THE
                    <i>FERMI</i>
                    LARGE AREA TELESCOPE ON ORBIT: EVENT CLASSIFICATION, INSTRUMENT RESPONSE FUNCTIONS, AND CALIBRATION

Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Atwood, W. B.; Axelsson, M.; Baldini, Luca; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Bonamente, E.; Borgland, A. W.; Bottacini, E.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Corbet, R. H. D.; Cutini, S.; D’Ammando, F.; Davis, David; Angelis, A. De; Deklotz, M.; Palma, F. de; Dermer, C. D.; Digel, S. W.; Silva, E. do Couto e; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Fukazawa, Yasushi; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Giebels, B.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hayashida, M.; Hays, E.; Horan, D.; Hou, X.; Hughes, R.; Jackson, M. S.; Jogler, T.; Jóhannesson, G.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kerr, M.; Knödlseder, J.; Kuss, M.; Landé, J.; Larsson, Stefan; Latronico, L.; Lavalley, C.; Lemoine‐Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Méhault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Моисеев, А. А.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Naumann-Godó, M.; Nemmen, R.; Nishino, Seiji; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Porter, T. A.; Racusin, J. L.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, O.; Reposeur, T.; Reyes, Luis; Ritz, S.; Rochester, Lynn; Romoli, C.; Roth, M.; Sadrozinski, H. F-W.; Sánchez, David; Parkinson, P. M. Saz; Sbarra, C.; Scargle, Jeffrey D.; Sgrò, C.; Siegal‐Gaskins, Jennifer M.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Stephens, T. E.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, Takaaki; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Tosti, G.; Troja, E.; Usher, T.; Vandenbroucke, J.; Klaveren, Brian Van; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wallace, E.; Winer, B. L.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.; Zimmer, S.

doi:10.1088/0067-0049/203/1/4

Cited by 482 publications

(430 citation statements)

References 46 publications

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“…20 We used binned likelihood analysis with the gtlike tool for the light curves and for the average spectral results. Systematic uncertainties can be estimated as ∼8% for the fluxes and ∼0.1 for the spectral slopes (Ackermann et al 2012). …”

Section: Lat Observations and Analysismentioning

confidence: 99%

Fermi-Lat Gamma-Ray Detections of Classical Novae V1369 Centauri 2013 and V5668 Sagittarii 2015

Cheung

Jean

Shore

et al. 2016

ApJ

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108

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We report the Fermi Large Area Telescope (LAT) detections of high-energy (>100 MeV) γ-ray emission from two recent optically bright classical novae, V1369 Centauri 2013 and V5668 Sagittarii 2015. At early times, Fermi target-of-opportunity observations prompted by their optical discoveries provided enhanced LAT exposure that enabled the detections of γ-ray onsets beginning ∼2 days after their first optical peaks. Significant γ-ray emission was found extending to 39-55 days after their initial LAT detections, with systematically fainter and longerduration emission compared to previous γ-ray-detected classical novae. These novae were distinguished by multiple bright optical peaks that encompassed the time spans of the observed γ-rays. The γ-ray light curves and spectra of the two novae are presented along with representative hadronic and leptonic models, and comparisons with other novae detected by the LAT are discussed.

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Section: Lat Observations and Analysismentioning

confidence: 99%

Fermi-Lat Gamma-Ray Detections of Classical Novae V1369 Centauri 2013 and V5668 Sagittarii 2015

Cheung

Jean

Shore

et al. 2016

ApJ

Self Cite

108

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“…The data set was produced with the so-called Pass 7 reprocessed (P7REP) version of the event analysis and selection criteria, which takes into account effects measured in flight that were not considered in pre-launch performance estimates, such as pile-up and accidental coincidence effects in the detector subsystems (Ackermann et al 2012a), and updated calibration constants, to include effects such as the degradation in the calorimeter light yield (Bregeon et al 2013). SOURCE class events were used in this work, excluding those coming from zenith angles larger than 100 • or detected when the rocking angle of the satellite was larger than 52 • to reduce contamination by atmospheric γ-rays from the Earth.…”

