Results for "Duncan R. Lorimer"

total 128193took 0.15s
The pulsar spectral index distributionFeb 08 2013Feb 11 2013The flux density spectra of radio pulsars are known to be steep and, to first order, described by a power-law relationship of the form S_{\nu} \propto \nu^{\alpha}, where S_{\nu} is the flux density at some frequency \nu and \alpha is the spectral index. ... More
Towards deeper neural networks for Fast Radio Burst detectionFeb 17 2019With the upcoming commensal surveys for Fast Radio Bursts (FRBs), and their high candidate rate, usage of machine learning algorithms for candidate classification is a necessity. Such algorithms will also play a pivotal role in sending real-time triggers ... More
SDSS J102347.6+003841: A Millisecond Radio Pulsar Binary That Had A Hot Disk During 2000-2001May 24 2009Aug 20 2009The Sloan Digital Sky Survey (SDSS) source J102347.6+003841 was recently revealed to be a binary 1.69 millisecond radio pulsar with a 4.75 hr orbital period and a ~0.2 M_sun companion. Here we analyze the SDSS spectrum of the source in detail. The spectrum ... More
The Millisecond Pulsars in NGC 6760Nov 06 2004Jan 22 2005We present the results of recent Arecibo and Green Bank observations of the globular cluster NGC 6760. Using Arecibo, a phase-coherent timing solution has been obtained for the previously known binary pulsar in this cluster, PSR J1911+0102A. We have also ... More
Non-Recycled Pulsars in Globular ClustersJan 04 2011We place limits on the population of non-recycled pulsars originating in globular clusters through Monte Carlo simulations and frequentist statistical techniques. We set upper limits on the birth rates of non-recycled cluster pulsars and predict how many ... More
Simultaneous radio and X-ray observations of PSR B0611+22Jul 26 2016We report results from simultaneous radio and X-ray observations of PSR B0611+22 which is known to exhibit bursting in its single-pulse emission. The pulse phase of the bursts vary with radio frequency. The bursts are correlated in 327/150~MHz datasets ... More
Testing the universality of free fall by tracking a pulsar in a stellar triple systemJul 05 2018Einstein's theory of gravity, general relativity, has passed stringent tests in laboratories, elsewhere in the Solar Sytem, and in pulsar binaries. Nevertheless it is known to be incompatible with quantum mechanics and must differ from the true behaviour ... More
PsrPopPy: An open-source package for pulsar population simulationsNov 14 2013Jan 20 2014We have produced a new software package for the simulation of pulsar populations, \textsc{PsrPopPy}, based on the \textsc{Psrpop} package. The codebase has been re-written in Python (save for some external libraries, which remain in their native Fortran), ... More
PSR J2021+3651: A New Gamma-Ray Pulsar CandidateFeb 08 2004The COS B high energy gamma-ray source 2CG 075+00, also known as GeV J2020+3658 or 3EG J2021+3716, has avoided identification with a low energy counterpart for over twenty years. We present a likely identification with the discovery and subsequent timing ... More
A 20 cm Search for Pulsars in Globular Clusters with Arecibo and the GBTFeb 08 2004We are conducting deep searches for radio pulsations at L-band (~ 20cm) towards more than 30 globular clusters using the 305m Arecibo telescope in Puerto Rico and the 100m Green Bank Telescope in West Virginia. With roughly three quarters of our search ... More
GBTrans: A commensal search for radio pulses with the Green Bank twenty metre telescopeMay 02 2019May 06 2019We describe GBTrans, a real-time search system designed to find fast radio bursts (FRBs) using the 20-m radio telescope at the Green Bank Observatory. The telescope has been part of the Skynet educational program since 2015. We give details of the observing ... More
The Galactic Millisecond Pulsar PopulationOct 09 2012Among the current sample of over 2000 radio pulsars known primarily in the disk of our Galaxy, millisecond pulsars now number almost 200. Due to the phenomenal success of blind surveys of the Galactic field, and targeted searches of Fermi gamma-ray sources, ... More
New limits on the strong equivalence principle from two long-period circular-orbit binary pulsarsApr 14 2004Following a brief review of the principles of the strong equivalence principle (SEP) and tests for its violation in the strong and weak gravitational field regimes, we present preliminary results of new tests using two long-period binary pulsars: J0407+1607 ... More
