S Shapiro

Publications (2)0 Total impact

• Source

  Available from: Howard Bushouse

  Article: A multiwavelength study of Sgr A*: the role of near-IR flares in production of X-ray, soft γ-ray, and submillimeter emission

  F Yusef-Zadeh, H Bushouse, C D Dowell, M Wardle, D Roberts, C Heinke, G C Bower, B Vila Vilaro, S Shapiro, A Goldwurm, G Belanger, Received ; Accepted
  01/2006;
• Source

  Available from: Howard Bushouse

  Article: A Multi-Wavelength Study of Sgr A*: The Role of Near-IR Flares in Production of X-ray, Soft $\gamma$-ray and Sub-millimeter Emission

  F. Yusef-Zadeh, H. Bushouse, C. D. Dowell, M. Wardle, D Roberts, C. Heinke, G. C. Bower, B. Vila Vilaro, S Shapiro, A. Goldwurm, G. Belanger
  [show abstract] [hide abstract]
  ABSTRACT: (abridged) We describe highlights of the results of two observing campaigns in 2004 to investigate the correlation of flare activity in Sgr A* in different wavelength regimes, using a total of nine ground and space-based telescopes. We report the detection of several new near-IR flares during the campaign based on {\it HST} observations. The level of near-IR flare activity can be as low as $\sim0.15$ mJy at 1.6 $\mu$m and continuous up to about 40% of the total observing time. Using the NICMOS instrument on the {\it HST}, the {\it XMM-Newton} and CSO observatories, we also detect simultaneous bright X-ray and near-IR flare in which we observe for the first time correlated substructures as well as simultaneous submillimeter and near-IR flaring. X-ray emission is arising from the population of near-IR-synchrotron-emitting relativistic particles which scatter submillimeter seed photons within the inner 10 Schwarzschild radii of Sgr A* up to X-ray energies. In addition, using the inverse Compton scattering picture, we explain the high energy 20-120 keV emission from the direction toward Sgr A*, and the lack of one-to-one X-ray counterparts to near-IR flares, by the variation of the magnetic field and the spectral index distributions of this population of nonthermal particles. In this picture, the evidence for the variability of submillimeter emission during a near-IR flare is produced by the low-energy component of the population of particles emitting synchrotron near-IR emission. Based on the measurements of the duration of flares in near-IR and submillimeter wavelengths, we argue that the cooling could be due to adiabatic expansion with the implication that flare activity may drive an outflow. Comment: 48 pages, 12 figures, ApJ (in press)
  10/2005;