arXiv subjects

Garvit Grover

Publications and source records attributed to Garvit Grover.

3 recordsLinked to original sources

arXiv2026

Discovery of a 24-millisecond pulsar in a very long orbit with the Murchison Widefield Array

We report the discovery of PSR J0125$-$5854, a pulsar with a spin period of 24 ms and a dispersion measure of 11.66 pc cm$^-3$ in the ongoing Southern-sky MWA Rapid Two-metre (SMART) survey with the Murchison Widefield Array (MWA). The pulsar is located at a high Galactic latitude of $-57^{\circ}$, and at a distance of 0.5$\text{-}$1 kpc per the Galactic electron density models. Follow-up observations with the MWA and MeerKAT telescopes have revealed that this pulsar is in a binary system with an orbital period of more than 290 days, and a steep spectrum (flux density, $ S \propto \nu^{\alpha} $, where $\nu$ is frequency and $ \alpha = -2.2 \pm 0.3 $). Analysis of current observational data hints at a potential binary configuration with an orbital period of $833.60 \pm 0.04$ days, a projected semi-major axis of $241.36 \pm 0.05$ light-seconds, and a minimum companion mass $0.4152 \pm 0.0001$ M$_\odot$, with a low eccentricity orbit of $0.0052 \pm 0.0006$. We discuss the potential formation channels for this system, and conjecture that the companion is likely a Helium white dwarf. Further observations are required in order to better constrain the orbital and spin parameters. We discuss the implications of this discovery, which emerged after processing a small fraction of survey data, on the prospects of finding more millisecond pulsars with the SMART survey, and with future surveys planned with the low-frequency SKA-Low.

astro-ph.HE↗

arXiv2025

The ONs and OFFs of Pulsar Radio Emission: Characterizing the Nulling Phenomenon

Radio emission from pulsars is known to exhibit a diverse range of emission phenomena, among which nulling, where the emission becomes temporarily undetectable, is an intriguing one. Observations suggest nulling is prevalent in many long-period pulsars and must be understood to obtain a more comprehensive picture of pulsar emission and its evolution. One of the limitations in observational characterisation of nulling is the limited signal-to-noise, making individual pulses often not easily distinguishable from noise or any putative faint emission. Although some of the approaches in the published literature attempt to address this, they lose efficacy when individual pulses appear indistinguishable from the noise, and as a result, can lead to less accurate measurements. Here we develop a new method (the $\mathbb{N}$sum algorithm) that uses sums of pulses for better distinguishability from noise and thus measures the nulling fraction more robustly. It can be employed for measuring nulling fractions in weaker pulsars and observations with a limited number of observed pulses. We compare our algorithm with the recently developed Gaussian Mixture Modelling approach, using both simulated and real data, and find that our approach yields consistent results for generic and weaker pulsars. We also explore quasi-periodicity in nulling and measure the related parameters for five pulsars, including PSRs~J1453$-$6413, J0950$+$0755 and J0026$-$1955, for which these are also the first such measurements. We compare and contrast our analysis of quasi-periodic nulling with previously published work and explore the use of spin-down energy loss ($\dot E$) to distinguish between different types of modulation behaviour.

astro-ph.HE↗

arXiv2025

Discovery of an RRAT-like pulsar via its single pulses in an MWA imaging survey

We report the discovery of PSR J0031$-$5726 in the GaLactic and Extragalactic All-sky MWA eXtended imaging survey at a Galactic latitude of $b \approx -60^\circ$. The pulsar exhibits both sporadic, extremely bright pulses reminiscent of rotating radio transients (RRATs) as well as a persistent, dimmer pulses. The bright pulses tend to arrive at later rotation phases than their dimmer counterparts, and have dramatically varying polarization angle curves, such that the integrated profile appears almost completely depolarized down to the system noise level. The rotation measure of individual pulses was found to sometimes vary by up to ${\sim}0.8\,$rad/m$^2$, but was otherwise generally consistent with its average (ionosphere-corrected) value of $10.0 \pm 0.1\,$rad/m$^2$. We surmise that J0031$-$5726 may represent a class of pulsar that is intermediate between normal pulsars and RRATs.

astro-ph.HE↗