakly interacting massive particles (WIMPs) inside a compact star can produce significant amount of heat that can change the thermal evolution of the star at later times. As a result, stars old enough to be quite cold might maintain higher temperature due to the released heat.The second type of constraints is related to asymmetric dark matter [14,21,[23][24][25][26][27]. In this case WIMPs carry a conserved quantum number and there is an asymmetry between the populations of WIMPs and anti-WIMPs, so that the annihilation is impossible in the present-day universe where only the WIMPs remain.…”

“…The second type of constraints is related to asymmetric dark matter [14,21,[23][24][25][26][27]. In this case WIMPs carry a conserved quantum number and there is an asymmetry between the populations of WIMPs and anti-WIMPs, so that the annihilation is impossible in the present-day universe where only the WIMPs remain.…”