TY - JOUR
T1 - Hubble Space Telescope Observations of the Old Pulsar PSR J0108-1431
AU - Abramkin, Vadim
AU - Shibanov, Yuriy
AU - Mignani, Roberto P.
AU - Pavlov, George G.
N1 - Funding Information:
We thank the referee for useful comments. Support for HST program #14249 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. We thank Bettina Posselt for providing the reduced XMM-Newton data. R.P.M. is grateful to Denise Taylor (STScI) for support during the HST observations.
Publisher Copyright:
© 2021. The American Astronomical Society. All rights reserved.
PY - 2021/4/16
Y1 - 2021/4/16
N2 - We present results of optical-UV observations of the 200 Myr old rotation-powered radio pulsar J0108-1431 with the Hubble Space Telescope. We found a putative candidate for the far-UV (FUV) pulsar counterpart, with the flux density f ν = 9.0 ± 3.2 nJy at λ = 1528 Å. The pulsar was not detected, however, at longer wavelengths, with 3σ upper limits of 52, 37, and 87 nJy at λ = 4326, 3355, and 2366 Å, respectively. Assuming that the pulsar counterpart was indeed detected in FUV, and the previously reported marginal U and B detections with the Very Large Telescope were real, the optical-UV spectrum of the pulsar can be described by a power-law model with a nearly flat f ν spectrum. Similar to younger pulsars detected in the optical, the slope of the nonthermal spectrum steepens in the X-ray range. The pulsar's luminosity in the 1500-6000 Å wavelength range, L ∼ 1.2 × 1027(d/210 pc)2 erg s-1, corresponds to a high efficiency of conversion of pulsar rotation energy-loss rate E to the optical-UV radiation,, depending on somewhat uncertain values of distance and spectral slope. The brightness temperature of the bulk neutron star surface does not exceed 59,000 K (3σ upper bound), as seen by a distant observer. If we assume that the FUV flux is dominated by a thermal component, then the surface temperature can be in the range of 27,000-55,000 K, Requiring a heating mechanism to operate in old neutron stars.
AB - We present results of optical-UV observations of the 200 Myr old rotation-powered radio pulsar J0108-1431 with the Hubble Space Telescope. We found a putative candidate for the far-UV (FUV) pulsar counterpart, with the flux density f ν = 9.0 ± 3.2 nJy at λ = 1528 Å. The pulsar was not detected, however, at longer wavelengths, with 3σ upper limits of 52, 37, and 87 nJy at λ = 4326, 3355, and 2366 Å, respectively. Assuming that the pulsar counterpart was indeed detected in FUV, and the previously reported marginal U and B detections with the Very Large Telescope were real, the optical-UV spectrum of the pulsar can be described by a power-law model with a nearly flat f ν spectrum. Similar to younger pulsars detected in the optical, the slope of the nonthermal spectrum steepens in the X-ray range. The pulsar's luminosity in the 1500-6000 Å wavelength range, L ∼ 1.2 × 1027(d/210 pc)2 erg s-1, corresponds to a high efficiency of conversion of pulsar rotation energy-loss rate E to the optical-UV radiation,, depending on somewhat uncertain values of distance and spectral slope. The brightness temperature of the bulk neutron star surface does not exceed 59,000 K (3σ upper bound), as seen by a distant observer. If we assume that the FUV flux is dominated by a thermal component, then the surface temperature can be in the range of 27,000-55,000 K, Requiring a heating mechanism to operate in old neutron stars.
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U2 - 10.3847/1538-4357/abe704
DO - 10.3847/1538-4357/abe704
M3 - Review article
AN - SCOPUS:85104619004
SN - 0004-637X
VL - 911
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 1
ER -