SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 8 - April 21, 2006

90 ASTROPHYSICS
Includes cosmology; celestial mechanics; space plasmas; and interstellar and interplanetary gases and dust.

20060010987 Ohio Univ., Athens, OH, USA

A Hadronic Synchrotron Mirror Model for the 'Orphan' Tev Flare in 1ES 1959+650

Bottcher, Markus; [2005]; 6 pp.; In English; Original contains black and white illustrations Contract(s)/Grant(s): NNG04GF70G; NAG5-13684; Copyright; Avail.: Other Sources

Very high energy gamma-ray flares of TeV blazars are generally accompanied by simultaneous flaring activity in X-rays. The recent observations by the Whipple collaboration of an 'orphan' TeV flare of 1 ES 1959+650 (without a simultaneous X-ray flare) are very difficult to reconcile with the standard leptonic synchrotron self-Compton model, which is routinely very successfully employed to explain the spectral energy distribution and spectral variability of TeV blazars. In this paper an alternative scenario is suggested in which the orphan TeV flare may originate from relativistic protons, interacting with an external photon field supplied by electron synchrotron radiation reflected off a dilute reflector. While the external photons will be virtually 'invisible' to the comoving ultrarelativistic electrons in the jet because of Klein-Nishina effects, their Doppler-boosted energy is high enough to excite a Delta-resonance from relativistic protons with Lorentz factors of gamma(sub p) approx. 10(exp 3)-10(exp 4). This model is capable of explaining the orphan TeV flare of 1ES 1959+650 with plausible parameters, thus constraining the number and characteristic energy of relativistic protons in the jet of this blazar. Author

Gamma Rays; Hadrons; Synchrotron Radiation; Mirrors; Proton Energy; Spectral Energy Distribution; Blazars

20060010988 Ruhr Univ., Bochum, Germany

Neutrino Emission in the Hadronic Synchrotron Mirror Model: The 'Orphan' Flare from 1ES 1959+650

Reimer, A.; Boettcher, M.; Postnikov, S.; Astrophysical Journal; September 2005; Volume 630, pp. 186-190; In English; Original contains black and white illustrations Contract(s)/Grant(s): NNG04GF70G; Copyright; Avail.: Other Sources

A challenge to standard leptonic synchrotron self-Compton (SSC) models is the so-called orphan TeV flares, i.e., enhanced very high energy (VHE) gamma-ray emission without any contemporaneous X-ray flaring activity, that have recently been observed in TeV blazars (e.g., 1ES 1959+650). In order to explain the orphan TeV flare of 1 ES 1959+650 observed in 2002 June, the so-called hadronic synchrotron mirror model has been developed. Here relativistic protons are proposed to exist in the jet and interact with reflected electron synchrotron radiation of the precursor SSC flare. If the reflector is located in the cloud region, time shifts of several days are possible between the precursor and the orphan flare. The external photons, blue-shifted in the comoving jet frame, are able to excite the Delta(1232) resonance when interacting with protons of Lorentz factors gamma(sub p) approx. 10(exp 3)-10(exp 4). The decay products of this resonance include charged pions, which, on decay, give rise to neutrino production during the orphan flare. In this paper we calculate the expected neutrino emission for the 2002 June 4 orphan TeV flare of 1ES 1959+650. We compare our results with the recent observations of AMANDA-II of a neutrino event in spatial and temporal coincidence with the orphan flare of this blazar. We find that the expected neutrino signal from the hadronic synchrotron mirror model is insufficient to explain the claimed neutrino signal from the direction of 1ES 1959+650. Author

Synchrotron Radiation; Neutrinos; Blazars; Electron Radiation; Gamma Rays; Reflected Waves; Mirrors

20060011001 California Univ., San Diego, La Jolla, CA, USA

X-RAY OBSERVATIONS of THE BLACK HOLE TRANSIENT 4U 1630-47 DURING 2 YEARS of X-RAYACTIVITY

Tomsick, John A.; Corbel, Stephane; Goldwurm, Andrea; Kaaret, Philip; Astrophysical Journal; September 2005; Volume 630, pp. 413-429; In English; Original contains black and white illustrations Contract(s)/Grant(s): NAG5-12703; Copyright; Avail.: Other Sources

The black hole candidate (BHC) X-ray transient 4U 1630-47 continuously produced strong X-ray emission for more than 2 years during its 2002-2004 outburst, which is one of the brightest and longest outbursts ever seen from this source. We use more than 300 observations made with the Rossi X-Ray Timing Explorer (RXTE) to study the source throughout the outburst, along with hard X-ray images from the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), which are critical for interpreting the RXTE data in this crowded field. The source exhibits extreme behaviors, which can be interpreted as an indication that the system luminosity approaches the Eddington limit. For 15 observations, fitting the spectral continuum with a disk-blackbody plus power-law model results in measured inner disk temperatures between 2.7 and 3.8 keV, and such temperatures are only rivaled by the brightest BHC systems, such as GRS 1915+105 and XTE J1550-564. If the high temperatures are caused by the dominance of electron scattering opacity in the inner regions of the accretion disk, it is theoretically required that the source luminosity be considerably higher than 20% of the Eddington limit. We detect a variety of high-amplitude variability, including hard 10-100 s flares, which peak at levels as much as 2-3 times higher than nonflare levels. The X-ray properties in 2002-2004 are significantly different from those seen during the 1998 outburst, which is the only outburst with detected radio jet emission. Our results support the 'jet line' concept recently advanced by Fender and coworkers. Our study allows for a test of the quantitative McClintock & Remillard spectral state definitions, and we find that these definitions alone do not provide a complete description of the outburst. Finally, for several of the observations, the high-energy emission is dominated by the nearby sources IGR J16320-4751 and IGR J16358-4726, and we provide information on when these sources were bright and on the nature of their energy spectra. Author

Accretion Disks; Black Holes (Astronomy); X Ray Timing Explorer; Radio Emission; Gamma Rays; Electron Scattering; Continuums; X Rays

Source: NASA