We present the SVOM mission that the Chinese National Space Agency and the French Space Agency have decided to jointly implement. SVOM has been designed to detect, characterise and quickly localise gamma-ray bursts (GRBs) and other types of high-energy transients. For this task the spacecraft will carry two widefield high-energy instruments: ECLAIRs, a hard X-ray imager, and the Gamma-Ray Monitor, a broadband spectrometer. Upon localising a transient, SVOM will quickly slew towards the source and start deep followup observations with two narrow-field telescopes: the Micro-channel X-ray Telescope in X-rays and the Visible Telescope in the visible. The nearly anti-solar pointing of SVOM combined with the fast transmission of GRB positions to the ground in less than 1 minute, will facilitate the observations of SVOM transients by the largest ground based telescopes.

O. Godet;J. Paul;J. Y. Wei;S. N. Zhang;J. L. Atteia;S. Basa;D. Barret;A. Claret;B. Cordier;J. G. Cuby;子高 戴;F. Daigne;J. Deng;Y. Dong;D. G̈otz;J. Hu;P. Mandrou;J. P. Osborne;Y. Qiu;J. Wang;B. Wu;C. Wu;为民 袁

2012

The equation of state (EOS), w(z), is the most important parameter of dark energy. We reconstruct the evolution of this EOS in a model-independent way using the latest cosmic microwave background (CMB) data from Planck and other observations, such as type Ia supernovae, the baryonic acoustic oscillation measurements (SDSS, 6dF, BOSS, and WiggleZ), and the Hubble parameter value H(z). The results show that the EOS is consistent with the cosmological constant at the 2σ confidence level, not preferring a dynamical dark energy. The uncorrelated EOS of dark energy constraints from Planck CMB data are much tighter than those from the WMAP 9-year CMB data.

F. Y. Wang;子高 戴

Physical Review D - Particles, Fields, Gravitation and Cosmology

2014-1-14

It is widely believed that magnetars could be born in core-collapse supernovae (SNe), binary neutron star (BNS) or binary white dwarf (BWD) mergers, or accretion-induced collapse (AIC) of white dwarfs. In this paper, we investigate whether magnetars could also be produced from neutron star-white dwarf (NSWD) mergers, motivated by FRB 180924-like fast radio bursts (FRBs) possibly from magnetars born in BNS/BWD/AIC channels suggested by Margalit et al. (2019). By a preliminary calculation, we find that NSWD mergers with unstable mass transfer could result in the NS acquiring an ultra-strong magnetic field via the dynamo mechanism due to differential rotation and convection or possibly via the magnetic flux conservation scenario of a fossil field. If NSWD mergers can indeed create magnetars, then such objects could produce at least a subset of FRB 180924-like FRBs within the framework of flaring magnetars, since the ejecta, local environments, and host galaxies of the final remnants from NSWD mergers resemble those of BNS/BWD/AIC channels. This NSWD channel is also able to well explain both the observational properties of FRB 180924-like and FRB 180916.J0158+65-like FRBs within a large range in local environments and host galaxies.

Shu Qing Zhong;子高 戴

Astrophysical Journal

2020-4-10

The observations of a nearby low-luminosity gamma-ray burst (GRB) 060218 associated with supernova SN 2006aj may imply an interesting astronomical picture where a supernova shock breakout locates behind a relativistic GRB jet. Based on this picture, we study neutrino emission for early afterglows of GRB 060218-like GRBs, where neutrinos are expected to be produced from photopion interactions in a GRB blast wave that propagates into a dense wind. Relativistic protons for the interactions are accelerated by an external shock, while target photons are basically provided by the incoming thermal emission from the shock breakout and its inverse-Compton scattered component. Because of a high estimated event rate of low-luminosity GRBs, we would have more opportunities to detect afterglow neutrinos from a single nearby GRB event of this type by IceCube. Such a possible detection could provide evidence for the picture described above.

云伟 俞;子高 戴;X. P. Zheng

Monthly Notices of the Royal Astronomical Society

2008-4

Active galactic nuclei and gamma-ray bursts (GRBs) are powerful astrophysical events with relativistic jets. In this Letter, the broadband spectral properties of GRBs and well-observed blazars are compared. The distribution of GRBs is consistent with the well-known blazar sequence including the νL _ν(5 GHz)-α_RX and νL _ν(5 GHz)-ν_peak correlations, where α_RX is defined as the broadband spectral slope in radio-to-X-ray bands, and ν_peak is defined as the spectral peak frequency. Moreover, GRBs occupy the low radio luminosity end of these sequences. These two correlations suggest that GRBs could have a radiation process, i.e., synchrotron radiation, similar to blazars both in the prompt emission and afterglow phases.

F. Y. Wang;S. X. Yi;子高 戴

Astrophysical Journal Letters

2014-5-1

In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.

