FERMI LAT OBSERVATIONS OF LS I+61°303: FIRST DETECTION OF AN ORBITAL MODULATION IN GeV GAMMA RAYS

被引:122
作者
Abdo, A. A. [1 ,2 ]
Ackermann, M. [3 ,4 ]
Ajello, M. [3 ,4 ]
Atwood, W. B. [5 ,6 ]
Axelsson, M. [7 ,8 ]
Baldini, L. [9 ]
Ballet, J. [10 ]
Barbiellini, G. [11 ,12 ]
Bastieri, D. [13 ,14 ]
Baughman, B. M. [15 ]
Bechtol, K. [3 ,4 ]
Bellazzini, R. [9 ]
Berenji, B. [3 ,4 ]
Blandford, R. [3 ,4 ]
Bloom, E. D. [3 ,4 ]
Bonamente, E. [16 ,17 ]
Borgland, A. W. [3 ,4 ]
Bregeon, J. [9 ]
Brez, A. [9 ]
Brigida, M. [18 ,19 ]
Bruel, P. [20 ]
Burnett, T. H. [21 ]
Caliandro, G. A. [18 ,19 ]
Cameron, R. A. [3 ,4 ]
Caraveo, P. A. [22 ]
Casandjian, J. M. [10 ]
Cavazzuti, E. [23 ]
Cecchi, C. [16 ,17 ]
Celik, Oe.
Charles, E. [3 ,4 ]
Chaty, S. [10 ]
Chekhtman, A. [2 ,24 ]
Cheung, C. C.
Chiang, J. [3 ,4 ]
Ciprini, S. [16 ,17 ]
Claus, R. [3 ,4 ]
Cohen-Tanugi, J. [25 ]
Cominsky, L. R. [26 ]
Conrad, J. [7 ,27 ,28 ]
Corbel, S. [10 ]
Corbet, R. [29 ]
Cutini, S. [23 ]
Dermer, C. D. [2 ]
de Angelis, A. [30 ,31 ]
de Luca, A. [32 ]
de Palma, F. [18 ,19 ]
Digel, S. W. [3 ,4 ]
Dormody, M. [5 ,6 ]
do Couto e Silva, E. [3 ,4 ]
Drell, P. S. [3 ,4 ]
机构
[1] Natl Acad Sci, Natl Res Council Res Associate, Washington, DC 20001 USA
[2] USN, Div Space Sci, Res Lab, Washington, DC 20375 USA
[3] Stanford Univ, WW Hansen Expt Phys Lab, Kavli Inst Particle Astrophys & Cosmol, Dept Phys, Stanford, CA 94305 USA
[4] Stanford Univ, WW Hansen Expt Phys Lab, Kavli Inst Particle Astrophys & Cosmol, SLAC Natl Accelerator Lab, Stanford, CA 94305 USA
[5] Univ Calif Santa Cruz, Santa Cruz Inst Particle Phys, Dept Phys, Santa Cruz, CA 95064 USA
[6] Univ Calif Santa Cruz, Santa Cruz Inst Particle Phys, Dept Astron & Astrophys, Santa Cruz, CA 95064 USA
[7] Oskar Klein Ctr Cosmo Particle Phys, SE-10691 Stockholm, Sweden
[8] Stockholm Univ, Dept Astron, SE-10691 Stockholm, Sweden
[9] Ist Nazl Fis Nucl, I-56127 Pisa, Italy
[10] Univ Paris Diderot, Serv Astrophys, CEA Saclay, CNRS,Lab AIM,CEA IRFU, F-91191 Gif Sur Yvette, France
[11] Sez Trieste, Ist Nazl Fis Nucl, I-34127 Trieste, Italy
[12] Univ Trieste, Dipartimento Fis, I-34127 Trieste, Italy
[13] Sez Padova, Ist Nazl Fis Nucl, I-35131 Padua, Italy
[14] Univ Padua, Dipartimento Fis G Galilei, I-35131 Padua, Italy
[15] Ohio State Univ, Dept Phys, Ctr Cosmol & Astroparticle Phys, Columbus, OH 43210 USA
[16] Sez Perugia, Ist Nazl Fis Nucl, I-06123 Perugia, Italy
[17] Univ Perugia, Dipartimento Fis, I-06123 Perugia, Italy
[18] Univ Politecn Bari, Dipartimento Fis M Merlin, I-70126 Bari, Italy
[19] Sez Bari, Ist Nazl Fis Nucl, I-70126 Bari, Italy
[20] Ecole Polytech, CNRS, Lab Leprince Ringuet, IN2P3, F-91128 Palaiseau, France
[21] Univ Washington, Dept Phys, Seattle, WA 98195 USA
[22] Ist Astrofis Spaziale & Fis Cosm, INAF, I-20133 Milan, Italy
[23] Agenzia Spaziale Italiana ASI Sci Data Ctr, I-00044 Rome, Italy
[24] George Mason Univ, Fairfax, VA 22030 USA
[25] Univ Montpellier 2, CNRS, IN2P3, Lab Phys Theor & Astroparticules, Montpellier, France
[26] Sonoma State Univ, Dept Phys & Astron, Rohnert Pk, CA 94928 USA
[27] Royal Inst Technol KTH, Dept Phys, SE-10691 Stockholm, Sweden
[28] Stockholm Univ, Dept Phys, SE-10691 Stockholm, Sweden
