Fast Radio Bursts (FRBs) are energetic, short, bright transients that occur frequently over the entire radio sky. The observational challenges following from their fleeting, generally one-off nature have prevented identification of the underlying sources producing the bursts. As the population of detected FRBs grows, the observed distributions of brightness, pulse width and dispersion measure now begin to take shape. Meaningful direct interpretation of these distributions is, however, made impossible by the selection effects that telescope and search pipelines invariably imprint on each FRB survey. Here we show that multi-dimensional FRB population synthesis can find a single, self-consistent population of FRB sources that can reproduce the real-life results of the major ongoing FRB surveys. This means that individual observed distributions can now be combined to derive the properties of the intrinsic FRB source population. The characteristics of our best-fit model for one-off FRBs agree with a population of magnetars. We extrapolate this model and predict the number of FRBs future surveys will find. For surveys that have commenced, the method we present here can already determine the composition of the FRB source class, and potentially even its subpopulations.
Supernova remnants (SNRs), star formation regions (SFRs), and pulsar wind nebulae (PWNe) are prime candidates for Galactic PeVatrons. The nonthermal high-energy (HE, $\varepsilon>100 \textrm{ MeV}$) and very high-energy (VHE, $\varepsilon>100 \textrm{ GeV}$) $γ$-ray emission from these sources should be a promising manifestation of acceleration processes. We investigate the possibility to explain the HE and VHE $γ$-ray emission from the sky region of the magnetar SGR 1900+14 as a signature of cosmic rays accelerated in above mentioned sources. To this end, we simulate the $γ$-ray emission from…
In the last 25 years, a new generation of X-ray satellites imparted a significant leap forward in our knowledge of X-ray pulsars. The discovery of accreting and transitional millisecond pulsars proved that disk accretion can spin up a neutron star to a very high rotation speed. The detection of MeV-GeV pulsed emission from a few hundreds of rotation-powered pulsars probed particle acceleration in the outer magnetosphere, or even beyond. Also, a population of two dozens of magnetars has emerged. INTEGRAL played a central role to achieve these results by providing instruments with high temporal …
We briefly review main observational properties of fast radio bursts (FRBs) and discuss two most popular hypothesis for the explanation of these enigmatic intense millisecond radio flashes. FRBs most probably originate on extragalactic distances, and their rate on the sky is about a few thousand per day with fluences above $\sim$~1~Jy~ms (or with fluxes larger than few tenths of Jy). Two leading scenarios describing these events include strong flares of magnetars and supergiant pulses of young radio pulsars with large rotational energy losses, correspondingly. At the moment, it is impossible t…
In order to discern the physical nature of many gamma-ray sources in the sky, we must look not only in spectral and spatial dimensions, but also understand their temporal variability. However, timing analysis of sources with a highly transient nature, such as magnetar bursts, is difficult: standard Fourier techniques developed for long-term variability generally observed, for example, from AGN often do not apply. Here, we present newly developed timing methods applicable to transient events of all kinds, and show their successful application to magnetar bursts observed with Fermi/GBM. Magnetar…
We currently know about 30 magnetars: seemingly isolated neutron stars whose properties can be (in part) comprehended only acknowledging that they are endowed with magnetic fields of complex morphology and exceptional intensity-at least in some components of the field structure. Although magnetars represent only a small percentage of the known isolated neutron stars, there are almost certainly many more of them, since most magnetars were discovered in transitory phases called outbursts, during which they are particularly noticeable. In outburst, in fact, a magnetar can be brighter in X-rays by…
We present the Galactic Radio Explorer (GReX), an all-sky monitor to probe the brightest bursts in the radio sky. Building on the success of STARE2, we will search for fast radio bursts (FRBs) emitted from Galactic magnetars as well as bursts from nearby galaxies. GReX will search down to ten microseconds time resolution, allowing us to find new super giant radio pulses from Milky Way pulsars and study their broadband emission. The proposed instrument will employ ultra-wide band (0.7-2 GHz) feeds coupled to a high performance (receiver temperature 10 K) low noise amplifier (LNA) originally dev…
17 Yr of Magnetar Bursts Observed with the Fermi Gamma-ray Burst Monitor