Jean J.M. in ’t Zand;Enrico Bozzo;Jin Lu Qu;向东 李;Lorenzo Amati;阳 陈;Immacolata Donnarumma;Victor Doroshenko;Stephen A. Drake;Margarita Hernanz;Peter A. Jenke;Thomas J. Maccarone;Simin Mahmoodifar;Domitilla de Martino;Alessandra De Rosa;Elena M. Rossi;Antonia Rowlinson;Gloria Sala;Giulia Stratta;Thomas M. Tauris;Joern Wilms;雪峰 吴;Ping Zhou;Iván Agudo;Diego Altamirano;Jean Luc Atteia;Nils A. Andersson;M. Cristina Baglio;David R. Ballantyne;Altan Baykal;Ehud Behar;Tomaso Belloni;Sudip Bhattacharyya;Stefano Bianchi;Anna Bilous;Pere Blay;João Braga;Søren Brandt;Edward F. Brown;Niccolò Bucciantini;Luciano Burderi;Edward M. Cackett;Riccardo Campana;Sergio Campana;Piergiorgio Casella;Yuri Cavecchi;Frank Chambers;Liang Chen;Yu Peng Chen;Jérôme Chenevez;Maria Chernyakova;Chi Chuan Jin;Riccardo Ciolfi;Elisa Costantini;Andrew Cumming;Antonino D’Aì;子高 戴;Filippo D’Ammando;Massimiliano De Pasquale;Nathalie Degenaar;Melania Del Santo;Valerio D’Elia;Tiziana Di Salvo;Gerry Doyle;Maurizio Falanga;Xi Long Fan;Robert D. Ferdman;Marco Feroci;Federico Fraschetti;Duncan K. Galloway;Angelo F. Gambino;Poshak Gandhi;Ming Yu Ge;Bruce Gendre;Ramandeep Gill;Diego Götz;Christian Gouiffès;Paola Grandi;Jonathan Granot;Manuel Güdel;Alexander Heger;Craig O. Heinke;Jeroen Homan;Rosario Iaria;Kazushi Iwasawa;Luca Izzo;Long Ji;Peter G. Jonker;Jordi José;Jelle S. Kaastra;Emrah Kalemci;Oleg Kargaltsev;Nobuyuki Kawai;Laurens Keek;Stefanie Komossa;Ingo Kreykenbohm;Lucien Kuiper;Devaky Kunneriath;Gang Li;恩维 梁;Manuel Linares;Francesco Longo;Fang Jun Lu;Alexander A. Lutovinov;Denys Malyshev;Julien Malzac;Antonios Manousakis;Ian McHardy;Missagh Mehdipour;Yun Peng Men;Mariano Méndez;Roberto P. Mignani;Romana Mikusincova;M. Coleman Miller;Giovanni Miniutti;Christian Motch;Joonas Nättilä;Emanuele Nardini;Torsten Neubert;Paul T. O’Brien;Mauro Orlandini;Julian P. Osborne;Luigi Pacciani;Stéphane Paltani;Maurizio Paolillo;Iossif E. Papadakis;Biswajit Paul;Alberto Pellizzoni;Uria Peretz;Miguel A. Pérez Torres;Emanuele Perinati;Chanda Prescod-Weinstein;Pablo Reig;Alessandro Riggio;Jerome Rodriguez;Pablo Rodríguez-Gil;Patrizia Romano;Agata Różańska;Takanori Sakamoto;Tuomo Salmi;Ruben Salvaterra;Andrea Sanna;Andrea Santangelo;Tuomas Savolainen;Stéphane Schanne;Hendrik Schatz;Li Jing Shao;Andy Shearer;Steven N. Shore;Ben W. Stappers;Tod E. Strohmayer;Valery F. Suleimanov;Jirí Svoboda;F. K. Thielemann;Francesco Tombesi;Diego F. Torres;Eleonora Torresi;Sara Turriziani;Andrea Vacchi;Stefano Vercellone;Jacco Vink;Jian Min Wang;Jun Feng Wang;Anna L. Watts;Shan Shan Weng;Nevin N. Weinberg;Peter J. Wheatley;Rudy Wijnands;Tyrone E. Woods;Stan E. Woosley;Shao Lin Xiong;Yu Peng Xu;Zhen Yan;George Younes;文飞 余;峰 袁;Luca Zampieri;Silvia Zane;Andrzej A. Zdziarski;Shuang Nan Zhang;Shu Zhang;Shuo Zhang;Xiao Zhang;Michael Zingale

