The University of Southampton
University of Southampton Institutional Repository

The optical afterglow of GW170817: An off-axis structured jet and deep constraints on a globular cluster origin

The optical afterglow of GW170817: An off-axis structured jet and deep constraints on a globular cluster origin
The optical afterglow of GW170817: An off-axis structured jet and deep constraints on a globular cluster origin

We present a revised and complete optical afterglow light curve of the binary neutron star merger GW170817, enabled by deep Hubble Space Telescope (HST) F606W observations at ≈584 days post-merger, which provide a robust optical template. The light curve spans ≈110-362 days, and is fully consistent with emission from a relativistic structured jet viewed off-axis, as previously indicated by radio and X-ray data. Combined with contemporaneous radio and X-ray observations, we find no spectral evolution, with a weighted average spectral index of , demonstrating that no synchrotron break frequencies evolve between the radio and X-ray bands over these timescales. We find that an extrapolation of the post-peak temporal slope of GW170817 to the luminosities of cosmological short gamma-ray bursts matches their observed jet break times, suggesting that their explosion properties are similar, and that the primary difference in GW170817 is viewing angle. Additionally, we place a deep limit on the luminosity and mass of an underlying globular cluster (GC) of L ≲ 6.7 × 103 L o, or M ≲ 1.3 × 104 M o, at least 4 standard deviations below the peak of the GC mass function of the host galaxy, NGC 4993. This limit provides a direct and strong constraint that GW170817 did not form and merge in a GC. As highlighted here, HST (and soon the James Webb Space Telescope) enables critical observations of the optical emission from neutron star merger jets and outflows.

2041-8205
Fong, W.
a9082fd0-2668-4f3f-819d-c89e53d26791
Blanchard, P. K.
738a5643-fc47-4fc7-ae86-c15f964b3566
Alexander, K. D.
016e8a95-77a4-4dd3-92fb-50b5cf476a12
Strader, J.
65549124-aafe-4b6e-a5cb-2ca8b2624843
Margutti, R.
7aa7e17c-2de9-4525-9451-567c13e94f63
Hajela, A.
53c0865b-10ed-4c2a-863d-4603cc93014e
Villar, V. A.
a31eab4f-a56f-4b5b-a93f-958b59c049df
Wu, Y.
4f8d9abc-87d8-4ed8-972a-47ab1c28b8e3
Ye, C. S.
5193a7aa-edb3-49c0-a667-f3ea564bc1f3
Berger, E.
5a5f6750-9e79-4f95-a7a0-417187fdf8bd
Chornock, R.
ad6ec7e5-6814-4dd5-9a70-ee6b499b4516
Coppejans, D.
9087eb84-f565-482c-b278-25715b96809c
Cowperthwaite, P. S.
5be93ba2-960a-4476-b6cc-6a151b7bb66a
Eftekhari, T.
2b66017f-1f29-4ec8-8898-cde680d52adb
Giannios, D.
eae95536-762d-4d29-97c8-368499754876
Guidorzi, C.
3507ae08-4510-4d1e-8759-832d1ad969bf
Kathirgamaraju, A.
e1232330-287b-438d-bc17-4f07f2546ccc
Laskar, T.
d15a25c5-a0ee-4543-bdd2-df9f8e22bcc6
Macfadyen, A.
19a94c57-5bbb-4325-b7d3-e38c63f42b85
Metzger, B. D.
a17349eb-ebea-49d9-95c6-f595ae025539
Nicholl, M.
25da1b2f-8de5-4c1d-b26a-a221457aff6e
Paterson, K.
b926e1ed-47b1-431d-90d8-09f4817d2ad3
Terreran, G.
2f09a675-b183-4089-b413-a570350da8fd
Sand, D. J.
1d5b9338-c884-4586-bf6b-32902d9c3f3f
Sironi, L.
efbe57fe-8a03-4310-8503-fc9475b92ef6
Williams, P. K.G.
5bda6d47-fb96-4c94-b838-8ba116703e29
Xie, X.
83115329-e0d6-47f9-a765-7a0c5aaf964c
Zrake, J.
7ee61418-5513-456b-8845-6d505966853e
Fong, W.
a9082fd0-2668-4f3f-819d-c89e53d26791
Blanchard, P. K.
738a5643-fc47-4fc7-ae86-c15f964b3566
Alexander, K. D.
016e8a95-77a4-4dd3-92fb-50b5cf476a12
Strader, J.
65549124-aafe-4b6e-a5cb-2ca8b2624843
Margutti, R.
7aa7e17c-2de9-4525-9451-567c13e94f63
Hajela, A.
53c0865b-10ed-4c2a-863d-4603cc93014e
Villar, V. A.
a31eab4f-a56f-4b5b-a93f-958b59c049df
Wu, Y.
4f8d9abc-87d8-4ed8-972a-47ab1c28b8e3
Ye, C. S.
5193a7aa-edb3-49c0-a667-f3ea564bc1f3
Berger, E.
5a5f6750-9e79-4f95-a7a0-417187fdf8bd
Chornock, R.
ad6ec7e5-6814-4dd5-9a70-ee6b499b4516
Coppejans, D.
9087eb84-f565-482c-b278-25715b96809c
Cowperthwaite, P. S.
5be93ba2-960a-4476-b6cc-6a151b7bb66a
Eftekhari, T.
2b66017f-1f29-4ec8-8898-cde680d52adb
Giannios, D.
eae95536-762d-4d29-97c8-368499754876
Guidorzi, C.
3507ae08-4510-4d1e-8759-832d1ad969bf
Kathirgamaraju, A.
e1232330-287b-438d-bc17-4f07f2546ccc
Laskar, T.
d15a25c5-a0ee-4543-bdd2-df9f8e22bcc6
Macfadyen, A.
19a94c57-5bbb-4325-b7d3-e38c63f42b85
Metzger, B. D.
a17349eb-ebea-49d9-95c6-f595ae025539
Nicholl, M.
25da1b2f-8de5-4c1d-b26a-a221457aff6e
Paterson, K.
b926e1ed-47b1-431d-90d8-09f4817d2ad3
Terreran, G.
2f09a675-b183-4089-b413-a570350da8fd
Sand, D. J.
1d5b9338-c884-4586-bf6b-32902d9c3f3f
Sironi, L.
efbe57fe-8a03-4310-8503-fc9475b92ef6
Williams, P. K.G.
5bda6d47-fb96-4c94-b838-8ba116703e29
Xie, X.
83115329-e0d6-47f9-a765-7a0c5aaf964c
Zrake, J.
7ee61418-5513-456b-8845-6d505966853e

