Testing dissipative magnetosphere model light curves and spectra with FERMI pulsars

Journal Article · Sun May 10 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/804/2/84· OSTI ID:22883232

Brambilla, Gabriele ^[1]; Kalapotharakos, Constantinos; Harding, Alice K.; Kazanas, Demosthenes ^[2]

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1. Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, I-20133 Milano (Italy)
2. Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

We explore the emission properties of a dissipative pulsar magnetosphere model introduced by Kalapotharakos et al. comparing its high-energy light curves and spectra, due to curvature radiation, with data collected by the Fermi LAT. The magnetosphere structure is assumed to be near the force-free solution. The accelerating electric field, inside the light cylinder (LC), is assumed to be negligible, while outside the LC it rescales with a finite conductivity (σ). In our approach we calculate the corresponding high-energy emission by integrating the trajectories of test particles that originate from the stellar surface, taking into account both the accelerating electric field components and the radiation reaction forces. First, we explore the parameter space assuming different value sets for the stellar magnetic field, stellar period, and conductivity. We show that the general properties of the model are in a good agreement with observed emission characteristics of young γ-ray pulsars, including features of the phase-resolved spectra. Second, we find model parameters that fit each pulsar belonging to a group of eight bright pulsars that have a published phase-resolved spectrum. The σ values that best describe each of the pulsars in this group show an increase with the spin-down rate ( E-dot ) and a decrease with the pulsar age, expected if pair cascades are providing the magnetospheric conductivity. Finally, we explore the limits of our analysis and suggest future directions for improving such models.

• OSTI ID: 22883232
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 804; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCELERATION
COMPARATIVE EVALUATIONS
CYLINDERS
EMISSION
MAGNETIC FIELDS
PULSARS
SPACE
SPECTRA
SURFACES
TEST PARTICLES