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Showing results for: [ Bhat, Ramesh ]
The Parkes Pulsar Timing Array (PPTA) project has three primary goals: (a) detection of gravitational waves from astronomical sources, (b) establishment of a pulsar timescale, and (c) improvement of o... moreur understanding of Solar-system dynamics. The PPTA is the oldest of three international pulsar timing groups. We have the smallest telescope and the smallest group, but the best measurements and the best results. Our bound on the strength of the incoherent gravitational wave background is the only bound which significantly constrains theoretical models. We have maintained our leading position because: we have the southern sky; we have a small but well-focussed group; we have the best-calibrated receivers; and we have been able to observe with an almost regular cadence of 15 to 20 days over a wide bandwidth. With this proposal we aim to maintain our pre-eminent position in the field. Unlike most observing proposals, this is a continuing proposal for which the observations will continue to improve bounds on ultra-low-frequency gravitational waves until they are finally detected. Continued Parkes observations will remain valuable at least until the first stage of the SKA is able to improve on our sensitivity and observing cadence. Even after the gravitational wave background is detected we will want to continue observations in support of the nascent field of gravitational wave astronomy!less
Australia Telescope National Facility - P456 - A millisecond pulsar timing array - Published 17 Nov 2019
Since the year 2005, the Parkes Pulsar Timing Array (PPTA) project has been placing ever more stringent constraints on the amplitude of a gravitational wave background signal. Such upper bounds on th... moree amplitude of the gravitational wave signal are currently dominated by a single pulsar: PSR J1909-3744. The upper bound with this pulsar alone already cuts into the range of tenable theoretical models. Further reducing the amplitude bound (by continued regular observations of this pulsar) will significantly narrow that range. The first evidence of gravitational waves in the pulsar data are likely to be observed in the timing for PSR J1909-3744, but with only a single pulsar we will not be able to make an unambiguous detection. However, knowledge of the likely signal strength (derived from this pulsar) will help to optimise the observing strategy for the detection of the gravitational wave signals with existing or future pulsar timing arrays.less
Australia Telescope National Facility - P895 - Where are the gravitational waves? - Published 15 Nov 2019
Australia Telescope National Facility - P456 - A millisecond pulsar timing array - Published 13 Nov 2019
SUPERBx looks at the highest Galactic latitudes in a search for pulsars and fast radio bursts (FRBs). We use optimised GPU codes and supercomputing to search for these, making discoveries in real time... more. Handling our data as it comes in is essential for the SKA Phase I era so this work applies directly to the high-data rates of next generation telescopes. Our pulsar discoveries are typically nearby scintillating sources, intermittent sources and those in interesting binary systems. Our FRB discoveries have discovery lags of ~1 second, rather than months/years and these feed rapid alerts to the world-wide follow-up community via a dedicated VOEvent format an Astronomer's Telegrams. The goal of this is to allow localisation of the discovered FRBs. This is key for identifying FRB host galaxies, so as to solve the mystery of their progenitors and to exploit their many uses as tools for precision cosmology measurements.less
Australia Telescope National Facility - P892 - SUPERBx - The SUrvey for Pulsars & Extragalactic Radio Bursts Extension - Published 07 Nov 2019
Australia Telescope National Facility - P456 - A millisecond pulsar timing array - Published 07 Nov 2019
We propose timing observations of the relativistic pulsar - white-dwarf binary PSR J1141-6545. This unique system offers access to a wide range of physics, from relativistic phenomena through pulsar e... moremission cone studies, to the structure and distribution of interstellar plasma along our line-of-sight. The recently installed Parkes Ultra Wide Band Low Frequency (UWL) receiver has opened up the possibility of performing first-ever studies of its orbital dynamics at high temporal resolution and study of the effects of the intra-binary medium on the dispersion and polarisation of the pulse profile. Our analysis of data obtained to date suggests that the pulsar would precess away from our line-of-sight in the next 3-5 years. Hence, regular observations are crucial to maximizing its science outcomeless
