skip to main content


Title: Keck spectroscopy of millisecond pulsar J2215+5135: a moderate-M

We present Keck spectroscopic measurements of the millisecond pulsar binary J2215+5135. These data indicate a neutron-star (NS) mass $${M}_{\mathrm{NS}}=1.6\;{M}_{\odot }$$, much less than previously estimated. The pulsar heats the companion face to $${T}_{D}\approx 9000$$ K; the large heating efficiency may be mediated by the intrabinary shock dominating the X-ray light curve. At the best-fit inclination i = 88 $$^o\atop{.}$$ 8, the pulsar should be eclipsed. Here, we find weak evidence for such eclipses in the pulsed gamma-rays; an improved radio ephemeris allows use of up to five times more Fermi-Large Area Telescope gamma-ray photons for a definitive test of this picture. If confirmed, the gamma-ray eclipse provides a novel probe of the dense companion wind and the pulsar magnetosphere.
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [4]
  1. Stanford Univ., CA (United States). Dept. of Physics
  2. Univ. of California, Berkeley, CA (United States). Dept. of Astronomy
  3. Univ. of California, Berkeley, CA (United States). Dept. of Astronomy
  4. CSIRO Astronomy and Space Science, Epping, NSW (Australia)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; AST-1211916; NNX11AO44G
Accepted Manuscript
Journal Name:
The Astrophysical Journal. Letters
Additional Journal Information:
Journal Volume: 809; Journal Issue: 1; Journal ID: ISSN 2041-8213
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE; National Aeronautic and Space Administration (NASA); National Science Foundation (NSF)
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; gamma rays; stars; pulsars
OSTI Identifier: