Research articles

search articles

My Pages

Stat

Members: 3645
Articles: 2'501'711
Articles rated: 2609

20 April 2024

» arxiv » 1207.0616

Article overview

Gamma-ray observations of the Orion Molecular Clouds with the Fermi Large Area Telescope
M. Ackermann ; M. Ajello ; A. Allafort ; E. Antolini ; L. Baldini ; J. Ballet ; G. Barbiellini ; D. Bastieri ; K. Bechtol ; R. Bellazzini ; B. Berenji ; R. D. Blandford ; E. D. Bloom ; E. Bonamente ; A. W. Borgland ; E. Bottacini ; T. J. Brandt ; J. Bregeon ; M. Brigida ; P. Bruel ; R. Buehler ; S. Buson ; G. A. Caliandro ; R. A. Cameron ; P. A. Caraveo ; C. Cecchi ; A. Chekhtman ; J. Chiang ; S. Ciprini ; R. Claus ; J. Cohen-Tanugi ; J. Conrad ; F. D'Ammando ; A. de Angelis ; F. de Palma ; C. D. Dermer ; E. do Couto e Silva ; P. S. Drell ; A. Drlica-Wagner ; T. Enoto ; L. Falletti ; C. Favuzzi ; S. J. Fegan ; E. C. Ferrara ; W. B. Focke ; Y. Fukazawa ; Y. Fukui ; P. Fusco ; F. Gargano ; D. Gasparrini ; S. Germani ; N. Giglietto ; F. Giordano ; M. Giroletti ; T. Glanzman ; G. Godfrey ; S. Guiriec ; D. Hadasch ; Y. Hanabata ; A. K. Harding ; M. Hayashida ; K. Hayashi ; D. Horan ; X. Hou ; R. E. Hughes ; M. S. Jackson ; G. Jóhannesson ; A. S. Johnson ; T. Kamae ; H. Katagiri ; J. Kataoka ; M. Kerr ; J. Knödlseder ; M. Kuss ; J. Lande ; S. Larsson ; S.-H. Lee ; F. Longo ; F. Loparco ; M. N. Lovellette ; P. Lubrano ; K. Makishima ; M. N. Mazziotta ; J. Mehault ; W. Mitthumsiri ; A. A. Moiseev ; C. Monte ; M. E. Monzani ; A. Morselli ; I. V. Moskalenko ; S. Murgia ; T. Nakamori ; M. Naumann-Godo ; S. Nishino ; J. P. Norris ; E. Nuss ; M. Ohno ; T. Ohsugi ; A. Okumura ; M. Orienti ; E. Orlando ; J. F. Ormes ; M. Ozaki ; D. Paneque ; J. H. Panetta ; D. Parent ; V. Pelassa ; M. Pesce-Rollins ; M. Pierbattista ; F. Piron ; G. Pivato ; T. A. Porter ; S. Rainò ; M. Razzano ; A. Reimer ; O. Reimer ; M. Roth ; H. F.-W. Sadrozinski ; C. Sgrò ; E. J. Siskind ; G. Spandre ; P. Spinelli ; A. W. Strong ; H. Takahashi ; T. Takahashi ; T. Tanaka ; J. G. Thayer ; J. B. Thayer ; O. Tibolla ; M. Tinivella ; D. F. Torres ; A. Tramacere ; E. Troja ; Y. Uchiyama ; T. L. Usher ; J. Vandenbroucke ; V. Vasileiou ; G. Vianello ; V. Vitale ; A. P. Waite ; P. Wang ; B. L. Winer ; K. S. Wood ; Z. Yang ; S. Zimmer ;
Date:	3 Jul 2012
Abstract:	We report on the gamma-ray observations of giant molecular clouds Orion A and B with the Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope. The gamma-ray emission in the energy band between sim100 MeV and sim100 GeV is predicted to trace the gas mass distribution in the clouds through nuclear interactions between the Galactic cosmic rays (CRs) and interstellar gas. The gamma-ray production cross-section for the nuclear interaction is known to sim10% precision which makes the LAT a powerful tool to measure the gas mass column density distribution of molecular clouds for a known CR intensity. We present here such distributions for Orion A and B, and correlate them with those of the velocity integrated CO intensity (WCO) at a 1{deg} imes1{deg} pixel level. The correlation is found to be linear over a WCO range of ~10 fold when divided in 3 regions, suggesting penetration of nuclear CRs to most of the cloud volumes. The Wco-to-mass conversion factor, Xco, is found to be sim2.3 imes10^20 cm-2(K km s-1)-1 for the high-longitude part of Orion A (l > 212{deg}), sim1.7 times higher than sim1.3 imes 10^20 found for the rest of Orion A and B. We interpret the apparent high Xco in the high-longitude region of Orion A in the light of recent works proposing a non-linear relation between H2 and CO densities in the diffuse molecular gas. Wco decreases faster than the H2 column density in the region making the gas "darker" to Wco.
Source:	arXiv, 1207.0616
Services:	Forum \| Review \| PDF \| Favorites

No review found.

Did you like this article?

This article or document is ...
important:
of broad interest:
readable:
new:
correct:
Global appreciation:

Note: answers to reviews or questions about the article must be posted in the forum section.
Authors are not allowed to review their own article. They can use the forum section.

browser Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)

ScienXe.org
» my Online CV
» Free

News, job offers and information for researchers and scientists:

home

contact

sitemap