XTE J1810-197 (PSR J1809-1943) was the first ever magnetar which was found to emit transient radio emission. It has recently undergone another radio and high-energy outburst. This is only the second radio outburst that has been observed from this source. We observed J1810-197 soon after its recent radio outburst at low radio frequencies using the Giant Metrewave Radio Telescope. We present the 650 MHz flux density evolution of the source in the early phases of the outburst, and its radio spectrum down to frequencies as low as 300 MHz. The magnetar also exhibits radio emission in the form of strong, narrow bursts. We show that the bursts have a characteristic intrinsic width of the order of 0.5-0.7 ms, and discuss their properties in the context of giant pulses and giant micropulses from other pulsars. We also show that the bursts exhibit spectral structures which cannot be explained by interstellar propagation effects. These structures might indicate a phenomenological link with the repeating fast radio bursts which also show interesting, more detailed frequency structures. While the spectral structures are particularly noticeable in the early phases of the outburst, these seem to be less prominent as well as less frequent in the later phases, suggesting an evolution of the underlying cause of these spectral structures.
We report on X-ray observations of the 5.54 s transient magnetar XTE J1810-197 using the XMM-Newton and Chandra observatories, analyzing new data from 2008 through 2014, and re-analyzing data from 2003 through 2007 with the benefit of these six years of new data. From the discovery of XTE J1810-197 during its 2003 outburst to the most recent 2014 observations, its 0.3-10 keV X-ray flux has declined by a factor of about 50 from 4.1E-11 to 8.1E-13 erg/cm^2/s. Its X-ray spectrum has now reached a steady state. Pulsations continue to be detected from a 0.3 keV thermal hot-spot that remains on the …
We present the long-term spectro-temporal evolution of the average radio emission properties of the magnetar XTE J1810-197 (PSR J1809-1943) following its most recent outburst in late 2018. We report the results from two and a half years of monitoring campaign with the upgraded Giant Metrewave Radio Telescope carried out over the frequency range of 300 - 1450 MHz. Our observations show intriguing time variability in the average profile width, flux density, spectral index and the broadband spectral shape. While the average profile width appears to gradually decrease at later epochs, the flux den…
In 2003, the magnetar XTE J1810-197 started an outburst that lasted until early 2007. In the following 11 years, the source stayed in a quiescent/low activity phase. XTE J1810-197 is one of the closest magnetars, hence its X-ray properties can be studied in detail even in quiescence and an extended monitoring has been carried out to study its long term timing and spectral evolution. Here, we report the results of new X-ray observations, taken between September 2017 and April 2018, with XMM-Newton, Chandra and Nicer. We derived a phase-connected timing solution yielding a frequency derivative o…
After spending almost a decade in a radio-quiet state, the Anomalous X-ray Pulsar XTE J1810-197 turned back on in early December 2018. We have observed this radio magnetar at 1.5 GHz with ~daily cadence since the first detection of radio re-activation on 8 December 2018. In this paper, we report on the current timing properties of XTE J1810-197 and find that the magnitude of the spin frequency derivative has increased by a factor of 2.6 over our 48-day data set. We compare our results with the spin-down evolution reported during its previous active phase in the radio band. We also present tota…
The return to the quiescent state of the Anomalous X-ray pulsar XTE J1810-197 following its 2003 outburst represents a unique opportunity to probe the surface emission properties of a magnetar. The quiescent emission of XTE J1810-197 is composed of two thermal components, one arising from the whole star surface, and the other from a small warm spot on it. By modeling the magnitude and shape of the pulse profile in narrow spectral bands, we have been able to constrain the physical characteristics and geometrical parameters of the system: the two angles that the line of sight and the spin axis m…
