Search

Several sources of repeating coherent bursts of radio emission with periods of many minutes have now been reported in the literature. These "ultra-long period" (ULP) sources have no clear multi-wavelength counterparts and challenge canonical pulsar emission models, leading to debate regarding their nature. In this work we report the discovery of a bright, highly-polarised burst of radio emission at low Galactic latitude as part of a wide-field survey for transient and variable radio sources. ASKAP\,J175534.9$-$252749.1 does not appear to repeat, with only a single intense two-minute $\sim$200-mJy burst detected from 60~hours of observations. The burst morphology and polarisation properties are comparable to those of classical pulsars but the duration is more than one hundred times longer, analogous to ULPs. Combined with the existing ULP population, this suggests that these sources have a strong Galactic latitude dependence and hints at an unexplored population of transient and variable radio sources in the thin disk of the Milky Way. The resemblance of this burst with both ULPs and pulsars calls for a unified coherent emission model for objects with spin periods from milliseconds to tens of minutes. However, whether or not these are all neutron stars or have the same underlying power source remains open for debate.

In addition to being the most magnetic objects in the known universe, magnetars are the only objects observed to generate fast-radio-burst-like emissions. The formation mechanism of magnetars is still highly debated, and may potentially be probed with the magnetar velocity distribution. We carried out a 3-year-long astrometric campaign on Swift J1818.0-1607 -- the fastest-spinning magnetar, using the Very Long Baseline Array. After applying the phase-calibrating 1D interpolation strategy, we obtained a small proper motion of 8.5 $\mathrm{mas~yr^{-1}}$ magnitude, and a parallax of $0.12\pm0.02$ mas (uncertainties at $1\,\sigma$ confidence throughout the Letter) for Swift J1818.0-1607. The latter is the second magnetar parallax, and is among the smallest neutron star parallaxes ever determined. From the parallax, we derived the distance $9.4^{+2.0}_{-1.6}$ kpc, which locates Swift J1818.0-1607 at the far side of the Galactic central region. Combined with the distance, the small proper motion leads to a transverse peculiar velocity $v_\perp=48^{+50}_{-16}$ $\mathrm{km~s^{-1}}$ -- a new lower limit to magnetar $v_\perp$. Incorporating previous $v_\perp$ estimates of seven other magnetars, we acquired $v_\perp=149^{+132}_{-68}$ $\mathrm{km~s^{-1}}$ for the sample of astrometrically studied magnetars, corresponding to the three-dimensional space velocity $\sim190^{+168}_{-87}$ $\mathrm{km~s^{-1}}$, smaller than the average level of young pulsars. Additionally, we found that the magnetar velocity sample does not follow the unimodal young pulsar velocity distribution reported by Hobbs et al. at $>2\,\sigma$ confidence, while loosely agreeing with more recent bimodal young pulsar velocity distributions derived from relatively small samples of quality astrometric determinations., Comment: 13 pages, 4 figures, 4 tables, accepted for publication in ApJL

Fast Radio Bursts (FRBs) are short-timescale transients of extragalactic origin. The number of detected FRBs has grown dramatically since their serendipitous discovery from archival data. Some FRBs have also been seen to repeat. The polarimetric properties of repeating FRBs show diverse behaviour and, at times, extreme polarimetric morphology, suggesting a complex magneto-ionic circumburst environment for this class of FRB. The polarimetric properties such as circular polarisation behaviour of FRBs are crucial for understanding their surrounding magnetic-ionic environment. The circular polarisation previously observed in some of the repeating FRB sources has been attributed to propagation effects such as generalised Faraday rotation (GFR), where conversion from linear to circular polarisation occurs due to the non-circular modes of transmission in relativistic plasma. The discovery burst from the repeating FRB$~$20180301A showed significant frequency-dependent circular polarisation behaviour, which was initially speculated to be instrumental due to a sidelobe detection. Here we revisit the properties given the subsequent interferometric localisation of the burst, which indicates that the burst was detected in the primary beam of the Parkes/Murriyang 20-cm multibeam receiver. We develop a Bayesian Stokes-Q, U, and V fit method to model the GFR effect, which is independent of the total polarised flux parameter. Using the GFR model we show that the rotation measure (RM) estimated is two orders of magnitude smaller and opposite sign ($\sim$28 rad$\,$m$^{-2}$) than the previously reported value. We interpret the implication of the circular polarisation on its local magnetic environment and reinterpret its long-term temporal evolution in RM., Comment: 13 pages, 9 figures, submitted to MNRAS

