Understanding the Nature of the Optical Emission in Gamma-Ray Bursts: Analysis from TAROT, COATLI, and RATIR Observations. (arXiv:2308.07882v1 [astro-ph.HE])

Understanding the Nature of the Optical Emission in Gamma-Ray Bursts: Analysis from TAROT, COATLI, and RATIR Observations. (arXiv:2308.07882v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Becerra_R/0/1/0/all/0/1">R. L. Becerra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Klotz_A/0/1/0/all/0/1">A. Klotz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Atteia_J/0/1/0/all/0/1">J. L. Atteia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guetta_D/0/1/0/all/0/1">D. Guetta</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Watson_A/0/1/0/all/0/1">A. M. Watson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Colle_F/0/1/0/all/0/1">F. De Colle</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Angulo_Valdez_C/0/1/0/all/0/1">C. Angulo-Valdez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Butler_N/0/1/0/all/0/1">N. R. Butler</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dichiara_S/0/1/0/all/0/1">S. Dichiara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fraija_N/0/1/0/all/0/1">N. Fraija</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Garcia_Cifuentes_K/0/1/0/all/0/1">K. Garcia-Cifuentes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kutyrev_A/0/1/0/all/0/1">A. S. Kutyrev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_W/0/1/0/all/0/1">W. H. Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pereyra_M/0/1/0/all/0/1">M. Pereyra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Troja_E/0/1/0/all/0/1">E. Troja</a>

We collected the optical light curve data of 227 gamma-ray bursts (GRBs)
observed with the TAROT, COATLI, and RATIR telescopes. These consist of 133
detections and 94 upper limits. We constructed average light curves in the
observer and rest frames in both X-rays (from {itshape Swift}/XRT) and in the
optical. Our analysis focused on investigating the observational and intrinsic
properties of GRBs. Specifically, we examined observational properties, such as
the optical brightness function of the GRBs at $T=1000$ seconds after the
trigger, as well as the temporal slope of the afterglow. We also estimated the
redshift distribution for the GRBs within our sample. Of the 227 GRBs analysed,
we found that 116 had a measured redshift. Based on these data, we calculated a
local rate of $rho_0=0.2$ Gpc$^{-3}$ yr$^{-1}$ for these events with $z<1$. To
explore the intrinsic properties of GRBs, we examined the average X-ray and
optical light curves in the rest frame. We use the {scshape afterglowpy}
library to generate synthetic curves to constrain the parameters typical of the
bright GRB jet, such as energy (${langle} {E_{0}}{rangle}sim
10^{53.6}$~erg), opening angle (${langle}theta_mathrm{core}{rangle}sim
0.2$~rad), and density (${langle}n_mathrm{0}{rangle}sim10^{-2.1}$
cm$^{-3}$). Furthermore, we analyse microphysical parameters, including the
fraction of thermal energy in accelerated electrons
(${langle}epsilon_e{rangle}sim 10^{-1.37}$) and in the magnetic field
(${langle}epsilon_B{rangle}sim10^{-2.26}$), and the power-law index of the
population of non-thermal electrons (${langle}p{rangle}sim 2.2$).

We collected the optical light curve data of 227 gamma-ray bursts (GRBs)
observed with the TAROT, COATLI, and RATIR telescopes. These consist of 133
detections and 94 upper limits. We constructed average light curves in the
observer and rest frames in both X-rays (from {itshape Swift}/XRT) and in the
optical. Our analysis focused on investigating the observational and intrinsic
properties of GRBs. Specifically, we examined observational properties, such as
the optical brightness function of the GRBs at $T=1000$ seconds after the
trigger, as well as the temporal slope of the afterglow. We also estimated the
redshift distribution for the GRBs within our sample. Of the 227 GRBs analysed,
we found that 116 had a measured redshift. Based on these data, we calculated a
local rate of $rho_0=0.2$ Gpc$^{-3}$ yr$^{-1}$ for these events with $z<1$. To
explore the intrinsic properties of GRBs, we examined the average X-ray and
optical light curves in the rest frame. We use the {scshape afterglowpy}
library to generate synthetic curves to constrain the parameters typical of the
bright GRB jet, such as energy (${langle} {E_{0}}{rangle}sim
10^{53.6}$~erg), opening angle (${langle}theta_mathrm{core}{rangle}sim
0.2$~rad), and density (${langle}n_mathrm{0}{rangle}sim10^{-2.1}$
cm$^{-3}$). Furthermore, we analyse microphysical parameters, including the
fraction of thermal energy in accelerated electrons
(${langle}epsilon_e{rangle}sim 10^{-1.37}$) and in the magnetic field
(${langle}epsilon_B{rangle}sim10^{-2.26}$), and the power-law index of the
population of non-thermal electrons (${langle}p{rangle}sim 2.2$).

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