We have analyzed XMM-Newton and Chandra observations of the transient magnetar XTE J1810-197, spanning more than 11 years, from the initial phases of the 2003 outburst to the current quiescent level. We investigated the evolution of the pulsar spin period and we found evidence for two distinct regimes: during the outburst decay, the spin derivative (nu_dot) was highly variable in the range -(2-4.5)x10^-13 Hz/s, while during quiescence the spin-down rate was more stable at an average value of -1x10^{-13} Hz/s. Only during ~3000 days (from MJD 54165 to MJD 56908) in the quiescent stage, it was p…
The Interstellar Scintillation of the Radio-Loud Magnetar XTE J1810-197
Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；University of Chinese Academy of Sciences（中国科学院大学）；State Key Laboratory of Radio Astronomy and Technology, Shanghai Astronomical Observatory, CAS（中国科学院上海天文台射电天文与技术重点实验室）；School of Physical Science and Technology, ShanghaiTech University（上海科技大学物理科学与技术学院）；School of Physics and Mechanical & Electrical Engineering, Institute of Astronomy and High Energy Physics, Hubei University of Education（湖北教育学院天体物理与高能物理研究所物理学与机械电气工程学院）
After 15 years, in late 2018, the magnetar XTE J1810-197 underwent a second recorded X-ray outburst event and reactivated as a radio pulsar. We initiated an X-ray monitoring campaign to follow the timing and spectral evolution of the magnetar as its flux decays using Swift, XMM-Newton, NuSTAR, and NICER observations. During the year-long campaign, the magnetar reproduced similar behaviour to that found for the first outburst, with a factor of two change in its spin-down rate from $\sim7.2\times10^{-12}$ s s$^{-1}$ to $\sim1.5\times10^{-11}$ s s$^{-1}$ after two months. Unique to this outburst,…
The anomalous X-ray pulsar XTE J1810$-$197 was the first magnetar found to emit pulsed radio emission. After spending almost a decade in a quiescent, radio-silent state, the magnetar was reported to have undergone a radio outburst in December, 2018. We observed radio pulsations from XTE J1810$-$197 during this early phase of its radio revival using the Ultra-Wideband Low receiver system of the Parkes radio telescope, obtaining wideband (704 MHz to 4032 MHz) polarization pulse profiles, single pulses and flux density measurements. Dramatic changes in polarization and rapid variations of the pos…
We report on the multi-frequency multi-epoch radio observations of the magnetar, XTE J1810-197, which exhibited a radio outburst from December 2018 after its 10-year quiescent period. We performed quasi-simultaneous observations with VERA (22 GHz), Hitachi (6.9 GHz and 8.4 GHz), Kashima (2.3 GHz), and Iitate (0.3 GHz) radio telescopes located in Japan to trace the variability of the magnetar radio pulsations during the observing period from 13 December 2018 to 12 June 2019. The pulse width goes narrower as the observing frequency goes higher, analogous to the general profile narrowing behavior…
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…
In this work we report on observations with the Neutron Star Interior Composition Explorer of the known neutron star X-ray transient XTE J1739-285. We observed the source in 2020 February and March, finding it in a highly active bursting state. Across a 20-day period, we detected 32 thermonuclear X-ray bursts, with an average burst recurrence time of $2.0^{+0.4}_{-0.3}$ hr. A timing and spectral analysis of the ensemble of X-ray bursts reveals homogeneous burst properties, evidence for short-recurrence time bursts, and the detection of a 386.5 Hz burst oscillation candidate. The latter is espe…
Since launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has detected many hundreds of bursts from magnetar sources. While the vast majority of these bursts have been attributed to several known magnetars, there is also a small sample of magnetar-like bursts of unknown origin. Here we present the Fermi/GBM magnetar catalog, giving the results of the temporal and spectral analyses of 440 magnetar bursts with high temporal and spectral resolution. This catalog covers the first five years of GBM magnetar observations, from July 2008 to June 2013. We provide durations, spectral parameters for…
We present the first detection of pulsations from a neutron star in the submillimeter range. The source is the magnetar XTE J1810-197, observed with the James Clerk Maxwell Telescope (JCMT) on 2020 February 27, 2020 July 9 and 2021 May 15. XTE J1810-197 is detected at 353 GHz ($λ=0.85\,$mm) in the three epochs, but not detected in the simultaneously-observed band at 666 GHz ($λ=0.45\,$mm). We measure an averaged flux density at 353 GHz of 6.7$\pm$1.0, 4.0$\pm$0.6, and 1.3$\pm$0.3 mJy and set 3$σ$ flux density upper limits at 666 GHz of 11.3, 4.7 and 4.3 mJy, at each of the three observing epoc…