Australia Telescope National Facility - P971 - Orbital dynamics and the intra-binary medium of PSR J1141-6545 - Published 04 Nov 2019
Australia Telescope National Facility - P456 - A millisecond pulsar timing array - Published 31 Oct 2019
Australia Telescope National Facility - P456 - A millisecond pulsar timing array - Published 29 Oct 2019
Australia Telescope National Facility - P971 - Orbital dynamics and the intra-binary medium of PSR J1141-6545 - Published 22 Oct 2019
Australia Telescope National Facility - P971 - Orbital dynamics and the intra-binary medium of PSR J1141-6545 - Published 17 Oct 2019
This is a request for observing time for the initial follow-up of pulsar discoveries from the low-latitude Galactic plane section of the HTRU survey (P630). We have now completed a first pass processi... moreng of the entire survey with our periodicity search algorithm as well as the partially-coherent segmented acceleration search pipeline, and have discovered 106 previously unknown pulsars. Interesting science can usually only be derived from a new pulsar after confirmation and a follow-up timing campaign is carried out. One year of initial timing is the minimum timespan required to fully characterise any newly-discovered pulsars, essential for deriving pulsar parameters such as the characteristic age, magnetic ?eld strength, spin-down rate, as well as to detect any unexpected behaviour of the pulsar which might result from emission instabilities. This follow-up timing project is necessary for following up on any interesting pulsar systems discovered from the HTRU Galactic plane survey. Since all of the pulsars on the observing list here are being followed-up for the first time, they will produce completely new and exciting results. In addition, this timing project will enable a large-scale examination of the Galactic plane pulsar population, exploring the true boundaries of pulsar parameter space.less
Australia Telescope National Facility - P860 - Initial Follow-up of Pulsar Discoveries from the HTRU Galactic Plane Survey - Published 16 Oct 2019
Australia Telescope National Facility - P895 - Where are the gravitational waves? - Published 15 Oct 2019
Australia Telescope National Facility - P892 - SUPERBx - The SUrvey for Pulsars & Extragalactic Radio Bursts Extension - Published 15 Oct 2019
Australia Telescope National Facility - P456 - A millisecond pulsar timing array - Published 14 Oct 2019
The paucity of known intermittent pulsars makes individual studies valuable from the perspective of understanding how these pulsars emit and how that emission is changing in time and as a function of ... morefrequency. The inherent difficulty in detecting these objects implies that their small population may well simply be a sampling bias, thus studying individual examples in details is fundamentally important in developing a complete understanding of the Galactic population. The Ultra-Wide-Band receiver and the MEDUSA backend provide unprecedented frequency coverage and will allow us to study the emission of the intermittent pulsar J1107-5907 in great detail. In particular, we will focus on the spectral characteristics of the emission, the frequency dependence of emission rates and the time scales on which the emission state switching occurs. By constraining the intermittency time scales we will be able to comment on model predictions, while the spectral index analysis will provide insights into the emission mechanism itself.less
Australia Telescope National Facility - P1013 - An ultra-wide-band study of the intermittent pulsar J1107-5907 - Published 10 Oct 2019
Australia Telescope National Facility - P895 - Where are the gravitational waves? - Published 07 Oct 2019
Australia Telescope National Facility - P456 - A millisecond pulsar timing array - Published 07 Oct 2019
Australia Telescope National Facility - P892 - SUPERBx - The SUrvey for Pulsars & Extragalactic Radio Bursts Extension - Published 07 Oct 2019
Australia Telescope National Facility - P860 - Initial Follow-up of Pulsar Discoveries from the HTRU Galactic Plane Survey - Published 06 Oct 2019
Australia Telescope National Facility - P892 - SUPERBx - The SUrvey for Pulsars & Extragalactic Radio Bursts Extension - Published 06 Oct 2019
Australia Telescope National Facility - P892 - SUPERBx - The SUrvey for Pulsars & Extragalactic Radio Bursts Extension - Published 05 Oct 2019
Australia Telescope National Facility - P892 - SUPERBx - The SUrvey for Pulsars & Extragalactic Radio Bursts Extension - Published 04 Oct 2019
Australia Telescope National Facility - P456 - A millisecond pulsar timing array - Published 02 Oct 2019
Australia Telescope National Facility - P456 - A millisecond pulsar timing array - Published 01 Oct 2019
