GAMMA-RAY OBSERVATIONS OF THE ORION MOLECULAR CLOUDS WITH THE FERMI LARGE AREA TELESCOPE

Markus Ackermann; Marco Ajello; A. Allafort; E. Antolini; Luca Baldini; Jean Ballet; Guido 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; Pascal 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. J 'Ohannesson; A. S. Johnson; T. Kamae; H. Katagiri; J. Kataoka; M. Kerr; Jürgen 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. Rain'O; M. Razzano; A. Reimer; O. Reimer; M. Roth; H. F.-W. Sadrozinski; C. Sgr'O; 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

doi:10.1088/0004-637X/756/1/4

Journal Articles The Astrophysical Journal Year : 2012

GAMMA-RAY OBSERVATIONS OF THE ORION MOLECULAR CLOUDS WITH THE FERMI LARGE AREA TELESCOPE

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Markus Ackermann

Function : Author

Marco Ajello

Function : Author

A. Allafort

Function : Author

E. Antolini

Function : Author

Luca Baldini

Function : Author

Jean Ballet

Function : Author

Astrophysique Interprétation Modélisation

Guido Barbiellini

Function : Author

D. Bastieri

Function : Author

K. Bechtol

Function : Author

R. Bellazzini

Function : Author

B. Berenji

Function : Author

R. D. Blandford

Function : Author

E. D. Bloom

Function : Author

E. Bonamente

Function : Author

A. W. Borgland

Function : Author

E. Bottacini

Function : Author

T. J. Brandt

Function : Author

Institut de recherche en astrophysique et planétologie

J. Bregeon

Function : Author
PersonId : 741214
IdHAL : johan-bregeon
ORCID : 0000-0002-6790-5328
IdRef : 095856943

M. Brigida

Function : Author

Pascal Bruel

Function : Author

Laboratoire Leprince-Ringuet

R. Buehler

Function : Author

S. Buson

Function : Author

G. A. Caliandro

Function : Author

R. A. Cameron

Function : Author

P. A. Caraveo

Function : Author

C. Cecchi

Function : Author

A. Chekhtman

Function : Author

J. Chiang

Function : Author

S. Ciprini

Function : Author

R. Claus

Function : Author

J. Cohen-Tanugi

Function : Author
PersonId : 3626
IdHAL : johann-cohen-tanugi
ORCID : 0000-0001-9022-4232
IdRef : 172626544

Laboratoire Univers et Particules de Montpellier

J. Conrad

Function : Author

F. d'Ammando

Function : Author

A. de Angelis

Function : Author

F. de Palma

Function : Author

C. D. Dermer

Function : Author

E. Do Couto E Silva

Function : Author

P. S. Drell

Function : Author

A. Drlica-Wagner

Function : Author

T. Enoto

Function : Author
PersonId : 764101
ORCID : 0000-0003-1244-3100

L. Falletti

Function : Author

C. Favuzzi

Function : Author

S. J. Fegan

Function : Author
PersonId : 740343
IdHAL : stephen-fegan
IdRef : 253133149

Laboratoire Leprince-Ringuet

E. C. Ferrara

Function : Author

W. B. Focke

Function : Author

Y. Fukazawa

Function : Author
PersonId : 760581
ORCID : 0000-0002-0921-8837

Y. Fukui

Function : Author

P. Fusco

Function : Author

F. Gargano

Function : Author

D. Gasparrini

Function : Author

S. Germani

Function : Author

N. Giglietto

Function : Author
PersonId : 755413
ORCID : 0000-0002-9021-2888

F. Giordano

Function : Author

M. Giroletti

Function : Author

T. Glanzman

Function : Author

G. Godfrey

Function : Author

S. Guiriec

Function : Author

D. Hadasch

Function : Author
PersonId : 761675
ORCID : 0000-0001-8663-6461

Y. Hanabata

Function : Author

A. K. Harding

Function : Author

M. Hayashida

Function : Author

K. Hayashi

Function : Author

D. Horan

Function : Author

Laboratoire Leprince-Ringuet

X. Hou

Function : Author

GLAST

R. E. Hughes

Function : Author

M. S. Jackson

Function : Author

G. J 'Ohannesson

Function : Author

A. S. Johnson

Function : Author

T. Kamae

Function : Author

H. Katagiri

Function : Author

J. Kataoka

Function : Author

M. Kerr

Function : Author

Jürgen Knödlseder

Function : Author
PersonId : 178646
IdHAL : jurgen-knodlseder
ORCID : 0000-0002-0014-7809
IdRef : 069521360

