61 research outputs found
Decade Long Timing Study of the Black Widow Millisecond Pulsar J1544+4937
Results from 11 years of radio timing for eclipsing black widow millisecond
pulsar (MSP) binary, J1544+4937, is presented in this paper. We report a
phase-connected timing model for this MSP, using observations with the Giant
Metrewave Radio Telescope (GMRT) at multiple frequencies and with Green Bank
Telescope (GBT). This is the longest-duration timing study of any galactic
field MSP with the GMRT. While extending the timing baseline from the existing
1.5 years to about a decade we report the first detection for a significant
value of proper motion ( 10.14(5) )
for this pulsar. Temporal variations of dispersion measure ( pc ) manifested by significant determination
of 1st, 2nd, and 3rd order DM derivatives are observed along the line of sight
to the pulsar. We also noticed frequency-dependent DM variations of the order
of , which could arise due to spatial electron
density variations in the interstellar medium. This study has revealed a
secular variation of the orbital period for this MSP for the first time. We
investigated possible causes and propose that variation in the gravitational
quadrupole moment of the companion could be responsible for the observed
temporal changes in the orbital period.Comment: 12 pages, 5 Figures, 2 Table, Accepted in the Astrophysical Journa
Decade-long timing of four GMRT discovered millisecond pulsars
The discovery and timing follow-up of millisecond pulsars (MSPs) are
necessary not just for their usefulness in Pulsar Timing Arrays (PTAs) but also
for investigating their own intriguing properties. In this work, we provide the
findings of the decade-long timing of the four MSPs discovered by the Giant
Metre-wave Radio Telescope (GMRT), including their timing precision, model
parameters, and newly detected proper motions. We compare the timing results
for these MSPs before and after the GMRT upgrade in 2017, characterise the
improvement in timing precision due to the bandwidth upgrade. We discuss the
suitability of these four GMRT MSPs as well as the usefulness of their
decade-long timing data for the PTA {experiments. It may aid} in the global
effort to improve the signal-to-noise (S/N) of recently detected signature of
gravitational waves in cross-correlation statistics of residuals of MSPs.Comment: Accepted in Astrophysical Journal (APJ) on October 31, 202
The GMRT High Resolution Southern Sky Survey for pulsars and transients -- VI: Discovery of nulling, localisation and timing of PSR J1244-4708
Many pulsars in the known population exhibit nulling, which is characterised
by a sudden cessation and subsequent restoration of radio emission. In this
work, we present the localization, timing, and emission properties of a GHRSS
discovered pulsar J1244-4708. Moreover, we find that this pulsar shows nulling
with a nulling fraction close to 60%. A quasi-periodicity is also seen in the
nulling from this pulsar with two timescales. We demonstrate the broadband
nature of nulling in this pulsar using simultaneous observations in band-3
(300-500 MHz) and band-4 (550-750 MHz) with the uGMRT. We also present a
comparison of the efficiency of various search approaches such as single pulse
search, Fast Folding Algorithm (FFA) based search, and Fast Fourier Transform
(FFT) based search to search for nulling pulsars. We demonstrated that the FFA
search is advantageous for detecting extreme nulling pulsars, which is also
confirmed with multiple epochs of observations for the nulling pulsars using
the GMRT.Comment: 13 pages, 11 figures, 1 table, Under minor revision in Astrophysical
Journa
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