Spectropolarimetric analysis of FRB 181112 at microsecond resolution: Implications for Fast Radio Burst emission mechanism
Hyerin Cho, Jean-Pierre Macquart, Ryan M. Shannon, Adam T. Deller, Ian S. Morrison, Ron D. Ekers, Keith W. Bannister, Wael Farah, Hao Qiu, Mawson W. Sammons, Ma… 展开作者
Hyerin Cho, Jean-Pierre Macquart, Ryan M. Shannon, Adam T. Deller, Ian S. Morrison, Ron D. Ekers, Keith W. Bannister, Wael Farah, Hao Qiu, Mawson W. Sammons, Matthew Bailes, Shivani Bhandari, Cherie K. Day, Clancy W. James, Chris J. Phillips, J. Xavier Prochaska, John Tuthill
We have developed a new coherent dedispersion mode to study the emission of Fast Radio Bursts that trigger the voltage capture capability of the Australian SKA Pathfinder (ASKAP) interferometer. In principle the mode can probe emission timescales down to 3 ns with full polarimetric information preserved. Enabled by the new capability, here we present a spectropolarimetric analysis of FRB 181112 detected by ASKAP, localized to a galaxy at redshift 0.47. At microsecond time resolution the burst is resolved into four narrow pulses with a rise time of just $15 μ$s for the brightest. The pulses have a diversity of morphology, but do not show evidence for temporal broadening by turbulent plasma along the line of sight, nor is there any evidence for periodicity in their arrival times. The pulses are highly polarized (up to 95%), with the polarization position angle varying both between and within pulses. The pulses have apparent rotation measures that vary by $15\pm 2\, {\rm rad \,m^{-2}}$ and apparent dispersion measures that vary by $0.041\pm 0.004\,{\rm pc\,cm^{-3}}$. Conversion between linear and circular polarization is observed across the brightest pulse. We conclude that the FRB 181112 pulses are most consistent with being a direct manifestation of the emission process or the result of propagation through a relativistic plasma close to the source. This demonstrates that our method, which facilitates high-time-resolution polarimetric observations of FRBs, can be used to study not only burst emission processes, but also a diversity of propagation effects present on the gigaparsec paths they traverse.
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…
Fast Radio Bursts (FRBs) are extreme astrophysical phenomena entering the realm of non-linear optics, a field developed in laser physics. A classical non-linear effect is self-modulation. We examine the propagation of FRBs through the circumburst environment using the idealised setup of a monochromatic linearly-polarised GHz wave propagating through a uniform plasma slab of density $N$ at distance $R$ from the source. We find that self-modulation occurs if the slab is located within a critical radius $R_{\rm crit}\sim 10^{17}(N/10^2{\rm\; cm}^{-3})(L/10^{42}{\rm\; erg\; s}^{-1}){\rm\; cm}$, wh…
Indian Institute of Science Education and Research Thiruvananthapuram（印度科学教育研究所特里凡得琅分校）；Department of Physics and Astronomy, University of California, Riverside（加州大学河滨分校物理与天文系）；Department of Astronomy, University of California Berkeley（加州大学伯克利分校天文系）；Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；Physik-Institut, University of Zurich（苏黎世大学物理学院）
Fast radio bursts (FRBs) are extragalactic radio flashes of unknown physical origin. Their high luminosities and short durations require extreme energy densities, like those found in the vicinity of neutron stars and black holes. Studying the burst intensities and polarimetric properties on a wide range of timescales, from milliseconds down to nanoseconds, is key to understanding the emission mechanism. However, high-time-resolution studies of FRBs are limited by their unpredictable activity levels, available instrumentation and temporal broadening in the intervening ionised medium. Here we sh…
The Real and Pseudo Dispersion Measures of FRB~20220912A
Zhejiang Laboratory（浙江实验室）；Institute for Astronomy, School of Physics, Zhejiang University（浙江大学物理学院天体物理研究所）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；New Cornerstone Science Laboratory, Department of Astronomy, Tsinghua University（清华大学天文系新基石科学实验室）；School of Computer Science and Engineering, Sichuan University of Science and Engineering（四川轻化工大学计算机科学与技术学院）
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）
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…
PSR B0950+08 is a bright non-recycled pulsar whose single-pulse fluence variability is reportedly large. Based on observations at two widely separated frequencies, 55 MHz (NenuFAR) and 1.4 GHz (Westerbork Synthesis Radio Telescope), we review the properties of these single pulses. We conclude that they are more similar to ordinary pulses of radio emission than to a special kind of short and bright Giant Pulses, observed from only a handful of pulsars. We argue that temporal variation of properties of interstellar medium along the line of sight to this nearby pulsar, namely the fluctuating size…
Searching For Fast Radio Transients And Radio Pulsars Using SPOTLIGHT
Indian Institute of Science（印度科学研究所）；National Centre for Radio Astrophysics - Tata Institute of Fundamental Research（国家射电天体物理中心 - 塔塔基础研究所）；Department of Physics, Indian Institute of Science（印度科学研究所物理系）
We discuss observational strategies to detect prompt bursts associated with gravitational wave events using the Australian Square Kilometre Array Pathfinder (ASKAP). Many theoretical models of binary neutron stars mergers predict that bright, prompt radio emission would accompany the merger. The detection of such prompt emission would greatly improve our knowledge of the physical conditions, environment, and location of the merger. However, searches for prompt emission are complicated by the relatively poor localisation for gravitational wave events, with the 90\% credible region reaching hund…