We have compiled the most comprehensive burst sample from magnetar 4U 0142+61, comprising 27 bursts from its three burst-active episodes in 2011, 2012 and the latest one in 2015 observed with Swift/BAT and Fermi/GBM. Bursts from 4U 0142+61 morphologically resemble typical short bursts from other magnetars. However, 4U 0142+61 bursts are less energetic compared to the bulk of magnetar bursts. We uncovered an extended tail emission following a burst on 2015 February 28, with a thermal nature, cooling over a time-scale of several minutes. During this tail emission, we also uncovered pulse peak ph…
We report on timing, flux density, and polarimetric observations of the transient magnetar and 5.54 s radio pulsar XTE J1810-197 using the GBT, Nancay, and Parkes radio telescopes beginning in early 2006, until its sudden disappearance as a radio source in late 2008. Repeated observations through 2016 have not detected radio pulsations again. The torque on the neutron star, as inferred from its rotation frequency derivative f-dot, decreased in an unsteady manner by a factor of 3 in the first year of radio monitoring. In contrast, during its final year as a detectable radio source, the torque d…
XTE J1701-407 is a newly discovered X-ray transient source. In this work we investigate its flux variability and study the intermediate long and short bursts discovered by Swift on July 17, and 27, 2008, respectively. So far, only one intermediate long burst, with a duration of ~18 minutes and ten days later a short burst, have been recorded from XTE J1701-407. We analyzed the public available data from Swift and RXTE, and compared the observed properties of the intermediate long burst with theoretical ignition condition and light curves to investigate the possible nuclear burning processes. T…
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）
Accreting millisecond X-ray pulsars (AMXPs) show burst oscillations during thermonuclear explosions of the accreted plasma which are markedly different from those observed in non-pulsating low mass X-ray binaries. The AMXP XTE J1814-338 is known for having burst oscillations that are phase locked (constant phase difference) and coincident with the accretion powered pulsations during all its thermonuclear bursts but the last one. In this work we use a coherent timing analysis to investigate this phenomenon in more detail and with higher time resolution than was done in the past. We confirm that…
Properties of the population of millisecond extragalactic radio bursts discovered by Thornton et al. (2013) are in good correspondence with the hypothesis that such events are related to hyperflares of magnetars, as was proposed by us after the first observation of an extragalactic millisecond radio burst by Lorimer et al. (2007). We also point that some of multiple millisecond radio bursts from M31 discovered by Rubio-Herrera et al. (2013) also can be related to weaker magnetar bursts.
The analogy of the host galaxy of the repeating fast radio burst (FRB) source FRB 121102 and those of long gamma-ray bursts (GRBs) and super-luminous supernovae (SLSNe) has led to the suggestion that young magnetars born in GRBs and SLSNe could be the central engine of repeating FRBs. We test such a hypothesis by performing dedicated observations of the remnants of six GRBs with evidence of having a magnetar central engine using the Arecibo telescope and the Robert C. Byrd Green Bank Telescope (GBT). A total of $\sim 20$ hrs of observations of these sources did not detect any FRB from these re…
Lyutikov (2002) predicted "radio emission from soft gamma-ray repeaters (SGRs) during their bursting activity". Detection of a Mega-Jansky radio burst in temporal coincidence with high energy bursts from a Galactic magnetar SGR 1935+2154 confirms that prediction. Similarity of this radio event with Fast Radio Bursts (FRBs) suggests that FRBs are produced within magnetar magnetospheres. We demonstrate that SGR 1935+2154 satisfies the previously derived constraints on the physical parameters at the FRBs' loci. Coherent radio emission is generated in the inner parts of the magnetosphere at $r< 10…
The investigation of pulsars between millimetre and optical wavelengths is challenging due to the faintness of the pulsar signals and the relative low sensitivity of the available facilities compared to 100-m class telescopes operating in the centimetre band. The Kinetic Inductance Detector (KID) technology offers large instantaneous bandwidths and a high sensitivity that can help to substantially increase the ability of existing observatories at short wavelengths to detect pulsars and transient emission. To investigate the feasibility of detecting pulsars with KIDs, we observed the anomalous …
