scholarly journals GRB 210121A: A Typical Fireball Burst Detected by Two Small Missions

2021 ◽  
Vol 922 (2) ◽  
pp. 237
Author(s):  
Xiangyu Ivy Wang ◽  
Xutao Zheng ◽  
Shuo Xiao ◽  
Jun Yang ◽  
Zi-Ke Liu ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Spectral Component ◽  
High Energy ◽  
Physical Models ◽  
Host Galaxy ◽  
Initial Radius ◽  
Peak Energy ◽  
Energy Indices ◽  
Sky Monitor ◽  
Integrated Detectors

Abstract The Chinese CubeSat Mission, Gamma Ray Integrated Detectors (GRID), recently detected its first gamma-ray burst, GRB 210121A, which was jointly observed by the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM). This burst is confirmed by several other missions, including Fermi and Insight-HXMT. We combined multimission observational data and performed a comprehensive analysis of the burst’s temporal and spectral properties. Our results show that the burst is relatively special in its high peak energy, thermal-like low-energy indices, and large fluence. By putting it to the E p –E γ,iso relation diagram with assumed distance, we found that this burst can be constrained at the redshift range of [0.3, 3.0]. The thermal spectral component is also confirmed by the direct fit of the physical models to the observed spectra. Interestingly, the physical photosphere model also constrained a redshift of z ∼ 0.3 for this burst, which helps us to identify a host galaxy candidate at such a distance within the location error box. Assuming that the host galaxy is real, we found that the burst can be best explained by the photosphere emission of a typical fireball with an initial radius of r 0 ∼ 3.2 × 107 cm.

scholarly journals GRB 171205A/SN 2017iuk: A local low-luminosity gamma-ray burst

2018 ◽  
Vol 619 ◽  
pp. A66 ◽  
Author(s):  
V. D’Elia ◽  
S. Campana ◽  
A. D’Aì ◽  
M. De Pasquale ◽  
S. W. K. Emery ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Host Galaxy ◽  
Isotropic Energy ◽  
Optical Telescope ◽  
X Ray ◽  
Hydrogen Column Density ◽  
Peak Energy ◽  
First Time

Context. Gamma-ray bursts (GRBs) occurring in the local Universe constitute an interesting sub-class of the GRB family, since their luminosity is on average lower than that of their cosmological analogs. Attempts to understand in a global way this peculiar behaviour is still not possible, since the sample of low redshift GRBs is small, and the properties of individual objects are too different from each other. In addition, their closeness (and consequently high fluxes) make these sources ideal targets for extensive follow-up even with small telescopes, considering also that these GRBs are conclusively associated with supernova (SN) explosions. Aims. We aim to contribute to the study of local bursts by reporting the case of GRB 171205A. This source was discovered by Swift Burst Alert Telescope (BAT) on 2017, December 5 and soon associated with a low redshift host galaxy (z = 0.037), and an emerging SN (SN 2017iuk). Methods. We analyzed the full Swift dataset, comprising the UV-Optical Telescope (UVOT), X-ray Telescope (XRT) and BAT data. In addition, we employed the Konus-Wind high energy data as a valuable extension at γ-ray energies. Results. The photometric SN signature is clearly visible in the UVOT u, b and ν filters. The maximum emission is reached at ∼13 (rest frame) days, and the whole bump resembles that of SN 2006aj, but lower in magnitude and with a shift in time of +2 d. A prebump in the ν-band is also clearly visible, and this is the first time that such a feature is not observed achromatically in GRB–SNe. Its physical origin cannot be easily explained. The X-ray spectrum shows an intrinsic Hydrogen column density NH,int = 7.4+4.1−3.6 × 1020 cm−2, which is at the low end of the N H, int, even considering just low redshift GRBs. The spectrum also features a thermal component, which is quite common in GRBs associated with SNe, but whose origin is still a matter of debate. Finally, the isotropic energy in the γ-ray band, Eiso = 2.18+0.63−5.0 × 1049 erg, is lower than those of cosmological GRBs. Combining this value with the peak energy in the same band, Ep = 125+141−37 keV, implies that GRB 171205A is an outlier of the Amati relation, as are some other low redshift GRBs, and its emission mechanism should be different from that of canonical, farther away GRBs.

