Follow-up Timing of Three GMRT Pulsars. (arXiv:1811.02907v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Surnis_M/0/1/0/all/0/1">Mayuresh P. Surnis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Joshi_B/0/1/0/all/0/1">Bhal Chandra Joshi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McLaughlin_M/0/1/0/all/0/1">Maura A. McLaughlin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+A%2E_K/0/1/0/all/0/1">Krishnakumar M. A.</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+K%2E_M/0/1/0/all/0/1">Manoharan P. K.</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Naidu_A/0/1/0/all/0/1">Arun Naidu</a>
We report on the results of multi-frequency follow-up observations of three
pulsars (PSRs J0026+6320, J2208+5500 and J2217+5733) discovered with the Giant
Metrewave Radio Telescope (GMRT). These observations were carried out with the
GMRT and the Ooty Radio Telescope (ORT). We report improved timing solutions
for all three pulsars. For PSR J2208+5500, we estimate the nulling fraction to
be 53(3)%. The steep spectrum of this pulsar, its single component profile,
and narrow pulse width suggest its single component to be a core component. If
so, this significant cessation of emission in a core component is inconsistent
with a geometric origin of nulls, such as those due to `empty’ sightline
traverses, and more likely due to intrinsic changes in the pulsar
magnetosphere. We have measured scatter-broadening timescales at 325 and 610
MHz for PSRs J0026+6320 and J2217+5733. The implied scatter-broadening
frequency scaling index of $-$2.9 for both pulsars is different from that
expected assuming Kolmogorov turbulence in the interstellar medium. We also
report spectral indices, obtained from imaging observations, for all three
pulsars for the first time. The spectra for two of these pulsars indicate a
possible spectral turnover between 100$-$300 MHz. Multi-frequency timing
analyses carried out for these pulsars have enabled us to determine dispersion
measures (DMs) with accuracies of 0.01 pc cmsups{–3}. This demonstrates the
usefulness of quasi-simultaneous multi-frequency multi-epoch timing
observations with the GMRT and the ORT for studying variations in DM for
millisecond pulsars.
We report on the results of multi-frequency follow-up observations of three
pulsars (PSRs J0026+6320, J2208+5500 and J2217+5733) discovered with the Giant
Metrewave Radio Telescope (GMRT). These observations were carried out with the
GMRT and the Ooty Radio Telescope (ORT). We report improved timing solutions
for all three pulsars. For PSR J2208+5500, we estimate the nulling fraction to
be 53(3)%. The steep spectrum of this pulsar, its single component profile,
and narrow pulse width suggest its single component to be a core component. If
so, this significant cessation of emission in a core component is inconsistent
with a geometric origin of nulls, such as those due to `empty’ sightline
traverses, and more likely due to intrinsic changes in the pulsar
magnetosphere. We have measured scatter-broadening timescales at 325 and 610
MHz for PSRs J0026+6320 and J2217+5733. The implied scatter-broadening
frequency scaling index of $-$2.9 for both pulsars is different from that
expected assuming Kolmogorov turbulence in the interstellar medium. We also
report spectral indices, obtained from imaging observations, for all three
pulsars for the first time. The spectra for two of these pulsars indicate a
possible spectral turnover between 100$-$300 MHz. Multi-frequency timing
analyses carried out for these pulsars have enabled us to determine dispersion
measures (DMs) with accuracies of 0.01 pc cmsups{–3}. This demonstrates the
usefulness of quasi-simultaneous multi-frequency multi-epoch timing
observations with the GMRT and the ORT for studying variations in DM for
millisecond pulsars.
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