White dwarf pulsars as possible cosmic ray electron-positron factories
Abstract
We suggest that white dwarf (WD) pulsars can compete with neutron star (NS) pulsars for producing the excesses of cosmic ray electrons and positrons (e±) observed by the PAMELA, ATIC/PPB-BETS, Fermi, and H.E.S.S. experiments. A merger of two WDs leads to a rapidly spinning WD with a rotational energy (∼1050erg) comparable to the NS case. The birth rate (∼10-2-10-3/yr/galaxy) is also similar, providing the right energy budget for the cosmic ray e±. Applying the NS theory, we suggest that the WD pulsars can in principle produce e± up to ∼10TeV. In contrast to the NS model, the adiabatic and radiative energy losses of e± are negligible since their injection continues after the expansion of the pulsar wind nebula, and hence it is enough that a fraction ∼1% of WDs are magnetized (∼107-109G) as observed. The long activity also increases the number of nearby sources (∼100), which reduces the Poisson fluctuation in the flux. The WD pulsars could dominate the quickly cooling e± above TeV energy as a second spectral bump or even surpass the NS pulsars in the observing energy range ∼10GeV-1TeV, providing a background for the dark matter signals and a nice target for the future AMS-02, CALET, and CTA experiment.
- Publication:
-
Physical Review D
- Pub Date:
- January 2011
- DOI:
- 10.1103/PhysRevD.83.023002
- arXiv:
- arXiv:1009.1141
- Bibcode:
- 2011PhRvD..83b3002K
- Keywords:
-
- 97.20.Rp;
- 98.70.Sa;
- Faint blue stars white dwarfs degenerate stars nuclei of planetary nebulae;
- Cosmic rays;
- Astrophysics - High Energy Astrophysical Phenomena;
- High Energy Physics - Phenomenology
- E-Print:
- 20 pages, 7 figures and 1 table