On the Origin of the Multi-GeV Photons from the Closest Burst with Intermediate Luminosity: GRB 190829A

Fraija, N.; Vereš, P.; Beniamini, Paz; Galván-Gaméz, A.; Metzger, Brian D.; Duran, R. Barniol; Becerra, R. L.

doi:10.3847/1538-4357/ac0aed

Cited by 40 publications

(24 citation statements)

References 133 publications

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“…To this end, it is necessary to apply these correlations as model discriminators only after correction for such biases. Indeed, for example the plateau emission in X-rays and optical, which reconciles with the existence of the 2D Dainotti relation, can be derived through the equations of a fast rotating NS, the so-called magnetar model [17][18][19][63][64][65]. In Rowlinson et al [66], Rea et al [67], Stratta et al [68] the derivation of the parameter space of the magnetic field and spin period have been computed accounting for selection biases and redshift evolution.…”

Section: Introductionmentioning

confidence: 99%

Accounting for Selection Bias and Redshift Evolution in GRB Radio Afterglow Data

et al. 2021

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Gamma-ray Bursts (GRBs) are highly energetic events that can be observed at extremely high redshift. However, inherent bias in GRB data due to selection effects and redshift evolution can significantly skew any subsequent analysis. We correct for important variables related to the GRB emission, such as the burst duration, T90*, the prompt isotropic energy, Eiso, the rest-frame end time of the plateau emission, Ta,radio*, and its correspondent luminosity La,radio, for radio afterglow. In particular, we use the Efron–Petrosian method presented in 1992 for the correction of our variables of interest. Specifically, we correct Eiso and T90* for 80 GRBs, and La,radio and Ta,radio* for a subsample of 18 GRBs that present a plateau-like flattening in their light curve. Upon application of this method, we find strong evolution with redshift in most variables, particularly in La,radio, with values similar to those found in past and current literature in radio, X-ray and optical wavelengths, indicating that these variables are susceptible to observational bias. This analysis emphasizes the necessity of correcting observational data for evolutionary effects to obtain the intrinsic behavior of correlations to use them as discriminators among the most plausible theoretical models and as reliable cosmological tools.

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Section: Introductionmentioning

confidence: 99%

Accounting for Selection Bias and Redshift Evolution in GRB Radio Afterglow Data

et al. 2021

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“…The main point of qualitative disagreement among these interpretations is the X-ray/optical peak at t ∼ 10 −2 days (i.e., around 10 3 s). Zhang et al (2020) attributed it to late central engine activity; Lu-Lu et al (2021) invoked the interaction of the blast wave with a preaccelerated electron-positron pair enriched shell formed due to annihilation of prompt emission photons, partly scattered by the dusty external medium; and Fraija et al (2021) proposed a magnetar spin-down-powered origin. Given that the reverse shock is a natural consequence of the jet interaction with the external medium, our interpretation (within which we are able to explain all of the data self-consistently) can be preferred with respect to these based on Occam's razor.…”

Section: Summary and Discussionmentioning

confidence: 99%

Multiwavelength View of the Close-by GRB 190829A Sheds Light on Gamma-Ray Burst Physics

Salafia

Ravasio

Yang

et al. 2022

ApJL

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We monitored the position of the close-by (about 370 Mpc) gamma-ray burst GRB 190829A, which originated from a massive star collapse, through very long baseline interferometry (VLBI) observations with the European VLBI Network and the Very Long Baseline Array, carrying out a total of nine observations between 9 and 117 days after the gamma-ray burst at 5 and 15 GHz, with a typical resolution of a few milliarcseconds. From a state-of-the art analysis of these data, we obtained valuable limits on the source size and expansion rate. The limits are in agreement with the size evolution entailed by a detailed modeling of the multiwavelength light curves with a forward-plus-reverse shock model, which agrees with the observations across almost 18 orders of magnitude in frequency (including the HESS data at TeV photon energies) and more than 4 orders of magnitude in time. Thanks to the multiwavelength, high-cadence coverage of the afterglow, inherent degeneracies in the afterglow model are broken to a large extent, allowing us to capture some unique physical insights; we find a low prompt emission efficiency of ≲10−3, a low fraction of relativistic electrons in the forward shock downstream χ e < 13% (90% credible level), and a rapid decay of the magnetic field in the reverse shock downstream after the shock crossing. While our model assumes an on-axis jet, our VLBI astrometry is not sufficiently tight as to exclude any off-axis viewing angle, but we can exclude the line of sight to have been more than ∼2° away from the border of the gamma-ray-producing region based on compactness arguments.

