Search Publications
Observable Signature of Merging Stellar-mass Black Holes in Active Galactic Nuclei
Perna, Rosalba; Tagawa, Hiromichi; Kimura, Shigeo S. +2 more
The origin of stellar-mass black hole mergers discovered through gravitational waves is being widely debated. Mergers in the disks of active galactic nuclei (AGNs) represent a promising source of origin, with possible observational clues in the gravitational-wave data. Beyond gravitational waves, a unique signature of AGN-assisted mergers is elect…
Polarization Properties of the Weakly Magnetized Neutron Star X-Ray Binary GS 1826-238 in the High Soft State
Wu, Kinwah; Enoto, Teruaki; Turolla, Roberto +94 more
The launch of the Imaging X-ray Polarimetry Explorer (IXPE) on 2021 December 9 has opened a new window in X-ray astronomy. We report here the results of the first IXPE observation of a weakly magnetized neutron star, GS 1826-238, performed on 2022 March 29-31 when the source was in a high soft state. An upper limit (99.73% confidence level) of 1.3…
Multi-messenger Model for the Prompt Emission from GRB 221009A
Bošnjak, Željka; Petropoulou, Maria; Rudolph, Annika +1 more
We present a multi-messenger model for the prompt emission from GRB 221009A within the internal shock scenario. We consider the time-dependent evolution of the outflow with its impact on the observed light curve from multiple collisions, as well as the self-consistent generation of the electromagnetic spectrum in synchrotron and inverse Compton-do…
Production of 44Ti and Iron-group Nuclei in the Ejecta of 3D Neutrino-driven Supernovae
Sieverding, Andre; Kresse, Daniel; Janka, Hans-Thomas
The radioactive isotopes 44Ti and 56Ni are important products of explosive nucleosynthesis, which play a key role in supernova (SN) diagnostics and have been detected in several nearby young SN remnants. However, most SN models based on nonrotating single stars predict yields of 44Ti that are much lower than the va…
A New Study on a Type Iax Stellar Remnant and its Probable Association with SN 1181
Hillier, D. John; Parker, Quentin A.; Ritter, Andreas +4 more
We report observations and modeling of the stellar remnant and presumed double-degenerate merger of Type Iax supernova Pa 30, which is the probable remnant of SN 1181 AD. It is the only known bound stellar SN remnant and the only star with Wolf-Rayet features that is neither a planetary nebula central star nor a massive Population I progenitor. We…
Deep X-Ray and Radio Observations of the First Outburst of the Young Magnetar Swift J1818.0-1607
Campana, S.; Tiengo, A.; Götz, D. +23 more
Swift J1818.0-1607 is a radio-loud magnetar with a spin period of 1.36 s and a dipolar magnetic field strength of B ~ 3 × 1014 G, which is very young compared to the Galactic pulsar population. We report here on the long-term X-ray monitoring campaign of this young magnetar using XMM-Newton, NuSTAR, and Swift from the activation of its …
Probing the Galactic Diffuse Continuum Emission with COSI
Boggs, Steven E.; Tomsick, John A.; Siegert, Thomas +10 more
In 2016, the Compton Spectrometer and Imager (COSI) had a successful 46 day flight on board NASA's Super Pressure Balloon platform. In this work, we report measurements of the Galactic diffuse continuum emission (GDCE) observed toward the inner Galaxy during the flight, which in the COSI energy band (0.2-5 MeV) is primarily generated from inverse …
Reanalysis of the X-Ray-burst-associated FRB 200428 with Insight-HXMT Observations
Zhang, S.; Zhang, S. N.; Dai, Z. G. +15 more
A double-peak X-ray burst from the Galactic magnetar SGR J1935+2154 was discovered to be associated with the two radio pulses of FRB 200428 separated by 28.97 ± 0.02 ms. Precise measurements of the timing and spectral properties of the X-ray bursts are helpful for understanding the physical origin of fast radio bursts. In this paper, we have recon…
MeV Gamma-Ray Source Contribution to the Inner Galactic Diffuse Emission
Mukherjee, Reshmi; Yoneda, Hiroki; Inoue, Yoshiyuki +2 more
The origin of the inner Galactic emission, measured by COMPTEL with a flux of ~10-2 MeV cm-2 s-1 sr-1 in the 1-30 MeV energy range from the inner Galactic region, has remained unsettled since its discovery. In this paper, we elaborate on a model of individual MeV gamma-ray sources unresolved by COMPTEL. …
Deep Search for Gamma-Ray Emission from the Accreting X-Ray Pulsar 1A 0535+262
Torres, D. F.; Li, J.; Ji, L. +2 more
Binary systems are a well-established subclass of gamma-ray sources. The high mass X-ray binary pulsar 1A 0535+262 has been considered to be a possible gamma-ray emitter for a long time, although former gamma-ray searches using the Fermi Large Area Telescope (LAT) and VERITAS data resulted in upper limits only. We aim at a deep search for gamma-ra…