------------------------------------------------------------------------ gammalines.tex A&A 508, 1 (2009) From: Ko Chung-Ming To: gcnews@aoc.nrao.edu Content-Type: multipart/alternative; boundary=0016367f92fb38f7ba047de2fb2a X-MailScanner-Information: Please contact the postmaster@aoc.nrao.edu for more information X-MailScanner: Found to be clean X-MailScanner-SpamCheck: not spam, SpamAssassin (not cached, score=0.001, required 5, autolearn=disabled, HTML_MESSAGE 0.00) X-MailScanner-From: cmko@gm.astro.ncu.edu.tw X-Spam-Status: No --0016367f92fb38f7ba047de2fb2a Content-Type: text/plain; charset=ISO-8859-1 %astro-ph/0909.2110 \documentclass[structabstract]{aa} \begin{document} \title{Nuclear interaction gamma-ray lines \\ from the Galactic center region} \author{V. A. Dogiel\inst{1,2}, V. Tatischeff\inst{3}, K. S. Cheng\inst{4}, D. O. Chernyshov\inst{1,2,4,5}, C. M. Ko\inst{2}\ thanks{cmko@astro.ncu.edu.tw }, \and W. H. Ip\inst{2} } \institute{I.E.Tamm Theoretical Physics Division of P.N.Lebedev Institute, Leninskii pr, 53, 119991 Moscow, Russia \and Institute of Astronomy, National Central University, Jhongli 320, Taiwan \and Centre de Spectrom\'etrie Nucl\'eaire et de Spectrom\'etrie de Masse, IN2P3-CNRS and Univ Paris-Sud, F-91405 Orsay Campus, France \and Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong, China \and Moscow Institute of Physics and Technology, Institutskii lane, 141700 Moscow Region, Dolgoprudnii, Russia} \abstract % aims heading (mandatory) {The accretion of stars onto the central supermassive black hole at the center of the Milky Way is predicted to generate large fluxes of subrelativistic ions in the Galactic center region. We analyze the intensity, shape, and spatial distribution of de-excitation gamma-ray lines produced by nuclear interactions of these energetic particles with the ambient medium. } % methods heading (mandatory) {We first estimated the amount and mean kinetic energy of particles released from the central black hole during star disruption. We then calculated the energy and spatial distributions of these particles in the Galactic center region from a kinetic equation. These particle distributions we are then used to derive the characteristics of the main nuclear interaction gamma-ray lines.} % results heading (mandatory) {Because the time period of star capture by the supermassive black hole is expected to be shorter than the lifetime of the ejected fast particles against Coulomb losses, the gamma-ray emission is predicted to be stationary. We find that the nuclear de-excitation lines should be emitted from a region with a maximum 5$^\circ$ angular radius. The total gamma-ray line flux below 8 MeV is calculated to be $\sim 10^{-4}$~photons~cm$^{-2}$~s$^{-1}$. The most promising lines for detection are those at 4.44 and $\sim$6.2~MeV, with a predicted flux in each line of $\sim 10^{-5}$~photons~cm$^{-2}$~s$^{-1}$. Unfortunately, it is unlikely that this emission can be detected with the INTEGRAL observatory. But the predicted line intensities appear to be within reach of future gamma-ray space instruments. A future detection of de-excitation gamma-ray lines from the Galactic center region would provide unique information on the high-energy processes induced by the central supermassive black hole and the physical conditions of the emitting region.} % conclusions heading (optional), leave it empty if necessary \keywords{Galaxy: center -- Radiation mechanisms: non-thermal -- Gamma rays: theory} --0016367f92fb38f7ba047de2fb2a Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
%astro-ph/0909.2110
=A0
\documentclass[structabstract]{aa}
\begin{document}

\title{Nuclear interaction gamma-ray lines \\ from the Galactic ce= nter region}
=A0
\author{V. A. Dogiel\inst{1,2}, V. Tatischeff\inst{3}, K. S. Cheng\ins= t{4},
D. O. Chernyshov\inst{1,2,4,5}, C. M. Ko\inst{2}\thanks{cmko@astro.ncu.edu.tw},
\and W. H. Ip\inst{2}
}
\institute{I.E.Tamm Theoretical Physics Division of P.N.Lebedev Instit= ute, Leninskii pr, 53,
119991 Moscow, Russia
\and
Institute of Astronomy, National Cent= ral University, Jhongli 320, Taiwan
\and
Centre de Spectrom\'etri= e Nucl\'eaire et de Spectrom\'etrie de Masse, IN2P3-CNRS
and Univ Paris-Sud, F-91405 Orsay Campus, France
\and
Department of Physics, University of Hong Kong, Pokfulam Road, Hong Ko= ng, China
\and
Moscow Institute of Physics and Technology, Institutskii lane,= 141700 Moscow Region,
Dolgoprudnii, Russia}
=A0
\abstract
% aims heading (mandatory)
{The accretion of stars onto the central= supermassive black hole at
the center of the Milky Way is predicted to = generate large fluxes of
subrelativistic ions in the Galactic center reg= ion. We analyze the
intensity, shape, and spatial distribution of de-excitation
gamma-ray li= nes produced by nuclear interactions of these energetic
particles with t= he ambient medium. }
% methods heading (mandatory)
{We first estimate= d the amount and mean kinetic energy of particles
released from the central black hole during star disruption. We
then cal= culated the energy and spatial distributions of
these particles in the G= alactic center region from a kinetic equation.
These particle distributi= ons we are then used to derive the characteristics of
the main nuclear interaction gamma-ray lines.}
% results heading (mandat= ory)
{Because the time period of star capture by the supermassive black = hole is
expected to be shorter than the lifetime of the ejected fast
particles against Coulomb losses, the gamma-ray emission is
predicted to= be stationary. We find that the nuclear de-excitation
lines should be e= mitted from a region with a maximum 5$^\circ$ angular
radius. The total = gamma-ray line flux below 8 MeV is calculated to
be $\sim 10^{-4}$~photons~cm$^{-2}$~s$^{-1}$. The most
promising lines f= or detection are those at 4.44 and $\sim$6.2~MeV,
with a predicted flux = in each line of
$\sim 10^{-5}$~photons~cm$^{-2}$~s$^{-1}$. Unfortunately= , it
is unlikely that this emission can be detected with the INTEGRAL
observa= tory. But the predicted line intensities appear to be
within reach of fu= ture gamma-ray space instruments. A future
detection of de-excitation ga= mma-ray lines from the Galactic
center region would provide unique information on the high-energy
proces= ses induced by the central supermassive black hole and
the physical cond= itions of the emitting region.}
% conclusions heading (optional), leave = it empty if necessary
\keywords{Galaxy: center=A0 --=A0 Radiation mechanisms: non-thermal=A0=A0=A0 --=A0 Gamma rays: theory}
=A0
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