INTEGRALconstraints on primordial black holes and particle dark matter

Abstract

The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite has yielded unprecedented measurements of the soft gamma-ray spectrum of our Galaxy. Here we use those measurements to set constraints on dark matter (DM) that decays or annihilates into photons with energies E ≈ 0.02-2 MeV. First, we revisit the constraints on particle DM that decays or annihilates to photon pairs. In particular, for decaying DM, we find that previous limits were overstated by roughly an order of magnitude. Our new, conservative analysis finds that the DM lifetime must satisfy τ ≳ 5 × 10 26 s × ðm χ =MeVÞ −1 for DM masses m χ ¼ 0.054-3.6 MeV. For MeV-scale DM that annihilates into photons INTEGRAL sets the strongest constraints to date. Second, we target ultralight primordial black holes (PBHs) through their Hawking radiation. This makes them appear as decaying DM with a photon spectrum peaking at E ≈ 5.77=ð8πGM PBH Þ, for a PBH of mass M PBH. We use the INTEGRAL data to demonstrate that, at 95% C.L., PBHs with masses less than 1.2 × 10 17 g cannot comprise all of the DM, setting the tightest bound to date on ultralight PBHs.

Primordial black holes as a dark matter candidate

“…The SPI/INTEGRAL limits on this line lead to limits on the PBH fraction which are similar to the gamma-ray limit for 10 16 g M PBH 10 17 g [158,159]. There are somewhat tighter constraints (that exclude f PBH = 1 up to M PBH ≈ 2 × 10 17 g) from INTEGRAL measurements of the Galactic diffuse flux in the MeV range [160]. There are also constraints from Super-Kamiokande measurements of the diffuse neutrino background [178].…”

“…Constraints on the fraction of DM in the form of PBHs f PBH , with mass M PBH , or in the form of compact objects, f CO , with mass M CO for each of the different types of constraint.In each case the excluded regions are shaded. Top left: evaporation constraints on PBHs (section 3.1): extragalactic gamma-ray background[55], CMB[153,154], dwarf Galaxy heating[155], EDGES 21 cm[156], Voyager e ±[157], 511 keV gammaray line[158,159] and the MeV Galactic diffuse flux[160]. Top middle: gravitational lensing constraints on compact objects (section 3.3): stellar microlensing (MACHO[161], EROS[12], OGLE[162], HSC[163]), Icarus lensing event[164], and supernovae magnification distribution[165].…”

Observability of dark matter substructure with pulsar timing correlations

“…This was modeled by an abrupt fall-off in density outside the scale radius r s in Eq. (54). For these subhalos, M = M s where M s is the mass contained inside the radius r s .…”

Neutrino and Positron Constraints on Spinning Primordial Black Hole Dark Matter

“…The lifetime of PBHs with masses less than 2.5 × 10 −19 M ⊙ (3.5 × 10 −19 M ⊙ ) for nonrotating (maximally rotating) black holes is less than the age of the Universe and it cannot contribute to the DM density [51][52][53][54]. The leading constraints on low-mass PBHs arise from the observation of photons [8,55,56], cosmic rays [9], and the 511 keV gamma-ray line [57,58]. Astrophysical observations of neutrinos have been used to constrain particle DM [59,60] and here we study its implications for PBHs.…”