Several conjectures have been put forward to explain the RRATs, the newest subclass of neutron stars, and their connections to other radio pulsars. This work discusses these conjectures in the context of the characteristic properties of the RRAT population. Contrary to expectations, it is seen that - a) the RRAT population is statistically un-correlated with the nulling pulsars, and b) the RRAT phenomenon is unlikely to be related to old age or death-line proximity. It is perhaps more likely that the special emission property of RRATs is a signature of them being later evolutionary phases of other types of neutron stars which may have resulted in restructuring of the magnetic fields.
RRAT J1541+4703: A Rotating Radio Transient Exhibiting Normal Pulsar States
Guizhou Normal University（贵州师范大学）；Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing, Guizhou Normal University（贵州师范大学贵州省射电天文与数据处理重点实验室）；Guizhou University（贵州大学）；School of Physics and Electronic Science, Guizhou Normal University（贵州师范大学物理与电子科学学院）；Guizhou Radio Astronomical Observatory（贵州射电天文观测台）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
Pulses from 16 previously known rotating radio transients (RRAT) have been searched at the 110 MHz daily monitor program for 4 to 5.5 years by using the Large-Phased-Array (LPA) at Pushchino. The total number of pulses detected in such a long observation interval is only 90 pulses for RRAT J0640+07 or is as high as 10,751 pulses for RRAT J0302+22. The number and amplitude of pulses varies at a time-scales from six to twenty months for RRATs J1336+33, J1404+11, J1848+15, J2051+12, J2105+22, and the pulse number can increase by one or two orders of magnitude in active phases. The long-term trend…
We have discovered 21 Rotating Radio Transients (RRATs) in data from the Green Bank Telescope (GBT) 350-MHz Drift-scan and the Green Bank North Celestial Cap pulsar surveys using a new candidate sifting algorithm. RRATs are pulsars with sporadic emission that are detected through their bright single pulses rather than Fourier domain searches. We have developed {\tt RRATtrap}, a single-pulse sifting algorithm that can be integrated into pulsar survey data analysis pipelines in order to find RRATs and Fast Radio Bursts. We have conducted follow-up observations of our newly discovered sources at …
We report the discovery of seven new Galactic pulsars with the Canadian Hydrogen Intensity Mapping Experiment's Fast Radio Burst backend (CHIME/FRB). These sources were first identified via single pulses in CHIME/FRB, then followed up with CHIME/Pulsar. Four sources appear to be rotating radio transients (RRATs), pulsar-like sources with occasional single pulse emission with an underlying periodicity. Of those four sources, three have detected periods ranging from 220 ms to 2.726 s. Three sources have more persistent but still intermittent emission and are likely intermittent or nulling pulsar…
The RRATalog: a Galactic census of rotating radio transients
West Virginia University（西弗吉尼亚大学）；Center for Gravitational Waves and Cosmology, West Virginia University（西弗吉尼亚大学引力波与宇宙学中心）；Shanghai Science and Technology Museum（上海科技馆）；Center for KINETIC Plasma Physics, West Virginia University（西弗吉尼亚大学等离子体物理中心）
Six years ago, the discovery of Rotating Radio Transients (RRATs) marked what appeared to be a new type of sparsely-emitting pulsar. Since 2006, more than 70 of these objects have been discovered in single-pulse searches of archival and new surveys. With a continual inflow of new information about the RRAT population in the form of new discoveries, multi-frequency follow-ups, coherent timing solutions, and pulse rate statistics, a view is beginning to form of the place in the pulsar population RRATs hold. Here we review the properties of neutron stars discovered through single pulse searches. …
Rotating Radio Transients (RRATs) represent a relatively new class of pulsar, primarily characterised by their sporadic bursting emission of single pulses on time scales of minutes to hours. In addition to the difficulty involved in detecting these objects, low-frequency ($<$300 MHz) observations of RRATs are sparse, which makes understanding their broadband emission properties in the context of the normal pulsar population problematic. Here, we present the simultaneous detection of RRAT J2325-0530 using the Murchison Widefield Array (154 MHz) and Parkes radio telescope (1.4 GHz). On a single-…