The Galactic Center is host to a population of extraordinary radio filaments, thin linear structures that trace out magnetic field lines running perpendicular to the Galactic plane. Using Murriyang, the 64 m Parkes radio telescope, we conducted a search for pulsars centered on the position of a compact source in the filament G359.0$-$0.2. We discovered a millisecond pulsar (MSP), PSR J1744$-$2946, with a period $P = 8.4$ ms, that is bound in a 4.8 hr circular orbit around a $M_{\rm c} > 0.05\,M_{\odot}$ companion. The pulsar dispersion measure of $673.7 \pm 0.1$ pc cm$^{-3}$ and Faraday rotation measure of $3011 \pm 3$ rad m$^{-2}$ are the largest of any known MSP. Its radio pulses are moderately scattered due to multi-path propagation through the interstellar medium, with a scattering timescale of $0.87 \pm 0.08$ ms at 2.6 GHz. Using MeerKAT, we localized the pulsar to a point source embedded in a low-luminosity radio filament, the "Sunfish", that is unrelated to G359.0$-$0.2. Our discovery of the first MSP within 1$^{\circ}$ of the Galactic Center hints at a large population of these objects detectable via high frequency surveys. The association with a filament points to pulsars as the energy source responsible for illuminating the Galactic Center radio filaments., Comment: 6 pages, 4 figures, 1 table. Accepted for publication in ApJ Letters

Radio emission from magnetars provides a unique probe of the relativistic, magnetized plasma within the near-field environment of these ultra-magnetic neutron stars. The transmitted waves can undergo birefringent and dispersive propagation effects that result in frequency-dependent conversions of linear to circularly polarized radiation and vice-versa, thus necessitating classification when relating the measured polarization to the intrinsic properties of neutron star and fast radio burst (FRB) emission sites. We report the detection of such behavior in 0.7-4 GHz observations of the P = 5.54 s radio magnetar XTE J1810$-$197 following its 2018 outburst. The phenomenon is restricted to a narrow range of pulse phase centered around the magnetic meridian. Its temporal evolution is closely coupled to large-scale variations in magnetic topology that originate from either plastic motion of an active region on the magnetar surface or free precession of the neutron star crust. Our model of the effect deviates from simple theoretical expectations for radio waves propagating through a magnetized plasma. Birefringent self-coupling between the transmitted wave modes, line-of-sight variations in the magnetic field direction and differences in particle charge or energy distributions above the magnetic pole are explored as possible explanations. We discuss potential links between the immediate magneto-ionic environments of magnetars and those of FRB progenitors., Comment: 22 pages (inc. extended data and supplementary materials), 12 figures, 3 tables. Published in Nature Astronomy

We present 294 pulsars found in GeV data from the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. Another 33 millisecond pulsars (MSPs) discovered in deep radio searches of LAT sources will likely reveal pulsations once phase-connected rotation ephemerides are achieved. A further dozen optical and/or X-ray binary systems co-located with LAT sources also likely harbor gamma-ray MSPs. This catalog thus reports roughly 340 gamma-ray pulsars and candidates, 10% of all known pulsars, compared to $\leq 11$ known before Fermi. Half of the gamma-ray pulsars are young. Of these, the half that are undetected in radio have a broader Galactic latitude distribution than the young radio-loud pulsars. The others are MSPs, with 6 undetected in radio. Overall, >235 are bright enough above 50 MeV to fit the pulse profile, the energy spectrum, or both. For the common two-peaked profiles, the gamma-ray peak closest to the magnetic pole crossing generally has a softer spectrum. The spectral energy distributions tend to narrow as the spindown power $\dot E$ decreases to its observed minimum near $10^{33}$ erg s$^{-1}$, approaching the shape for synchrotron radiation from monoenergetic electrons. We calculate gamma-ray luminosities when distances are available. Our all-sky gamma-ray sensitivity map is useful for population syntheses. The electronic catalog version provides gamma-ray pulsar ephemerides, properties and fit results to guide and be compared with modeling results., Comment: 142 pages. Accepted by the Astrophysical Journal Supplement

