Evidence for a Photospheric Component in the Prompt Emission of the Short GRB 120323a and Its Effects on the GRB Hardness-Luminosity Relation

Guiriec, S.; Daigne, F.; Hascoët, Romain; Vianello, G.; Ryde, F.; Mochkovitch, R.; Kouveliotou, C.; Xiong, S. L.; Bhat, P. N.; Foley, S.; Gruber, D.; Burgess, J. Michael; McGlynn, S.; McEnery, J. E.; Gehrels, N.

doi:10.1088/0004-637x/770/1/32

Cited by 152 publications

(281 citation statements)

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“…We performed a fine-time analysis of GRB 131014A, following the same procedure as presented in Guiriec et al (2010Guiriec et al ( , 2011Guiriec et al ( , 2013Guiriec et al ( , 2015a. The time intervals used for this analysis are displayed in Figure 1 (b).…”

Section: Analysis Methodologymentioning

confidence: 99%

“…As a result of this new multi-component model, a strong correlation has been found between the time-resolved energy flux of C nTh , F , i nTh and its corresponding νF ν peak energy, E peak,i nTh (hereafter F E i nTh peak,i nTh -relation; Guiriec et al 2013Guiriec et al , 2015aGuiriec et al , 2015b. 7 When fitted to a PL, the indices of the F E i nTh peak,i nTh -relations are very similar for all GRBs (i.e., ∼1.4), and when corrected for the redshift (i.e., in the source frame) a universal relation for all GRBs appears between the timeresolved luminosities of the non-thermal component, L i nTh and its νF ν peak energy in the rest frame, E peak,i nTh,rest (hereafter…”

Section: Introductionmentioning

confidence: 97%

“…Over the past few years, the paradigm for the prompt emission of both short and long gamma-ray bursts (GRBs) has evolved from a single-hump keV-MeV νF ν spectrum to a double-hump scenario (Guiriec et al 2011(Guiriec et al , 2013(Guiriec et al , 2015a; it has been proposed that the two humps correspond to two separate emission processes: (i) a thermal-like component-usually adequately approximated with a blackbody (BB) spectrumthat may be the footprint of the GRB jet photosphere predicted by the fireball model (Cavallo & Rees 1978;Goodman 1986;Paczynski 1986;Shemi & Piran 1990;Rees & Meszaros 1992, 1994Meszaros & Rees 1993, Mészáros 2002 and (ii) a nonthermal-like component that may be related to particle acceleration processes within the GRB jet such as internal shocks (Rees & Meszaros 1994;Kobayashi et al 1997;Daigne & Mochkovitch 1998) and/or magnetic reconnection mechanisms (Zhang & Yan 2011;Zhang & Zhang 2014). Despite its non-thermal shape, this component may also be interpreted as strongly reprocessed photospheric emission episodes (Giannios 2006(Giannios , 2008Pe'er et al 2006;Beloborodov 2010Beloborodov , 2011Beloborodov , 2013Vurm et al 2011;Beloborodov et al 2014;Vurm & Beloborodov 2015).…”

Section: Introductionmentioning

confidence: 99%

“…nTh,rest -- Guiriec et al 2013Guiriec et al , 2015a. Because C Th is usually energetically subdominant, it is often challenging to capture its exact spectral shape.…”

Section: Introductionmentioning

confidence: 99%

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GRB 131014A: A LABORATORY FOR STUDYING THE THERMAL-LIKE AND NON-THERMAL EMISSIONS IN GAMMA-RAY BURSTS, AND THE NEW ${L}_{{\rm{i}}}^{\mathrm{nTh}}-{E}_{\mathrm{peak},{\rm{i}}}^{\mathrm{nTh},\mathrm{rest}}$ RELATION

Guiriec

Mochkovitch

Piran

et al. 2015

ApJ

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Over the past years, evidence has been accumulated on the existence of a thermal-like component during the prompt phase of Gamma Ray Bursts (GRBs). However, this component, often associated with the GRB jet's photosphere, is usually subdominant compared to a much stronger non-thermal one. The prompt emission of GRB 131014A-detected by the Fermi Gamma-ray Space Telescope (hereafter Fermi)-provides an unique opportunity to trace the history of this thermal-like component. Indeed, the thermal emission in GRB 131014A is much more intense than in other GRBs and a pure thermal episode is observed during the initial 0.16 s. The thermal-like component cools monotonically during the first second while the non-thermal emission kicks off. The intensity of the non-thermal component progressively increases until being energetically dominant at late time similarly to what is typically observed. This is a perfect scenario to disentangle the thermal component from the nonthermal one. The initial decaying and cooling phase of the thermal-like component is followed by a strong re-brightening and a re-heating episode; however, despite a much brighter second emission phase, the temperature of the thermal component does not reach its initial value. This re-brightening episode is followed by a global constant cooling until the end of the burst. We note that a shallower low-energy spectral slope than the typical index value +1, corresponding to a pure Planck function, better matches with the thermal-like spectral shape; a spectral index around +0.6 seems to be in better agreement with the data. The non-thermal component is adequately fitted with a Band function whose low and high energy power law indices are ∼-0.7 and <∼-3, respectively; this is also statistically globally equivalent to a cutoff power law with a ∼-0.7 index. This is in agreement with our previous results. Finally, a strong correlation is observed between the time-resolved energy flux, F nTh i , and the corresponding spectral peak energy, E nTh peak,i , of the non-thermal component with a slope similar to the one reported in our previous articles. Assuming a universal relation between the time-resolved luminosity of the non-thermal component, L nTh i , and its rest frame E nTh peak,i , E rest,nTh peak,i , that we derived from a limited sample of GRBs detected by Fermi, we estimate a redshift of ∼1.55 for GRB 131014A that is a typical value for long GRBs. These observational results are consistent with the models in which the non-thermal emission is produced well above the GRB jet photosphere but they may also be compatible with other scenarios (e.g., dissipative photosphere) that are not discussed in this article.