Rotating radio transients (RRATs), loosely defined as objects that are discovered through only their single pulses, are sporadic pulsars that have a wide range of emission properties. For many of them, we must measure their periods and determine timing solutions relying on the timing of their individual pulses, while some of the less sporadic RRATs can be timed by using folding techniques as we do for other pulsars. Here, based on Parkes and Green Bank Telescope (GBT) observations, we introduce our results on eight RRATs including their timing-derived rotation parameters, positions, and disper…
Using five year monitoring observations, we did a blind search for pulses for rotating radio transient (RRAT) J0139+33 and PSR B0320+39. At the interval \pm 1.5m of the time corresponding to the source passing through the meridian, we detected 39377 individual pulses for the pulsar B0320+39 and 1013 pulses for RRAT J0139+33. The share of registered pulses from the total number of observed periods for the pulsar B0320+39 is 74%, and for the transient J0139+33 it is 0.42%. Signal-to-noise ratio (S/N) for the strongest registered pulses is approximately equal to: S/N = 262 (for B0320+39) and S/N …
We report on the discovery of extended X-ray emission around the high magnetic field Rotating Radio Transient J1819-1458. Using a 30ks Chandra ACIS-S observation, we found significant evidence for extended X-ray emission with a peculiar shape: a compact region out to 5.5", and more diffuse emission extending out to ~13" from the source. The most plausible interpretation is a nebula somehow powered by the pulsar, although the small number of counts prevents a conclusive answer on the nature of this emission. RRAT J1819-1458's spin-down energy loss rate (Edot~3x10^{32} erg/s) is much lower than …
More than 100 rotating radio transients (RRATs) have been discovered since 2006. However, it is unclear whether RRATs radiate in the nulling states. PSR J0628+0909 has been classified as an RRAT. In this paper, we study the single pulses and integrated pulse profile of PSR J0628+0909 to check whether we can detect pulsed radio emission in the nulling states. We also aim to study the polarization of the RRAT and its relationship to the general pulsar population. We used the Five-hundred-meter Aperture Spherical radio Telescope (FAST) to observe PSR J0628+0909 in the frequency range from 1.0 to …
The search for rotating radio transients (RRAT) at declination from -9o to +42o was carried out in the semi-annual monitoring data obtained on the Large Phased Array (LPA) radio telescope at the frequency of 111 MHz. A neural network was used to search for candidates. 4 new RRATs were detected, having dispersion measures (DM) 5-16 pc/cm3. A comparison with an earlier RRAT search conducted using the same data shows that the neural network reduced the amount of interference by 80 times, down to 1.3% of the initial amount of interferences. The loss of real pulsar pulses does not exceed 6% of thei…
A model for pulsars with polar-cap magnetic flux density B antiparallel with rotational spin is described. It recognizes the significance of two elementary processes, proton production in electromagnetic showers and photoelectric transitions in ions accelerated through the blackbody radiation field, which must be present at the polar cap in the antiparallel case, but not for pulsars of the opposite spin direction. The two populations are likely to be indistinguishable observationally until curvature radiation pair creation ceases to be possible. The model generates, and provides a physically r…
Rotating Radio Transients (RRATs) are a subclass of pulsars first identified in 2006 that are detected only in searches for single pulses and not through their time averaged emission. Here, we present the results of observations of 19 RRATs using the first station of the Long Wavelength Array (LWA1) at frequencies between 30 MHz and 88 MHz. The RRATs observed here were first detected in higher frequency pulsar surveys. Of the 19 RRATs observed, 2 sources were detected and their dispersion measures, periods, pulse profiles, and flux densities are reported and compared to previous higher frequen…
Nearly all fast radio RRAT-type transients that are pulsars with rare pulses have been previously detected using decimetre wavelengths. We present here 34 transients detected at metre wavelengths in our daily monitoring at declinations -9o < decl. < +42o. 25 transients are new RRATs. We confirmed the detection of 7 RRATs based on our early observations. One of the 34 detected transients was determined to be a new pulsar J1326+3346. At the same time, out of 35 RRATs detected at the decimetre wavelengths and included in the studied area, only one was detected by us J1848+1518. The periods of 6 R…