How else can we detect Fast Radio Bursts?May 05 2016May 26 2016We discuss possible electromagnetic signals accompanying Fast Radio Bursts (FRBs) that are expected in the scenario where FRBs originate in neutron star magnetospheres. For models involving Crab-like giant pulses, no appreciable contemporaneous emission ... More
Flares from Galactic centre pulsars: a new class of X-ray transients?Mar 17 2016Despite intensive searches, the only pulsar within 0.1 pc of the central black hole in our Galaxy, Sgr A*, is a radio-loud magnetar. Since magnetars are rare among the Galactic neutron star population, and a large number of massive stars are already known ... More
The luminosity function of cluster pulsarsDec 21 2010We study luminosities of millisecond pulsars in globular clusters by fitting the observed luminosity distribution with single and double power laws. We use simulations to model the observed distribution as the brighter part of some parent distribution ... More
Verifying and Reporting Fast Radio BurstsAug 23 2018Fast Radio Bursts (FRBs) are a class of short-duration transients at radio wavelengths with inferred astrophysical origin. The prototypical FRB is a broadband signal that occurs over the extent of the receiver frequency range, is narrow in time, and is ... More
ALFABURST: A realtime fast radio burst monitor for the Arecibo telescopeNov 13 2015Fast radio bursts (FRBs) constitute an emerging class of fast radio transient whose origin continues to be a mystery. Realizing the importance of increasing coverage of the search parameter space, we have designed, built, and deployed a realtime monitor ... More
The Green Bank Telescope 350 MHz Drift-scan Survey I: Survey Observations and the Discovery of 13 PulsarsSep 19 2012Oct 23 2012Over the summer of 2007, we obtained 1191 hours of `drift-scan' pulsar search observations with the Green Bank Telescope at a radio frequency of 350 MHz. Here we describe the survey setup, search procedure, and the discovery and follow-up timing of thirteen ... More
The Green Bank Telescope 350 MHz Drift-scan Survey II: Data Analysis and the Timing of 10 New Pulsars, Including a Relativistic BinarySep 19 2012Oct 23 2012We have completed a 350 MHz drift scan survey using the Robert C. Byrd Green Bank Telescope with the goal of finding new radio pulsars, especially millisecond pulsars that can be timed to high precision. This survey covered ~10300 square degrees and all ... More
Fast Radio BurstsApr 16 2019The discovery of radio pulsars over a half century ago was a seminal moment in astronomy. It demonstrated the existence of neutron stars, gave a powerful observational tool to study them, and has allowed us to probe strong gravity, dense matter, and the ... More
The Probability Distribution of the Double Neutron Star Coalescence Rate and Predictions for More DetectionsDec 02 2002We present an analysis method that allows us to estimate the Galactic formation of radio pulsar populations based on their observed properties and our understanding of survey selection effects. More importantly, this method allows us to assign a statistical ... More
PSR J1907+0918 - a young radio pulsar near SGR 1900+14 and G42.8+0.6May 19 2000Jul 12 2000We have extensively searched for periodic signals from the soft-gamma repeater SGR 1900+14, at 430 and 1410 MHz with the Arecibo telescope. Our observations did not reveal the 5.16-s periodicity discovered at X-ray wavelengths by Hurley et al. (1998). ... More
Luminosities of recycled radio pulsars in globular clustersJul 22 2011Using Monte Carlo simulations, we model the luminosity distribution of recycled pulsars in globular clusters as the brighter, observable part of an intrinsic distribution and find that the observed luminosities can be reproduced using either log-normal ... More
Enhanced Rates of Fast Radio Bursts from Galaxy ClustersNov 13 2017Fast Radio Bursts (FRBs) have so far been detected serendipitously across the sky. We consider the possible enhancement in the FRB rate in the direction of galaxy clusters, and compare the predicted rate from a large sample of galaxy clusters to the expected ... More
A search for pulsars in supernova remnantsJan 12 1998We have carried out a sensitive search for young pulsars associated with supernova remnants using the 76-m Lovell radio telescope at Jodrell Bank. The observations were made at 606 MHz using a system with a bandwidth of 8 MHz and a set noise temperature ... More
Isolated pulsar spin evolution on the P-Pdot DiagramJan 14 2010We look at two contrasting spin-down models for isolated radio pulsars and, accounting for selection effects, synthesize observable populations. While our goal is to reproduce all of the observable characteristics, in this paper we pay particular attention ... More
Future prospects for ground-based gravitational wave detectors $-$ The Galactic double neutron star merger rate revisitedNov 09 2018Feb 28 2019We present the Galactic merger rate for double neutron star (DNS) binaries using the observed sample of eight DNS systems merging within a Hubble time. This sample includes the recently discovered, highly relativistic DNS systems J1757$-$1854 and J1946+2052, ... More
GREENBURST: a commensal fast radio burst search back-end for the Green Bank TelescopeMar 13 2019We describe the design and deployment of GREENBURST, a commensal Fast Radio Burst (FRB) search system at the Green Bank Telescope. GREENBURST uses the dedicated L-band receiver tap to search over the 960$-$1920 MHz frequency range for pulses with dispersion ... More
Effect of PSR J0737-3039 on the DNS Merger Rate and Implications for GW DetectionAug 14 2006We present the current estimates of the Galactic merger rate of double-neutron-star (DNS) systems. Using a statistical analysis method, we calculate the probability distribution function (PDF) of the rate estimates, which allows us to assign confidence ... More
The detectability of eccentric binary pulsarsJan 15 2014Studies of binary pulsars provide insight into various theories of physics. Detection of such systems is challenging due to the Doppler modulation of the pulsed signal caused by the orbital motion of the pulsar. We investigated the loss of sensitivity ... More
Arecibo timing observations of 17 pulsars along the Galactic planeDec 05 2001We present phase-coherent timing solutions obtained for the first time for 17 pulsars discovered at Arecibo by Hulse & Taylor (1975ab) in a 430-MHz survey of the Galactic plane. This survey remains the most sensitive of the Galactic plane at 430 MHz and ... More
On the detectability of eccentric binary pulsarsFeb 20 2013Mar 27 2013By generalizing earlier work of Johnston & Kulkarni, we present a detailed description of the reduction in the signal-to-noise ratio for observations of binary pulsars. We present analytical expressions, and provide software, to calculate the sensitivity ... More
Gauge Invariant Effective Potentials and Higgs Mass BoundsApr 28 1997May 12 1997The problem of defining a gauge invariant effective potential with a strict energetic interpretation is examined in the context of spontaneously broken gauge theories. It is shown that such a potential can be defined in terms of a composite gauge invariant ... More
A very massive neutron star: relativistic Shapiro delay measurements of PSR J0740+6620Apr 14 2019Despite its importance to our understanding of physics at supranuclear densities, the equation of state (EoS) of matter deep within neutron stars remains poorly understood. Millisecond pulsars (MSPs) are among the most useful astrophysical objects in ... More
Derived Equivalences of K3 Surfaces and Twined Elliptic GeneraJun 20 2015Dec 30 2015We use the unique canonically-twisted module over a certain distinguished super vertex operator algebra---the moonshine module for Conway's group---to attach a weak Jacobi form of weight zero and index one to any symplectic derived equivalence of a projective ... More
Heartbeat of the Mouse: a young radio pulsar associated with the axisymmetric nebula G359.23-0.82Sep 23 2002We report the discovery of PSR J1747-2958, a radio pulsar with period P = 98 ms and dispersion measure DM = 101 pc/cc, in a deep observation with the Parkes telescope of the axially-symmetric "Mouse" radio nebula (G359.23-0.82). Timing measurements of ... More
On the normalised FRB luminosity functionAug 29 2018Thirty-three fast radio bursts (FRBs) had been detected by March 2018. Although the sample size is still limited, meaningful statistical studies can already be carried out. The normalised luminosity function places important constraints on the intrinsic ... More
Detecting fast radio bursts at decametric wavelengthsSep 04 2016Nov 07 2016Fast radio bursts (FRBs) are highly dispersed, sporadic radio pulses that are likely extragalactic in nature. Here we investigate the constraints on the source population from surveys carried out at frequencies $<1$~GHz. All but one FRB has so far been ... More
Variability of the Pulsed Radio Emission from the Large Magellanic Cloud Pulsar PSR J0529-6652Nov 19 2012We 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 ... More