scholarly journals On the High‐Energy Spectral Component and Fine Time Structure of Terrestrial Gamma Ray Flashes

2019 ◽  
Vol 124 (14) ◽  
pp. 7484-7497 ◽  
Author(s):  
M. Marisaldi ◽  
M. Galli ◽  
C. Labanti ◽  
N. Østgaard ◽  
D. Sarria ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Spectral Component ◽  
High Energy ◽  
Time Structure ◽  
Fine Time

scholarly journals Spectral properties of gamma-ray bursts observed by the Suzaku wide-band all-sky monitor

2019 ◽  
Vol 71 (4) ◽  
Author(s):  
Norisuke Ohmori ◽  
Kazutaka Yamaoka ◽  
Makoto Yamauchi ◽  
Yuji Urata ◽  
Masanori Ohno ◽  
...  
Keyword(s):  
Short Duration ◽  
Power Law ◽  
Spectral Properties ◽  
Gamma Ray ◽  
Wide Band ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Sky Monitor ◽  
S Peak ◽  
Single Power

Abstract We have systematically studied the spectral properties of 302 localized gamma-ray bursts (GRBs) observed by the Suzaku wide-band all-sky monitor (WAM) from 2005 August to 2010 December. The energy spectra in the 100–5000 keV range integrated over the entire emission and the 1 s peak were fitted by three models: a single power law, a power law with an exponential cutoff (CPL), and the GRB Band function (GRB). Most of the burst spectra were well fitted by a single power law. The average photon index α was −2.11 and −1.73 for long and short bursts, respectively. For the CPL and GRB models, the low-energy and high-energy photon indices (α and β) for the entire emission spectra were consistent with previous measurements. The averages of the α and β were −0.90 and −2.65 for long-duration GRBs, while the average α was −0.55 and the β was not well constrained for short-duration GRBs. However, the average peak energy Epeak was 645 and 1286 keV for long- and short-duration GRBs respectively, which are higher than previous Fermi/GBM measurements (285 keV and 736 keV). The α and Epeak of the 1 s peak spectra were larger, i.e., the spectra were harder, than the total fluence spectra. Spectral simulations based on Fermi-GBM results suggest that the higher Epeaks measured by the Suzaku WAM could be due to detector selection bias, mainly caused by the limited energy range above 100 keV.

scholarly journals THE VERY BRIGHT AND NEARBY GRB130427A: THE EXTRA HARD SPECTRAL COMPONENT AND IMPLICATIONS FOR VERY HIGH-ENERGY GAMMA-RAY OBSERVATIONS OF GAMMA-RAY BURSTS

2014 ◽  
Vol 28 ◽  
pp. 1460174
Author(s):  
PAK-HIN THOMAS TAM
Keyword(s):  
Gamma Ray ◽  
Spectral Component ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Prompt Gamma ◽  
Large Area ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

The extended high-energy gamma-ray (>100 MeV) emission occurring after the prompt gamma-ray bursts (GRBs) is usually characterized by a single power-law spectrum, which has been explained as the afterglow synchrotron radiation. We report on the Fermi Large Area Telescope (LAT) observations of the >100 MeV emission from the very bright and nearby GRB 130427A, up to ~100 GeV. By performing time-resolved spectral fits of GRB 130427A, we found a strong evidence of an extra hard spectral component above a few GeV that exists in the extended high-energy emission of this GRB. This extra spectral component may represent the first clear evidence of the long sought-after afterglow inverse Compton emission. Prospects for observations at the very high-energy gamma-rays, i.e., above 100 GeV, are described.

