AGILE detection of transient gamma-ray emission from the PSR B1259-63 region

ATel #2772; M. Tavani (INAF-IASF-Rm and Univ. Tor Vergata), F. Lucarelli, C. Pittori, F. Verrecchia (ASDC), A. Bulgarelli, F. Gianotti, M. Trifoglio (INAF/IASF Bologna), E. Striani (Univ. Tor Vergata), S. Sabatini, G. Piano (INAF/IASF Roma), A. Argan, A. Trois, G. De Paris, V. Vittorini, E. Costa, I. Donnarumma, M. Feroci, L. Pacciani, E. Del Monte, F. Lazzarotto, P. Soffitta, Y. Evangelista, I. Lapshov (INAF-IASF-Rm), A. Chen, A. Giuliani (INAF-IASF-Milano), M. Marisaldi, G. Di Cocco, C. Labanti, F. Fuschino, M. Galli (INAF/IASF Bologna), P. Caraveo, S. Mereghetti, F. Perotti (INAF/IASF Milano), G. Pucella, M. Rapisarda (ENEA-Roma), A. Pellizzoni, M. Pilia (INAF/OA-Cagliari), G. Barbiellini, F. Longo (INFN Trieste), P. Picozza, A. Morselli (INFN and Univ. Tor Vergata), M. Prest (Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), S. Vercellone, F. D'Ammando (INAF/IASF-Palermo), P. W. Cattaneo, A. Rappoldi (INFN Pavia), P. Giommi, P. Santolamazza (ASDC), S. Colafrancesco and L. Salotti (ASI)
on 5 Aug 2010; 13:04 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Carlotta Pittori (carlotta.pittori@asdc.asi.it)

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AGILE is detecting transient gamma-ray emission above 100 MeV from a source near the Galactic plane and positionally consistent with the binary pulsar PSR B1259-63 (J2000 coordinates: RA: 13 02 47.66, Dec: -63 50 08.6; l = 304.1836, b = -0.9916).

Integrating from 2010-08-02 06:40 UT to 2010-08-04 04:00 UT, a preliminary maximum likelihood analysis yields a detection centered at Galactic coordinates (l,b) = (304.7,-0.8) ± 0.6 (stat.) ± 0.1 (syst.) (RA=196.9,Dec=-63.7 J2000), with a significance level of about 4.5 sigma, and a gamma-ray flux above 2 x 10E-6 ph/cm2/sec for photon energies above 100 MeV. An independent analysis based on the false discovery rate (FDR) method gives a probability of less than 0.001 for the signal to be consistent with the null hypothesis.

We note that this transient gamma-ray source is positionally consistent with the pulsar binary system PSR B1259-63 made of a 49.96 sec radio pulsar orbiting around a Be star companion in a highly elliptical orbit (of period P = 3.38 yrs). The pulsar is now in the approaching-to-periastron part of the orbit, and is expected to reach the region close to periastron in mid-December 2010. Time variable high-energy emission (ATel #249, M. Beilicke et al.) can be produced by the interaction of the relativistic pulsar wind with the gaseous outflow from the Be star companion (e.g., Tavani & Arons, 1997, ApJ, 499, 439).

Multifrequency observations of the PSR B1259-63 region are strongly encouraged as well as monitoring of the binary pulsar system.