Modeling of the gamma-ray pulsed spectra of Geminga, Crab, and Vela with synchro-curvature radiation

Abstract

$\gamma$-ray spectra of pulsars have been mostly studied in a phenomenological way, by fitting them to a cut-off power-law function. Here, we analyze a model where pulsed emission comes from synchro-curvature processes in a gap. We calculate the variation of kinetic energy of magnetospheric particles along the gap and the associated radiated spectra, considering an effective particle distribution. We fit the phase-averaged and phase-resolved Fermi-LAT spectra of the three brightest gamma-ray pulsars: Geminga, Crab, and Vela, and constrain the three free parameters we leave free in the model. Our best-fit models well reproduce the observed data, apart from residuals above a few GeV in some cases, range for which the inverse Compton scattering likely becomes the dominant mechanism. In any case, the flat slope at low-energy (< GeV) seen by Fermi-LAT both in the phase-averaged and phase-resolved spectra of most pulsars, including the ones we studied, requires that most of the detected radiation below ~ GeV is produced during the beginning of the particle trajectories, when radiation mostly come from the loss of perpendicular momentum.

11 pages, 9 figures, 2 tables. Published in MNRAS main journal

References in corpus (9)

• Observation of Pulsed Gamma-rays Above 25 GeV from the Crab Pulsar with MAGIC
• Particle Accelerator in Pulsar Magnetospheres: Super Goldreich-Julian Current with Ion Emission from the Neutron Star Surface
• Outer-gap vs. Slot-gap Models for Pulsar High Energy Emissions: The Case of the Crab Pulsar
• Testing dissipative magnetosphere model light curves and spectra with FERMI pulsars
• Fermi-LAT Detection of Pulsed Gamma-rays Above 50 GeV from the Vela Pulsar
• An assessment of the pulsar outer gap model. I: Assumptions, uncertainties, and implications for the gap size and the accelerating field
• A stacked analysis of 115 pulsars observed by the Fermi LAT
• A Search for Pulsations from Geminga Above 100 GeV with VERITAS
• An assessment of the pulsar outer gap model. II: Implications for the predicted $\gamma$-ray spectra

Cited by in corpus (9)

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• A systematic synchro-curvature modelling of pulsar $\gamma$-ray spectra unveils hidden trends
• Gamma-ray emission from PSR J0007+7303 using 7 years of Fermi Large Area Telescope observations
• Efficiency of Synchrotron Radiation from Rotation-Powered Pulsars
• Synchro-curvature emitting regions in high-energy pulsar models
• Dissecting the emission from LHAASO J0341+5258: implications for future multi-wavelength observations
• Prospects for the characterization of the VHE emission from the Crab Nebula and Pulsar with the Cherenkov Telescope Array
• Energy release from magnetospheres deformed by gravitational waves
• Inferring pulsar periods from synchro-curvature spectra