scholarly journals Gamma-ray Bursts at the Highest Energies

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 503
Author(s):  
Lara Nava
Keyword(s):  
Gamma Ray ◽  
Current Knowledge ◽  
Spectral Component ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Special Focus ◽  
High Energy Radiation ◽  
Energy Radiation ◽  
Very High Energy ◽  
Very High

Emission from Gamma-ray bursts is thought to be powered mainly by synchrotron radiation from energetic electrons. The same electrons might scatter these synchrotron seed photons to higher (>10 GeV) energies, building a distinct spectral component (synchrotron self-Compton, SSC). This process is expected to take place, but its relevance (e.g., the ratio between the SSC and synchrotron emitted power) is difficult to predict on the basis of current knowledge of physical conditions at GRB emission sites. Very high-energy radiation in GRBs can be produced also by other mechanisms, such as synchrotron itself (if PeV electrons are produced at the source), inverse Compton on external seed photons, and hadronic processes. Recently, after years of efforts, very high-energy radiation has been finally detected from at least four confirmed long GRBs by the Cherenkov telescopes H.E.S.S. and MAGIC. In all four cases, the emission has been recorded during the afterglow phase, well after the end of the prompt emission. In this work, I give an overview, accessible also to non-experts of the field, of the recent detections, theoretical implications, and future challenges, with a special focus on why very high-energy observations are relevant for our understanding of Gamma-ray bursts and which long-standing questions can be finally answered with the help of these observations.

scholarly journals GRB 190114C in the nuclear region of an interacting galaxy

2020 ◽  
Vol 633 ◽  
pp. A68 ◽  
Author(s):  
A. de Ugarte Postigo ◽  
C. C. Thöne ◽  
S. Martín ◽  
J. Japelj ◽  
A. J. Levan ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Formation Rate ◽  
High Energy ◽  
Host Galaxy ◽  
Nuclear Region ◽  
Star Forming ◽  
Environmental Properties ◽  
Very High Energy ◽  
Imaging And Spectroscopy ◽  
Very High

Context. For the first time, very high energy emission up to the TeV range has been reported for a gamma-ray burst (GRB). It is still unclear whether the environmental properties of GRB 190114C might have contributed to the production of these very high energy photons, or if it is solely related to the released GRB emission. Aims. The relatively low redshift of the GRB (z = 0.425) allows us to study the host galaxy of this event in detail, and to potentially identify idiosyncrasies that could point to progenitor characteristics or environmental properties that might be responsible for this unique event. Methods. We used ultraviolet, optical, infrared, and submillimetre imaging and spectroscopy obtained with the HST, the VLT, and ALMA to obtain an extensive dataset on which the analysis of the host galaxy is based. Results. The host system is composed of a close pair of interacting galaxies (Δv = 50 km s−1), both of which are well detected by ALMA in CO(3-2). The GRB occurred within the nuclear region (∼170 pc from the centre) of the less massive but more star-forming galaxy of the pair. The host is more massive (log(M/M⊙) = 9.3) than average GRB hosts at this redshift, and the location of the GRB is rather unique. The higher star formation rate was probably triggered by tidal interactions between the two galaxies. Our ALMA observations indicate that both host galaxy and companion have a high molecular gas fraction, as has been observed before in interacting galaxy pairs. Conclusions. The location of the GRB within the core of an interacting galaxy with an extinguished line of sight is indicative of a denser environment than typically observed for GRBs and could have been crucial for the generation of the very high energy photons that were observed.

scholarly journals Resolving the excess of long GRB’s at low redshift in the Swift era

2020 ◽  
Vol 493 (1) ◽  
pp. 1479-1491 ◽  
Author(s):  
Truong Le ◽  
Cecilia Ratke ◽  
Vedant Mehta
Keyword(s):  
Physical Parameter ◽  
Power Law ◽  
Gamma Ray ◽  
Hubble Constant ◽  
High Energy ◽  
Star Formation History ◽  
Physical Parameters ◽  
Data Set ◽  
Energy Indices ◽  
Parameter Values

