Showing papers by "F. Frontera published in 2022"
TL;DR: A detailed follow-up of the very energetic GRB 210905A at a high redshift of z = 6.312 and its luminous X-ray and optical afterglow was presented in this article .
Abstract: We present a detailed follow-up of the very energetic GRB 210905A at a high redshift of z = 6.312 and its luminous X-ray and optical afterglow. We obtained a photometric and spectroscopic follow-up in the optical and near-infrared (NIR), covering both the prompt and afterglow emission from a few minutes up to 20 Ms after burst. With an isotropic gamma-ray energy release of Eiso = 1.27E54 erg, GRB 210905A lies in the top ~7% of gamma-ray bursts (GRBs) in terms of energy released. Its afterglow is among the most luminous ever observed. It starts with a shallow evolution that can be explained by energy injection, and it is followed by a steeper decay, while the spectral energy distribution is in agreement with slow cooling in a constant-density environment within the standard fireball theory. A jet break at ~ 46.2+-16.3 d (~6.3 d rest-frame) has been observed in the X-ray light curve; however, it is hidden in the H band due to the contribution from the likely host galaxy, the fourth GRB host at z>6 known to date. We derived a half-opening angle of 8.4+-1.0 degrees, which is the highest ever measured for a z>6 burst, but within the range covered by closer events. The resulting collimation-corrected gamma-ray energy release of 1E52 erg is also among the highest ever measured. The moderately large half-opening angle argues against recent claims of an inverse dependence of the half-opening angle on the redshift. The total jet energy is likely too large to be sustained by a standard magnetar, and it suggests that the central engine of this burst was a newly formed black hole. Despite the outstanding energetics and luminosity of both GRB 210905A and its afterglow, we demonstrate that they are consistent with those of less distant bursts, indicating that the powering mechanisms and progenitors do not evolve significantly with redshift.
8 citations
TL;DR: In this paper , the authors reported the properties of the Insight-HXMT gamma-ray bursts, including their trigger time, duration, spectral parameters, peak fluxes of different timescales, and fluence.
Abstract: The Hard X-ray Modulation Telescope (Insight-HXMT) is China’s first X-ray astronomy satellite. It was launched on 2017 June 15. The anticoincidence CsI detectors of the High Energy X-ray telescope (HE) on board Insight-HXMT could serve as an all-sky gamma-ray monitor in about 0.2–3 MeV. In its first four years of operation, Insight-HXMT has detected 322 gamma-ray bursts (GRBs) by the offline search pipeline, including blind search and targeted search. For the GOLDEN sample of Insight-HXMT GRBs, joint analyses were performed with other GRB missions, including the Fermi Gamma-ray Burst Monitor (Fermi/GBM), the Swift Burst Alert Telescope (Swift/BAT), and the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM). The analyses showed that Insight-HXMT can provide a better constraint on the GRB spectrum at a higher-energy band. The properties of Insight-HXMT GRBs are reported in detail, including their trigger time, duration, spectral parameters, peak fluxes of different timescales, and fluence. This catalog is an official product of the Insight-HXMT GRB team.
7 citations
31 Aug 2022
TL;DR: In this article , the authors present the latest technological developments of the TRILL (technological readiness increase for Laue lenses) project, supported by ASI, devoted to the advancement of the technological readiness of Laue lens.
Abstract: Hard x-/soft gamma-ray astronomy (>100 keV) is a crucial field for the study of important astrophysical phenomena such as the 511 keV positron annihilation line in the galactic center region and its origin, gamma-ray bursts, soft gamma-ray repeaters, nuclear lines from SN explosions and more. However, several key questions in this field require sensitivity and angular resolution that are hardly achievable with present technology. A new generation of instruments suitable to focus hard x-/soft gamma-rays is necessary to overcome the technological limitations of current direct-viewing telescopes. One solution is using Laue lenses based on Bragg’s diffraction in a transmission configuration. To date, this technology is in an advanced stage of development and further efforts are being made in order to significantly increase its technology readiness level (TRL). To this end, massive production of suitable crystals is required, as well as an improvement of the capability of their alignment. Such a technological improvement could be exploited in stratospheric balloon experiments and, ultimately, in space missions with a telescope of about 20 m focal length, capable of focusing over a broad energy pass-band. We present the latest technological developments of the TRILL (technological readiness increase for Laue lenses) project, supported by ASI, devoted to the advancement of the technological readiness of Laue lenses. We show the method we developed for preparing suitable bent germanium and silicon crystals and the latest advancements in crystals alignment technology.
