Host Galaxy of Gw170817/Em170817
Po-Chieh Yu1*, Chow-Choong Ngeow1, Wing-Huen Ip1
1Graduate Institute of Astronomy, National Central University, Taoyuan, Taiwan
* Presenter:Po-Chieh Yu,
On August 17, 2017 at 12∶41:04 UTC, the Advanced LIGO and Advanced Virgo gravitational-wave detectors made their first observation of a merging of two neutron stars (GW170817). Since neutron stars merger is the candidate site for nuclear synthesis of heavy elements such as gold, investigation of such events can help in understanding the origin of the these heavy elements – one of the mystery in modern astrophysics. The electromagnetic (EM) counterpart of GW170817, EM170817, was reported in galaxy NGC 4993. Here we present an analysis of the host galaxy of EM170817 and compare the environments with other hosts of sGRB (short Gamma-ray Burst). Archival HST F606W data show complicated dust lanes extending a few kpc from the nucleus superimposed on an elliptical galaxy, similar to many other early-type galaxies. The dust lanes may be the result of a minor merger that occurred as long as several Gyr ago. Archival spectrum and broadband spectral-energy distribution indicated that the stellar mass of the galaxy ∼ 3 × 1010 solar mass and the star formation rate (SFR) ∼ 3 × 10-3 solar mass per yr. The time since the last burst of star formation ended is ∼2 Gyr, implying a relatively long timescale for the merger of the NS-NS binary system since progenitors of neutron stars are short-lived.

Keywords: galaxies