Search Publications
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…
Accretion Geometry in the Hard State of the Black Hole X-Ray Binary MAXI J1820+070
Zdziarski, Andrzej A.; Szanecki, Michał; Niedźwiecki, Andrzej +2 more
We study X-ray spectra from the outburst rise of the accreting black hole binary MAXI J1820+070. We find that models having the disk inclinations within those of either the binary or the jet imply significant changes of the accretion disk inner radius during the luminous part of the hard spectral state, with that radius changing from >100 to ∼1…
Probing Kilonova Ejecta Properties Using a Catalog of Short Gamma-Ray Burst Observations
Berger, E.; Smith, N.; Chornock, R. +11 more
The discovery of GW170817 and GRB 170817A in tandem with AT 2017gfo cemented the connection between neutron star mergers, short gamma-ray bursts (GRBs), and kilonovae. To investigate short GRB observations in the context of diverse kilonova behavior, we present a comprehensive optical and near-IR catalog of 85 bursts discovered over 2005-2020 on t…
Enhanced Localization of Transients Based on a Novel Cross-correlation Method
Huang, Y.; Zhang, S. N.; Zhao, Y. +12 more
Locating gamma-ray transients including gamma-ray bursts (GRBs) and soft gamma repeater (SGR) bursts is of great importance in multi-messenger and multi-wavelength astronomy, such as guiding optical and radio follow-up observations and evaluating the association of a GRB with a gravitational wave or an SGR with a galaxy or fast radio burst (FRB). …
Hybrid Comptonization and Electron-Positron Pair Production in the Black-hole X-Ray Binary MAXI J1820+070
Poutanen, Juri; Zdziarski, Andrzej A.; Szanecki, Michał +6 more
We study X-ray and soft gamma-ray spectra from the hard state of the accreting black-hole binary MAXI J1820+070. We perform an analysis of two joint spectra from NuSTAR and INTEGRAL, covering the range of 3-650 keV, and of an average joint spectrum over the rise of the hard state, covering the 3-2200 keV range. The spectra are well modeled by Comp…
The X-Ray Bursts of XTE J1739-285: A NICER Sample
Chakrabarty, Deepto; Arzoumanian, Zaven; Güver, Tolga +10 more
In this work, we report on observations with the Neutron Star Interior Composition Explorer of the known neutron star X-ray transient XTE J1739-285. We observed the source in 2020 February and March, finding it in a highly active bursting state. Across a 20 day period, we detected 32 thermonuclear X-ray bursts, with an average burst recurrence tim…
Primordial Black Holes Formation and Secondary Gravitational Waves in Nonminimal Derivative Coupling Inflation
Karami, Kayoomars; Teimoori, Zeinab; Rezazadeh, Kazem
We study the possibility of the primordial black holes (PBHs) formation with the aim of finding a considerable fraction of dark matter (DM), using the gravitationally enhanced friction mechanism which arises from a nonminimal derivative coupling between the scalar field and the gravity. Assuming the nonminimal coupling parameter as a special funct…
NICER Discovery of Millisecond X-Ray Pulsations and an Ultracompact Orbit in IGR J17494-3030
Chakrabarty, Deepto; Ray, Paul S.; Wolff, Michael T. +11 more
We report the detection of 376.05 Hz (2.66 ms) coherent X-ray pulsations in NICER observations of a transient outburst of the low-mass X-ray binary IGR J17494-3030 in 2020 October/November. The system is an accreting millisecond X-ray pulsar in a 75-minute ultracompact binary. The mass donor is most likely a ≃0.02 M⊙ finite-entropy whit…
INTEGRAL Limits on Past High-energy Activity from FRB 20200120E in M81
Götz, D.; Mereghetti, S.; Rigoselli, M. +1 more
The repeating fast radio burst FRB 20200120E is located in a globular cluster belonging to the nearby M81 galaxy. Its small distance (3.6 Mpc) and accurate localization make it an interesting target to search for bursting activity at high energies. From 2003 November to 2021 September, the INTEGRAL satellite has obtained an exposure time of 18 Ms …
Fermi-GBM Observations of GRB 210812A: Signatures of a Million Solar Mass Gravitational Lens
Veres, P.; Fraija, N.; Bhat, N. +1 more
Observing gravitationally lensed objects in the time domain is difficult, and well-observed time-varying sources are rare. Lensed gamma-ray bursts (GRBs) offer improved timing precision for this class of objects, complementing observations of quasars and supernovae. The rate of lensed GRBs is highly uncertain, approximately one in 1000. The Gamma-…