# A VLA Study of High-redshift GRBs. I. Multiwavelength Observations and Modeling of GRB 140311A

Tanmoy Laskar, Edo Berger, Ryan Chornock, Raffaella Margutti, Wen-fai Fong, B. Ashley Zauderer

Research output: Contribution to journalArticle

3 Citations (Scopus)

### Abstract

We present the first results from a recently concluded study of GRBs at z gsim 5 with the Karl G. Jansky Very Large Array (VLA). Spanning 1 to 85.5 GHz and 7 epochs from 1.5 to 82.3 days, our observations of GRB 140311A are the most detailed joint radio and millimeter observations of a GRB afterglow at z gsim 5 to date. In conjunction with optical/near-IR and X-ray data, the observations can be understood in the framework of radiation from a single blast wave shock with energy ${E}_{{\rm{K}},\mathrm{iso}}\approx 8.5\times {10}^{53}$ erg expanding into a constant density environment with density, ${n}_{0}\approx 8$ ${\mathrm{cm}}^{-3}$. The X-ray and radio observations require a jet break at ${t}_{\mathrm{jet}}\approx 0.6$ days, yielding an opening angle of ${\theta }_{\mathrm{jet}}\approx 4^\circ$ and a beaming-corrected blast wave kinetic energy of ${E}_{{\rm{K}}}\approx 2.2\times {10}^{50}$ erg. The results from our radio follow-up and multiwavelength modeling lend credence to the hypothesis that detected high-redshift GRBs may be more tightly beamed than events at lower redshift. We do not find compelling evidence for reverse shock emission, which may be related to fast cooling driven by the moderately high circumburst density.
Language English 65 Astrophysical Journal 858 1 10.3847/1538-4357/aab8f5 Published - 4 May 2018

### Cite this

A VLA Study of High-redshift GRBs. I. Multiwavelength Observations and Modeling of GRB 140311A. / Laskar, Tanmoy; Berger, Edo; Chornock, Ryan; Margutti, Raffaella; Fong, Wen-fai; Zauderer, B. Ashley.

In: Astrophysical Journal, Vol. 858, No. 1, 04.05.2018, p. 65.

Research output: Contribution to journalArticle

Laskar, Tanmoy ; Berger, Edo ; Chornock, Ryan ; Margutti, Raffaella ; Fong, Wen-fai ; Zauderer, B. Ashley. / A VLA Study of High-redshift GRBs. I. Multiwavelength Observations and Modeling of GRB 140311A. In: Astrophysical Journal. 2018 ; Vol. 858, No. 1. pp. 65.
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AU - Chornock, Ryan

AU - Margutti, Raffaella

AU - Fong, Wen-fai

AU - Zauderer, B. Ashley

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AB - We present the first results from a recently concluded study of GRBs at z gsim 5 with the Karl G. Jansky Very Large Array (VLA). Spanning 1 to 85.5 GHz and 7 epochs from 1.5 to 82.3 days, our observations of GRB 140311A are the most detailed joint radio and millimeter observations of a GRB afterglow at z gsim 5 to date. In conjunction with optical/near-IR and X-ray data, the observations can be understood in the framework of radiation from a single blast wave shock with energy ${E}_{{\rm{K}},\mathrm{iso}}\approx 8.5\times {10}^{53}$ erg expanding into a constant density environment with density, ${n}_{0}\approx 8$ ${\mathrm{cm}}^{-3}$. The X-ray and radio observations require a jet break at ${t}_{\mathrm{jet}}\approx 0.6$ days, yielding an opening angle of ${\theta }_{\mathrm{jet}}\approx 4^\circ$ and a beaming-corrected blast wave kinetic energy of ${E}_{{\rm{K}}}\approx 2.2\times {10}^{50}$ erg. The results from our radio follow-up and multiwavelength modeling lend credence to the hypothesis that detected high-redshift GRBs may be more tightly beamed than events at lower redshift. We do not find compelling evidence for reverse shock emission, which may be related to fast cooling driven by the moderately high circumburst density.

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