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Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
Lee, H. M.; Williams, D.; Mitra, S. +1153 more
On 2017 August 17, the gravitational-wave event GW170817 was observed by the Advanced LIGO and Virgo detectors, and the gamma-ray burst (GRB) GRB 170817A was observed independently by the Fermi Gamma-ray Burst Monitor, and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory. The probability of t…
INTEGRAL Detection of the First Prompt Gamma-Ray Signal Coincident with the Gravitational-wave Event GW170817
Sunyaev, R.; Hanlon, L.; Mereghetti, S. +20 more
We report the INTernational Gamma-ray Astrophysics Laboratory (INTEGRAL) detection of the short gamma-ray burst GRB 170817A (discovered by Fermi-GBM) with a signal-to-noise ratio of 4.6, and, for the first time, its association with the gravitational waves (GWs) from binary neutron star (BNS) merging event GW170817 detected by the LIGO and Virgo o…
Placing the Spotted T Tauri Star LkCa 4 on an HR Diagram
Herczeg, Gregory J.; Jose, Jessy; Liu, Chun-Fan +12 more
Ages and masses of young stars are often estimated by comparing their luminosities and effective temperatures to pre-main-sequence stellar evolution tracks, but magnetic fields and starspots complicate both the observations and evolution. To understand their influence, we study the heavily spotted weak-lined T-Tauri star LkCa 4 by searching for sp…
A Neutron Star Binary Merger Model for GW170817/GRB 170817A/SSS17a
Lee, W. H.; Rest, A.; Foley, R. J. +14 more
The merging neutron star gravitational-wave event GW170817 has been observed throughout the entire electromagnetic spectrum from radio waves to γ-rays. The resulting energetics, variability, and light curves are shown to be consistent with GW170817 originating from the merger of two neutron stars, in all likelihood followed by the prompt gravitati…
The Konus-Wind Catalog of Gamma-Ray Bursts with Known Redshifts. I. Bursts Detected in the Triggered Mode
Cline, T.; Hurley, K.; Golenetskii, S. +8 more
In this catalog, we present the results of a systematic study of gamma-ray bursts (GRBs) with reliable redshift estimates detected in the triggered mode of the Konus-Wind (KW) experiment during the period from 1997 February to 2016 June. The sample consists of 150 GRBs (including 12 short/hard bursts) and represents the largest set of cosmological…
The Chandra COSMOS Legacy Survey: Energy Spectrum of the Cosmic X-Ray Background and Constraints on Undetected Populations
Treister, E.; Comastri, Andrea; Elvis, Martin +15 more
Using Chandra observations in the 2.15 deg2 COSMOS-legacy field, we present one of the most accurate measurements of the Cosmic X-ray Background (CXB) spectrum to date in the [0.3-7] keV energy band. The CXB has three distinct components: contributions from two Galactic collisional thermal plasmas at kT ∼ 0.27 and 0.07 keV and an extrag…
Living on a Flare: Relativistic Reflection in V404 Cyg Observed by NuSTAR during Its Summer 2015 Outburst
Harrison, F. A.; Stern, D.; Fabian, A. C. +19 more
We present first results from a series of NuSTAR observations of the black hole X-ray binary V404 Cyg obtained during its summer 2015 outburst, primarily focusing on observations during the height of this outburst activity. The NuSTAR data show extreme variability in both the flux and spectral properties of the source. This is partly driven by str…
iPTF 16asu: A Luminous, Rapidly Evolving, and High-velocity Supernova
Cenko, S. B.; Sollerman, J.; Hurley, K. +23 more
Wide-field surveys are discovering a growing number of rare transients whose physical origin is not yet well understood. Here we present optical and UV data and analysis of intermediate Palomar Transient Factory (iPTF) 16asu, a luminous, rapidly evolving, high-velocity, stripped-envelope supernova (SN). With a rest-frame rise time of just four day…
Bimodal Long-lasting Components in Short Gamma-Ray Bursts: Promising Electromagnetic Counterparts to Neutron Star Binary Mergers
Sakamoto, Takanori; Kisaka, Shota; Ioka, Kunihito
Long-lasting emission of short gamma-ray bursts (GRBs) is crucial to reveal the physical origin of the central engine as well as to detect electromagnetic (EM) counterparts to gravitational waves (GWs) from neutron star binary mergers. We investigate 65 X-ray light curves of short GRBs, which is six times more than previous studies, by combining b…
Observations of the GRB Afterglow ATLAS17aeu and Its Possible Association with GW 170104
Inserra, C.; Rest, A.; Smartt, S. J. +26 more
We report the discovery and multiwavelength data analysis of the peculiar optical transient, ATLAS17aeu. This transient was identified in the sky map of the LIGO gravitational wave event GW 170104 by our ATLAS and Pan-STARRS coverage. ATLAS17aeu was discovered 23.1 hr after GW 170104 and rapidly faded over the next three nights, with a spectrum re…