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“…However, multi-wavelength follow up of these events has proved a fundamental tool to test the afterglow emission model: for GRB 190829A, e.g., the VHE emission detected by the H.E.S.S. telescopes has been firstly interpreted as synchrotron emission (H. E. S. S. Collaboration et al 2021), while multi-wavelength follow up studies agree for an SSC emission origin (Salafia et al 2021;Zhang et al 2021;Fraija et al 2021).…”

Section: Introductionmentioning

confidence: 99%

VLBI observations of GRB 201015A, a relatively faint GRB with a hint of Very High Energy gamma-ray emission

Giarratana,

Rhodes,

Marcote

et al. 2022

Preprint

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Context. A total of four long duration Gamma-Ray Bursts (GRBs) have been confirmed at very high energy (≥100 GeV) with large significance hitherto, and any possible peculiarities of these bursts will become clearer as the number of detected events increases. Multi-wavelength follow-up campaigns are required to extract information on the physical conditions within the jets that lead to the very high energy counterpart, hence they are crucial to unveil the properties of this class of bursts. Aims. GRB 201015A is a long-duration GRB detected using the MAGIC telescopes from ∼40 s after the burst. If confirmed, this would be the fifth and least luminous GRB ever detected at this energies. The goal of this work is to constrain the global and microphysical parameters of its afterglow phase, and discuss the main properties of this burst in a broader context. Methods. Since the radio band, together with frequent optical and X-rays observations, proved to be a fundamental tool to overcome the degeneracy in the afterglow modelling, we performed a radio follow-up of GRB 201015A over twelve different epochs, from 1.4 days (2020 October 17) to 117 days (2021 February 9) post-burst, with the Karl G. Jansky Very Large Array, e-MERLIN and the European VLBI Network. We include optical and X-rays observations, performed with the Multiple Mirror Telescope and the Chandra X-ray Observatory respectively, together with publicly available data, in order to build the multi-wavelength light curves and to compare them with the standard fireball model. Results. We detected a point-like transient, consistent with the position of GRB 201015A until 23 and 47 days post-burst at 1.5 and 5 GHz, respectively. No emission was detected in subsequent radio observations. The source was detected also in both optical (1.4 and 2.2 days post-burst) and X-ray (8.4 and 13.6 days post-burst) observations. Conclusions. The multi-wavelength afterglow light curves can be explained with the standard model for a GRB seen on-axis, which expands and decelerates into a medium with a homogeneous density. A circumburst medium with a wind-like profile is disfavoured. Notwithstanding the high resolution provided by the VLBI, we could not pinpoint any expansion or centroid displacement of the outflow. If the GRB is seen at the viewing angle θ which maximises the apparent velocity β app , i.e. θ ∼ β −1 app , we estimate that the Lorentz factor for the possible proper motion is Γ α ≤ 40 in right ascension and Γ δ ≤ 61 in declination. On the other hand, if the GRB is seen on-axis, the size of the afterglow is ≤5 pc and ≤16 pc at 25 and 47 days. Finally, the early peak in the optical light curve suggests the presence of a reverse shock component before 0.01 days from the burst.

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On the Origin of the Multi-GeV Photons from the Closest Burst with Intermediate Luminosity: GRB 190829A

Cited by 40 publications

References 133 publications

Accounting for Selection Bias and Redshift Evolution in GRB Radio Afterglow Data

Accounting for Selection Bias and Redshift Evolution in GRB Radio Afterglow Data

Multiwavelength View of the Close-by GRB 190829A Sheds Light on Gamma-Ray Burst Physics

VLBI observations of GRB 201015A, a relatively faint GRB with a hint of Very High Energy gamma-ray emission

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