Designing an Optimal Kilonova Search Using DECam for Gravitational-wave Events
Abstract
We address the problem of optimally identifying all kilonovae detected via gravitational-wave emission in the upcoming LIGO/Virgo/KAGRA observing run, O4, which is expected to be sensitive to a factor of ~7 more binary neutron star (BNS) alerts than previously. Electromagnetic follow-up of all but the brightest of these new events will require >1 m telescopes, for which limited time is available. We present an optimized observing strategy for the DECam during O4. We base our study on simulations of gravitational-wave events expected for O4 and wide-prior kilonova simulations. We derive the detectabilities of events for realistic observing conditions. We optimize our strategy for confirming a kilonova while minimizing telescope time. For a wide range of kilonova parameters, corresponding to a fainter kilonova compared to GW170817/AT 2017gfo, we find that, with this optimal strategy, the discovery probability for electromagnetic counterparts with the DECam is ~80% at the nominal BNS gravitational-wave detection limit for O4 (190 Mpc), which corresponds to an ~30% improvement compared to the strategy adopted during the previous observing run. For more distant events (~330 Mpc), we reach an ~60% probability of detection, a factor of ~2 increase. For a brighter kilonova model dominated by the blue component that reproduces the observations of GW170817/AT 2017gfo, we find that we can reach ~90% probability of detection out to 330 Mpc, representing an increase of ~20%, while also reducing the total telescope time required to follow up events by ~20%.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2024
- DOI:
- 10.3847/1538-4357/ad0462
- arXiv:
- arXiv:2302.04878
- Bibcode:
- 2024ApJ...960..122B
- Keywords:
-
- Gravitational wave astronomy;
- Astronomical methods;
- Astrostatistics tools;
- Transient detection;
- 675;
- 1043;
- 1887;
- 1957;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Instrumentation and Methods for Astrophysics;
- General Relativity and Quantum Cosmology
- E-Print:
- 26 pages, 11 figures, accepted by ApJ