The Probability Distribution of Binary Pulsar Coalescence Rate Estimates. II. Neutron Star-White Dwarf BinariesFeb 06 2004Aug 10 2004We consider the statistics of pulsar binaries with white dwarf companions (NS-WD). Using the statistical analysis method developed by Kim et al. (2003) we calculate the Galactic coalescence rate of NS-WD binaries due to gravitational-wave emission. We ... More
On gigahertz spectral turnovers in pulsarsOct 06 2015Pulsars are known to emit non-thermal radio emission that is generally a power-law function of frequency. In some cases, a turnover is seen at frequencies around 100~MHz. Kijak et al. have reported the presence of a new class of ''Gigahertz Peaked Spectrum'' ... More
Detecting fast radio bursts at decametric wavelengthsSep 04 2016Sep 13 2016Fast radio bursts (FRBs) are highly dispersed, sporadic radio pulses that are likely extragalactic in nature. Here we investigate the constraints on the source population from surveys carried out at frequencies $<1$~GHz. All but one FRB has so far been ... More
An Upper Limit on the Coalescence Rate of Double Neutron-Star Binaries in the GalaxyJul 29 1999Sep 30 1999In the context of assessing the detectability of the coalescence of two neutron stars (NS) by currently built gravitational-wave experiments, we present a way of obtaining an upper limit to the coalescence rate in the Galaxy. We consider the NS/NS progenitors ... More
On Pulsar Distance Measurements and their UncertaintiesJun 03 2012Accurate distances to pulsars can be used for a variety of studies of the Galaxy and its electron content. However, most distance measures to pulsars have been derived from the absorption (or lack thereof) of pulsar emission by Galactic HI gas, which ... More
Jumping the energetics queue: Modulation of pulsar signals by extraterrestrial civilizationsNov 19 2013Aug 14 2014It has been speculated that technological civilizations evolve along an energy consumption scale first formulated by Kardashev, ranging from human-like civilizations that consume energy at a rate of $\sim 10^{19}$ erg s$^{-1}$ to hypothetical highly advanced ... More
Radio and X-ray observations of the intermittent pulsar J1832+0029Aug 31 2012We report on radio and X-ray observations of PSR 1832+0029, a 533-ms radio pulsar discovered in the Parkes Multibeam Pulsar Survey. From radio observations taken with the Parkes, Lovell and Arecibo telescopes, we show that this pulsar exhibits two spindown ... More
Pulsar science with the Five hundred metre Aperture Spherical TelescopeAug 12 2009Aug 17 2009With a collecting area of 70 000 m^2, the Five hundred metre Aperture Spherical Telescope (FAST) will allow for great advances in pulsar astronomy. We have performed simulations to estimate the number of previously unknown pulsars FAST will find with ... More
VOEvent Standard for Fast Radio BurstsOct 23 2017Fast radio bursts are a new class of transient radio phenomena currently detected as millisecond radio pulses with very high dispersion measures. As new radio surveys begin searching for FRBs a large population is expected to be detected in real-time, ... More
The hunt for new pulsars with the Green Bank TelescopeMar 21 2013The Green Bank Telescope (GBT) is the largest fully steerable radio telescope in the world and is one of our greatest tools for discovering and studying radio pulsars. Over the last decade, the GBT has successfully found over 100 new pulsars through large-area ... More
The Giant Flare of 1998 August 27 from SGR 1900+14: I. An Interpretive Study of BeppoSAX and Ulysses ObservationsOct 24 2000The giant flare of 1998 August 27 from SGR 1900+14 was extraordinary in many ways: it was the most intense flux of gamma rays ever detected from a source outside our solar system; it was longer than any previously detected burst from a soft gamma repeater ... More
A Survey of the Galactic Plane for Dispersed Pulses with the Australian Square Kilometre Array PathfinderMar 12 2019We report the results from a survey of the Galactic plane for dispersed single pulses using the Australian SKA Pathfinder (ASKAP). We searched for rare bright dispersed radio pulses comprising 160 pointings covering 4800 deg$^2$ of the Galactic plane ... More
Meromorphic Jacobi Forms of Half-Integral Index and Umbral Moonshine ModulesJul 05 2017In this work we consider an association of meromorphic Jacobi forms of half-integral index to the pure D-type cases of umbral moonshine, and solve the module problem for four of these cases by constructing vertex operator superalgebras that realise the ... More