University of Alabama in Huntsville（亨茨维尔阿拉巴马大学）；Sabancı University, Faculty of Engineering and Natural Sciences（萨班哲大学工程与自然科学学院）；Beijing Normal University（北京师范大学）；Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University（北京师范大学天文与前沿科学研究院）；Universities Space and Research Association（大学空间研究协会）；University of Galway（高威大学）；Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville（亨茨维尔阿拉巴马大学空间等离子体与高空大气研究中心）；Rice University（莱斯大学）
XTE J1810-197 (J1810) was the first magnetar identified to emit radio pulses, and has been extensively studied during a radio-bright phase in 2003$-$2008. It is estimated to be relatively nearby compared to other Galactic magnetars, and provides a useful prototype for the physics of high magnetic fields, magnetar velocities, and the plausible connection to extragalactic fast radio bursts. Upon the re-brightening of the magnetar at radio wavelengths in late 2018, we resumed an astrometric campaign on J1810 with the Very Long Baseline Array, and sampled 14 new positions of J1810 over 1.3 years. …
We explore heavy element nucleosynthesis in neutrino-driven winds from rapidly-rotating, strongly magnetized proto-neutron stars for which the magnetic dipole is aligned with the rotation axis, and the field is assumed to be a static force-free configuration. We process the proto-magnetar wind trajectories calculated by Vlasov et al 2014 through the r-process nuclear reaction network SkyNet using contemporary models for the evolution of the wind electron fraction during the proto-neutron star cooling phase. Although we do not find a successful second or third peak r-process for any rotation pe…
The contemporaneous detection of gravitational waves and gamma rays from the GW170817/GRB 170817A, followed by kilonova emission a day after, confirmed compact binary neutron-star mergers as progenitors of short-duration gamma-ray bursts (GRBs), and cosmic sources of heavy r-process nuclei. However, the nature (and lifespan) of the merger remnant and the energy reservoir powering these bright gamma-ray flashes remains debated, while the first minutes after the merger are unexplored at optical wavelengths. Here, we report the earliest discovery of bright thermal optical emission associated with…
We present the earliest X-ray observations of the 2018 outburst of XTE J1810-197, the first outburst since its 2003 discovery as the prototypical transient and radio-emitting anomalous X-ray pulsar (AXP). The Monitor of All-sky X-ray Image (MAXI) detected XTE J1810-197 immediately after a November 20-26 visibility gap, contemporaneous with its reactivation as a radio pulsar, first observed on December 8. On December 13 the Nuclear Spectroscopic Telescope Array (NUSTAR) detected X-ray emission up to at least 30 keV, with a spectrum well-characterized by a blackbody plus power-law model with tem…
AMEGO-X, the All-sky Medium Energy Gamma-Ray Observatory eXplorer, is a proposed instrument designed to bridge the so-called "MeV gap" by surveying the sky with unprecedented sensitivity from ~100 keV to about one GeV. This energy band is of key importance for multi-messenger and multi-wavelength studies but it is nevertheless currently under-explored. AMEGO-X addresses this situation by proposing a design capable of detecting and imaging gamma rays via both Compton interactions and pair production processes. However, some of the objects that AMEGO-X will study, such as gamma-ray bursts and ma…
Our understanding of the universe relies mostly on electromagnetism. As photons are the messengers, fundamental physics is concerned in testing their properties. Photon mass upper limits have been earlier set through pulsar observations, but new investigations are offered by the excess of dispersion measure (DM) sometimes observed with pulsar and magnetar data at low frequencies, or with the fast radio bursts (FRBs), of yet unknown origin. Arguments for the excess of DM do not reach a consensus, but are not mutually exclusive. Thus, we remind that for massive electromagnetism, dispersion goes …
Fast Radio Bursts (FRBs) are highly energetic transient events with duration of order of microseconds to milliseconds and of unknown origin. They are known to lie at cosmological distances, through localisation to host galaxies. Recently, an FRB-like event was seen from the Milky Way magnetar SGR 1935+2154 by the CHIME and STARE2 telescopes. This is the only magnetar that has produced FRB events in our galaxy. Finding similar events in the Milky Way is of great interest to understanding FRB progenitors. Such events will be strongly affected by the turbulent interstellar medium in the Milky Way…
Giant radio pulses in the magnetar XTE J1810-197 detected with the IAR's telescopes
Instituto de Astronomía Teórica y Experimental, CONICET-UNC（理论与实验天文学研究所）；Facultad de Matemática, Astronomía, Física y Computación, UNC（数学、天文学、物理与计算学院）；Instituto Argentino de Radioastronomía（阿根廷射电天文研究所）；Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata（拉普拉塔国立大学天文与地球物理科学学院）；Department of Space, Earth and Environment, Chalmers University of Technology（查尔姆斯理工大学空间、地球与环境系）
