Detection of a Glitch in PSR J0908$-$4913 by UTMOST

The Astrophysical Journal, 2009

Sixteen pulsars have been discovered so far in blind searches of photons collected with the Large Area Telescope on the Fermi Gamma-ray Space Telescope. We here report the discovery of radio pulsations from two of them. PSR J1741-2054, with period P = 413 ms, was detected in archival Parkes telescope data and subsequently has been detected at the Green Bank Telescope (GBT). Its received flux varies greatly due to interstellar scintillation and it has a very small dispersion measure of DM = 4.7 pc cm −3 , implying a distance of ≈ 0.4 kpc and possibly the smallest luminosity of any known radio pulsar. At this distance, for isotropic emission, its gamma-ray luminosity above 0.1 GeV corresponds to 25% of the spin-down luminosity ofĖ = 9.4 × 10 33 erg s −1. The gamma-ray profile occupies 1/3 of pulse phase and has three closely-spaced peaks with the first peak lagging the radio pulse by δ = 0.29 P. We have also identified a soft Swift source that is the likely X-ray counterpart. In many respects PSR J1741-2054 resembles the Geminga pulsar. The second source, PSR J2032+4127, was detected at the GBT. It has P = 143 ms, and its DM = 115 pc cm −3 suggests a distance of ≈ 3.6 kpc, but we consider it likely that it is located within the Cyg OB2 stellar association at half that distance. The radio emission is nearly 100% linearly polarized, and the main radio peak precedes by δ = 0.15 P the first of two narrow gamma-ray peaks that are separated by ∆ = 0.50 P. The second peak has a harder spectrum than the first one, following a trend observed in young gamma-ray pulsars. Faint, diffuse X-ray emission in a Chandra image is possibly its pulsar wind nebula. PSR J2032+4127 likely accounts for the EGRET source 3EG J2033+4118, while its pulsar wind is responsible for the formerly unidentified HEGRA source TeV J2032+4130. PSR J2032+4127 is coincident in projection with MT91 213, a Be star in Cyg OB2, although apparently not a binary companion of it.

The Astrophysical Journal, 1997

We report the discovery and follow-up timing observations of the 63 ms radio pulsar, PSR J1105−6107. The pulsar is young, having a characteristic age of only 63 kyr and, from its dispersion measure, is estimated to be at a distance of ∼7 kpc from the Sun. We consider its possible association with the nearby supernova remnant G290.1−0.8 (MSH 11−61A); an association requires that the pulsar's proper motion be ∼22 mas yr −1 (corresponding to ∼650 km s −1 for a distance of 7 kpc) directed away from the remnant center, assuming that the characteristic age is the true age. The pulsar's spin-down luminosity, 2.5×10 36 erg s −1 , is in the 1 Hubble Fellow 2 Current address: Kvednaberget 12, 4033 Forus, Norway top 1% of all known pulsar spin-down luminosities. Given its estimated distance, PSR J1105−6107 is therefore likely to be observable at high energies. Indeed, it is coincident with the known CGRO/EGRET source 2EG J1103−6106; we consider the possible association and conclude that it is likely.

Journal of Physics: Conference Series, 2018

PSR J10203+0038 is a transitional millisecond pulsar (tMSP) in an eclipsing binary system, which has been observed to switch between the radio loud millisecond pulsar (MSP) and low-mass-X-ray binary (LMXB) states. This behavior offers a great opportunity to study the origin of MSPs and confirming the 'recycling' scenario, a theoretical model of MSP's origin. We develop an automated pipeline to monitor the system using Python programming language and Source-Extractor software for detecting the objects and measuring its magnitude. We obtain a series of observations with the 0.6m PROMPT-8 telescope at Cerro Tololo in Chile. The magnitude threshold for alert has been set 16.884 mag in R filter. When the magnitude of the system increases over the limit, 16.884 mag in filter R, the pipeline will alert us about the next possible switching of this system. The pipeline has been running on server at National Astronomical Research of Thailand (NARIT) since January 2018. We have found that, during January and February 2018, the system still remains in LMXB state.

