Search Publications
Primordial black holes as a dark matter candidate
Kavanagh, Bradley J.; Green, Anne M.
The detection of gravitational waves from mergers of tens of Solar mass black hole binaries has led to a surge in interest in primordial black holes (PBHs) as a dark matter candidate. We aim to provide a (relatively) concise overview of the status of PBHs as a dark matter candidate, circa Summer 2020. First we review the formation of PBHs in the e…
Repeating behaviour of FRB 121102: periodicity, waiting times, and energy distribution
Kramer, M.; Seymour, A.; Scholz, P. +7 more
Detections from the repeating fast radio burst FRB 121102 are clustered in time, noticeable even in the earliest repeat bursts. Recently, it was argued that the source activity is periodic, suggesting that the clustering reflected a not-yet-identified periodicity. We performed an extensive multiwavelength campaign with the Effelsberg telescope, th…
Direct Detection of Hawking Radiation from Asteroid-Mass Primordial Black Holes
Profumo, Stefano; Coogan, Adam; Morrison, Logan
Light, asteroid-mass primordial black holes, with lifetimes in the range between hundreds to several millions times the age of the Universe, are well-motivated candidates for the cosmological dark matter. Using archival COMPTEL data, we improve over current constraints on the allowed parameter space of primordial black holes as dark matter by stud…
Near future MeV telescopes can discover asteroid-mass primordial black hole dark matter
Muñoz, Julian B.; Ray, Anupam; Laha, Ranjan +1 more
Primordial black holes (PBHs), formed out of large overdensities in the early Universe, are a viable dark matter (DM) candidate over a broad range of masses. Ultralight, asteroid-mass PBHs with masses around 1017 g are particularly interesting as current observations allow them to constitute the entire DM density. PBHs in this mass rang…
The ART-XC telescope on board the SRG observatory
Sunyaev, R.; Krivonos, R.; Sazonov, S. +59 more
Astronomical Roentgen Telescope - X-ray Concentrator (ART-XC) is the hard X-ray instrument with grazing incidence imaging optics on board the Spektr-Roentgen-Gamma (SRG) observatory. The SRG observatory is the flagship astrophysical mission of the Russian Federal Space Program, which was successively launched into orbit around the second Lagrangia…
A bright γ-ray flare interpreted as a giant magnetar flare in NGC 253
Mitrofanov, I.; Hurley, K.; von Kienlin, A. +33 more
Soft γ-ray repeaters exhibit bursting emission in hard X-rays and soft γ-rays. During the active phase, they emit random short (milliseconds to several seconds long), hard-X-ray bursts, with peak luminosities1 of 1036 to 1043 erg per second. Occasionally, a giant flare with an energy of around 1044 to 10…
Primordial black holes and stochastic gravitational wave background from inflation with a noncanonical spectator field
Cai, Rong-Gen; Chen, Chao; Fu, Chengjie
We investigate the enhancement of the curvature perturbations in a single-field slow-roll inflation with a spectator scalar field kinetically coupled to the inflaton. The coupling term with a periodic function of inflaton triggers the exponential growth of the spectator field perturbations, which indirectly amplifies the curvature perturbations to…
Primordial black holes and scalar-induced secondary gravitational waves from inflationary models with a noncanonical kinetic term
Gao, Qing; Gong, Yungui; Yi, Zhu +1 more
With the enhancement mechanism provided by a noncanonical kinetic term with a peak, the amplitude of primordial curvature perturbations can be enhanced by seven orders of magnitude at small scales while keeping to be consistent with observations at large scales. The peak function and inflationary potential are not restricted in this mechanism. We …
Identification of a Local Sample of Gamma-Ray Bursts Consistent with a Magnetar Giant Flare Origin
Cenko, S. B.; Hurley, K.; Ridnaia, A. +23 more
Cosmological gamma-ray bursts (GRBs) are known to arise from distinct progenitor channels: short GRBs mostly from neutron star mergers and long GRBs from a rare type of core-collapse supernova (CCSN) called collapsars. Highly magnetized neutron stars called magnetars also generate energetic, short-duration gamma-ray transients called magnetar gian…
INTEGRAL x-ray constraints on sub-GeV dark matter
Pinetti, Elena; Fornengo, Nicolao; Cirelli, Marco +1 more
Light dark matter (DM), defined here as having a mass between 1 MeV and about 1 GeV, is an interesting possibility both theoretically and phenomenologically, at one of the frontiers of current progress in the field of DM searches. Its indirect detection via gamma rays is challenged by the scarcity of experiments in the MeV-GeV region. We look ther…