Peculiar groups of X-ray emitting isolated neutron stars, which include magnetars, the "Magnificent Seven", and central compact objects in supernova remnants, escape detection in standard pulsar surveys. Yet, they constitute a key element in understanding the neutron star evolution and phenomenology. Their use in population studies in the galactic scale has been hindered by the scarcity of their detection. The all-sky survey of eROSITA on-board the forthcoming Spectrum-RG mission has the unique potential to unveil the X-ray faint part of the population and constrain evolutionary models. To cre…
The time domain of the sky has been only sparsely explored. Nevertheless, recent discoveries from limited surveys and serendipitous discoveries indicate that there is much to be found on timescales from nanoseconds to years and at wavelengths from meters to millimeters. These observations have revealed unexpected phenomena such as rotating radio transients and coherent pulses from brown dwarfs. Additionally, archival studies have found not-yet identified radio transients without optical or high-energy hosts. In addition to the known classes of radio transients, possible other classes of object…
Fast radio bursts are mysterious millisecond-duration transients prevalent in the radio sky. Rapid accumulation of data in recent years has facilitated an understanding of the underlying physical mechanisms of these events. Knowledge gained from the neighboring fields of gamma-ray bursts and radio pulsars also offered insight. Here I review developments in this fast-moving field.Two generic categories of radiation model invoking either magnetospheres of compact objects (neutron stars or black holes) or relativistic shocks launched from such objects have been much debated. The recent detection …
The phenomenon of fast radio bursts (FRBs) was discovered in 2007. These are powerful (0.1-100 Jy) single radio pulses with durations of several milliseconds, large dispersion measures, and record high brightness temperatures suggesting coherent emission mechanism. As of time of writing, 32 FRBs were recorded. There is also one repeating source from which already hundreds of bursts have been detected. The FRB rate is estimated to amount up to several thousand per day over the sky, and their isotropic sky distribution likely suggests a cosmological origin. Since the discovery, different hypothe…
It has long been expected that in some scenarios when a white dwarf (WD) grows to the Chandrasekhar limit, it can undergo an accretion induced collapse (AIC) to form a rapidly rotating neutron star. Nevertheless, the detection of such events has so far evaded discovery, likely because the optical, supernova-like emission is expected to be dim and short-lived. Here we propose a novel signature of AIC: a transient radio source lasting for a few months. Rapid rotation along with flux freezing and dynamo action can grow the WD's magnetic field to magnetar strengths during collapse. The spindown of…
The impending era of wide-field radio surveys has the potential to revolutionize our understanding of astrophysical transients. Here we evaluate the prospects of a wide range of planned and hypothetical radio surveys using the properties and volumetric rates of known and hypothetical classes of extragalactic synchrotron radio transients (e.g., on- and off-axis gamma-ray bursts [GRB], supernovae, tidal disruption events [TDE], compact object mergers). Utilizing these sources and physically motivated considerations we assess the allowed phase-space of radio luminosity and peak timescale for extr…
The repeating fast radio burst FRB 20200120E is located in a globular cluster belonging to the nearby M81 galaxy. Its small distance (3.6 Mpc) and accurate localization make it an interesting target to search for bursting activity at high energies. From November 2003 to September 2021, the INTEGRAL satellite has obtained an exposure time of 18 Ms on the M81 sky region. We used these data to search for hard X-ray bursts from FRB 20200120E using the IBIS/ISGRI instrument, without finding any significant candidate, down to an average fluence limit of $\sim10^{-8}$ erg cm$^{-2}$ (20-200 keV). The …
Fast Radio Bursts (FRBs) are a mysterious flash phenomenon detected in radio wavelengths with a duration of only a few milliseconds, and they may also have prompt gamma-ray flashes. Here we carry out a blind search for msec-duration gamma-ray flashes using the 7-year Fermi Large Area Telescope (Fermi-LAT) all-sky gamma-ray data. About 100 flash candidates are detected, but after removing those associated with bright steady point sources, we find no flash events at high Galactic latitude region (|b|>20 deg). Events at lower latitude regions are consistent with statistical flukes originating fro…
