Abstract
The progenitor system of the compact binary merger GW190425 had a total mass of 3.4+0.3−0.1 M☉ (90th-percentile confidence region) as measured from its gravitational wave signal. This mass is significantly different from the Milky Way (MW) population of binary neutron stars (BNSs) that are expected to merge in a Hubble time and from that of the first BNS merger, GW170817. Here, we explore the expected electromagnetic (EM) signatures of such a system. We make several astrophysically motivated assumptions to further constrain the parameters of GW190425. By simply assuming that both components were NSs, we reduce the possible component masses significantly, finding m1 = 1.85+0.27−0.19 M☉ and m2 = 1.47+0.16−0.18 M☉. However, if the GW190425 progenitor system was an NS-black hole (BH) merger, we find best-fitting parameters m1 = 2.19+0.21−0.17 M☉ and m2 = 1.26+0.10−0..08 M☉. For a well-motivated BNS system where the lighter NS has a mass similar to the mass of non-recycled NSs in MW BNS systems, we find m1 = 2.03+0.15−0.14 M☉ and m2 = 1.35 ± 0.09 M☉, corresponding to only 7 per cent mass uncertainties. For all scenarios, we expect a prompt collapse of the resulting remnant to a BH. Examining detailed models with component masses similar to our best-fitting results, we find the EM counterpart to GW190425 is expected to be significantly redder and fainter than that of GW170817. We find that almost all reported search observations were too shallow to detect the expected counterpart to GW190425. If the LIGO-Virgo Collaboration promptly provides the chirp mass, the astronomical community can adapt their observations to improve the likelihood of detecting a counterpart for similarly 'high-mass' BNS systems.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 190-198 |
| Number of pages | 9 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 494 |
| Issue number | 1 |
| DOIs | |
| State | Published - May 1 2020 |
Funding
The UCSC team is supported in part by NASA grant NNG17PX03C, NSF grant AST-1815935, the Gordon and Betty Moore Foundation, the Heising-Simons Foundation, and by fellowships from the David and Lucile Packard Foundation to RJF. ER-R thanks the Heising-Simons Foundation, the Danish National Research Foundation (DNRF132), and NSF (AST-1911206 and AST-1852393) for support. DAC acknowledges support from the National Science Foundation Graduate Research Fellowship under Grant DGE1339067. JS is also supported by the A. F. Morrison Fellowship at Lick Observatory. This work was only possible because of the LVC and its members. Their tireless work operating the GW detectors, analysing the data, and providing data to the community has sped discovery in the nascent field. We especially thank them for providing the posterior data sets soon after LVC20 was made public. We thank the anonymous referee for constructive and elucidating comments. Much of this manuscript was conceived while RJF attended the Hirschegg 2020 workshop. We thank the organizers and attendees, especially B. C?t?, S. De, R. Essick, R. Gamba, G. Raaijmakers, S. Reddy, and L. Roberts for enlightening conversations about GW190425. We also thank P. Brady, D. Lin, P. Macias, B. Margalit, M. Safarzadeh, S. Woosley, and X.-J. Zhu for additional help and conversations. The UCSC team is supported in part by NASA grant NNG17PX03C, NSF grant AST-1815935, the Gordon and Betty Moore Foundation, the Heising-Simons Foundation, and by fellowships from the David and Lucile Packard Foundation to RJF. ER-R thanks the Heising-Simons Foundation, the Danish National Research Foundation (DNRF132), and NSF (AST-1911206 and AST-1852393) for support. DAC acknowledges support from the National Science Foundation Graduate Research Fellowship under Grant DGE1339067. JS is also supported by the A. F. Morrison Fellowship at Lick Observatory.
Keywords
- Gravitational waves
- Stars: neutron
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science