Science China: Physics, Mechanics and Astronomy

2019-2-1

The ejecta composition is an open question in gamma-ray burst (GRB) physics ¹ . Some GRBs possess a quasi-thermal spectral component in the time-resolved spectral analysis ², suggesting a hot fireball origin. Others show a featureless non-thermal spectrum known as the Band function ^3-5, consistent with a synchrotron radiation origin ^5,6 and suggesting that the jet is Poynting-flux dominated at the central engine and probably in the emission region as well ^7,8 . There are also bursts showing a sub-dominant thermal component and a dominant synchrotron component ⁹, suggesting a probable hybrid jet composition ¹⁰ . Here, we report an extraordinarily bright GRB 160625B, simultaneously observed in gamma-ray and optical wavelengths, whose prompt emission consists of three isolated episodes separated by long quiescent intervals, with the durations of each sub-burst being approximately 0.8 s, 35 s and 212 s, respectively. Its high brightness (with isotropic peak luminosity L _p,iso ≈ 4 × 10⁵³ erg s^-1) allows us to conduct detailed time-resolved spectral analysis in each episode, from precursor to main burst and to extended emission. The spectral properties of the first two sub-bursts are distinctly different, allowing us to observe the transition from thermal to non-thermal radiation between well-separated emission episodes within a single GRB. Such a transition is a clear indication of the change of jet composition from a fireball to a Poynting-flux-dominated jet.

B. B. Zhang;B. Zhang;A. J. Castro-Tirado;子高 戴;P. H.T. Tam;X. Y. Wang;Y. D. Hu;S. Karpov;A. Pozanenko;F. W. Zhang;E. Mazæva;P. Minæv;A. Volnova;S. Oates;H. Gao;雪峰 吴;L. Shao;Q. W. Tang;G. Beskin;A. Biryukov;S. Bondar;E. Ivanov;E. Katkova;N. Orekhova;A. Perkov;V. Sasyuk;L. Mankiewicz;A. F. Żarnecki;A. Cwiek;R. Opiela;A. Zadrożny;R. Aptekar;D. Frederiks;D. Svinkin;A. Kusakin;R. Inasaridze;O. Burhonov;V. Rumyantsev;E. Klunko;A. Moskvitin;T. Fatkhullin;V. V. Sokolov;A. F. Valeev;S. Jeong;I. H. Park;M. D. Caballero-García;R. Cunniffe;J. C. Tello;P. Ferrero;S. B. Pandey;M. Jelínek;F. K. Peng;R. Sánchez-Ramrez;A. Castellón

Nature Astronomy

2018-1-1

Optical rebrightenings in the afterglows of some gamma-ray bursts (GRBs) are unexpected within the framework of the simple external shock model. While it has been suggested that the central engines of some GRBs are newly born magnetars, we aim to relate the behaviors of magnetars to the optical rebrightenings. A newly born magnetar will lose its rotational energy in the form of Poynting-flux, which may be converted into a wind of electron-positron pairs through some magnetic dissipation processes. As proposed by Dai, this wind will catch up with the GRB outflow and a long-lasting reverse shock (RS) would form. By applying this scenario to GRB afterglows, we find that the RS propagating back into the electron-positron wind can lead to an observable optical rebrightening and a simultaneous X-ray plateau (or X-ray shallow decay). In our study, we select four GRBs (i.e., GRB 080413B, GRB 090426, GRB 091029, and GRB 100814A), of which the optical afterglows are well observed and show clear rebrightenings. We find that they can be well interpreted. In our scenario, the spin-down timescale of the magnetar should be slightly smaller than the peak time of the rebrightening, which can provide a clue to the characteristics of the magnetar.

J. J. Geng;雪峰 吴;永锋 黄;L. Li;子高 戴

Astrophysical Journal

2016-7-10

When an emitting spherical shell with a constant Lorentz factor turns off emission abruptly at some radii, its highlatitude emission would obey the relation of α (the temporal index) = 2 + β (the spectral index). However, this relation is violated by the X-ray fares in some gamma-ray bursts (GRBs), whose a is much more steeper. We show that the synchrotron radiation should be anisotropic when the angular distribution of accelerated electrons has a preferable orientation, and this anisotropy would naturally lead to a steeper decay for the high-latitude emission if the intrinsic emission is limb-brightened. We use this simple toy model to reproduce the temporal and spectral evolution of X-ray flares. We show that our model can well interpret the steep decay of the X-ray flares in the three GRBs selected as an example. Recent simulations on particle acceleration may support the specific anisotropic distribution of the electrons adopted in our work. Reversely, confirmation of the anisotropy in the radiation would provide meaningful clues to the details of electron acceleration in the emitting region.

Jin Jun Geng;永锋 黄;子高 戴

Astrophysical Journal Letters

2017-5-20

Soft γ-ray repeaters are at determined distances and their positions are known accurately. If observed, afterglows from their soft γ-ray bursts will provide important dues to the study of the so called "classical γ-ray bursts". On applying the popular fireball/blastwave model of classical γ-ray bursts to soft γ-ray repeaters, it is found that their x-ray and optical afterglows are detectable. Monitoring of the three repeaters is solicited.

Yong Feng Huang;子高 戴;埮 陆

Chinese Physics Letters

1998