On 2009 June 5, the Gamma-ray Burst Monitor (GBM) onboard the Fermi Gamma-ray Space Telescope triggered on two short, and relatively dim bursts with spectral properties similar to Soft Gamma Repeater (SGR) bursts. Independent localizations of the bursts by triangulation with the Konus-RF and with the Swift satellite, confirmed their origin from the same, previously unknown, source. The subsequent discovery of X-ray pulsations with the Rossi X-ray Timing Explorer (RXTE), confirmed the magnetar nature of the new source, SGR J0418+5729. We describe here the Fermi/GBM observations, the discovery a…
Massive, rapidly-spinning magnetar remnants produced as a result of binary neutron star (BNS) mergers may deposit a fraction of their energy into the surrounding kilonova ejecta, powering a synchrotron radio signal from the interaction of the ejecta with the circumburst medium. We present 6.0 GHz Very Large Array (VLA) observations of nine, low-redshift short gamma-ray bursts (SGRBs; $z<0.5$) on rest-frame timescales of $\approx2.4-13.9$ yr following the bursts. We place $3σ$ limits on radio continuum emission of $F_ν\lesssim6-20\,μ$Jy at the burst positions, or $L_ν\lesssim(0.6-8.3)\times10^{…
At the time of defining the science objectives of the INTernational Gamma-Ray Astrophysics Laboratory (INTEGRAL), such a rapid and spectacular development of multi-messenger astronomy could not have been predicted, with new impulsive phenomena becoming accessible through different channels. Neutrino telescopes have routinely detected energetic neutrino events coming from unknown cosmic sources since 2013. Gravitational wave detectors opened a novel window on the sky in 2015 with the detection of the merging of two black holes and in 2017 with the merging of two neutron stars, followed by signa…
We discuss possible electromagnetic signals accompanying Fast Radio Bursts (FRBs) that are expected in the scenario where FRBs originate in neutron star magnetospheres. For models involving Crab-like giant pulses, no appreciable contemporaneous emission is expected at other wavelengths. Magnetar giant flares, driven by the reconfiguration of the magnetosphere, however, can produce both contemporaneous bursts at other wavelengths as well as afterglow-like emission. We conclude that the best chances are: (i) prompt short GRB-like emission; (ii) a contemporaneous optical flash that can reach nake…
[Abridged] We present a search for fast optical transients (~0.5 hr-1 day) using repeated observations of the Pan-STARRS1 Medium-Deep Survey (PS1/MDS) fields. Our search takes advantage of the consecutive g/r-band observations (16.5 min in each filter), by requiring detections in both bands, with non-detections on preceding and subsequent nights. We identify 19 transients brighter than 22.5 AB mag (S/N>10). Of these, 11 events exhibit quiescent counterparts in the deep PS1/MDS templates that we identify as M4-M9 dwarfs. The remaining 8 transients exhibit a range of properties indicative of mai…
The High Time Resolution Universe survey for pulsars and transients is the first truly all-sky pulsar survey, taking place at the Parkes Radio Telescope in Australia and the Effelsberg Radio Telescope in Germany. Utilising multibeam receivers with custom built all-digital recorders the survey targets the fastest millisecond pulsars and radio transients on timescales of 64 us to a few seconds. The new multibeam digital filter-bank system at has a factor of eight improvement in frequency resolution over previous Parkes multibeam surveys, allowing us to probe further into the Galactic plane for s…
The spectrum of the persistent radio source associated with FRB 20190417A
Istituto Nazionale di Astrofisica - Istituto di Radioastronomia（意大利国家天体物理研究所射电天文研究所）；South African Radio Astronomy Observatory（南非射电天文台）；Centre for Radio Astronomy Techniques and Technologies (RATT), Department of Physics and Electronics, Rhodes University（罗德斯大学物理与电子学院射电天文技术与方法中心）；Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Cagliari（意大利国家天体物理研究所卡利亚里天文台）；Dipartimento di Fisica e Astronomia - Università di Bologna（博洛尼亚大学物理与天文学系）；Scuola Universitaria Superiore IUSS Pavia（帕维亚高等大学）
We present the discovery of a slowly-evolving, extragalactic radio transient, FIRST J141918.9+394036, identified by comparing a catalog of radio sources in nearby galaxies against new observations from the Very Large Array Sky Survey. Analysis of other archival data shows that FIRST J141918.9+394036 faded by a factor of ~50 over 23 years, from a flux of ~26 mJy at 1.4 GHz in 1993 to an upper limit of 0.4 mJy at 3 GHz in 2017. FIRST J141918.9+394036 is likely associated with the small star-forming galaxy SDSS J141918.81+394035.8 at a redshift z=0.01957 (d=87 Mpc), which implies a peak luminosit…
The Australian Square Kilometre Array Pathfinder (ASKAP) will give us an unprecedented opportunity to investigate the transient sky at radio wavelengths. In this paper we present VAST, an ASKAP survey for Variables and Slow Transients. VAST will exploit the wide-field survey capabilities of ASKAP to enable the discovery and investigation of variable and transient phenomena from the local to the cosmological, including flare stars, intermittent pulsars, X-ray binaries, magnetars, extreme scattering events, interstellar scintillation, radio supernovae and orphan afterglows of gamma ray bursts. I…
