An Archival Search for Neutron-Star Mergers in Gravitational Waves and Very-High-Energy Gamma Rays

Abstract

The recent discovery of electromagnetic signals in coincidence with neutron-star mergers has solidified the importance of multimessenger campaigns in studying the most energetic astrophysical events. Pioneering multimessenger observatories, such as LIGO/Virgo and IceCube, record many candidate signals below the detection significance threshold. These sub-threshold event candidates are promising targets for multimessenger studies, as the information provided by them may, when combined with contemporaneous gamma-ray observations, lead to significant detections. Here we describe a new method that uses such candidates to search for transient events using archival very-high-energy gamma-ray data from imaging atmospheric Cherenkov telescopes (IACTs). We demonstrate the application of this method to sub-threshold binary neutron star (BNS) merger candidates identified in Advanced LIGO's first observing run. We identify eight hours of archival VERITAS observations coincident with seven BNS merger candidates and search them for TeV emission. No gamma-ray emission is detected; we calculate upper limits on the integral flux and compare them to a short gamma-ray burst model. We anticipate this search method to serve as a starting point for IACT searches with future LIGO/Virgo data releases as well as in other sub-threshold studies for multimessenger transients, such as IceCube neutrinos. Furthermore, it can be deployed immediately with other current-generation IACTs, and has the potential for real-time use that places minimal burden on experimental operations. Lastly, this method may serve as a pilot for studies with the Cherenkov Telescope Array, which has the potential to observe even larger fields of view in its divergent pointing mode.

References in corpus (24)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Multi-messenger Observations of a Binary Neutron Star Merger
• Gravitational Waves and Gamma-rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
• Advanced LIGO
• GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run
• LIGO: The Laser Interferometer Gravitational-Wave Observatory
• Swope Supernova Survey 2017a (SSS17a), the Optical Counterpart to a Gravitational Wave Source
• The Physics of Gamma-Ray Bursts and Relativistic Jets
• Observations of the Crab Nebula with H.E.S.S
• Illuminating Gravitational Waves: A Concordant Picture of Photons from a Neutron Star Merger
• Background Modelling in Very-High-Energy gamma-ray Astronomy
• The First VERITAS Telescope
• Teraelectronvolt emission from the $\gamma$-ray burst GRB 190114C
• A very-high-energy component deep in the Gamma-ray Burst afterglow
• The major upgrade of the MAGIC telescopes, Part I: The hardware improvements and the commissioning of the system
• Observation of inverse Compton emission from a long $\gamma$-ray burst
• VERITAS Observations of the gamma-Ray Binary LS I +61 303
• Gamma-Hadron Separation Methods for the VERITAS Array of Four Imaging Atmospheric Cherenkov Telescopes
• TeV gamma-ray observations of the binary neutron star merger GW170817 with H.E.S.S
• IceCube Search for Neutrinos Coincident with Compact Binary Mergers from LIGO-Virgo's First Gravitational-Wave Transient Catalog
• Search method for coincident events from LIGO and IceCube detectors
• Cherenkov Telescope Array is Well Suited to Follow Up Gravitational Wave Transients
• Sub-threshold binary neutron star search in Advanced LIGO's first observing run
• How to search for multiple messengers -- a general framework beyond two messengers

Cited by in corpus (1)

• The Very Energetic Radiation Imaging Telescope Array System (VERITAS)