Neutron star cooling implications and magnetic field of the Vela Junior central compact object from all XMM–Newton and Chandra spectra

Document Type

Journal Article

Role

Author

Journal Title

Monthly Notices of the Royal Astronomical Society

Volume

546

Issue

3

Publication Date

1-19-2026

Abstract

The central compact object (CCO) in the Vela Junior supernova remnant is a young neutron star whose relatively low Xray flux and small distance suggest it has a mass high enough to activate fast neutrino cooling processes. Here we analyse all XMM–Newton MOS and pn and Chandra ACIS-S spectra of the Vela Junior CCO, with observations taking place over the 9 yr from 2001 to 2010. We find that the best-fitting flux and spectral model parameters do not vary significantly when treating each observation independently, and therefore we fit all the spectra simultaneously using various spectral models to characterize the predominantly thermal emission from the neutron star surface. Our results indicate the Vela Junior CCO has an atmosphere composed of hydrogen, a hot spot temperature (unredshifted) of 3.5 × 106 K, and a colder surface temperature of (6.6–8.8)×105 K. Possible absorption lines at ≈0.6 and 0.9 keV provide evidence for the firsttime of an average surface magnetic field B ≈ 3 × 1010 G for this CCO, which is similar to the magnetic field of other CCOs. At the accurate new Vela Junior distance of 1.4 kpc, the observed luminosity that is dominated by the hot spot is ∼ 5 × 1032 erg s−1. The luminosity from the rest of the colder surface is (1.3–4.0) × 1032 erg s−1. The cool luminosity and temperature imply the Vela Junior CCO is indeed colder than many other young neutron stars and probably has a high mass that triggered fast neutrino cooling.

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