The Indian Pulsar Timing Array: First data release

Abstract

We present the pulse arrival times and high-precision dispersion measure estimates for 14 millisecond pulsars observed simultaneously in the 300 $-$ 500 MHz and 1260 $-$ 1460 MHz frequency bands using the upgraded Giant Metrewave Radio Telescope. The data spans over a baseline of 3.5 years (2018-2021), and is the first official data release made available by the Indian Pulsar Timing Array collaboration. This data release presents a unique opportunity for investigating the interstellar medium effects at low radio frequencies and their impact on the timing precision of pulsar timing array experiments. In addition to the dispersion measure time series and pulse arrival times obtained using both narrowband and wideband timing techniques, we also present the dispersion measure structure function analysis for selected pulsars. Our ongoing investigations regarding the frequency dependence of dispersion measures have been discussed. Based on the preliminary analysis for five millisecond pulsars, we do not find any conclusive evidence of chromaticity in dispersion measures. Data from regular simultaneous two-frequency observations are presented for the first time in this work. This distinctive feature leads us to the highest precision dispersion measure estimates obtained so far for a subset of our sample. Simultaneous multi-band upgraded Giant Metrewave Radio Telescope observations in 300 $-$ 500 MHz and 1260 $-$ 1460 MHz are crucial for high-precision dispersion measure estimation and for the prospect of expanding the overall frequency coverage upon the combination of data from the various Pulsar Timing Array consortia in the near future. Parts of the data presented in this work are expected to be incorporated into the upcoming third data release of the International Pulsar Timing Array.

Wide-band Timing of the Parkes Pulsar Timing Array UWL Data

“…For instance, wide-band analysis presented in NG12.5 did not report the need for FD parameters because the TOAs were effectively calculated only for two subbands (as opposed to eight subbands shown in Figure 5), which obscured any such detectable drifts. Similarly, Tarafdar et al (2022) also presented both narrow-and wide-band timing of 14 pulsars as the first data release from the InPTA and explicitly showed no need for additional corrections for frequency-dependent effects. However, InPTA analysis was also performed on only two subbands and produced narrowband, frequency-resolved templates by iteratively fitting for DM to the multiband observations.…”

“…The three major pillars of PTA, working under a joint venture as the International Pulsar Timing Array (IPTA; Manchester & IPTA 2013), are the European Pulsar Timing Array (EPTA; Desvignes et al 2016), the North American Nanoherthz Observatory for Gravitational waves (NANOGrav; McLaughlin 2013), and the Parkes Pulsar Timing Array (PPTA; Hobbs 2013). They have also been recently joined by the Indian Pulsar Timing Array (InPTA; Paul et al 2019;Tarafdar et al 2022) and are supported by the Chinese Pulsar Timing Array (CPTA; Lee 2016) and the MeerKAT Pulsar Timing Array (MPTA; Miles et al 2023).…”

The Gravitational-wave Background Null Hypothesis: Characterizing Noise in Millisecond Pulsar Arrival Times with the Parkes Pulsar Timing Array

“…Decades-long pulsar timing experiments have been ongoing in Australia (the Parkes PTA (PPTA); Manchester et al 2013), Europe (the European PTA (EPTA); Kramer & Champion 2013), and in North America (North American Nanohertz Observatory for Gravitational Waves (NANOGrav); Demorest et al 2013). These groups, in addition to more recent projects established in China (Chinese PTA (CPTA); Lee 2016) and India (Indian PTA (InPTA); Tarafdar et al 2022), and with the MeerKAT radio telescope in South Africa (MeerKAT PTA (MPTA); Miles et al 2023) and the Fermi-Large Area Telescope (FERMI-LAT Collaboration et al 2022), form the set of global experiments searching for nanohertz-frequency GWs. The International PTA (IPTA; Hobbs et al 2010), comprising several of these experiments (EPTA, InPTA, NANOGrav, PPTA), improves the sensitivity to GWs by combining its constituent data sets.…”

Splitting the lentils: Clues to galaxy/black hole coevolution from the discovery of offset relations for non-dusty versus dusty (wet-merger-built) lenticular galaxies in theMbh–M*,spheroid andMbh–M*,galaxy diagrams

“…This, in turn, benefits our expectations for the local influence of these waves on the arrival time of pulsed emission from pulsars located in an array around us (Foster & Backer 1990;Sesana et al 2008a;Burke-Spolaor et al 2019). Ongoing experiments to indirectly detect these waves include the Parkes Pulsar Timing Array (PPTA: Manchester et al 2013;Shannon et al 2013;Goncharov et al 2022), the European Pulsar Timing Array (EPTA: Lentati et al 2015;Chen et al 2021), the North American Nanohertz Observatory for Gravitational Waves (NANOGrav: Arzoumanian et al 2021;Middleton et al 2021), plus newcomers such as the Indian Pulsar Timing Array (Tarafdar et al 2022), and the South African MeerTime Pulsar Timing Array (Spiewak et al 2022). It is thus a large global enterprise.…”