FERMI LARGE AREA TELESCOPE DETECTION OF GRAVITATIONAL LENS DELAYED γ-RAY FLARES FROM BLAZAR B0218+357

Journal Article · Thu Feb 20 00:00:00 EST 2014 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/782/2/L14· OSTI ID:22363985

Cheung, C. C.; Grove, J. E. ^[1]; Larsson, S. ^[2]; Scargle, J. D. ^[3]; Amin, M. A. ^[4]; Blandford, R. D.; Chiang, J.; Marshall, P. J. ^[5]; Bulmash, D. ^[6]; Ciprini, S. ^[7]; Corbet, R. H. D. ^[8]; Falco, E. E. ^[9]; Wood, D. L. ^[10]; Ajello, M. ^[11]; Bastieri, D. ^[12]; Chekhtman, A. ^[13]; D'Ammando, F.; Giroletti, M. ^[14]; Lott, B. ^[15]; others, and

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1. Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States)
2. Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm (Sweden)
3. Space Sciences Division, NASA Ames Research Center, Moffett Field, CA 94035-1000 (United States)
4. Kavli Institute for Cosmology and Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
5. W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)
6. Department of Physics, Stanford University, Stanford, CA 94305 (United States)
7. Agenzia Spaziale Italiana (ASI) Science Data Center, I-00133 Roma (Italy)
8. Center for Research and Exploration in Space Science and Technology (CRESST) and NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
9. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
10. Praxis Inc., Alexandria, VA 22303 (United States)
11. Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States)
12. Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy)
13. Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030 (United States)
14. INAF Istituto di Radioastronomia, I-40129 Bologna (Italy)
15. Centre d'Études Nucléaires de Bordeaux Gradignan, IN2P3/CNRS, Université Bordeaux 1, BP120, F-33175 Gradignan Cedex (France)

Using data from the Fermi Large Area Telescope (LAT), we report the first clear γ-ray measurement of a delay between flares from the gravitationally lensed images of a blazar. The delay was detected in B0218+357, a known double-image lensed system, during a period of enhanced γ-ray activity with peak fluxes consistently observed to reach >20-50 × its previous average flux. An auto-correlation function analysis identified a delay in the γ-ray data of 11.46 ± 0.16 days (1σ) that is ∼1 day greater than previous radio measurements. Considering that it is beyond the capabilities of the LAT to spatially resolve the two images, we nevertheless decomposed individual sequences of superposing γ-ray flares/delayed emissions. In three such ∼8-10 day-long sequences within a ∼4 month span, considering confusion due to overlapping flaring emission and flux measurement uncertainties, we found flux ratios consistent with ∼1, thus systematically smaller than those from radio observations. During the first, best-defined flare, the delayed emission was detailed with a Fermi pointing, and we observed flux doubling timescales of ∼3-6 hr implying as well extremely compact γ-ray emitting regions.

• OSTI ID: 22363985
• Journal Information: Astrophysical Journal Letters, Vol. 782, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BLACK HOLES
CORRELATION FUNCTIONS
GALAXIES
GAMMA DETECTION
GAMMA RADIATION
GRAVITATIONAL LENSES
IMAGES
PHOTON EMISSION
QUASARS
STELLAR FLARES
TELESCOPES