The noise in millisecond pulsar (MSP) timing data can include contributions from observing instruments, the interstellar medium, the solar wind, solar system ephemeris errors, and the pulsars themselves. The noise environment must be accurately characterized in order to form the null hypothesis from which signal models can be compared, including the signature induced by nanohertz-frequency gravitational waves (GWs). Here we describe the noise models developed for each of the MSPs in the Parkes Pulsar Timing Array (PPTA) third data release, which have been used as the basis of a search for the isotropic stochastic GW background. We model pulsar spin noise, dispersion measure variations, scattering variations, events in the pulsar magnetospheres, solar wind variability, and instrumental effects. We also search for new timing model parameters and detected Shapiro delays in PSR~J0614$-$3329 and PSR~J1902$-$5105. The noise and timing models are validated by testing the normalized and whitened timing residuals for Gaussianity and residual correlations with time. We demonstrate that the choice of noise models significantly affects the inferred properties of a common-spectrum process. Using our detailed models, the recovered common-spectrum noise in the PPTA is consistent with a power law with a spectral index of $\gamma=13/3$, the value predicted for a stochastic GW background from a population of supermassive black hole binaries driven solely by GW emission., Comment: 18 pages, 10 figures. Accepted for publication in ApJL

We present the third data release from the Parkes Pulsar Timing Array (PPTA) project. The release contains observations of 32 pulsars obtained using the 64-m Parkes "Murriyang" radio telescope. The data span is up to 18 years with a typical cadence of 3 weeks. This data release is formed by combining an updated version of our second data release with $\sim 3$ years of more recent data primarily obtained using an ultra-wide-bandwidth receiver system that operates between 704 and 4032 MHz. We provide calibrated pulse profiles, flux-density dynamic spectra, pulse times of arrival, and initial pulsar timing models. We describe methods for processing such wide-bandwidth observations, and compare this data release with our previous release., Comment: 15 pages, 6 figures. Accepted for publication in PASA

Pulsar timing arrays aim to detect nanohertz-frequency gravitational waves (GWs). A background of GWs modulates pulsar arrival times and manifests as a stochastic process, common to all pulsars, with a signature spatial correlation. Here we describe a search for an isotropic stochastic gravitational-wave background (GWB) using observations of 30 millisecond pulsars from the third data release of the Parkes Pulsar Timing Array (PPTA), which spans 18 years. Using current Bayesian inference techniques we recover and characterize a common-spectrum noise process. Represented as a strain spectrum $h_c = A(f/1 {\rm yr}^{-1})^{\alpha}$, we measure $A=3.1^{+1.3}_{-0.9} \times 10^{-15}$ and $\alpha=-0.45 \pm 0.20$ respectively (median and 68% credible interval). For a spectral index of $\alpha=-2/3$, corresponding to an isotropic background of GWs radiated by inspiraling supermassive black hole binaries, we recover an amplitude of $A=2.04^{+0.25}_{-0.22} \times 10^{-15}$. However, we demonstrate that the apparent signal strength is time-dependent, as the first half of our data set can be used to place an upper limit on $A$ that is in tension with the inferred common-spectrum amplitude using the complete data set. We search for spatial correlations in the observations by hierarchically analyzing individual pulsar pairs, which also allows for significance validation through randomizing pulsar positions on the sky. For a process with $\alpha=-2/3$, we measure spatial correlations consistent with a GWB, with an estimated false-alarm probability of $p \lesssim 0.02$ (approx. $2\sigma$). The long timing baselines of the PPTA and the access to southern pulsars will continue to play an important role in the International Pulsar Timing Array., Comment: 19 pages, 10 figures, Accepted for publication in ApJL