The most common form of magnetar activity is short X-ray bursts, with durations from milliseconds to seconds, and luminosities ranging from $10^{36}$ to $10^{43}\ {\rm erg}\,{\rm s}^{-1}$. Recently, an X-ray burst from the galactic magnetar SGR 1935+2154 was detected to be coincident with two fast radio burst (FRB) like events from the same source, providing evidence that FRBs may be linked to magnetar bursts. Using fully 3D force-free electrodynamics simulations, we show that such magnetar bursts may be produced by Alfvén waves launched from localized magnetar quakes: a wave packet propagates…
In this paper, we present statistics of soft gamma repeater (SGR) bursts from SGR J1550-5418, SGR 1806-20 and SGR 1900+14 by adding new bursts from Kırmızıbayrak et al. (2017) detected with the Rossi X-ray Timing Explorer (RXTE). We find that the fluence distributions of magnetar bursts are well described by power-law functions with indices 1.84, 1.68, and 1.65 for SGR J1550-5418, SGR 1806-20 and SGR 1900+14, respectively. The duration distributions of magnetar bursts also show power-law forms. Meanwhile, the waiting time distribution can be described by a non-stationary Poisson process with a…
Magnetars and many of the magnetar-related objects are summarized together and discussed. It is shown that there is an abuse of language in the use of "magnetar". Anomalous X-ray pulsars and soft gamma-ray repeaters are well-known magnetar candidates. The current so called anti-magnetar (for central compact objects), accreting magnetar (for superslow X-ray pulsars in high mass X-ray binaries), and millisecond magnetar (for the central engine of some gamma-ray bursts), they may not be real magnetars in present understandings. Their observational behaviors are not caused by the magnetic energy. …
Rotation-powered pulsars and magnetars are two different observational manifestations of neutron stars: rotation powered pulsars are rapidly spinning objects that are mostly observed as pulsating radio sources, while magnetars, neutron stars with the highest known magnetic fields, often emit short-duration X-ray bursts. Here we report simultaneous observations of the high-magnetic-field radio pulsar PSR J1119-6127 at X-ray, with XMM-Newton & NuSTAR, and at radio energies with Parkes radio telescope, during a period of magnetar-like bursts. The rotationally powered radio emission shuts off coin…
We explore possible effects of a magnetar burst on the radio, X-ray, and gamma-ray flux of a pulsar wind nebula (PWN). We assume that the burst injects electron-positron pairs or powers the magnetic field and explore the total energy at injection and the spectral index needed in order to increase the X-ray flux by about one order of magnitude, as well as its decay time until reaching quiescence. We also explore magnetically powered phenomenology that could explain a temporary increase of the PWN synchrotron emitted flux and perhaps the relatively common lack of PWNe surrounding magnetars. This…
Recent observations of the periodic Fast Radio Burst source 180916.J0158+65 (FRB 180916) find small linear polarization position angle swings during and between bursts, with a burst activity window that becomes both narrower and earlier at higher frequencies. Although the observed chromatic activity window disfavors models of periodicity in FRB 180916 driven by the occultation of a neutron star by the optically-thick wind from a stellar companion, the connection to theories where periodicity arises from the motion of a bursting magnetar remains unclear. In this paper, we show how altitude-depe…
Recently, one fast radio burst, FRB 200428, was detected from the Galactic magnetar SGR J1935+2154 during one X-ray burst. This suggests that magnetars can make FRBs. On the other hand, the majority of X-ray bursts from SGR J1935+2154 are not associated with FRBs. One possible reason for such rarity of FRB-SGR-burst associations is that the FRB emission is much more narrowly beamed than the SGR burst emission. If such an interpretation is correct, one would expect to detect radio bursts with viewing angles somewhat outside the narrow emission beam. These "slow" radio bursts (SRBs) would have b…
A Coherent Search for New Galactic Magnetars using Fermi/GBM and follow-up Swift/BAT: 7 Candidates and a Large Burst Catalog
Weizmann Institute of Science（魏茨曼科学研究所）；University of California at Santa Barbara（加州大学圣塔芭芭拉分校）；International Centre for Theoretical Sciences, Tata Institute of Fundamental Research（印度基本研究学院国际理论科学中心）
