Search Publications
A Comprehensive Study of Type I (Thermonuclear) Bursts in the New Transient SRGA J144459.2–604207
Chen, Yupeng; Zhang, Shu; Li, Xiaobo +11 more
We report an analysis of Insight-HXMT observations of the newly discovered accreting millisecond pulsar SRGA J144459.2–604207. During the outburst, detected in 2024 February by SRG/ART-XC, the broadband persistent spectrum was well fitted by an absorbed Comptonization model. We detected 60 type I X-ray bursts in the Insight-HXMT medium energy (ME)…
Imaging and Spectral Fitting of Bright Gamma-Ray Sources with the COSI Balloon Payload
Yoneda, Hiroki; Tomsick, John A.; Cangemi, Floriane +17 more
The Compton Spectrometer and Imager balloon payload (COSI-Balloon) is a wide field-of-view Compton gamma-ray telescope that operates in the 0.2–5 MeV bandpass. COSI-Balloon had a successful 46 day flight in 2016 during which the instrument observed the Crab Nebula, Cygnus X-1, and Centaurus A. Using the data collected by the COSI-Balloon instrumen…
Testing the Universality of Self-organized Criticality in Galactic, Extragalactic, and Black Hole Systems
Göǧüş, Ersin; Aschwanden, Markus J.
In this study, we test whether the power law slopes (α F ) for fluxes (F), and (α E ) for energies (E) are universal in their size distributions,
GRB 241107A: A Giant Flare from a Close-by Extragalactic Magnetar?
Mereghetti, Sandro; Salvaterra, Ruben; Ubertini, Pietro +5 more
We report the results on the short gamma-ray burst GRB 241107A, obtained with the IBIS instrument on board the INTEGRAL satellite. The burst had a duration of about 0.2 s, a fluence of 8 × 10‑7 erg cm‑2 in the 20 keV–10 MeV range, and a hard spectrum, characterized by a peak energy of 680 keV. The position of GRB 241107A has …
Broadband γ-Ray Spectrum of Supernova Remnant Cassiopeia A
Liu, B.; Liu, Y.; Zhang, Yong +311 more
The core-collapse supernova remnant (SNR) Cassiopeia A (Cas A) is one of the brightest galactic radio sources with an angular radius of
Signature of a Seyfert-like Component in Blazar 3C 273 and Its Reflection-based Explanation
Gaur, Haritma; Pal, Main; Anjum, Muhammad S. +4 more
We present the results of blazar 3C 273 from simultaneous observations obtained using the XMM-Newton and NuSTAR satellites during the period 2015–2019 in five epochs. When the spectra are modeled with a power law, significant residuals arise below ∼2 keV and in the energy range of 30–78 keV in NuSTAR data. Residuals in the lower energy band repres…
The Disk Wind Contribution to the Gamma-Ray Emission from the Nearby Seyfert Galaxy GRS 1734‑292
Fukazawa, Yasushi; Inoue, Yoshiyuki; Yamada, Tomoya +4 more
Radio-quiet Seyfert galaxies have been detected in GeV gamma rays by the Fermi Large Area Telescope (LAT), but the origin of much of this emission is unclear. We consider the nearby example GRS 1734‑292, which exhibits weak starburst and jet activities that are insufficient to explain the observed gamma-ray flux. With the first detailed multiwavel…
High-energy Jet Emission from GRS 1758–258 and 1E 1740.7–2942 with INTEGRAL?
Ubertini, Pietro; Bazzano, Angela; Rodi, James
GRS 1758–258 and 1E 1740.7–2942 are two long-known persistent black hole binaries in the Galactic center region. Using the International Gamma-Ray Astrophysics Laboratory (INTEGRAL)'s extensive monitoring of the Galactic center and bulge, we studied their temporal and spectral evolutions in the 30–610 keV energy range from 2003 March through 2022 …
New 511 keV Line Data Provide Strongest sub-GeV Dark Matter Constraints
Silk, Joseph; De la Torre Luque, Pedro; Balaji, Shyam
We explore the 511 keV emission associated with sub-GeV dark matter (DM) particles that can produce electron–positron pairs and form positronium after thermalizing. We use ∼16 yr of data from the Spectrometer on INTEGRAL to constrain DM properties, including the full positron propagation and losses, and the suppression of free electron density awa…
An IXPE-led X-Ray Spectropolarimetric Campaign on the Soft State of Cygnus X-1: X-Ray Polarimetric Evidence for Strong Gravitational Lensing
Ingram, Adam; Kaaret, Philip; Wu, Kinwah +134 more
We present the first X-ray spectropolarimetric results for Cygnus X-1 in its soft state from a campaign of five IXPE observations conducted during 2023 May–June. Companion multiwavelength data during the campaign are likewise shown. The 2–8 keV X-rays exhibit a net polarization degree PD = 1.99% ± 0.13% (68% confidence). The polarization signal is…