We present Clusterrank, a new algorithm for identifying dispersed astrophysical pulses. Such pulses are commonly detected from Galactic pulsars and rotating radio transients (RRATs), which are neutron stars with sporadic radio emission. More recently, isolated, highly dispersed pulses dubbed fast radio bursts (FRBs) have been identified as the potential signature of an extragalactic cataclysmic radio source distinct from pulsars and RRATs. Clusterrank helped us discover 14 pulsars and 8 RRATs in data from the Arecibo 327 MHz Drift Pulsar Survey (AO327). The new RRATs have DMs in the range $23.…
We describe the ongoing `Survey for Magnetars, Intermittent pulsars, Rotating radio transients and Fast radio bursts' (SMIRF), performed using the newly refurbished UTMOST telescope. SMIRF repeatedly sweeps the southern Galactic plane performing real-time periodicity and single-pulse searches, and is the first survey of its kind carried out with an interferometer. SMIRF is facilitated by a robotic scheduler which is capable of fully autonomous commensal operations. We report on the SMIRF observational parameters, the data analysis methods, the survey's sensitivities to pulsars, techniques to m…
Here I will review the high time resolution radio sky, focusing on millisecond scales. This is primarily occupied by neutron stars, the well-known radio pulsars and the recently identified group of transient sources known as Rotating RAdio Transients (RRATs). The RRATs appear to be abundant in the Galaxy, which at first glance may be difficult to reconcile with the observed supernova rate. However, as I will discuss, it seems that the RRATs can be explained as pulsars which are either extreme nullers, highly variable or weak/distant. I will re-cap some recent results including a re-analysis of…
Rotating radio transients (RRATs) are a sub-class of pulsars characterized by sporadic emission and thus can generally only be studied by analysis of their single-pulses. Here we present a single-pulse analysis using 11 years of timing data at 1400~MHz of three RRATs, PSRs~J1819$-$1458, J1317$-$5759, and J1913$+$1330. We perform a spectral analysis on the single-pulses of these RRATs for the first time, finding their mean spectral indices to be $-1.1 \pm 0.1$, $-0.6 \pm 0.1$, and $-1.2 \pm 0.2$ respectively, within the known range of pulsar spectral indices. We find no evidence for narrowband …
We present a newly implemented single-pulse pipeline for the PALFA survey to efficiently identify single radio pulses from pulsars, Rotating Radio Transients (RRATs) and Fast Radio Bursts (FRBs). We have conducted a sensitivity analysis of this new pipeline in which multiple single pulses with a wide range of parameters were injected into PALFA data sets and run through the pipeline. Based on the recovered pulses, we find that for pulse widths $\rm < 5\ ms$ the sensitivity of the PALFA pipeline is at most a factor of $\rm \sim 2$ less sensitive to single pulses than our theoretical predictions…
Rotating Radio Transients (RRATs) are a class of pulsars characterized by sporadic bursts of radio emission, which make them difficult to detect in typical periodicity-based pulsar searches. Using newly developed post-processing techniques for automatically identifying single bright astrophysical pulses, such as those emitted from RRATs, we have discovered approximately 30 new RRAT candidates in data from the Green Bank Telescope 350 MHz drift-scan survey. A total of 6 of these have already been confirmed and the remainder look extremely promising. Here we describe these techniques and present…
A search for pulse signals was carried out in a new sky area included in the monitoring program for the search for pulsars and transients. Processing of several months data recorded in six frequency channels with a total bandwidth of 2.5 MHz showed that, on average, 4 pulses per hour are observed in each of the 24 connected stationary beams. Of these pulses, 18.3% are similar to those of pulsars. They are visible in one or two neighboring beams and have a pronounced dispersion shift, that is, they are recorded first at a high and then at a low frequency, which indicates the possible passage of…