Magnetars younger than one century are expected to be hyper active. Besides winds powered by rotation they generate frequent magnetic flares, which launch powerful blast waves into the wind. These internal shocks act as masers producing fast (millisecond) radio bursts (FRBs) with the following properties. (1) GHz radio emission occurs at radii $r\sim 10^{14}$ cm and lasts $\lesssim 1$ ms in observer's time. (2) Induced scattering in the surrounding wind does not suppress the radio burst. (3) The emission has linear polarization set by the magnetar rotation axis. (4) The emission drifts to lowe…
The spin-down energy of millisecond magnetars has been invoked to explain X-ray afterglow observations of a significant fraction of short and long gamma-ray bursts. Here, we extend models previously introduced in the literature, incorporating radiative losses with the spin down of a magnetar central engine through an arbitrary braking index. Combining this with a model for the tail of the prompt emission, we show that our model can better explain the data than millisecond-magnetar models without radiative losses or those that invoke spin down solely through vacuum dipole radiation. We find tha…
National Changhua University of Education（国立彰化师范大学）；Kyoto University（京都大学）；RIKEN Center for Advanced Photonics (RAP)（理化学研究所先进光子学中心）；NASA Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）；University of Maryland, Baltimore County（马里兰大学巴尔的摩县分校）；The George Washington University（乔治华盛顿大学）；Haverford College（哈弗福德学院）；University of Maryland, College Park（马里兰大学帕克分校）；Center for Research and Exploration in Space Science and Technology, NASA/GSFC（NASA/戈达德太空飞行中心空间科学与技术探索研究中心）；University of Cagliari（卡利亚里大学）；Institut de Recherche en Astrophysique et Planétologie, UPS-OMP, CNRS, CNES（天体物理学与行星学研究所以）
We applied the Bayesian blocks representation technique to search for the dimmest bursts from two magnetars: we identified 320 events from SGR J0501+4516 using a deep XMM-Newton observation and 404 bursts from SGR J1550-5418 using two Swift/XRT pointings. The fluence level of our sample for both sources are about 1-2 orders of magnitude lower than earlier studies. We systematically investigated morphological characteristics and duration distributions of these bursts, as these properties are directly obtained from their Bayesian blocks profiles. We also studied the spectral behavior of the dimm…
Eclipsed X-ray Bursts from Magnetar SGR J1935+2154 and the Fireball Measurements
Central China Normal University（华中师范大学）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；National Astronomical Data Center（国家天文数据中心）；University of Chinese Academy of Sciences（中国科学院大学）
The neutron-star X-ray transient XTE J1701-462 was observed for $\sim$3 Ms with \xte during its 2006-2007 outburst. Here we report on the discovery of three type-I X-ray bursts from XTE J1701-462. They occurred as the source was in transition from the typical Z-source behavior to the typical atoll-source behavior, at $\sim10%$ of the Eddington luminosity. The first burst was detected in the Z-source flaring branch; the second in the vertex between the flaring and normal branches; and the third in the atoll-source soft state. The detection of the burst in the flaring branch cast doubts on earli…
The recent discovery of a Mega-Jansky radio burst occurring simultaneously with short X-ray bursts from the Galactic magnetar (strongly magnetized neutron star (NS)) SGR 1935+2154 is a smoking gun for the hypothesis that some cosmological fast radio bursts (FRBs) arise from magnetar bursts. We argue that the X-ray bursts with high temperature $T \gtrsim 30$ keV entail an electron--positron ($e^{\pm}$) outflow from a trapped--expanding fireball, polluting the NS magnetosphere before the FRB emission. The $e^{\pm}$ outflow is opaque to FRB photons, and is strongly Compton-dragged by the X-ray bu…
We synthesize the known information about Fast Radio Bursts and radio magnetars, and describe an allowed origin near nuclei of external, but non-cosmological, galaxies. This places them at $z\ll1$, within a few hundred megaparsecs. In this scenario, the high DM is dominated by the environment of the FRB, modelled on the known properties of the Milky Way Center, whose innermost 100pc provides 1000 pc/cm$^3$. A radio loud magnetar is known to exist in our galactic center, within $\sim$2 arc seconds of Sgr A*. Based on the polarization, DM, and scattering properties of this known magnetar, we ext…
