The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VII. Properties of the Host Galaxy and Constraints on the Merger Timescale
By P. Blanchard, E. Berger, W. Fong, M. Nicholl, J. Leja, C. Conroy, K. Alexander, Raffaella Margutti, P. G. Williams, Zoheyr Doctor and 14 more. 2017
152 citations recorded by the source corpus.
We present the properties of NGC 4993, the host galaxy of GW170817, the first gravitational-wave (GW) event from the merger of a binary neutron star (BNS) system and the first with an electromagnetic (EM) counterpart. We use both archival photometry and new optical/near-IR imaging and spectroscopy, together with stellar population synthesis models to infer the global properties of the host galaxy. We infer a star formation history peaked at ago, with subsequent exponential decline leading to a low current star formation rate of 0.01 yr−1, which we convert into a binary merger timescale probability distribution. We find a median merger timescale of Gyr, with a 90% confidence range of . This in turn indicates an initial binary separation of , comparable to the inferred values for Galactic BNS systems. We also use new and archival Hubble Space Telescope images to measure a projected offset of the optical counterpart of 2.1 kpc (0.64re) from the center of NGC 4993 and to place a limit of mag on any pre-existing emission, which rules out the brighter half of the globular cluster luminosity function. Finally, the age and offset of the system indicates it experienced a modest natal kick with an upper limit of ∼200 km s−1. Future GW–EM observations of BNS mergers will enable measurement of their population delay time distribution, which will directly inform their viability as the dominant source of r-process enrichment in the universe.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/6a635e0b2a28acd4fbb668f103bf01e751d11748
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Citations in the corpus
- The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. II. UV, Optical, and Near-infrared Light Curves and Comparison to Kilonova Models (2017, background): “We assume a negligible reddening contribution from the host (Blanchard et al. 2017).”
- Progenitors of gravitational wave mergers: binary evolution with the stellar grid-based code ComBinE (2018, background): “The sGRB associated with GW170817 is located within the effective radius of its host galaxy (e.g. Blanchard et al. 2017).”
- Stellar Population Inference with Prospector (2020, background): “…spatially resolved spectroscopy (Patŕıcio et al. 2018; Oyarzún et al. 2019), in modeling the host galaxies of supernovae and gravitational wave events (Blanchard et al. 2017a,b; Nicholl et al. 2017), and in modeling gravitationally lensed high-redshift quiescent galaxies (Ebeling et al. 2018).”
- The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. III. Optical and UV Spectra of a Blue Kilonova from Fast Polar Ejecta (2017, methodology): “The counterpart—variously named SSS17a, DLT17ck, and AT 2017gfo—resides in the galaxy NGC 49931 (see Blanchard et al. 2017a, for host galaxy analysis).”
- Gravitational waves from neutron star mergers and their relation to the nuclear equation of state (2019, background): “In addition to the GW measurement, additional information has been obtained through the electomagnetic emission (in the gamma-ray, x-ray, ultraviolet, optical, infrared, and radio bands) related to GW170817, named GRB 170817A (for the gamma-ray burst) and AT2017gfo for the rest of the astronomical t”
- The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VI. Radio Constraints on a Relativistic Jet and Predictions for Late-time Emission from the Kilonova Ejecta (2017, background): “Our radio observations of the host galaxy, NGC 4993, are discussed in Blanchard et al. (2017).”
- The Combined Ultraviolet, Optical, and Near-infrared Light Curves of the Kilonova Associated with the Binary Neutron Star Merger GW170817: Unified Data Set, Analytic Models, and Physical Implications (2017, background): “…curve (or close equivalent) for each filter, instrument, and telescope combination.7 Photometric modeling of the host galaxy, NGC 4993, suggests that the host environment contributes minimal extinction (Blanchard et al. 2017).8 We therefore only include a correction for Milky Way extinction, with -”