On the Discrete Groups of Mathieu MoonshineDec 05 2012Aug 25 2013We prove that a certain space of cusp forms for the Hecke congruence group of a given level is one-dimensional if and only if that level is the order of an element of the second largest Mathieu group. As such, our result furnishes a direct analogue of ... More
Rademacher Sums and Rademacher SeriesOct 10 2012We exposit the construction of Rademacher sums in arbitrary weights and describe their relationship to mock modular forms. We introduce the notion of Rademacher series and describe several applications, including the determination of coefficients of Rademacher ... More
On Rademacher Sums, the Largest Mathieu Group, and the Holographic Modularity of MoonshineOct 18 2011Recently a conjecture has been proposed which attaches (mock) modular forms to the largest Mathieu group. This may be compared to monstrous moonshine, in which modular functions are attached to elements of the Monster group. One of the most remarkable ... More
O'Nan moonshine and arithmeticFeb 12 2017Mar 17 2019Answering a question posed by Conway and Norton in their seminal 1979 paper on moonshine, we prove the existence of a graded infinite-dimensional module for the sporadic simple group of O'Nan, for which the McKay--Thompson series are weight $3/2$ modular ... More
Pariah moonshineSep 26 2017Finite simple groups are the building blocks of finite symmetry. The effort to classify them precipitated the discovery of new examples, including the monster, and six pariah groups which do not belong to any of the natural families, and are not involved ... More
A Population of Non-Recycled Pulsars Orginating in Globular ClustersJul 09 2012Jul 10 2012We explore the enigmatic population of long-period, apparently non-recycled pulsars in globular clusters, building on recent work by Boyles et al (2011). This population is difficult to explain if it formed through typical core collapse supernovae, leading ... More
A Study of Single Pulses in the Parkes Multibeam Pulsar SurveyJun 30 2018We reprocessed the Parkes Multibeam Pulsar Survey, searching for single pulses out to a DM of 5000 pc cm$^{-3}$ with widths of up to one second. We recorded single pulses from 264 known pulsars and 14 Rotating Radio Transients. We produced amplitude distributions ... More
Millisecond Pulsars in 47 TucanaeNov 19 1999Recent observations of the globular cluster 47 Tuc, made with the Parkes telescope at a wavelength of 20 cm, have resulted in the discovery of nine new millisecond pulsars, all in binary systems. The number of timing solutions available has risen from ... More
The Galactic Double-Neutron-Star Merger Rate: Most Current EstimatesMay 27 2004Aug 11 2004We summarize our results on the Galactic merger rate of double neutron stars (DNS) in view of the recent discovery of PSR J0737-3039. We also present previously unpublished results for the 'global' probability distribution of merger rate values that incorporate ... More
The Galactic Formation Rate of Eccentric Neutron Star-White Dwarf BinariesAug 13 2004In this paper we consider the population of eccentric binaries with a neutron star and a white dwarf that has been revealed in our galaxy in recent years through binary pulsar observations. We apply our statistical analysis method (Kim, Kalogera, & Lorimer ... More
Multifrequency Observations of Radio Pulse Broadening and Constraints on Interstellar Electron Density MicrostructureJan 07 2004We have made observations of 98 low-Galactic-latitude pulsars to measure pulse broadening caused by multipath propagation through the interstellar medium. Data were collected with the 305-m Arecibo telescope at four radio frequencies between 430 and 2380 ... More
Josephson Effect Between Triplet Superconductors: A Self-Test for the Order Parameter Symmetry of Bechgaard SaltsFeb 04 2003We show that the Josephson effect between triplet superconductors is sensitive to the relative orientation of the d-vectors across the junction. In addition, we point out that the temperature and angular dependence of the Josephson effect can help distinguish ... More
Radio Pulsar PopulationsMar 13 2019Mar 18 2019Our understanding of the neutron star population is informed to a great degree by large-scale surveys that have been carried out by radio facilities during the past fifty years. We summarize some of the recent breakthroughs in our understanding of the ... More
Finite Groups of Essential Dimension 2Dec 09 2009Sep 25 2010We classify all finite groups of essential dimension 2 over an algebraically closed field of characteristic 0.