Fong, W., Blanchard, P. K., Alexander, K. D., Strader, J., Margutti, R., Hajela, A., Villar, V. A., Wu, Y., Ye, C. S., Berger, E., Chornock, R., Coppejans, D., Cowperthwaite, P. S., Eftekhari, T., Giannios, D., Guidorzi, C., Kathirgamaraju, A., Laskar, T., Macfadyen, A., Metzger, B. D., Nicholl, M., Paterson, K., Terreran, G., Sand, D. J., Sironi, L., Williams, P. K.G., Xie, X. and Zrake, J. (2019) The optical afterglow of GW170817: An off-axis structured jet and deep constraints on a globular cluster origin. The Astrophysical Journal Letters, 883 (1), [L1]. (doi:10.3847/2041-8213/ab3d9e).

Record type: Article

Abstract

We present a revised and complete optical afterglow light curve of the binary neutron star merger GW170817, enabled by deep Hubble Space Telescope (HST) F606W observations at ≈584 days post-merger, which provide a robust optical template. The light curve spans ≈110-362 days, and is fully consistent with emission from a relativistic structured jet viewed off-axis, as previously indicated by radio and X-ray data. Combined with contemporaneous radio and X-ray observations, we find no spectral evolution, with a weighted average spectral index of , demonstrating that no synchrotron break frequencies evolve between the radio and X-ray bands over these timescales. We find that an extrapolation of the post-peak temporal slope of GW170817 to the luminosities of cosmological short gamma-ray bursts matches their observed jet break times, suggesting that their explosion properties are similar, and that the primary difference in GW170817 is viewing angle. Additionally, we place a deep limit on the luminosity and mass of an underlying globular cluster (GC) of L ≲ 6.7 × 103 L o, or M ≲ 1.3 × 104 M o, at least 4 standard deviations below the peak of the GC mass function of the host galaxy, NGC 4993. This limit provides a direct and strong constraint that GW170817 did not form and merge in a GC. As highlighted here, HST (and soon the James Webb Space Telescope) enables critical observations of the optical emission from neutron star merger jets and outflows.

Text
The Optical Afterglow of GW170817_An Off-axis Structured Jet and Deep Constraints on a Globular Cluster Origin - Accepted Manuscript
Restricted to Repository staff only until 17 September 2020.
Request a copy

More information

Accepted/In Press date: 20 August 2019
e-pub ahead of print date: 17 September 2019

Identifiers

Local EPrints ID: 435320
URI: http://eprints.soton.ac.uk/id/eprint/435320
ISSN: 2041-8205
PURE UUID: a44d361c-5a49-445a-ab30-815d111128c8
ORCID for X. Xie: ORCID iD orcid.org/0000-0002-2798-6880

Catalogue record

Date deposited: 30 Oct 2019 17:30
Last modified: 27 Jan 2020 13:58

Export record

Altmetrics

Contributors

Author: W. Fong
Author: P. K. Blanchard
Author: K. D. Alexander
Author: J. Strader
Author: R. Margutti
Author: A. Hajela
Author: V. A. Villar
Author: Y. Wu
Author: C. S. Ye
Author: E. Berger
Author: R. Chornock
Author: D. Coppejans
Author: P. S. Cowperthwaite
Author: T. Eftekhari
Author: D. Giannios
Author: C. Guidorzi
Author: A. Kathirgamaraju
Author: T. Laskar
Author: A. Macfadyen
Author: B. D. Metzger
Author: M. Nicholl
Author: K. Paterson
Author: G. Terreran
Author: D. J. Sand
Author: L. Sironi
Author: P. K.G. Williams
Author: X. Xie ORCID iD
Author: J. Zrake

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×