Investigation of the long-term evolution of rotating radio transients (RRATs) is important to understand the evolutionary connections between the isolated neutron star populations in a single picture. The X-ray luminosities of RRATs (except one source) are not known. In the fallback disc model, we have developed a method to estimate the dipole field strengths of RRATs without X-ray information. We have found that RRATs could have dipole field strengths, $B_0$, at the poles ranging from $\sim 7 \times 10^9$ G to $\sim 6 \times 10^{11}$ G which fill the gap between the $B_0$ ranges of central co…
At present, J1819-1458 is the only rotating radio transient (RRAT) detected in X-rays. We have studied the long-term evolution of this source in the fallback disc model. The model can reproduce the period, period derivative and X-ray luminosity of J1819-1458 simultaneously in the accretion phase at ages $\sim 2 \times 10^5$ yr. We obtained reasonable model curves with a magnetic dipole field strength $B_0 \sim 5 \times 10^{11}$ G on the pole of the neutron star, which is much weaker than the field inferred from the dipole-torque formula. With this $B_0$ and the measured period, we find J1819-1…
We report on the first near-infrared observations obtained for Rotating RAdio Transients (RRATs). Using adaptive optics devices mounted on the ESO Very Large Telescope (VLT), we observed two objects of this class: RRAT J1819-1458, and RRAT J1317-5759. These observations have been performed in 2006 and 2008, in the J, H and Ks bands. We found no candidate infrared counterpart to RRAT J1317-5759, down to a limiting magnitude of Ks ~ 21. On the other hand, we found a possible candidate counterpart for RRAT J1819-1458, having a magnitude of Ks=20.96+/-0.10 . In particular, this is the only source …
The analysis of individual pulses of four rotating radio transients (RRATs), previously discovered in a monitoring survey running for 5.5 years at the frequency of 111 MHz, is presented. At a time interval equivalent to five days of continuous observations for each RRAT, 90, 389, 206, and 157 pulses were detected in J0640+07, J1005+30, J1132+25, and J1336+33, respectively. The investigated RRATs have a different distribution of the pulses amplitude. For J0640+07 and J1132+25, the distribution is described by a single exponent over the entire range of flux densities. For J1005+30 and J1336+33, …
The rotating radio transients are sporadic pulsars which are difficult to detect through periodicity searches. By using a single-pulse search method, we can discover these sources, measure their periods, and determine timing solutions. Here we introduce our results on six RRATs based on Parkes and Green Bank Telescope(GBT) observations, along with a comparison of the spin-down properties of RRATs and normal pulsars.
We present the results of the most sensitive and comprehensive survey yet undertaken for radio pulsars and fast transients in the Andromeda galaxy (M31) and its satellites, using the Westerbork Synthesis Radio Telescope (WSRT) at a central frequency of 328 MHz. We used the WSRT in a special configuration called 8gr8 (eight-grate) mode, which provides a large instantaneous field-of-view, about 5 square degrees per pointing, with good sensitivity, long dwell times (up to 8 hours per pointing), and good spatial resolution (a few arc minutes) for locating sources. We have searched for both periodi…
The Northern High Time Resolution Universe pulsar survey: III. Single-pulse search continuation, follow-up observations, and initial results
Radboud University（拉德堡德大学）；Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；ASTRON, the Netherlands Institute for Radio Astronomy（荷兰射电天文研究所）；University of Manchester（曼彻斯特大学）
Forty years passed since the optical identification of the first isolated neutron star (INS), the Crab pulsar. 25 INSs have been now identified in the optical (O), near-ultraviolet (nUV), or near-infrared (nIR), hereafter UVOIR, including rotation-powered pulsars (RPPs), magnetars, and X-ray-dim INSs (XDINSs), while deep investigations have been carried out for compact central objects (CCOs), Rotating RAdio transients (RRATs), and high-magnetic field radio pulsars (HBRPs). In this review I describe the status of UVOIR observations of INSs, their emission properties, and I present the results f…
Timing and statistical analysis of single-pulse search pulsar discoveries from the PALFA survey
