Discovery of gamma- and X-ray pulsations from the young and energetic PSR J1357−6429 with Fermi and XMM-Newton

M. Lemoine-Goumard (1) , V. E. Zavlin , M.-H. Grondin , R. Shannon , David Stanley Smith (1) , M. Burgay , F. Camilo , J. Cohen-Tanugi (2) , P. C. C. Freire , J. E. Grove , L. Guillemot , S. Johnston , M. Keith , M. Kramer , R. N. Manchester , P. F. Michelson , D. Parent , A. Possenti , P. S. Ray , M. Renaud , S. E. Thorsett , P. Weltevrede , M. T. Wolff

1 GLAST
2 LUPM - Laboratoire Univers et Particules de Montpellier

Since the launch of the Fermi satellite, the number of known gamma-ray pulsars has increased tenfold. Most gamma-ray detected pulsars are young and energetic, and many are associated with TeV sources. PSR J1357-6429 is a high spin-down power pulsar (Edot = 3.1 * 10^36 erg/s), discovered during the Parkes multibeam survey of the Galactic plane, with significant timing noise typical of very young pulsars. In the very-high-energy domain, H.E.S.S. has reported the detection of the extended source HESS J1356-645 (intrinsic Gaussian width of 12') whose centroid lies 7' from PSR J1357-6429. Using a rotational ephemeris obtained with 74 observations made with the Parkes telescope at 1.4 GHz, we phase-fold more than two years of gamma-ray data acquired by Fermi-LAT as well as those collected with XMM-Newton, and perform gamma-ray spectral modeling. Significant gamma and X-ray pulsations are detected from PSR J1357-6429. The light curve in both bands shows one broad peak. Gamma-ray spectral analysis of the pulsed emission suggests that it is well described by a simple power-law of index 1.5 +/- 0.3stat +/- 0.3syst with an exponential cut-off at 0.8 +/- 0.3stat +/- 0.3syst GeV and an integral photon flux above 100 MeV of (6.5 +/- 1.6stat +/- 2.3syst) * 10^-8 cm^-2 s^-1. The X-ray spectra obtained from the new data provide results consistent with those reported by Zavlin (2007). Upper limits on the gamma-ray emission from its potential pulsar wind nebula (PWN) are also reported. Assuming a distance of 2.4 kpc, the Fermi LAT energy flux yields a gamma-ray luminosity for PSR J1357-6429 of L_gamma = (2.13 +/- 0.25stat +/- 0.83syst) * 10^34 erg/s, consistent with an L_gamma \propto sqrt(Edot) relationship. The Fermi non-detection of the pulsar wind nebula associated with HESS J1356-645 provides new constraints on the electron population responsible for the extended TeV emission.

Mots clés: pulsars: individual: PSR J1357; 6429; gamma rays: general; pulsars: general

Domaines: Phénomènes cosmiques de haute energie [astro-ph.HE]; Phénomènes cosmiques de haute energie [astro-ph.HE]

M. Lemoine-Goumard, V. E. Zavlin, M.-H. Grondin, R. Shannon, David Stanley Smith, et al.. Discovery of gamma- and X-ray pulsations from the young and energetic PSR J1357−6429 with Fermi and XMM-Newton. Astronomy and Astrophysics - A&A, 2011, 533, pp.A102. ⟨10.1051/0004-6361/201117413⟩. ⟨in2p3-00656586⟩