We report the radio and high-energy properties of a new outburst from the radio-loud magnetar 1E 1547.0$-$5408. Following the detection of a short burst from the source with Swift-BAT on 2022 April 7, observations by NICER detected an increased flux peaking at $(6.0 \pm 0.4) \times 10^{-11}$ erg s$^{-1}$ cm$^{-2}$ in the soft X-ray band, falling to the baseline level of $1.7\times10^{-11}$ erg s$^{-1}$ cm$^{-2}$ over a 17-day period. Joint spectroscopic measurements by NICER and NuSTAR indicated no change in the hard non-thermal tail despite the prominent increase in soft X-rays. Observations at radio wavelengths with Murriyang, the 64-m Parkes radio telescope, revealed that the persistent radio emission from the magnetar disappeared at least 22 days prior to the initial Swift-BAT detection and was re-detected two weeks later. Such behavior is unprecedented in a radio-loud magnetar, and may point to an unnoticed slow rise in the high-energy activity prior to the detected short-bursts. Finally, our combined radio and X-ray timing revealed the outburst coincided with a spin-up glitch, where the spin-frequency and spin-down rate increased by $0.2 \pm 0.1$ $\mu$Hz and $(-2.4 \pm 0.1) \times 10^{-12}$ s$^{-2}$ respectively. A linear increase in spin-down rate of $(-2.0 \pm 0.1) \times 10^{-19}$ s$^{-3}$ was also observed over 147 d of post-outburst timing. Our results suggest that the outburst may have been associated with a reconfiguration of the quasi-polar field lines, likely signalling a changing twist, accompanied by spatially broader heating of the surface and a brief quenching of the radio signal, yet without any measurable impact on the hard X-ray properties., Comment: Accepted to ApJ, 18 pages, 7 figures. Fixed typo in abstract and discussion

We report the detection of FRB20191107B with the UTMOST radio telescope at a dispersion measure (DM) of 714.9 ${\rm pc~cm^{-3}}$. The burst consists of three components, the brightest of which has an intrinsic width of only 11.3 $\mu$s and a scattering tail with an exponentially decaying time-scale of 21.4 $\mu$s measured at 835 MHz. We model the sensitivity of UTMOST and other major FRB surveys to such narrow events. We find that $>60\%$ of FRBs like FRB20191107B are being missed, and that a significant population of very narrow FRBs probably exists and remains underrepresented in these surveys. The high DM and small scattering timescale of FRB20191107B allows us to place an upper limit on the strength of turbulence in the Intergalactic Medium (IGM), quantified as scattering measure (SM), of ${\rm SM_{IGM} < 8.4 \times 10^{-7} ~kpc~m^{-20/3}}$. Almost all UTMOST FRBs have full phase information due to real-time voltage capture which provides us with the largest sample of coherently dedispersed single burst FRBs. Our 10.24 $\mu$s time resolution data yields accurately measured FRB scattering timescales. We combine the UTMOST FRBs with 10 FRBs from the literature and find no obvious evidence for a DM-scattering relation, suggesting that IGM is not the dominant source of scattering in FRBs. We support the results of previous studies and identify the local environment of the source in the host galaxy as the most likely region which dominates the observed scattering of our FRBs.

The study of impulsive astrophysical radio emission makes it possible to probe the intervening plasma between the emission source and the Earth. In cold electron-ion plasmas, the circular propagating wave modes primarily alter the linear polarization plane that scales with the inverse-square of the emission frequency. In relativistic plasmas, the wave modes are elliptically polarized, and it is possible to convert linearly polarized emission into circular and vice versa. Fast radio bursts (FRBs) enable the study of not only the electron-ion plasma of the intergalactic medium but potentially the extreme magneto-ionic medium in which these intense pulses are produced. Here we report on the polarimetric analysis of a repeat burst from the FRB 20201124A source. The burst displayed a significant frequency-dependent circularly polarized component, unlike other bursts from this source or any other FRB found to date. We model the frequency dependence of the circular polarization using a phenomenological generalized Faraday rotation framework. We find that the observed circular polarization in the burst can be adequately explained by the propagation of an initially linearly polarised burst signal through a relativistic plasma along the line of sight from the progenitor., Comment: 8 pages, 4 figures; accepted for publication in Physical Review D

Boasting supreme magnetic strengths, magnetars are among the prime candidates to generate fast radio bursts. Several theories have been proposed for the formation mechanism of magnetars, but have not yet been fully tested. As different magnetar formation theories expect distinct magnetar space velocity distributions, high-precision astrometry of Galactic magnetars can serve as a probe for the formation theories. In addition, magnetar astrometry can refine the understanding of the distribution of Galactic magnetars. This distribution can be compared against fast radio bursts (FRBs) localized in spiral galaxies, in order to test the link between FRBs and magnetars. Swift J1818.0-1607 is the hitherto fastest-spinning magnetar and the fifth discovered radio magnetar. In an ongoing astrometric campaign, we have observed Swift J1818.0-1607 for one year using the Very Long Baseline Array, and have determined a precise proper motion as well as a tentative parallax for the magnetar., Comment: 4 pages, 2 figures, to be published in Proceedings of the International Astronomical Union (363)

