The NANOGrav 12.5-year Data Set: Wideband Timing of 47 Millisecond Pulsars

Abstract

We present a new analysis of the profile data from the 47 millisecond pulsars comprising the 12.5-year data set of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), which is presented in a parallel paper (Alam et al. submitted to ApJS ; NG12.5). Our reprocessing is performed using "wideband" timing methods, which use frequency-dependent template profiles, simultaneous time-of-arrival (TOA) and dispersion measure (DM) measurements from broadband observations, and novel analysis techniques. In particular, the wideband DM measurements are used to constrain the DM portion of the timing model. We compare the ensemble timing results to NG12.5 by examining the timing residuals, timing models, and noise model components. There is a remarkable level of agreement across all metrics considered. Our best-timed pulsars produce encouragingly similar results to those from NG12.5. In certain cases, such as high-DM pulsars with profile broadening, or sources that are weak and scintillating, wideband timing techniques prove to be beneficial, leading to more precise timing model parameters by 10 − 15%. The high-precision multi-band measurements in several pulsars indicate frequency-dependent DMs. The TOA volume is reduced by a factor of 33, which may ultimately facilitate computational speed-ups for complex pulsar timing array analyses. This first wideband pulsar timing data set is a stepping stone, and its consistent results with NG12.5 assure us that such data sets are appropriate for gravitational wave analyses.

Circumbinary Disk Accretion into Spinning Black Hole Binaries

“…From then on, the emission of gravitational waves becomes an efficient mechanism for energy and angular momentum extraction until coalescence (Pretorius 2005;Campanelli et al 2006;Baker et al 2006). This emission of gravitational waves makes SMBBHs the primary targets in the mHZ frequency window by the future Laser Interferometer Space Antenna (LISA, Amaro-Seoane et al 2017) and by pulsar timing techniques in the nHz range (Alam et al 2020;Babak et al 2016;Reardon et al 2016).…”

High Precision Measurements of Interstellar Dispersion Measure with the upgraded GMRT

“…Amongst these, PSR J2145−0750 has low solar elongations between December to February every year. This implies that DM for this pulsar has excess contribution from solar wind every year when it is close to the Sun (Kumar et al 2013;Tiburzi et al 2019Tiburzi et al , 2020Alam et al 2020;Donner et al 2020). DM can also be enhanced in case of a violent solar event, such as a coronal mass ejection (CME) or a CME-solar wind or CME-CME interaction, where the electron density in the line of sight can get enhanced.…”

“…The DM of a pulsar can vary with time due a number of reasons that include the relative motion of the pulsar with respect to the observer, solar wind, terrestrial ionosphere, and the dynamical nature of the IISM. Typical DM variations observed in pulsars range from 10 −3 -10 −4 pc cm −3 (Kumar et al 2013;Alam et al 2020;Donner et al 2020). If these variations are not accounted for, systematic errors of the order of 1 µs or more can arise while correcting for the DM delay to generate infinitefrequency ToAs in the solar system barycentre (SSB) frame (Hobbs et al 2006;Edwards et al 2006).…”

“…There are three established PTA efforts and they are the Parkes Pulsar Timing Array (PPTA: Hobbs 2013; Kerr et al 2020), the European Pulsar Timing Array (Kramer & Champion 2013;Desvignes et al 2016), and the North American Nanohertz Observatory for Gravitational Waves (NANOGrav: McLaughlin 2013; Alam et al 2020). In addition, PTA efforts are gathering pace in India under the auspices of the Indian Pulsar Timing Array (InPTA: Joshi et al 2018).…”

Mini-disk accretion onto spinning black hole binaries: quasi-periodicities and outflows

“…At those separations, energy and angular momentum is extracted from the system by gravitational radiation until the BHs merge (Pretorius 2005;Campanelli et al 2006a;Baker et al 2006). In the near future, gravitational waves from SMBBH mergers might be observable in the mHZ frequency band by the Laser Interferometer Space Antenna (LISA, Amaro-Seoane et al 2017) and by pulsar timing techniques in the nHz range (Alam et al 2020;Babak et al 2016;Reardon et al 2016).…”