3 citations
TL;DR: In this paper , phase-resolved spectral analysis of the accreting pulsar 1A 0535+262 was performed based on observations of Insight-HXMT during the 2020 type II outburst of the source.
Abstract: We have performed phase-resolved spectral analysis of the accreting pulsar 1A 0535+262 based on observations of Insight-HXMT during the 2020 type II outburst of the source. We focus on the two-dimensional dependence of the cyclotron resonance scattering features (CRSFs) along the outburst time and at different phases. The fundamental CRSF line (f-CRSF) shows different time- and phase-dependent behaviors. At higher luminosity, the phase profile of the f-CRSF energy changes from a single peak to double peaks, with the transition occurring at MJD 59185. On the contrary, the first harmonic CRSF (first CRSF) at ∼100 keV is only detected within a narrow phase range (0.8−1.0) accompanied by a shallow f-CRSF line. Based on these results, we speculate that when the source enters the supercritical regime, the higher accretion column height can significantly enhance the harmonic line at a narrow phase through an “anti-pencil” beam at a higher energy band. At the same time, it will also affect the behavior of the fundamental line.
2 citations
31 Aug 2022
TL;DR: The X/Gamma-ray Imaging Spectrometer (XGIS) as discussed by the authors was developed and studied for the THESEUS mission project, capable of covering an exceptionally wide energy band (2 keV − 10 MeV), with imaging capabilities and location accuracy <15 arcmin up to 150 keV over a Field of View of 2.
Abstract: We describe the science case, design and expected performances of the X/Gamma-ray Imaging Spectrometer (XGIS), a GRB and transients monitor developed and studied for the THESEUS mission project, capable of covering an exceptionally wide energy band (2 keV – 10 MeV), with imaging capabilities and location accuracy <15 arcmin up to 150 keV over a Field of View of 2sr, a few hundreds eV energy resolution in the X-ray band (<30 keV) and few micro seconds time resolution over the whole energy band. Thanks to a design based on a modular approach, the XGIS can be easily re-scaled and adapted for fitting the available resources and specific scientific objectives of future high-energy astrophysics missions, and especially those aimed at fully exploiting GRBs and high-energy transients for multi-messenger astrophysics and fundamental physics.
2 citations
31 Aug 2022
TL;DR: The ASTENA experiment was proposed as an innovative mission concept to face some of the most debated questions in hard x-ray/gamma-ray astronomy as mentioned in this paper , which was done through the use of instruments based on groundbreaking technologies, capable of providing unprecedented broad energy passband in a wide field of view, high sensitivity observations and, at the same time, sub-arcminute localization of gamma-ray sources and polarimetric measurement.
Abstract: Hard-x/soft gamma-rays are probes of the most powerful phenomena in the universe. Unlike soft x-ray astrophysics, this band has benefited less from the technological advancement due to the difficulty to absorb this radiation and to the lack of focusing instrumentation. For these reasons the quest for innovative soft gamma-ray instrumentation is pressing and their effective recognition and realization are urgent. In this context, and in the framework of the AHEAD project, funded by the European Commission, the ASTENA experiment was proposed as an innovative mission concept to face some of the most debated questions in hard x-/gamma-ray astronomy. This effort will be done through the use of instruments based on groundbreaking technologies, capable of providing unprecedented broad energy passband in a wide field of view, high sensitivity observations and, at the same time, sub-arcminute localization of gamma-ray sources and polarimetric measurement. In this paper we describe the instruments on board ASTENA, the technologies involved, the performances achievable with their exploitation and their level of readiness.
1 citations
30 Nov 2022
TL;DR: In this paper , the Advanced Surveyor of Transient Events and Nuclear Astrophysics (ASTENA) mission is proposed, which includes two instruments: a Wide Field Monitor with Imaging and Spectroscopic (WFM-IS, 2 keV - 20 MeV) and a Narrow Field Telescope (NFT, 50 - 700 keV).