ABSTRACT Utilizing more than 100 long gamma-ray bursts (LGRBs) in the Swift-Ryan-2012 sample that includes the observed redshifts and jet angles, Le & Mehta performed a timely study of the rate density of LGRBs with an assumed broken power-law GRB spectrum and obtained a GRB-burst-rate functional form that gives acceptable fits to the pre-Swift and Swift redshift, and jet angle distributions. The results indicated an excess of LGRBs at redshift below z ∼ 2 in the Swift sample. In this work, we are investigating if the excess is caused by the cosmological Hubble constant H0, the gamma-ray energy released ${\cal E}_{*\gamma }$, the low- and high-energy indices (α, β) of the Band function, the minimum and maximum jet angles θj, min and θj, max, or that the excess is due to a bias in the Swift-Ryan-2012 sample. Our analyses indicate that none of the above physical parameters resolved the excess problem, but suggesting that the Swift-Ryan-2012 sample is biased with possible afterglow selection effect. The following model physical parameter values provide the best fit to the Swift-Ryan-2012 and pre-Swift samples: the Hubble constant $H_0 = 72 \, {\rm km s^{-1} Mpc^{-1}}$, the energy released ${\cal E}_{*\gamma }\sim 4.47 \times 10^{51}$ erg, the energy indices α ∼ 0.9 and β ∼ −2.13, the jet angles of θj, max ∼ 0.8 rad, and θj, min ∼ 0.065 and ∼0.04 rad for pre-Swift and Swift, respectively, s ∼ −1.55 the jet angle power-law index, and a GRB formation rate that is similar to the Hopkins & Beacom observed star formation history and as extended by Li. Using the Swift Gamma-Ray Burst Host Galaxy Legacy Survey (SHOALS) Swift-Perley LGRB sample and applying the same physical parameter values as above, however, our model provides consistent results with this data set and indicating no excess of LGRBs at any redshift.

scholarly journals A multiwavelength analysis of a collection of short-duration GRBs observed between 2012 and 2015

2019 ◽  
Vol 485 (4) ◽  
pp. 5294-5318 ◽  
Author(s):  
S B Pandey ◽  
Y Hu ◽  
Ao J Castro-Tirado ◽  
A S Pozanenko ◽  
R Sánchez-Ramírez ◽  
...  
Keyword(s):  
Short Duration ◽  
Gamma Ray ◽  
High Energy ◽  
Photometric Data ◽  
Host Galaxy ◽  
Late Time ◽  
Time Data ◽  
Emission Data ◽  
Temporal Decay ◽  
Prompt Emission

Abstract We investigate the prompt emission and the afterglow properties of short-duration gamma-ray burst (sGRB) 130603B and another eight sGRB events during 2012–2015, observed by several multiwavelength facilities including the Gran Canarias Telescope 10.4 m telescope. Prompt emission high energy data of the events were obtained by INTEGRAL-SPI-ACS, Swift-BAT, and Fermi-GBM satellites. The prompt emission data by INTEGRAL in the energy range of 0.1–10 MeV for sGRB 130603B, sGRB 140606A, sGRB 140930B, sGRB 141212A, and sGRB 151228A do not show any signature of the extended emission or precursor activity and their spectral and temporal properties are similar to those seen in case of other short bursts. For sGRB 130603B, our new afterglow photometric data constrain the pre-jet-break temporal decay due to denser temporal coverage. For sGRB 130603B, the afterglow light curve, containing both our new and previously published photometric data is broadly consistent with the ISM afterglow model. Modeling of the host galaxies of sGRB 130603B and sGRB 141212A using the LePHARE software supports a scenario in which the environment of the burst is undergoing moderate star formation activity. From the inclusion of our late-time data for eight other sGRBs we are able to: place tight constraints on the non-detection of the afterglow, host galaxy, or any underlying ‘kilonova’ emission. Our late-time afterglow observations of the sGRB 170817A/GW170817 are also discussed and compared with the sub-set of sGRBs.