Astrophysical Journal, 2003

We present the results of first deep optical observations of the field of the old (∼ 10 8 yr), nearby, isolated pulsar J0108−1431, in an attempt to detect its optical counterpart. The observations were performed using the FORS1 instrument at the focus of the European Southern Observatory Antu Telescope of the VLT. Observations with the Australia Telescope Compact Array (ATCA) were made to determine an accurate position for the radio pulsar at the current epoch. The imaging data, obtained in the V , B, and U passbands reveal no counterpart at the revised radio position down to V ≃ 28, B ≃ 28.6 and U ≃ 26.4. For a distance of 130 pc, estimated from the pulsar's dispersion measure, our constraints on the optical flux put an upper limit of T = 4.5 × 10 4 K for the surface temperature of the neutron star, assuming a stellar radius R ∞ = 13 km. Our new radio position allows us to place an upper limit on the pulsar proper motion of 82 mas yr −1 which, for d = 130 pc, implies a transverse velocity 50 km sec −1 .

The Astrophysical Journal, 2020

We present long-term observations of two intermittent pulsars, PSRs J1832+0029 and J1841−0500 using the Parkes 64 m radio telescope. The radio emission for these pulsars switches "off" for year-long durations. Our new observations have enabled us to improve the determination of the on-off timescales and the spin down rates during those emission states. In general our results agree with previous studies of these pulsars, but we now have significantly longer data spans. We have identified two unexpected signatures in the data. Weak emission was detected in a single observation of PSR J1832+0029 during an "off" emission state. For PSR J1841−0500, we identified a quasi-periodic fluctuation in the intensities of the detectable single pulses, with a modulation period between 21 and 36 pulse periods.

Monthly Notices of the Royal Astronomical Society, 2012

We present the results from timing observations with the GMRT of the young pulsar J1833−1034, in the galactic supernova remnant G21.5−0.9. We detect the presence of 4 glitches in this pulsar over a period of 5.5 years, making it one of a set of pulsars that show fairly frequent glitches. The glitch amplitudes, characterized by the fractional change of the rotational frequency, range from 1 × 10 −9 to 7 × 10 −9 , with no evidence for any appreciable relaxation of the rotational frequency after the glitches. The fractional changes observed in the frequency derivative are of the order of 10 −5 . We show conclusively that, in spite of having significant timing noise, the sudden irregularities like glitches detected in this pulsar can not be modeled as smooth timing noise. Our timing solution also provides a stable estimate of the second derivative of the pulsar spin-down model, and a plausible value for the braking index of 1.857, which, like the value for other such young pulsars, is much less than the canonical value of 3.0. PSR J1833−1034 appears to belong to a class of pulsars exhibiting fairly frequent occurrence of low amplitude glitches. This is further supported by an estimate of the glitch activity parameter, A g = 1.53 × 10 −15 s −2 , which is found to be significantly lower than the trend of glitch activity versus characteristic age (or spin frequency derivative) that a majority of the glitching pulsars follow. We present evidence for a class of such young pulsars, including the Crab, where higher internal temperature of the neutron star could be responsible for the nature of the observed glitch activity.

Monthly Notices of the Royal Astronomical Society, 2004

We report the discovery and initial timing observations of a 55.7-ms pulsar, J0609+2130, found during a 430-MHz drift-scan survey with the Arecibo radio telescope. With a spin-down rate of 3.1 × 10 −19 s s −1 and an inferred surface dipole magnetic field of only 4.2 × 10 9 G, J0609+2130 has very similar spin parameters to the isolated pulsar J2235+1506 found by Camilo, Nice & Taylor. While the origin of these weakly magnetized isolated neutron stars is not fully understood, one intriguing possibility is that they are the remains of high-mass X-ray binary systems which were disrupted by the supernova explosion of the secondary star.