Abstract: Gamma-ray astronomy is a branch whose potential has not yet been fully exploited. The observations of elemental and isotopic abundances in supernova (SN) explosions are key probes not only of the stellar structure and evolution but also for understanding the physics that makes Type-Ia SNe as standard candles for the study of the Universe expansion properties. In spite of its crucial role, nuclear astrophysics remains a poorly explored field mainly for the typical emission lines intensity which are vanishing small and requires very high sensitivities of the telescopes. Furthermore, in spite that the Galactic bulge-dominated intensity of positron annihilation line at 511 keV has been measured, its origin is still a mystery due to the poor angular resolution and insufficient sensitivity of the commonly employed instrumentation in the sub-MeV energy domain. To answer these scientific issues a jump in sensitivity and angular resolution with respect to the present instrumentation is required. Conceived within the EU project AHEAD, a new high energy mission, capable of tackling the previously mentioned topics, has been proposed. This concept of mission named ASTENA (Advanced Surveyor of Transient Events and Nuclear Astrophysics), includes two instruments: a Wide Field Monitor with Imaging and Spectroscopic (WFM-IS, 2 keV - 20 MeV) capabilities and a Narrow Field Telescope (NFT, 50 - 700 keV). Thanks to the combination of angular resolution, sensitivity and large FoV, ASTENA will be a breakthrough in the hard X and soft gamma–ray energy band, also enabling polarimetry in this energy band. In this talk the science goals of the mission are discussed, the payload configuration is described and expected performances in observing key targets are shown.
TL;DR: In this article , the presence of two sources, one of which may be related to the GRB, was detected simultaneously by the BeppoSAX GRBM and WFC 1 with a localization uncertainty of 2′ (error circle radius).
Abstract: GRB000615 was detected simultaneously by the BeppoSAX GRBM and WFC 1 with a localization uncertainty of 2′ (error circle radius). X-ray emission was detected only in the 0.1–4 keV range during a NFI observation started ≃ 10 hours after the trigger time. The positional and temporal analysis shows the presence of two sources, one of which may be related to the GRB.
TL;DR: In this paper , the authors reported on the 0.5-200 keV spectral properties of Cyg X-1 observed at different epochs with the Narrow Field Instrum entsofthe BeppoSAX satellite.
Abstract: A B ST R A C T W e report on the 0.5{200 keV spectralproperties ofCyg X-1 observed at di erent epochs with the Narrow Field Instrum entsofthe BeppoSAX satellite. The source wasin itssoftstate during the rst observation of1996 June. In the second observation of1996 Septem ber,the source had param eterscharacteristic to itshard state. A softX-ray excess,a broad Fe K line and Com pton re ection areclearly detected in both states.Thesoft-statebroad-band continuum iswellm odeled by adisk blackbody (accountingforthesoftexcess)and Com pton upscatteringof thedisk photonsby ahybrid,therm al/non-therm al,plasm a,probablyform ingacoronaabovethe disk (also giving riseto theCom pton-re ection com ponent).In thehard state,theprim ary hard X-ray spectrum can bewellm odeled by Com pton upscattering ofa weak blackbody em ission by a therm alplasm a ata tem perature of 60 keV.The softexcessis then explained by therm al Com ptonization ofthe sam e blackbody em ission by anotherhotplasm a cloud characterized by a low valueofitsCom pton param eter.Finally,we nd thecharacteristicratio ofthebolom etric ux in thesoftstateto thatin thehard stateto beabout3.Thisvalueism uch m orecom patible with theoriesofstatetransitionsthan thepreviously reported (and likely underestim ated)value of1.5.
30 Nov 2022
TL;DR: Hard X/soft Gamma-ray astronomy is a key field for the study of important astro- physical phenomena such as the electromagnetic counterparts of gravitational waves, gamma-ray bursts, black holes physics and many more as mentioned in this paper .
Abstract: Hard X-/soft Gamma-ray astronomy is a key field for the study of important astro- physical phenomena such as the electromagnetic counterparts of gravitational waves, gamma-ray bursts, black holes physics and many more. However, the spatial localiza- tion, imaging capabilities and sensitivity of the measurements are strongly limited for the energy range > 70 keV due to the lack of focusing instruments operating in this energy band. A new
22 Jun 2022