PSR B1508+55 is known to have a single component profile above 300 MHz. However, when we study it at frequencies below 100 MHz using the first station of the Long Wavelength Array, it shows multiple components. These include the main pulse, a precursor, a postcursor, and a trailing component. The separation of the trailing component from the main peak evolves over the course of a three year study. This evolution is likely an effect of the pulse signal getting refracted off an ionized gas cloud (acting as a lens) leading to what appears to be a trailing component in the profile as the pulsar signal traverses the interstellar medium. Using this interpretation, we identify the location and electron density of the lens affecting the pulse profile.
Observations with the Parkes radio telescope of the eclipsing millisecond binary pulsar PSR J1748$-$2446A, which is in the globular cluster Terzan 5, are presented. These include the first observations of this pulsar in the 3\,GHz frequency band, along with simultaneous observations in the 700\,MHz band and new observations around 1400\,MHz. We show that the pulsar signal is not eclipsed in the 3\,GHz band and observe the known eclipses in the lower frequency bands. We find that the observed pulse signal becomes depolarized during particular orbital phases and postulate that this depolarizatio…
Several pulsars show sudden cessation of pulsed emission, which is known as nulling. The number of known nulling pulsars has not been significantly enhanced in the last decade, although the pulsar population has more than doubled following the Parkes multi-beam pulsar survey. A systematic follow-up study of the new pulsars, discovered in this survey, is being carried out by us at 325-MHz with GMRT. The peculiar nulling behaviour of PSR J1738-2330, observed as a part of this 325-MHz GMRT survey, is reported in this paper. The pulsar appears to show a periodic null-burst cycle with an upper limi…
Pulse nulling is one of many single pulse phenomena exhibited by radio pulsars. The broadband nature of this phenomena remained unexplained due to lack of coordinated observations. We are reporting broadband nulling behaviour of a well known nulling pulsar PSR B2319+60. The simultaneous observations were carried out at four different frequencies using the Giant Meterwave Radio telescope (325 and 610 MHz), the Westerbork Synthesis Radio Telescope (1420 MHz) and the Effelsberg radio telescope (5100 MHz). The nulling fractions were estimated at all four observed frequencies, which suggest similar…
In this paper we analyze high time resolution single pulse data of PSR B0809+74 at 820 MHz. We compare the subpulse phase behavior, undocumented at 820 MHz, with previously published results. The subpulse period changes over time and we measure a subpulse phase jump, when visible, that ranges from 95 to 147 degrees. We find a correlation between the subpulse modulation, subpulse phase, and orthogonal polarization modes. This variety of complicated behavior is not well understood and is not easily explained within the framework of existing models, most of which are founded on the drifting spark…
PSR J1825$-$0935 (PSR B1822$-$09) switches between radio-quiet (Q-mode) and radio-bright (B-mode) modes. The Q-mode is known to have a periodic fluctuation that modulates both the interpulse and the main pulse with the same period. Earlier investigators argued that the periodic Q-mode modulation is associated with drifting subpulses. We report on single-pulse observations of PSR J1825$-$0935 that were made using the Parkes 64-m radio telescope with a central frequency of 1369 MHz. The high-sensitivity observations revealed that the periodic Q-mode modulation is in fact a periodic longitude-sta…
PSR J0742-2822 exhibits two distinct emission states that are identified by discrete changes in the observed pulse profile. These changes have previously been shown to correlate with changes in the derivative of the pulse frequency. In this paper, we use observations with the Parkes radio telescope at a centre frequency of 1369 and 3100 MHz to produce high phase resolution polarisation profiles for the two modes and perform a detailed study of the correlation between observed pulse shape and spin-down rate. We find no correlation for at least 200 days prior to a glitch in the pulsar at MJD 550…
Single pulse observations, characterizing in detail, the nulling behaviour of PSR B1706$-$16 are being reported for the first time in this paper. Our regular long duration monitoring of this pulsar reveals long nulls of 2 to 5 hours with an overall nulling fraction of 31$\pm$2\%. The pulsar shows two distinct phases of emission. It is usually in an active phase, characterized by pulsations interspersed with shorter nulls, with a nulling fraction of about 15 \%, but it also rarely switches to an inactive phase, consisting of long nulls. The nulls in this pulsar are concurrent between 326.5 and …