A new technique for timing the double pulsar systemFeb 28 2009Apr 02 2009In 2004, McLaughlin et al. discovered a phenomenon in the radio emission of PSR J0737-3039B (B) that resembles drifting sub-pulses. The repeat rate of the sub-pulses is equal to the spin frequency of PSR J0737-3039A (A); this led to the suggestion that ... More
The Archimedean limit of random sorting networksFeb 25 2018Mar 19 2018A sorting network (also known as a reduced decomposition of the reverse permutation), is a shortest path from $12 \cdots n$ to $n \cdots 21$ in the Cayley graph of the symmetric group $S_n$ generated by adjacent transpositions. We prove that in a uniform ... More
Equivariant unirationality of del Pezzo surfaces of degree 3 and 4Oct 30 2014Oct 03 2016A variety X with an action of a finite group G is said to be G-unirational if there is a G-equivariant dominant rational map V -> X where V is a faithful linear representation of G. This generalizes the usual notion of unirationality. We determine when ... More
Timing Observations of Rotating Radio TransientsAug 26 2009Aug 27 2009We present radio timing measurements of six rotating radio transient (RRAT) sources discovered in the Parkes Multibeam Pulsar Survey. These provide four new phase-connected timing solutions and two updated ones, making a total of seven of the original ... More
Detecting pulsars in the Galactic centreNov 21 2016Although high-sensitivity surveys have revealed a number of highly dispersed pulsars in the inner Galaxy, none have so far been found in the Galactic centre (GC) region, which we define to be within a projected distance of 1~pc from Sgr~A*. This null ... More
Population modelling of FRBs from intrinsic propertiesFeb 26 2019We develop a formalism to estimate the intrinsic properties of FRBs from observations by assuming a fixed DM contribution from a MW-like host galaxy, pulse temporal broadening models for turbulent plasma and a flat FRB energy spectrum. We then perform ... More
Bursting emission from B0611+22Feb 07 2014Over 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 ... More
Detecting pulsars in the Galactic centreNov 21 2016Jun 28 2017Although high-sensitivity surveys have revealed a number of highly dispersed pulsars in the inner Galaxy, none have so far been found in the Galactic centre (GC) region, which we define to be within a projected distance of 1~pc from Sgr~A*. This null ... More
A necessary and sufficient condition for global convergence of the complex zeros of random orthogonal polynomialsJan 22 2019Consider random polynomials of the form $G_n = \sum_{i=0}^n \xi_i p_i$, where the $\xi_i$ are i.i.d. non-degenerate complex random variables, and $\{p_i\}$ is a sequence of orthonormal polynomials with respect to a regular measure $\tau$ supported on ... More
Essential Dimensions of A_7 and S_7Aug 22 2009We show that Y. Prokhorov's "Simple Finite Subgroups of the Cremona Group of Rank 3" implies that, over any field of characteristic 0, the essential dimensions of the alternating group, A_7, and the symmetric group, S_7, are 4.
Optimal Polygonal Representation of Planar GraphsApr 08 2011In this paper, we consider the problem of representing graphs by polygons whose sides touch. We show that at least six sides per polygon are necessary by constructing a class of planar graphs that cannot be represented by pentagons. We also show that ... More
Discovery of Pulsations and a Possible Spectral Feature in the X-ray Emission from Rotating Radio Transient J1819-1458Aug 08 2007PSR J1819-1458 is a rotating radio transient (RRAT) source with an inferred surface dipole magnetic field strength of 5e13 G and a 4.26-s spin period. We present XMM-Newton observations of the X-ray counterpart of this source, CXOU J181939.1-145804, in ... More
Introducing Decorated HODs: modeling assembly bias in the galaxy-halo connectionDec 09 2015The connection between galaxies and dark matter halos is often inferred from data using probabilistic models, such as the Halo Occupation Distribution (HOD). Conventional HOD formulations assume that only halo mass governs the galaxy-halo connection. ... More
The Metallicity of Pre-Galactic Globular Clusters: Observational consequences of the first starsSep 06 2003We explore a scenario where metal-poor globular clusters (GCs) are enriched by the first supernovae in the Universe. If the first stars in a 10^7 Msun dark halo were very massive (>180 Msun), then a pair instability supernova from a single massive star ... More
Rates and Characteristics of Intermediate Mass Ratio Inspirals Detectable by Advanced LIGOMay 02 2007May 13 2008Gravitational waves (GWs) from the inspiral of a neutron star (NS) or stellar-mass black hole (BH) into an intermediate-mass black hole (IMBH) with mass between ~50 and ~350 solar masses may be detectable by the planned advanced generation of ground-based ... More
Umbral MoonshineApr 12 2012Oct 17 2013We describe surprising relationships between automorphic forms of various kinds, imaginary quadratic number fields and a certain system of six finite groups that are parameterised naturally by the divisors of twelve. The Mathieu group correspondence recently ... More