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Section: Analysis Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

“…nTh,rest -- Guiriec et al 2013Guiriec et al , 2015a. Because C Th is usually energetically subdominant, it is often challenging to capture its exact spectral shape.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

GRB 131014A: A LABORATORY FOR STUDYING THE THERMAL-LIKE AND NON-THERMAL EMISSIONS IN GAMMA-RAY BURSTS, AND THE NEW ${L}_{{\rm{i}}}^{\mathrm{nTh}}-{E}_{\mathrm{peak},{\rm{i}}}^{\mathrm{nTh},\mathrm{rest}}$ RELATION

Guiriec

Mochkovitch

Piran

et al. 2015

ApJ

Self Cite

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show abstract

“…The observed emission can be entirely from the photosphere wherein the broadness is contributed by the continuous or localised subphotospheric dissipation of the kinetic energy or Poynting flux (Beloborodov 2010(Beloborodov , 2013Giannios 2012;Pe'er, Mészáros & Rees 2005;Iyyani et al 2015), or may be due to the geometrical effects of the jet emission and its structure (Lundman, Pe'er & Ryde 2013;Beloborodov 2011;Basak & Rao 2015a). Or, the photospheric emission can be a sub-dominant component (Burgess et al 2014;Axelsson et al 2012;Iyyani et al 2013;Guiriec et al 2011Guiriec et al , 2013. All the models have certain pros and cons and confront issues in justifying the constraints obtained from observations.…”

Section: Introductionmentioning

confidence: 99%

Surprise in simplicity: an unusual spectral evolution of a single pulse GRB 151006A

Basak

Iyyani

Chand

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present a detailed analysis of GRB 151006A, the first GRB detected by Astrosat CZT Imager (CZTI). We study the long term spectral evolution by exploiting the capabilities of Fermi and Swift satellites at different phases, which is complemented by the polarization measurement with the CZTI. While the light curve of the GRB in different energy bands show a simple pulse profile, the spectrum shows an unusual evolution. The first phase exhibits a hard-to-soft (HTS) evolution until ∼ 16 − 20 s, followed by a sudden increase in the spectral peak reaching a few MeV. Such a dramatic change in the spectral evolution in case of a single pulse burst is reported for the first time. This is captured by all models we used namely, Band function, Blackbody+Band and two blackbodies+power law. Interestingly, the Fermi Large Area Telescope (LAT) also detects its first photon (> 100 MeV) during this time. This new injection of energy may be associated with either the beginning of afterglow phase, or a second hard pulse of the prompt emission itself which, however, is not seen in the otherwise smooth pulse profile. By constructing Bayesian blocks and studying the hardness evolution we find a good evidence for a second hard pulse. The Swift data at late epochs (> T 90 of the GRB) also shows a significant spectral evolution consistent with the early second phase. The CZTI data (100-350 keV), though having low significance (1σ), show high values of polarization in the two epochs (77% to 94%), in agreement with our interpretation.

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Gamma-Ray Bursts as Sources of Strong Magnetic Fields

Granot¹,

Piran²,

Bromberg³

et al. 2016

The Strongest Magnetic Fields in the Universe

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Evidence for a Photospheric Component in the Prompt Emission of the Short GRB 120323a and Its Effects on the GRB Hardness-Luminosity Relation

Cited by 152 publications

References 105 publications

GRB 131014A: A LABORATORY FOR STUDYING THE THERMAL-LIKE AND NON-THERMAL EMISSIONS IN GAMMA-RAY BURSTS, AND THE NEW ${L}_{{\rm{i}}}^{\mathrm{nTh}}-{E}_{\mathrm{peak},{\rm{i}}}^{\mathrm{nTh},\mathrm{rest}}$ RELATION

GRB 131014A: A LABORATORY FOR STUDYING THE THERMAL-LIKE AND NON-THERMAL EMISSIONS IN GAMMA-RAY BURSTS, AND THE NEW ${L}_{{\rm{i}}}^{\mathrm{nTh}}-{E}_{\mathrm{peak},{\rm{i}}}^{\mathrm{nTh},\mathrm{rest}}$ RELATION

Surprise in simplicity: an unusual spectral evolution of a single pulse GRB 151006A

Gamma-Ray Bursts as Sources of Strong Magnetic Fields

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