We report on a systematic search for hard X-ray and gamma-ray emission in coincidence with fast radio bursts (FRBs) observed by the AGILE satellite. We used 13 years of AGILE archival data searching for time coincidences between exposed FRBs and events detectable by the MCAL (0.4-100 MeV) and GRID (50 MeV-30 GeV) detectors at timescales ranging from milliseconds to days/weeks. The current AGILE sky coverage allowed us to extend the search for high-energy emission preceding and following the FRB occurrence. We considered all FRBs sources currently included in catalogues, and identified a sub-sa…
Fast radio bursts (FRBs) are mysterious bright millisecond-duration radio bursts at cosmological distances. While young magnetars have been put forward as the leading source candidate, recent observations suggest there may be multiple FRB progenitor classes. It has long been theorised that FRBs could be emitted from compact object mergers - cataclysmic events such as binary neutron star (BNS) mergers that may be detectable in gravitational waves (GWs) by the ground-based Laser Interferometer Gravitational Wave Observatory (LIGO)and Virgo. Here we report a potential coincidence between the only…
We summarize our understanding of millisecond radio bursts from an extragalactic population of sources. FRBs occur at an extraordinary rate, thousands per day over the entire sky with radiation energy densities at the source about ten billion times larger than those from Galactic pulsars. We survey FRB phenomenology, source models and host galaxies, coherent radiation models, and the role of plasma propagation effects in burst detection. The FRB field is guaranteed to be exciting: new telescopes will expand the sample from the current ~80 unique burst sources (and a few secure localizations an…
We report on the host association of FRB 20181030A, a repeating fast radio burst (FRB) with a low dispersion measure (DM, 103.5 pc cm$^{-3}$) discovered by CHIME/FRB Collaboration et al. (2019a). Using baseband voltage data saved for its repeat bursts, we localize the FRB to a sky area of 5.3 sq. arcmin (90% confidence). Within the FRB localization region, we identify NGC 3252 as the most promising host, with an estimated chance coincidence probability $< 2.5 \times 10^{-3}$. Moreover, we do not find any other galaxy with M$_{r} < -15$ AB mag within the localization region to the maximum estim…
A second-scale periodicity in an active repeating fast radio burst source
School of Astronomy and Space Science, Nanjing University（南京大学天文与空间科学学院）；Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education（现代天体学与天体物理学教育部重点实验室（南京大学））；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；School of Physics and Astromoy, Anqing Normal University（安庆师范大学物理与天文学院）；Institute of Astronomy and Astrophysics, Anqing Normal University（安庆师范大学天体物理研究所）；Guizhou Provincial Laboratory of Big Data, College of Big Data and Information Engineering, Guizhou University（贵州大学大数据与信息工程学院贵州省大数据重点实验室）；Xinjiang Astronomical Observatory, Chinese Academy of Sciences（中国科学院新疆天文台）；State Key Laboratory of Radio Astronomy and Technology, Chinese Academy of Sciences（中国科学院射电天文与技术国家重点实验室）；Xinjiang Key Laboratory of Radio Astrophysics（新疆射电天文重点实验室）；College of Astronomy and Space Science, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）
Fast Radio Bursts are bright, unresolved, non-repeating, broadband, millisecond flashes, found primarily at high Galactic latitudes, with dispersion measures much larger than expected for a Galactic source. The inferred all-sky burst rate is comparable to the core-collapse supernova rate out to redshift 0.5. If the observed dispersion measures are assumed to be dominated by the intergalactic medium, the sources are at cosmological distances with redshifts of 0.2 to 1. These parameters are consistent with a wide range of source models. One fast radio burst showed circular polarization [21(7)%] …
McGill University（麦吉尔大学）；University of Amsterdam（阿姆斯特丹大学）；Nicolaus Copernicus University（尼古拉·哥白尼大学）；ASTRON, Netherlands Institute for Radio Astronomy（荷兰射电天文研究所 (ASTRON)）；Curtin University（科廷大学）；University of Orleans（奥尔良大学）；Chalmers University of Technology（查尔姆斯理工大学）；Joint Institute for VLBI ERIC（甚长基线干涉测量欧洲研究基础设施合作联合研究所）；The University of Manchester（曼彻斯特大学）；University of Cape Town（开普敦大学）；African Institute for Mathematical Sciences（非洲数学科学研究所）
After the detection of gravitational waves from compact binary coalescences, the search for transient gravitational-wave signals with less well-defined waveforms for which matched filtering is not well-suited is one of the frontiers for gravitational-wave astronomy. Broadly classified into "short" $ \lesssim 1~$\,s and "long" $ \gtrsim 1~$\,s duration signals, these signals are expected from a variety of astrophysical processes, including non-axisymmetric deformations in magnetars or eccentric binary black hole coalescences. In this work, we present a search for long-duration gravitational-wav…