Umbral Moonshine and the Niemeier LatticesJul 22 2013Jul 22 2014In this paper we relate umbral moonshine to the Niemeier lattices: the 23 even unimodular positive-definite lattices of rank 24 with non-trivial root systems. To each Niemeier lattice we attach a finite group by considering a naturally defined quotient ... More
BeppoSAX and Ulysses data on the giant flare from SGR 1900+14Dec 23 1999The extraordinary giant flare of 1998 August 27 from SGR 1900+14 was the most intense event ever detected from this or any other cosmic source (even more intense than the famous March 5th 1979 event). It was longer than any previous burst from SGR1900+14 ... More
Radio Properties of Rotating Radio Transients I: searches for periodicities and randomness in pulse arrival timesJul 05 2011We have analysed the long- and short-term time dependence of the pulse arrival times and the pulse detection rates for eight Rotating Radio Transient (RRAT) sources from the Parkes Multi-beam Pulsar Survey (PMPS). We find significant periodicities in ... More
GMRT Galactic Plane Pulsar and Transient Survey and the Discovery of PSR J1838+1523May 14 2018We report the results of a blind pulsar survey carried out with the Giant Metrewave Radio Telescope (GMRT) at 325 MHz. The survey covered about 10\% of the region between Galactic longitude 45$^{\circ} < l <$ 135$^{\circ}$ and Galactic latitude 1$^{\circ} ... More
Binary and Millisecond Pulsars at the New MillenniumApr 24 2001We review the properties and applications of binary and millisecond pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population to over 1300. There ... More
IAU 177 - A week in reviewNov 15 1999Nov 17 1999A look back at the recent IAU meeting "Pulsar Astronomy 2000 and beyond" held in Bonn.
Blind surveys for radio pulsars and transientsDec 21 2010Dec 22 2010The main reasons for searching for pulsars are to: (i) get an accurate census of the neutron star population and its origin and evolution; (ii) connect neutron stars to other stellar populations in the Galaxy and globular clusters; (iii) study Galactic ... More
Recent discoveries of energetic young radio pulsarsJan 16 2003The observed population of young radio pulsars has grown substantially in recent years due to a combination of large-scale surveys and deep targeted searches. Many of the pulsars are associated with supernova remnants and/or unidentified gamma-ray sources. ... More
The dynamics of Galactic centre pulsars: constraining pulsar distances and intrinsic spin-downApr 25 2019Through high-precision radio timing observations, we show that five recycled pulsars in the direction of the Galactic Centre (GC) have anomalous spin period time derivative ($\dot P$) measurements -- PSRs J1748$-$3009, J1753$-$2819, J1757$-$2745, and ... More
Neutron Star Birth RatesNov 30 1999A crucial test any proposed evolutionary scenario must pass is can the birth rate of the sources we see be sustained by the proposed progenitor population? In this review, I investigate the methods used to determine the birth rates of normal and millisecond ... More
Binary and Millisecond PulsarsNov 05 2008We review the main properties, demographics and applications of binary and millisecond radio pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population ... More
Radio pulsar populationsAug 11 2010The goal of this article is to summarize the current state of play in the field of radio pulsar statistics. Simply put, from the observed sample of objects from a variety of surveys with different telescopes, we wish to infer the properties of the underlying ... More
The Galactic population and birth rate of radio pulsarsAug 28 2003We review current understanding of the underlying, as opposed to the observed, pulsar population. The observed sample is heavily biased by selection effects, so that surveys see less than 10% of all potentially observable pulsars. We compare various techniques ... More
Binary and Millisecond PulsarsNov 09 2005We review the main properties, demographics and applications of binary and millisecond radio pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population ... More
Radio Pulsars - An Observer's PerspectiveNov 17 1999Dec 01 1999Pulsar astronomy is currently enjoying one of the most productive phases in its history. In this review, I outline some of the basic observational aspects and summarise some of the latest results of searches for pulsars in the disk of our Galaxy and its ... More
Pulsar Searches - Tricks of the TradeJan 12 1998The study of pulsars has come a long way since their accidental discovery as ``scruff'' on pen chart recordings of the radio sky at 81 MHz by Jocelyn Bell and Anthony Hewish at Cambridge some thirty years ago. The present sample of almost 800 objects ... More
Transient radio bursts from rotating neutron starsNov 19 2005Nov 22 2005The `radio sky' is relatively unexplored for transient signals, although the potential of radio-transient searches is high, as demonstrated recently by the discovery of a previously unknown type of source which varies on timescales of minutes to hours. ... More