The mechanism that produces fast radio burst (FRB) emission is poorly understood. Targeted monitoring of repeating FRB sources provides the opportunity to fully characterize the emission properties in a manner impossible with one-off bursts. Here, we report observations of the source of FRB 20201124A, with the Australian Square Kilometre Array Pathfinder (ASKAP) and the ultra-wideband low (UWL) receiver at the Parkes 64-m radio telescope (Murriyang). The source entered a period of emitting bright bursts during early 2021 April. We have detected 16 bursts from this source. One of the bursts detected with ASKAP is the brightest burst ever observed from a repeating FRB source with an inferred fluence of $640\pm70$ Jy ms. Of the five bursts detected with the Parkes UWL, none display any emission in the range 1.1--4 GHz. All UWL bursts are highly polarized, with their Faraday rotation measures (RMs) showing apparent variations. We obtain an average RM of $-614$ rad m$^{-2}$ for this FRB source with a standard deviation of $16$ rad m$^{-2}$ in the UWL bursts. In one of the UWL bursts, we see evidence of significant circularly polarized emission with a fractional extent of $47\pm1$ per cent. Such a high degree of circular polarization has never been seen before in bursts from repeating FRB sources. We also see evidence for significant variation in the linear polarization position angle in the pulse profile of this UWL repeat burst. Models for repeat burst emission will need to account for the increasing diversity in the burst polarization properties., Comment: 14 pages, 8 figures; accepted for publication in MNRAS

We report on a timing programme of 74 young pulsars that have been observed by the Parkes 64-m radio telescope over the past decade. Using modern Bayesian timing techniques, we have measured the properties of 124 glitches in 52 of these pulsars, of which 74 are new. We demonstrate that the glitch sample is complete to fractional increases in spin-frequency greater than $\Delta\nu^{90\%}_{g}/\nu \approx 8.1 \times 10^{-9}$. We measure values of the braking index, $n$, in 33 pulsars. In most of these pulsars, their rotational evolution is dominated by episodes of spin-down with $n > 10$, punctuated by step changes in the spin-down rate at the time of a large glitch. The step changes are such that, averaged over the glitches, the long-term $n$ is small. We find a near one-to-one relationship between the inter-glitch value of $n$ and the change in spin-down of the previous glitch divided by the inter-glitch time interval. We discuss the results in the context of a range of physical models., Comment: 24 pages, 9 figures and 9 tables. Published in MNRAS. (Fixed typo in the abstract and conclusion)

Generalised Faraday rotation can induce frequency-dependent conversion between the linear and circular polarisation spectra of compact radio sources such as pulsars, fast radio bursts and active galactic nuclei. I devise a simple phenomenological model that can be used to measure the effects of generalised Faraday rotation on the linearly and circularly polarised spectra of these sources. The model is theory-agnostic, with an arbitrary wavelength dependence, and hence can accommodate for a variety of potential generalised Faraday rotation inducing media. It can also be combined with additional observables to infer the physical properties of the intervening medium., Comment: 5 pages, 3 figures, 1 table, software implementation: https://github.com/mlower/rmnest. Comments welcome!

A recent measurement of the proper motion of PSR J0908-4913 shows that it is a fast moving object at a distance of some 3 kpc. Here we present evidence that the pulsar is located at the edge of a previously unknown, filled-centre supernova remnant, G270.4-1.0. The velocity vector of the pulsar points directly away from the centre of the remnant. The putative association of the pulsar with SNR G270.4-1.0 implies the pulsar is ~12kyr old, significantly less than its characteristic age of 110kyr. We show that the rotation axis of the pulsar points in the direction of the proper motion. Rotation measure and dispersion measure variations are seen over time, likely indicating the pulsar is passing behind a filament of the remnant., Comment: Accepted for publication in MNRAS