Institut de recherche en astrophysique et planétologie

M. Kuss

Function : Author

J. Lande

Function : Author

Institut de recherche en astrophysique et planétologie

S. Larsson

Function : Author

S.-H. Lee

Function : Author

F. Longo

Function : Author
PersonId : 755442
ORCID : 0000-0003-2501-2270

F. Loparco

Function : Author

M. N. Lovellette

Function : Author

P. Lubrano

Function : Author

K. Makishima

Function : Author

M. N. Mazziotta

Function : Author

J. Mehault

Function : Author

Laboratoire Univers et Particules de Montpellier

W. Mitthumsiri

Function : Author

A. A. Moiseev

Function : Author

C. Monte

Function : Author

M. E. Monzani

Function : Author

A. Morselli

Function : Author

I. V. Moskalenko

Function : Author

S. Murgia

Function : Author

T. Nakamori

Function : Author
PersonId : 760584
ORCID : 0000-0002-7308-2356

M. Naumann-Godo

Function : Author

S. Nishino

Function : Author

J. P. Norris

Function : Author

E. Nuss

Function : Author

Laboratoire Univers et Particules de Montpellier

M. Ohno

Function : Author

T. Ohsugi

Function : Author

A. Okumura

Function : Author

M. Orienti

Function : Author

E. Orlando

Function : Author

J. F. Ormes

Function : Author

M. Ozaki

Function : Author
PersonId : 759061
ORCID : 0000-0002-1320-9781

D. Paneque

Function : Author
PersonId : 755279
ORCID : 0000-0002-2830-0502

J. H. Panetta

Function : Author

D. Parent

Function : Author

V. Pelassa

Function : Author

Laboratoire Univers et Particules de Montpellier

M. Pesce-Rollins

Function : Author
PersonId : 760585
ORCID : 0000-0003-1790-8018

M. Pierbattista

Function : Author

Astrophysique Interprétation Modélisation

F. Piron

Function : Author
PersonId : 172749
IdHAL : frederic-piron
ORCID : 0000-0001-6885-7156

Laboratoire Univers et Particules de Montpellier

G. Pivato

Function : Author

T.A. Porter

Function : Author

S. Rain'O

Function : Author

M. Razzano

Function : Author

A. Reimer

Function : Author
PersonId : 755465
ORCID : 0000-0001-8604-7077

O. Reimer

Function : Author

M. Roth

Function : Author

H. F.-W. Sadrozinski

Function : Author

C. Sgr'O

Function : Author

E. J. Siskind

Function : Author

G. Spandre

Function : Author

P. Spinelli

Function : Author

A. W. Strong

Function : Author

H. Takahashi

Function : Author

T. Takahashi

Function : Author

T. Tanaka

Function : Author
PersonId : 756461
ORCID : 0000-0002-4383-0368

J. G. Thayer

Function : Author

J. B. Thayer

Function : Author

O. Tibolla

Function : Author

M. Tinivella

Function : Author

D. F. Torres

Function : Author

A. Tramacere

Function : Author

E. Troja

Function : Author

Y. Uchiyama

Function : Author

T. L. Usher

Function : Author

J. Vandenbroucke

Function : Author

V. Vasileiou

Function : Author

Laboratoire Univers et Particules de Montpellier

G. Vianello

Function : Author

V. Vitale

Function : Author
PersonId : 760184
ORCID : 0000-0001-8040-7852

A. P. Waite

Function : Author

P. Wang

Function : Author

B. L. Winer

Function : Author

K. S. Wood

Function : Author

Z. Yang

Function : Author

S. Zimmer

Function : Author

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 ∼100 MeV and ∼100 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 ∼10% 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◦ × 1◦ pixel level. The correlation is found to be linear over a WCO range of ∼10-fold when divided in three regions, suggesting penetration of nuclear CRs to most of the cloud volumes. The WCO-to-mass conversion factor, XCO, is found to be ∼2.3 × 1020 cm−2 (K km s−1)−1 for the high-longitude part of Orion A (l > 212◦), ∼1.7 times higher than ∼1.3 × 1020 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 nonlinear 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.

Keywords

gamma rays: ISM ISM: clouds ISM: general ISM: individual objects (Orion A and Orion B) Online-only material: color figures

Domains

Physics [physics] Astrophysics [astro-ph] High Energy Astrophysical Phenomena [astro-ph.HE] Sciences of the Universe [physics] Astrophysics [astro-ph] High Energy Astrophysical Phenomena [astro-ph.HE]

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Submitted on : Wednesday, October 31, 2012-9:54:54 AM

Last modification on : Wednesday, February 1, 2023-6:44:10 PM

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in2p3-00747339 , version 1 (31-10-2012)

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HAL Id : in2p3-00747339 , version 1
ARXIV : 1207.0616
DOI : 10.1088/0004-637X/756/1/4

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Markus Ackermann, Marco Ajello, A. Allafort, E. Antolini, Luca Baldini, et al.. GAMMA-RAY OBSERVATIONS OF THE ORION MOLECULAR CLOUDS WITH THE FERMI LARGE AREA TELESCOPE. The Astrophysical Journal, 2012, 756, pp.4. ⟨10.1088/0004-637X/756/1/4⟩. ⟨in2p3-00747339⟩

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GAMMA-RAY OBSERVATIONS OF THE ORION MOLECULAR CLOUDS WITH THE FERMI LARGE AREA TELESCOPE

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