The Parkes pulsar timing array second data release: timing analysis

The main goal of pulsar timing array experiments is to detect correlated signals such as nanohertz-frequency gravitational waves. Pulsar data collected in dense monitoring campaigns can also be used study the stars themselves, their binary companions, and intervening ionised interstellar medium. Timing observations are extraordinarily sensitive changes path length between Earth, enabling precise measurements positions, distances velocities, shapes orbits. Here we present a analysis 25 pulsars observed part Parkes Array (PPTA) project over time spans up 24 yr. from second release PPTA, which have extended by including legacy data. We make first detection Shapiro delay four Southern (PSRs J1017$-$7156, J1125$-$6014, J1545$-$4550, J1732$-$5049), parallax six pulsars. prominent PSR J1125$-$6014 implies neutron star mass $M_p = 1.5 \pm 0.2 M_\odot$ (68% credibility interval). Measurements both relativistic periastron advance J1600$-$3053 yield large but uncertain 2.06^{+0.44}_{-0.41}$ M$_\odot$ measure distance J1909$-$3744 precision 10 lyr, indicating that for wave periods decade, provides coherent baseline experiments.