Searching for optical companions to four binary millisecond pulsars with the Gran Telescopio Canarias
Zharikov, S. V.; Karpova, A. V.; Zyuzin, D. A.; Shibanov, Yu A.; Cabrera-Lavers, A.; Freire, P. C. C.; Kirichenko, A. Yu; López, E. A.; Fonseca, E.
Mexico, Russia, Guatemala, Germany, Canada, Spain
Abstract
We report on multiband photometric observations of four binary millisecond pulsars with the Gran Telescopio Canarias. The observations led to detection of binary companions to PSRs J1630+3734, J1741+1351, and J2042+0246 in the Sloan g', r', and I' bands. Their magnitudes in the r' band are ≈24.4, 24.4, and 24.0, respectively. We also set a 3σ upper limit on the brightness of the PSR J0557+1550 companion in the r' band of ≈25.6 mag. Combining the optical data with the radio timing measurements and white dwarf cooling models, we show that the detected companions are cool low-mass white dwarfs with temperatures and ages in the respective ranges of (4-7) × 103 K and 2-5 Gyr. All the detected white dwarfs are found to likely have either pure hydrogen or mixed helium-hydrogen atmospheres.