We report results of the INTEGRAL Target of Opportunity observations of the transient X-ray burster XTE J1810-189. The observations were performed on April 3--6, 2008, soon after the discovery of the source and near the peak of its outburst. That time the source had a flux of about 50 mCrab and exhibited a hard Comptonized X-ray spectrum extending well above 100 keV. Being approximated by a power law with an exponetial cut-off in the broad 3--100 keV energy band it gave the average photon index $Γ\simeq 1.6$ and $kT_{cutoff}\simeq 67$ keV. We found only slight indications for changes in the in…
A fireball of radiation plasma created near the surface of a neutron star (NS) expands under its own pressure along magnetic field lines, and produces photon emission and relativistic matter outflow. We comprehensively classify the expanding fireball evolution into five cases and obtain the photospheric luminosity and the kinetic energy of the outflow, taking into account key processes; lateral diffusion of photons escaping from a magnetic flux tube, effects of strong magnetic field, baryon loading from the NS surface, and radiative acceleration via cyclotron resonant scattering, some of which…
In this paper, we revisit the scenario that an internal gradual magnetic dissipation takes place within the wind from a newborn millisecond magnetar can be responsible for gamma-ray burst production. We show that a combination of two emission components in this model, i.e., the photospheric emission from the wind and the synchrotron radiation within the magnetic reconnection region, can give a reasonable fit to the observed spectrum of the prompt emission phase of GRB 160804A. We obtain the physical parameters through a Monte Carlo procedure and deduce the initial spin period and magnetic fiel…
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…
The origin of the X-ray afterglows of gamma-ray bursts has regularly been debated. We fit both the fireball-shock and millisecond-magnetar models of gamma-ray bursts to the X-ray data of GRB 130603B and 140903A. We use Bayesian model selection to answer the question of which model best explains the data. This is dependent on the maximum allowed non-rotating neutron star mass $M_{\textrm{TOV}}$, which depends solely on the unknown nuclear equation of state. We show that the data for GRB140903A favours the millisecond-magnetar model for all possible equations of state, while the data for GRB1306…
The recent discovery of a Galactic fast radio burst (FRB) occurring simultaneously with an X-ray burst (XRB) from the Galactic magnetar SGR J1935+2154 implies that at least some FRBs arise from magnetar activities. We propose that FRBs are triggered by crust fracturing of magnetars, with the burst event rate depending on the magnetic field strength in the crust. Since the crust fracturing rate is relatively higher in polar regions, FRBs are preferred to be triggered near the directions of multipolar magnetic poles. Crust fracturing produces Alfvén waves, forming a charge starved region in the …
Since their discovery in 2007, much effort has been devoted to uncovering the sources of the extragalactic, millisecond-duration fast radio bursts (FRBs). A class of neutron star known as magnetars is a leading candidate source of FRBs. Magnetars have surface magnetic fields in excess of $10^{14}$ G, the decay of which powers a range of high-energy phenomena. Here we present the discovery of a millisecond-duration radio burst from the Galactic magnetar SGR 1935+2154, with a fluence of $1.5\pm 0.3$ Mega-Jansky milliseconds. This event, termed ST 200428A(=FRB 200428), was detected on 28 April 20…
The magnetar 1E~1547$-$5408 recently exhibited two periods of outburst, beginning on 2008 October 3 and 2009 January 22. Here we present an analysis of the persistent radiative evolution and a statistical study of the burst properties during the 2009 outburst using the {\em Swift} X-ray Telescope (XRT). We find that the 1--10 keV flux increased by a factor of $\sim500$ and hardened significantly, peaking $\sim6$ hours after the onset of the outburst. The observed pulsed fraction exhibited an anti-correlation with phase-averaged flux. Properties of the several hundred X-ray bursts during the 20…
We report on simultaneous radio and X-ray observations of the radio-emitting magnetar 1E1547.0-5408 on 2009 January 25 and February 3, with the 64-m Parkes radio telescope and the Chandra and XMM-Newton X-ray observatories. The magnetar was observed in a period of intense X-ray bursting activity and enhanced X-ray emission. We report here on the detection of two radio bursts from 1E1547.0-5408, reminiscent of Fast Radio Bursts (FRBs). One of the radio bursts was anticipated by ~1s (about half a rotation period of the pulsar) by a bright SGR-like X-ray burst, resulting in a F_radio/F_X ~ 10^-9.…