In certain pulsar timing experiments, where observations are scheduled approximately periodically (e.g. daily), timing models with significantly different frequencies (including but not limited to glitch models with different frequency increments) return near-equivalent timing residuals. The average scheduling aperiodicity divided by the phase error due to time-of-arrival uncertainties is a useful indicator of when the degeneracy is important. Synthetic data are used to explore the effect of this degeneracy systematically. It is found that phase-coherent tempo2 or temponest-based approaches are biased sometimes toward reporting small glitch sizes regardless of the true glitch size. Local estimates of the spin frequency alleviate this bias. A hidden Markov model is free from bias towards small glitches and announces explicitly the existence of multiple glitch solutions but sometimes fails to recover the correct glitch size. Two glitches in the UTMOST public data release are re-assessed, one in PSR J1709$-$4429 at MJD 58178 and the other in PSR J1452$-$6036 at MJD 58600. The estimated fractional frequency jump in PSR J1709$-$4429 is revised upward from $\Delta f/f = (54.6\pm 1.0) \times 10^{-9}$ to $\Delta f/f = (2432.2 \pm 0.1) \times 10^{-9}$ with the aid of additional data from the Parkes radio telescope. We find that the available UTMOST data for PSR J1452$-$6036 are consistent with $\Delta f/f = 270 \times 10^{-9} + N/(fT)$ with $N = 0,1,2$, where $T \approx 1\,\text{sidereal day}$ is the observation scheduling period. Data from the Parkes radio telescope can be included, and the $N = 0$ case is selected unambiguously with a combined dataset., Comment: Accepted for publication in MNRAS. 16 pages, 12 figures

Radio-loud magnetars display a wide variety of radio-pulse phenomenology seldom seen among the population of rotation-powered pulsars. Spectropolarimetry of the radio pulses from these objects has the potential to place constraints on their magnetic topology and unveil clues about the magnetar radio emission mechanism. Here we report on eight observations of the magnetar Swift J1818.0$-$1607 taken with the Parkes Ultra-Wideband Low receiver covering a wide frequency range from 0.7 to 4 GHz over a period of 5 months. The magnetar exhibits significant temporal profile evolution over this period, including the emergence of a new profile component with an inverted spectrum, two distinct types of radio emission mode switching, detected during two separate observations, and the appearance and disappearance of multiple polarization modes. These various phenomena are likely a result of ongoing reconfiguration of the plasma content and electric currents within the magnetosphere. Geometric fits to the linearly polarized position angle indicate we are viewing the magnetar at an angle of $\sim$99$^{\circ}$ from the spin axis, and its magnetic and rotation axes are misaligned by $\sim$112$^{\circ}$. While conducting these fits, we found the position angle swing had reversed direction on MJD 59062 compared to observations taken 15 days earlier and 12 days later. We speculate this phenomena may be evidence the radio emission from this magnetar originates from magnetic field lines associated with two co-located magnetic poles that are connected by a coronal loop., Comment: 13 pages, 10 figures, 4 tables. Accepted to MNRAS

The soft-gamma repeater Swift J1818.0$-$1607 is only the fifth magnetar found to exhibit pulsed radio emission. Using the Ultra-Wideband Low receiver system of the Parkes radio telescope, we conducted a 3 h observation of Swift J1818.0$-$1607. Folding the data at a rotation period of $P = 1.363$ s, we obtained wideband polarization profiles and flux density measurements covering radio frequencies between 704-4032 MHz. After measuring, and then correcting for the pulsar's rotation measure of $1442.0 \pm 0.2$ rad m$^{-2}$, we find the radio profile is between 80-100 per cent linearly polarized across the wide observing band, with a small amount of depolarization at low frequencies that we ascribe to scatter broadening. We also measure a steep spectral index of $\alpha = -2.26^{+0.02}_{-0.03}$ across our large frequency range, a significant deviation from the flat or inverted spectra often associated with radio-loud magnetars. The steep spectrum and temporal rise in flux density bears some resemblance to the behaviour of the magnetar-like, rotation-powered pulsar PSR J1119$-$6127. This leads us to speculate that Swift J1818.0$-$1607 may represent an additional link between rotation-powered pulsars and magnetars., Comment: 10 pages, 5 figures and 1 table. Revised version accepted for publication in The Astrophysical Journal Letters