scholarly journals A new fitting function for GRB MeV spectra based on the internal shock synchrotron model

2020 ◽  
Vol 640 ◽  
pp. A91 ◽  
Author(s):  
M. Yassine ◽  
F. Piron ◽  
F. Daigne ◽  
R. Mochkovitch ◽  
F. Longo ◽  
...  
Keyword(s):  
Physical Model ◽  
Gamma Ray ◽  
Spectral Component ◽  
Emission Spectra ◽  
High Energy ◽  
Spectral Energy ◽  
Parametric Function ◽  
Time Resolved ◽  
Internal Shock ◽  
Prompt Emission

Aims. The physical origin of the gamma-ray burst (GRB) prompt emission is still a subject of debate. Internal shock models have been widely explored, owing to their ability to explain most of the high-energy properties of this emission phase. While the Band function or other phenomenological functions are commonly used to fit GRB prompt emission spectra, we propose a new parametric function that is inspired by an internal shock physical model. We use this function as a proxy of the model to compare it easily to GRB observations. Methods. We built a parametric function that represents the spectral form of the synthetic bursts provided by our internal shock synchrotron model (ISSM). We simulated the response of the Fermi instruments to the synthetic bursts and fit the obtained count spectra to validate the ISSM function. Then, we applied this function to a sample of 74 bright GRBs detected by the Fermi GBM, and we computed the width of their spectral energy distributions around their peak energy. For comparison, we also fit the phenomenological functions that are commonly used in the literature. Finally, we performed a time-resolved analysis of the broadband spectrum of GRB 090926A, which was jointly detected by the Fermi GBM and LAT. This spectrum has a complex shape and exhibits a power-law component with an exponential cutoff at high energy, which is compatible with inverse Compton emission attenuated by gamma-ray internal absorption. Results. This work proposes a new parametric function for spectral fitting that is based on a physical model. The ISSM function reproduces 81% of the spectra in the GBM bright GRB sample, versus 59% for the Band function, for the same number of parameters. It gives also relatively good fits to the GRB 090926A spectra. The width of the MeV spectral component that is obtained from the fits of the ISSM function is slightly larger than the width from the Band fits, but it is smaller when observed over a wider energy range. Moreover, all of the 74 analyzed spectra are found to be significantly wider than the synthetic synchrotron spectra. We discuss possible solutions to reconcile the observations with the internal shock synchrotron model, such as an improved modeling of the shock microphysics or more accurate spectral measurements at MeV energies.

scholarly journals A panchromatic view of relativistic jets in narrow-line Seyfert 1 galaxies

2016 ◽  
Author(s):  
Filippo D'Ammando ◽  
Monica Orienti ◽  
Justin Finke ◽  
Josefin Larsson ◽  
Marcello Giroletti ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Systematic Investigation ◽  
Host Galaxy ◽  
Narrow Line ◽  
Relativistic Jets ◽  
Large Area ◽  
Very High Energy ◽  
Very High ◽  
Level Analysis

The discovery by the Large Area Telescope on board Fermi of variable gamma-ray emission from radio-loud narrow-line Seyfert 1 (NLSy1) galaxies revealed the presence of a possible third class of AGN with relativistic jets in addition to blazars and radio galaxies. Considering that NLSy1 are usually hosted in spiral galaxies, this finding poses intriguing questions about the nature of these objects and the formation of relativistic jets. We report on a systematic investigation of the gamma-ray properties of a sample of radio-loud NLSy1, including the detection of new objects, using 7 years of Fermi-LAT data with the new Pass 8 event-level analysis. In addition we discuss the radio-to-very-high-energy properties of the gamma-ray emitting NLSy1, their host galaxy, and black hole mass in the context of the blazar scenario and the unification of relativistic jets at different scales.

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