J/ApJ/934/L17ivo://CDS.VizieR/J/ApJ/934/L17doi:10.26093/cds/vizier.19349017CDSRomani R.W.Kandel D.Filippenko A.V.Brink T.G.Zheng W.2025-05-21T20:14:29Z2025-03-26T14:58:31ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frpulsarsvisible-astronomyspectroscopyneutron-starsWe describe Keck-telescope spectrophotometry and imaging of the companion of the "black widow" pulsar PSR J0952-0607, the fastest known spinning neutron star (NS) in the disk of the Milky Way. The companion is very faint at minimum brightness, presenting observational challenges, but we have measured multicolor light curves and obtained radial velocities over the illuminated "day" half of the orbit. The model fits indicate system inclination i=59.8{deg}+/-1.9{deg} and a pulsar mass M_NS_=2.35+/-0.17M_{sun}_, the largest well-measured mass found to date. Modeling uncertainties are small, since the heating is not extreme; the companion lies well within its Roche lobe and a simple direct-heating model provides the best fit. If the NS started at a typical pulsar birth mass, nearly 1M_{sun}_ has been accreted; this may be connected with the especially low intrinsic dipole surface field, estimated at 6x10^7^G. Joined with reanalysis of other black widow and redback pulsars, we find that the minimum value for the maximum NS mass is M_max_>2.19M_{sun}_ (2.09M_{sun}_) at 1{sigma} (3{sigma}) confidence. This is ~0.15M_{sun}_ heavier than the lower limit on M_max_ implied by the white dwarf-pulsar binaries measured via radio Shapiro-delay techniques.2022ApJ...934L..17Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/934/L17CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/psr : ATNF Pulsar Catalogue (Manchester+, 2005)J/ApJ/908/L46 : LC & radial velocities for PSRJ1810+1744 (Romani+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/934/L17https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/934/L17http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/934/L17https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/934/L17https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/934/L17http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/934/L17GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalRadiodefaultJ/ApJ/934/L17/spectra*List of the reduced, cleaned FITS spectra for PSR J0952-0607 and the comparison star over six observing epochs (Data behind Figures 1-3)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDSpectrum IDmeta.id;meta.maincharPhase[0.02/1] Binary phase of barycentered midpoint (1)time.phasedoubleFilePName of the FITS file in subdirectory "sp" for J0952; column added by CDSmeta.id;meta.fitscharfitsPDownload the FITS file for PSR J0952-0607meta.ref.urlcharspPInteractive spectrum plotmeta.ref.urlcharFileCName of the FITS file in subdirectory "sp" for the comparison star; column added by CDSmeta.id;meta.fitscharfitsCDownload the FITS file for the comparison starmeta.ref.urlcharspCInteractive spectrum plotmeta.ref.urlchar