We have studied the variability of PSR J0529-6652, a radio pulsar in the LMC, using observations conducted at 1390 MHz with the Parkes 64-m telescope. PSR J0529-6652 is detectable as a single pulse emitter, with amplitudes that classify the pulses as giant pulses. This makes PSR J0529-6652 the second known giant pulse emitter in the LMC, after PSR B0540-69. The fraction of the emitted pulses detectable from PSR J0529-6652 at this frequency is roughly two orders of magnitude greater than it is for either PSR B0540-69 or the Crab pulsar (if the latter were located in the LMC). We have measured a…
Over the past decade it has become apparent that a class of `bursting pulsars' exist with the discovery of PSR J1752+2359 and PSR J1938+2213. In these pulsars, a sharp increase in the emission is observed that then tends to systematically drop-off from pulse-to-pulse. In this paper we describe the discovery of such a relationship in high-sensitivity observations of the young (characteristic age of 90,000 yrs) 0.33 s pulsar B0611+22 at both 327 MHz and 1400 MHz with the Arecibo radio telescope. While Nowakowski previously showed that B0611+22 has mode-switching properties, the data presented he…
We show the results of microsecond resolution radio data analysis focused on flux measurements of single pulses of PSR B1133+16. The data were recorded at 4.85 GHz and 8.35 GHz with 0.5 GHz and 1.1 GHz bandwidth, respectively, using Radio Telescope Effelsberg (MPIfR). The most important conclusion of the analysis is, that the strongest single pulse emission at 4.85 GHz and 8.35 GHz contributes almost exclusively to the trailing part of the leading component of the pulsar mean profile, whereas studies at lower frequencies report that the contribution is spread almost uniformly covering all phas…
We report on the properties of strong pulses from PSR B0656+14 by analyzing the data obtained using Urumqi 25-m radio telescope at 1540 MHz from August 2007 to September 2010. In 44 hrs of observational data, a total of 67 pulses with signal-to-noise ratios above a 5-σ threshold were detected. The peak flux densities of these pulses are 58 to 194 times that of the average profile, and the pulse energies of them are 3 to 68 times that of the average pulse. These pulses are clustered around phases about 5 degrees ahead of the peak of the average profile. Comparing with the width of the average p…
A successful attempt was made to analyse about 6000 single pulses of PSR B1133+16 obtained with the 100-meter Effelsberg radio-telescope. The high resolution (60 micro-seconds) data were taken at a frequency of 8.35 GHz with a bandwidth of 1.1 GHz. In order to examine the pulse-to-pulse intensity modulations, we performed both the longitude- and the harmonic-resolved fluctuation spectral analysis. We identified the low frequency feature associated with an amplitude modulation at f4 ~ 0.033 P1^(-1), which can be interpreted as the circulation time P4 ~ 30 P1 of the underlying subbeam carousel m…
We report the discovery of a previously unidentified pulsar as part of a radio campaign to identify neutron star companions to low-mass white dwarfs (LMWDs) using the Robert C.\ Byrd Green Bank Telescope (GBT). PSR J0802-0955, which is coincident with the position of a WD with a mass of 0.2 solar masses, has a pulse period of 571 ms. Because of its relatively long pulse period, the lack of radial velocity (RV) variations in the radio data, and GBT's large beam size at the observing frequency of 340 MHz, we conclude that PSR J0802-0955 is unassociated with the LMWD at roughly the same position …
Ultra-Wideband Polarimetry of the April 2021 Profile Change Event in PSR J1713+0747
Macquarie University（麦考瑞大学）；Australia Telescope National Facility, CSIRO（澳大利亚望远镜国家设施，CSIRO）；Xinjiang Astronomical Observatory, Chinese Academy of Sciences（中国科学院新疆天文台）；School of Physics and Astronomy, Monash University（蒙纳士大学物理与天文学学院）；Space Science Division, Naval Research Laboratory（海军研究实验室空间科学部）；Centre for Astrophysics and Supercomputing, Swinburne University of Technology（斯威本科技大学天体物理学与超级计算中心）
We present the results of wide-band (720-2400 MHz) study of PSR B1821-24A (J1824-2452A, M28A), an energetic millisecond pulsar visible in radio, X-rays and gamma-rays. In radio, the pulsar has a complex average profile which spans >85% of the spin period and exhibits strong evolution with observing frequency. For the first time we measure phase-resolved polarization properties and spectral indices of radio emission throughout almost all of the on-pulse window. We combine this knowledge with the high-energy information to compare M28A to other known gamma-ray millisecond pulsars and to speculat…
We report on polarimetric observations of 100 pulsars centered on 774 MHz, made using the Green Bank Telescope, presenting their polarization profiles and polarized flux densities and comparing them with previous observations when possible. For 67 pulsars, these are the first such measurements made. Polarization profiles of 8 millisecond pulsars in our sample show wide profiles and flat position-angle curves. Strong linear polarization, sometimes approaching 100% of the total intensity, has been detected in all or a part of the average pulse profiles of some pulsars. In general, circular polar…