West Virginia University（西弗吉尼亚大学）；Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut)（马克斯·普朗克引力物理学研究所（爱因斯坦研究所））；University of Wisconsin - Milwaukee（威斯康星大学密尔沃基分校）；Cornell Center for Astrophysics and Planetary Science（康奈尔天体物理学与行星科学中心）；South African Radio Astronomy Observatory（南非射电天文观测站）；Franklin and Marshall College（富兰克林和马歇尔学院）
Forty years elapsed since the optical identification of the first isolated neutron star (INS), the Crab pulsar. 25 INSs have been now identified in the optical (O), near-ultraviolet (nUV), or near-infrared (nIR), hereafter UVOIR, including rotation-powered pulsars (RPPs), magnetars, and X-ray-dim INSs (XDINSs), while deep investigations have been carried out for compact central objects (CCOs), Rotating RAdio transients (RRATs), and high-magnetic field radio pulsars (HBRPs). In this review I describe the status of UVOIR observations of INSs, their emission properties, and I present recent resul…
We study the polarization properties of 22 known rotating radio transients (RRATs) with the 64-m Parkes radio telescope and present the Faraday rotation measures (RMs) for the 17 with linearly polarized flux exceeding the off-pulse noise by 3$σ$. Each RM was estimated using a brute-force search over trial RMs that spanned the maximum measurable range $\pm1.18 \times 10^5 \, \mathrm{rad \, m^2}$ (in steps of 1 $\mathrm{rad \, m^2}$), followed by an iterative refinement algorithm. The measured RRAT RMs are in the range |RM| $\sim 1$ to $\sim 950$ rad m$^{-2}$ with an average linear polarization …
The connection between the radio emission from "lightnings" produced by the absorption of high-energy photons from the cosmic gamma-ray background in a neutron star magnetosphere and radio bursts from rotating radio transients (RRATs) is investigated. The lightning length reaches 1000 km; the lightning radius is 100 m and is comparable to the polar cap radius. If a closed magnetosphere is filled with a dense plasma, then lightnings are efficiently formed only in the region of open magnetic field lines. For the radio emission from a separate lightning to be observed, the polar cap of the neutro…
We present the longest-term timing study so far of three Rotating Radio Transients (RRATs) - J1819-1458, J1840-1419 and J1913+1330 - performed using the Lovell, Parkes and Green Bank telescopes over the past decade. We study long-term and short- term variations of the pulse emission rate from these RRATs and report a marginal indication of a long-term increase in pulse detection rate over time for PSR J1819-1458 and J1913+1330. For PSR J1913+1330, we also observe a two orders of magnitude variation in the observed pulse detection rates across individual epochs, which may constrain the models e…
We present an ongoing survey with the Nançay Radio Telescope at L-band. The targeted area is $74^\circ \lesssim l <150^\circ$ and $3.5^\circ < |b| < 5^\circ$. This survey is characterized by a long integration time (18 min), large bandwidth (512 MHz) and high time and frequency resolution (64 $μ$s and 0.5 MHz) giving a nominal sensitivity limit of 0.055 mJy for long period pulsars. This is about 2 times better than the mid-latitude HTRU survey, and is designed to be complementary with current large scale surveys. This survey will be more sensitive to transients (RRATs, intermittent pulsars), d…
While fewer in number than the dominant rotation-powered radio pulsar population, peculiar classes of isolated neutron stars (INSs) -- which include magnetars, the ROSAT-discovered "Magnificent Seven" (M7), rotating radio transients (RRATs), and central compact objects in supernova remnants (CCOs) -- represent a key element in understanding the neutron star phenomenology. We report the results of an observational campaign to study the properties of the source 2XMM J104608.7-594306. Its evolutionary state is investigated by means of deep dedicated observations obtained with XMM-Newton, the ESO …
Discovery of an Extremely Luminous Sporadic Radio Pulsar
York University（约克大学）；McGill University（麦吉尔大学）；Trottier Space Institute, McGill University（麦吉尔大学特罗蒂尔太空研究所）；West Virginia University（西弗吉尼亚大学）；Center for Gravitational Waves and Cosmology, West Virginia University（西弗吉尼亚大学引力波与宇宙学中心）；MIT Kavli Institute for Astrophysics and Space Research（麻省理工学院卡弗里天体物理学与空间研究所）；Massachusetts Institute of Technology（麻省理工学院）；University of British Columbia（不列颠哥伦比亚大学）；Cornell Center for Astrophysics and Planetary Science（康奈尔天体物理学与行星科学中心）；Cornell University（康奈尔大学）
研究人员借助CHIME/FRB发现极亮偶发RRAT PSR J2108+5055，测定其多项天体物理参数，估算同类源数量，还证实FAST可在本星系群内探测到该脉冲星的脉冲。
