Dr. Bettina Posselt

Abstract:

We describe the ongoing Relativistic Binary programme (RelBin), a part of the MeerTime large survey project with the MeerKAT radio telescope. RelBin is primarily focused on observations of relativistic effects in binary pulsars to enable measurements of neutron star masses and tests of theories of gravity. We selected 25 pulsars as an initial high priority list of targets based on their characteristics and observational history with other telescopes. In this paper, we provide an outline of the programme, and present polarization calibrated pulse profiles for all selected pulsars as a reference catalogue along with updated dispersion measures. We report Faraday rotation measures for 24 pulsars, twelve of which have been measured for the first time. More than a third of our selected pulsars show a flat position angle swing confirming earlier observations. We demonstrate the ability of the Rotating Vector Model, fitted here to seven binary pulsars, including the Double Pulsar (PSR J0737-3039A), to obtain information about the orbital inclination angle. We present a high time resolution light curve of the eclipse of PSR J0737-3039A by the companion's magnetosphere, a high-phase-resolution position angle swing for PSR J1141-6545, an improved detection of the Shapiro delay of PSR J1811-2405, and pulse scattering measurements for PSRs J1227-6208, J1757-1854, and J1811-1736. Finally, we demonstrate that timing observations with MeerKAT improve on existing data sets by a factor of, typically, 2-3, sometimes by an order of magnitude.

Abstract:

<jats:title>Abstract</jats:title> <jats:p>We describe system verification tests and early science results from the pulsar processor (PTUSE) developed for the newly commissioned 64-dish SARAO MeerKAT radio telescope in South Africa. MeerKAT is a high-gain (<jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" mimetype="image" xlink:href="S1323358020000193_inline1.png" /> <jats:tex-math> ${\sim}2.8\,\mbox{K Jy}^{-1}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>) low-system temperature (<jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" mimetype="image" xlink:href="S1323358020000193_inline2.png" /> <jats:tex-math> ${\sim}18\,\mbox{K at }20\,\mbox{cm}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>) radio array that currently operates at 580–1 670 MHz and can produce tied-array beams suitable for pulsar observations. This paper presents results from the MeerTime Large Survey Project and commissioning tests with PTUSE. Highlights include observations of the double pulsar <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" mimetype="image" xlink:href="S1323358020000193_inline3.png" /> <jats:tex-math> $\mbox{J}0737{-}3039\mbox{A}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>, pulse profiles from 34 millisecond pulsars (MSPs) from a single 2.5-h observation of the Globular cluster Terzan 5, the rotation measure of Ter5O, a 420-sigma giant pulse from the Large Magellanic Cloud pulsar PSR <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" mimetype="image" xlink:href="S1323358020000193_inline4.png" /> <jats:tex-math> $\mbox{J}0540{-}6919$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>, and nulling identified in the slow pulsar PSR J0633–2015. One of the key design specifications for MeerKAT was absolute timing errors of less than 5 ns using their novel precise time system. Our timing of two bright MSPs confirm that MeerKAT delivers exceptional timing. PSR <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" mimetype="image" xlink:href="S1323358020000193_inline5.png" /> <jats:tex-math> $\mbox{J}2241{-}5236$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> exhibits a jitter limit of <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" mimetype="image" xlink:href="S1323358020000193_inline6.png" /> <jats:tex-math> $&lt;4\,\mbox{ns h}^{-1}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> whilst timing of PSR <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" mimetype="image" xlink:href="S1323358020000193_inline7.png" /> <jats:tex-math> $\mbox{J}1909{-}3744$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> over almost 11 months yields an rms residual of 66 ns with only 4 min integrations. Our results confirm that the MeerKAT is an exceptional pulsar telescope. The array can be split into four separate sub-arrays to time over 1 000 pulsars per day and the future deployment of S-band (1 750–3 500 MHz) receivers will further enhance its capabilities.</jats:p>

Abstract:

© 2020 The Author(s). We report here on initial results from the Thousand-Pulsar-Array (TPA) programme, part of the Large Survey Project 'MeerTime' on the MeerKAT telescope. The interferometer is used in the tied-array mode in the band from 856 to 1712 MHz, and the wide band coupled with the large collecting area and low receiver temperature make it an excellent telescope for the study of radio pulsars. The TPA is a 5 year project, which aims at to observing (a) more than 1000 pulsars to obtain high-fidelity pulse profiles, (b) some 500 of these pulsars over multiple epochs, and (c) long sequences of single-pulse trains from several hundred pulsars. The scientific outcomes from the programme will include the determination of pulsar geometries, the location of the radio emission within the pulsarmagnetosphere, the connection between the magnetosphere and the crust and core of the star, tighter constraints on the nature of the radio emission itself, as well as interstellar medium studies. First, results presented here include updated dispersion measures, 26 pulsars with Faraday rotation measures derived for the first time, and a description of interesting emission phenomena observed thus far.