[29] Univ Maryland Baltimore Cty, Baltimore, MD 21250 USA
[30] Univ Udine, Dipartimento Fis, I-33100 Udine, Italy
[31] Grp Coll Udine, Sez Trieste, Ist Nazl Fis Nucl, I-33100 Udine, Italy
[32] IUSS, I-27100 Pavia, Italy
[33] Univ Grenoble 1, Observ Sci Univers, F-38041 Grenoble 9, France
[34] CNRS, Ctr Etud Nucl Bordeaux Gradignan, IN2P3, UMR 5797, F-33175 Gradignan, France
[35] Univ Bordeaux, Ctr Etud Nucl Bordeaux Gradignan, UMR 5797, F-33175 Gradignan, France
[36] Hiroshima Univ, Dept Phys Sci, Hiroshima 7398526, Japan
[37] Univ Maryland, College Pk, MD 20742 USA
[38] Univ Alabama, Huntsville, AL 35899 USA
[39] Waseda Univ, Shinjuku Ku, Tokyo 1698050, Japan
[40] RIKEN, Inst Phys & Chem Res, Cosm Radiat Lab, Wako, Saitama 3510198, Japan
[41] Tokyo Inst Technol, Dept Phys, Meguro, Tokyo 1528551, Japan
[42] CNRS UPS, Ctr Etud Spatiale Rayonnements, F-31028 Toulouse 4, France
[43] Sez Roma Tor Vergata, Ist Nazl Fis Nucl, I-00133 Rome, Italy
[44] Univ Tokyo, Grad Sch Sci, Dept Phys, Bunkyo Ku, Tokyo 1130033, Japan
[45] Max Planck Inst Extraterr Phys, D-85748 Garching, Germany
[46] Univ Denver, Dept Phys & Astron, Denver, CO 80208 USA
[47] Sterrenkundig Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands
[48] Inst Ciencies Espai IEEC CSIC, Barcelona 08193, Spain
[49] Leopold Franzens Univ Innsbruck, Inst Astro & Teilchenphys, A-6020 Innsbruck, Austria
[50] NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA
基金
瑞典研究理事会; 美国国家航空航天局;
关键词
binaries: close; gamma rays: observations; stars: variables: other; X-rays: binaries; X-rays: individual (LS I+61 degrees 303); SOURCE 2CG 135+01; I+61 303; MICROQUASAR LS-I+61-303; BINARIES LS-5039; AREA TELESCOPE; PULSAR WIND; SPACED DATA; EGRET DATA; H-ALPHA; COS-B;
D O I
10.1088/0004-637X/701/2/L123
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
This Letter presents the first results from the observations of LS I + 61 degrees 303 using Large Area Telescope data from the Fermi Gamma-Ray Space Telescope between 2008 August and 2009 March. Our results indicate variability that is consistent with the binary period, with the emission being modulated at 26.6 +/- 0.5 days. This constitutes the first detection of orbital periodicity in high-energy gamma rays (20 MeV-100 GeV, HE). The light curve is characterized by a broad peak after periastron, as well as a smaller peak just before apastron. The spectrum is best represented by a power law with an exponential cutoff, yielding an overall flux above 100 MeV of 0.82 +/- 0.03(stat) +/- 0.07(syst) 10(-6) ph cm(-2) s(-1), with a cutoff at 6.3 +/- 1.1(stat) +/- 0.4(syst) GeV and photon index Gamma = 2.21 +/- 0.04(stat) +/- 0.06(syst). There is no significant spectral change with orbital phase. The phase of maximum emission, close to periastron, hints at inverse Compton scattering as the main radiation mechanism. However, previous very high-energy gamma ray (>100 GeV, VHE) observations by MAGIC and VERITAS show peak emission close to apastron. This and the energy cutoff seen with Fermi suggest that the link between HE and VHE gamma rays is nontrivial.
引用
收藏
页码:L123 / L128
页数:6
相关论文
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