While pulsars possess exceptional rotational stability, large scale timing studies have revealed at least two distinct types of irregularities in their rotation: red timing noise and glitches. Using modern Bayesian techniques, we investigated the timing noise properties of 300 bright southern-sky radio pulsars that have been observed over 1.0-4.8 years by the upgraded Molonglo Observatory Synthesis Telescope (MOST). We reanalysed the spin and spin-down changes associated with nine previously reported pulsar glitches, report the discovery of three new glitches and four unusual glitch-like events in the rotational evolution of PSR J1825$-$0935. We develop a refined Bayesian framework for determining how red noise strength scales with pulsar spin frequency ($\nu$) and spin-down frequency ($\dot{\nu}$), which we apply to a sample of 280 non-recycled pulsars. With this new method and a simple power-law scaling relation, we show that red noise strength scales across the non-recycled pulsar population as $\nu^{a} |\dot{\nu}|^{b}$, where $a = -0.84^{+0.47}_{-0.49}$ and $b = 0.97^{+0.16}_{-0.19}$. This method can be easily adapted to utilise more complex, astrophysically motivated red noise models. Lastly, we highlight our timing of the double neutron star PSR J0737$-$3039, and the rediscovery of a bright radio pulsar originally found during the first Molonglo pulsar surveys with an incorrectly catalogued position., Comment: Accepted by MNRAS. 28 pages, 8 figures, 8 tables

We report the first detection of a glitch in the radio pulsar PSR J0908$-$4913 (PSR B0906$-$49) during regular timing observations by the Molonglo Observatory Synthesis Telescope (MOST) as part of the UTMOST project., Comment: 2 pages, 1 table

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 position angle of linear polarization across the main pulse and in time have been observed. The pulse profile exhibits similar structures throughout our three observations (over a week time scale), displaying a small amount of profile evolution in terms of polarization and pulse width across the wideband. We measured a flat radio spectrum across the band with a positive spectral index, in addition to small levels of flux and spectral index variability across our observing span. The observed wideband polarization properties are significantly different compared to those taken after the 2003 outburst, and therefore provide new information about the origin of radio emission., Comment: 7 pages, 4 figures, accepted by ApJ Letters

Bayesian parameter estimation is fast becoming the language of gravitational-wave astronomy. It is the method by which gravitational-wave data is used to infer the sources' astrophysical properties. We introduce a user-friendly Bayesian inference library for gravitational-wave astronomy, Bilby. This python code provides expert-level parameter estimation infrastructure with straightforward syntax and tools that facilitate use by beginners. It allows users to perform accurate and reliable gravitational-wave parameter estimation on both real, freely-available data from LIGO/Virgo, and simulated data. We provide a suite of examples for the analysis of compact binary mergers and other types of signal model including supernovae and the remnants of binary neutron star mergers. These examples illustrate how to change the signal model, how to implement new likelihood functions, and how to add new detectors. Bilby has additional functionality to do population studies using hierarchical Bayesian modelling. We provide an example in which we infer the shape of the black hole mass distribution from an ensemble of observations of binary black hole mergers., Comment: Submitted for publication

We report the detection of a glitch event in the pulsar J1709$-$4429 (also known as B1706$-$44) during regular monitoring observations with the Molonglo Observatory Synthesis Telescope (UTMOST). The glitch was found during timing operations, in which we regularly observe over 400 pulsars with up to daily cadence, while commensally searching for Rotating Radio Transients, pulsars, and FRBs. With a fractional size of $\Delta\nu/\nu \approx 52.4 \times10^{-9}$, the glitch reported here is by far the smallest known for this pulsar, attesting to the efficacy of glitch searches with high cadence using UTMOST., Comment: 3 pages, 1 figure

When binary black holes form in the field, it is expected that their orbits typically circularize before coalescence. In galactic nuclei and globular clusters, binary black holes can form dynamically. Recent results suggest that $\approx5\%$ of mergers in globular clusters result from three-body interactions. These three-body interactions are expected to induce significant orbital eccentricity $\gtrsim 0.1$ when they enter the Advanced LIGO band at a gravitational-wave frequency of 10 Hz. Measurements of binary black hole eccentricity therefore provide a means for determining whether or not dynamic formation is the primary channel for producing binary black hole mergers. We present a framework for performing Bayesian parameter estimation on gravitational-wave observations of black hole inspirals. Using this framework, and employing the non-spinning, inspiral-only EccentricFD waveform approximant, we determine the minimum detectable eccentricity for an event with masses and distance similar to GW150914. At design sensitivity, we find that the current generation of advanced observatories will be sensitive to orbital eccentricities of $\gtrsim0.05$ at a gravitational-wave frequency of 10 Hz, demonstrating that existing detectors can use eccentricity to distinguish between circular field binaries and globular cluster triples. We compare this result to eccentricity distributions predicted to result from three black hole binary formation channels, showing that measurements of eccentricity could be used to infer the population properties of binary black holes., Comment: 12 pages, 7 figures, 2 tables