Monthly Notices of the Royal Astronomical Society, 2016

We use observations from the Boolardy Engineering Test Array (BETA) of the Australian Square Kilometre Array Pathfinder (ASKAP) telescope to search for transient radio sources in the field around the intermittent pulsar PSR J1107−5907. The pulsar is thought to switch between an 'off' state in which no emission is detectable, a weak state and a strong state. We ran three independent transient detection pipelines on two-minute snapshot images from a 13 h BETA observation in order to (1) study the emission from the pulsar, (2) search for other transient emission from elsewhere in the image and (3) to compare the results from the different transient detection pipelines. The pulsar was easily detected as a transient source and, over the course of the observations, it switched into the strong state three times giving a typical timescale between the strong emission states of 3.7 h. After the first switch it remained in the strong state for almost 40 min. The other strong states lasted less than 4 min. The second state change was confirmed using observations with the Parkes radio telescope. No other transient events were found and we place constraints on the surface density of such events on these timescales. The high sensitivity Parkes observations enabled us to detect individual bright pulses during the weak state and to study the strong state over a wide observing band. We conclude by showing that future transient surveys with ASKAP will have the potential to probe the intermittent pulsar population.

The Astrophysical Journal, 2013

We present a study of PSR J1723−2837, an eclipsing, 1.86 ms millisecond binary radio pulsar discovered in the Parkes Multibeam survey. Radio timing indicates that the pulsar has a circular orbit with a 15 hr orbital period, a lowmass companion, and a measurable orbital period derivative. The eclipse fraction of ∼15% during the pulsar's orbit is twice the Roche lobe size inferred for the companion. The timing behavior is significantly affected by unmodeled systematics of astrophysical origin, and higher-order orbital period derivatives are needed in the timing solution to account for these variations. We have identified the pulsar's (non-degenerate) companion using archival ultraviolet, optical, and infrared survey data and new optical photometry. Doppler shifts from optical spectroscopy confirm the star's association with the pulsar and indicate a pulsar-to-companion mass ratio of 3.3 ± 0.5, corresponding to a companion mass range of 0.4 to 0.7 M ⊙ and an orbital inclination angle range of between 30 • and 41 • , assuming a pulsar mass range of 1.4-2.0 M ⊙. Spectroscopy indicates a spectral type of G for the companion and an inferred Roche-lobe-filling distance that is consistent with the distance estimated from radio dispersion. The features of PSR J1723−2837 indicate that it is likely a "redback" system. Unlike the five other Galactic redbacks discovered to date, PSR J1723−2837 has not been detected as a γ-ray source with Fermi. This may be due to an intrinsic spin-down luminosity that is much smaller than the measured value if the unmeasured contribution from proper motion is large.

The Astrophysical Journal, 2003

We report on a timing analysis of archival observations of the anomalous X-ray pulsar 1RXS J170849.0À400910 made with the RXTE Proportional Counter Array. We detect a new large glitch (D= ' 3 Â 10 À6 ) that occurred between 2001 March 27 and May 6, with an associated large increase in the spin-down rate (D _ = _ ' 0:3). The short time (1.5 yr) elapsed from the previously detected glitch and the large amplitude of the new spin-up place this source among the most frequent glitchers, with large average glitch amplitudes, similar to those of the Vela pulsar. The source shows different recoveries after the glitches: in the first one it is well described by a long-term linear trend similar to those seen in Vela-like glitches; in the second case the recovery is considerably faster and is better described by an exponential plus a fractional change in the long-term spin-down rate of the order of 1%. No recovery of the latter is detected, but additional observations are necessary to confirm this result. We find minor but significant changes in the average pulse profile after both glitches. No bursts were detected in any light curve, but our search was limited in sensitivity with respect to short (t < 60 ms) bursts. Observed glitch properties are compared to those of radio pulsar glitches; current models are discussed in light of our results. It appears that glitches may represent yet another peculiarity of anomalous X-ray pulsars. Starquake-based models appear to be preferred on qualitative grounds. Alternative models can be applied to individual glitches but fail in explaining both. Thus the two events may as well arise from two different mechanisms.