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Title: The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. IV. Detection of Near-infrared Signatures of r -process Nucleosynthesis with Gemini-South

Abstract

We present a near-infrared spectral sequence of the electromagnetic counterpart to the binary neutron star merger GW170817 detected by Advanced Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo. Our data set comprises seven epochs of J + H spectra taken with FLAMINGOS-2 on Gemini-South between 1.5 and 10.5 days after the merger. In the initial epoch, the spectrum is dominated by a smooth blue continuum due to a high-velocity, lanthanide-poor blue kilonova component. Starting the following night, all of the subsequent spectra instead show features that are similar to those predicted in model spectra of material with a high concentration of lanthanides, including spectral peaks near 1.07 and 1.55 μ m. Our fiducial model with 0.04 M {sub ⊙} of ejecta, an ejection velocity of v = 0.1 c , and a lanthanide concentration of X {sub lan} = 10{sup −2} provides a good match to the spectra taken in the first five days, although it over-predicts the late-time fluxes. We also explore models with multiple fitting components, in each case finding that a significant abundance of lanthanide elements is necessary to match the broad spectral peaks that we observe starting at 2.5 days after the merger. These data provide direct evidence thatmore » binary neutron star mergers are significant production sites of even the heaviest r -process elements.« less

Authors:
 [1]; ; ; ; ; ; ; ;  [2];  [3]; ;  [4]; ;  [5];  [6];  [7];  [8];  [9];  [10];
  1. Astrophysical Institute, Department of Physics and Astronomy, 251B Clippinger Lab, Ohio University, Athens, OH 45701 (United States)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  3. Departments of Physics and Astronomy, and Theoretical Astrophysics Center, University of California, Berkeley, CA 94720-7300 (United States)
  4. Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States)
  5. Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States)
  6. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States)
  7. Department of Physics, Syracuse University, Syracuse NY 13224 (United States)
  8. Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)
  9. The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
  10. Department of Physics, University of Oregon, Eugene, OR 97403 (United States)
Publication Date:
OSTI Identifier:
22654363
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 848; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; BINARY STARS; CONCENTRATION RATIO; DETECTION; GRAVITATIONAL WAVES; INTERFEROMETERS; NEUTRON STARS; NUCLEOSYNTHESIS; R PROCESS; SPECTRA

Citation Formats

Chornock, R., Berger, E., Cowperthwaite, P. S., Nicholl, M., Villar, V. A., Alexander, K. D., Blanchard, P. K., Eftekhari, T., Williams, P. K. G., Kasen, D., Fong, W., Margutti, R., Annis, J., Frieman, J. A., Brout, D., Brown, D. A., Chen, H. -Y., Drout, M. R., Farr, B., Foley, R. J., E-mail: chornock@ohio.edu, and others, and. The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. IV. Detection of Near-infrared Signatures of r -process Nucleosynthesis with Gemini-South. United States: N. p., 2017. Web. doi:10.3847/2041-8213/AA905C.
Chornock, R., Berger, E., Cowperthwaite, P. S., Nicholl, M., Villar, V. A., Alexander, K. D., Blanchard, P. K., Eftekhari, T., Williams, P. K. G., Kasen, D., Fong, W., Margutti, R., Annis, J., Frieman, J. A., Brout, D., Brown, D. A., Chen, H. -Y., Drout, M. R., Farr, B., Foley, R. J., E-mail: chornock@ohio.edu, & others, and. The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. IV. Detection of Near-infrared Signatures of r -process Nucleosynthesis with Gemini-South. United States. https://doi.org/10.3847/2041-8213/AA905C
Chornock, R., Berger, E., Cowperthwaite, P. S., Nicholl, M., Villar, V. A., Alexander, K. D., Blanchard, P. K., Eftekhari, T., Williams, P. K. G., Kasen, D., Fong, W., Margutti, R., Annis, J., Frieman, J. A., Brout, D., Brown, D. A., Chen, H. -Y., Drout, M. R., Farr, B., Foley, R. J., E-mail: chornock@ohio.edu, and others, and. 2017. "The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. IV. Detection of Near-infrared Signatures of r -process Nucleosynthesis with Gemini-South". United States. https://doi.org/10.3847/2041-8213/AA905C.
@article{osti_22654363,
title = {The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. IV. Detection of Near-infrared Signatures of r -process Nucleosynthesis with Gemini-South},
author = {Chornock, R. and Berger, E. and Cowperthwaite, P. S. and Nicholl, M. and Villar, V. A. and Alexander, K. D. and Blanchard, P. K. and Eftekhari, T. and Williams, P. K. G. and Kasen, D. and Fong, W. and Margutti, R. and Annis, J. and Frieman, J. A. and Brout, D. and Brown, D. A. and Chen, H. -Y. and Drout, M. R. and Farr, B. and Foley, R. J., E-mail: chornock@ohio.edu and others, and},
abstractNote = {We present a near-infrared spectral sequence of the electromagnetic counterpart to the binary neutron star merger GW170817 detected by Advanced Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo. Our data set comprises seven epochs of J + H spectra taken with FLAMINGOS-2 on Gemini-South between 1.5 and 10.5 days after the merger. In the initial epoch, the spectrum is dominated by a smooth blue continuum due to a high-velocity, lanthanide-poor blue kilonova component. Starting the following night, all of the subsequent spectra instead show features that are similar to those predicted in model spectra of material with a high concentration of lanthanides, including spectral peaks near 1.07 and 1.55 μ m. Our fiducial model with 0.04 M {sub ⊙} of ejecta, an ejection velocity of v = 0.1 c , and a lanthanide concentration of X {sub lan} = 10{sup −2} provides a good match to the spectra taken in the first five days, although it over-predicts the late-time fluxes. We also explore models with multiple fitting components, in each case finding that a significant abundance of lanthanide elements is necessary to match the broad spectral peaks that we observe starting at 2.5 days after the merger. These data provide direct evidence that binary neutron star mergers are significant production sites of even the heaviest r -process elements.},
doi = {10.3847/2041-8213/AA905C},
url = {https://www.osti.gov/biblio/22654363}, journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 848,
place = {United States},
year = {2017},
month = {10}
}

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