Section: Data Selectionmentioning

confidence: 99%

“…The inferred properties of the sources may also be affected by uncertainties in the characterisation of the LAT instrument. According to Ackermann et al (2012a), the magnitude of the systematic error arising from uncertainties in the effective area, point spread function, and energy dispersion, is about 0.1 on the spectral index and about 10% on the photon and energy fluxes (for the analysis of a not-too-hard point source in the 0.1−100 GeV range). These systematic uncertainties are therefore of the same order as the statistical uncertainties on spectral indices and fluxes for the three brightest point sources in the LMC.…”

Section: Systematic Uncertaintiesmentioning

confidence: 99%

Deep view of the Large Magellanic Cloud with six years ofFermi-LAT observations

Ackermann¹,

Albert²,

Atwood³

et al. 2016

A&A

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Context. The nearby Large Magellanic Cloud (LMC) provides a rare opportunity of a spatially resolved view of an external star-forming galaxy in γ-rays. The LMC was detected at 0.1-100 GeV as an extended source with CGRO/EGRET and using early observations with the Fermi-LAT. The emission was found to correlate with massive star-forming regions and to be particularly bright towards 30 Doradus. Aims. Studies of the origin and transport of cosmic rays (CRs) in the Milky Way are frequently hampered by line-of-sight confusion and poor distance determination. The LMC offers a complementary way to address these questions by revealing whether and how the γ-ray emission is connected to specific objects, populations of objects, and structures in the galaxy. Methods. We revisited the γ-ray emission from the LMC using about 73 months of Fermi-LAT P7REP data in the 0.2-100 GeV range. We developed a complete spatial and spectral model of the LMC emission, for which we tested several approaches: a simple geometrical description, template-fitting, and a physically driven model for CR-induced interstellar emission. Results. In addition to identifying PSR J0540−6919 through its pulsations, we find two hard sources positionally coincident with plerion N 157B and supernova remnant N 132D, which were also detected at TeV energies with H.E.S.S. We detect an additional soft source that is currently unidentified. Extended emission dominates the total flux from the LMC. It consists of an extended component of about the size of the galaxy and additional emission from three to four regions with degree-scale sizes. If it is interpreted as CRs interacting with interstellar gas, the large-scale emission implies a large-scale population of ∼1-100 GeV CRs with a density of ∼30% of the local Galactic value. On top of that, the three to four small-scale emission regions would correspond to enhancements of the CR density by factors 2 to 6 or higher, possibly more energetic and younger populations of CRs compared to the large-scale population. An alternative explanation is that this is emission from an unresolved population of at least two dozen objects, such as pulsars and their nebulae or supernova remnants. This small-scale extended emission has a spatial distribution that does not clearly correlate with known components of the LMC, except for a possible relation to cavities and supergiant shells. Conclusions. The Fermi-LAT GeV observations allowed us to detect individual sources in the LMC. Three of the newly discovered sources are associated with rare and extreme objects. The 30 Doradus region is prominent in GeV γ-rays because PSR J0540−6919 and N 157B are strong emitters. The extended emission from the galaxy has an unexpected spatial distribution, and observations at higher energies and in radio may help to clarify its origin.

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“…We checked that the inclusion of a larger number of sources to the fit did not significantly affect the derived light curve, resulting only in minor changes of the flux estimates. In this way, we extracted the source fluxes in the 0.1−510 GeV energy band (the maximal energy is set by the maximal energy considered in the Pass 7 Instrument Response Functions, Ackermann et al 2012). We estimated the significance of detection in each time bin using the test statistic value (TS, Mattox et al 1996), obtained from the fit.…”

Section: Fermi/lat Data Analysismentioning

confidence: 99%

Microlensingconstraintson the size of the gamma-ray emission region in blazar B0218+357

Vovk

Neronov

2016

A&A

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Context.Observations of the effect of microlensing in gravitationally lensed quasars could potentially be used to study the structure of the source on very small distance scales -down to the size of the supermassive black hole, that powers the quasar activity. Aims. We search for the microlensing effect in the γ-ray band using the signal from a gravitationally lensed blazar, B0218+357. Methods. We develop a method to deconvolve the contributions from the two images of the source, which allows us to reconstruct the flaring light curve in the γ-ray band. We use this method to study the evolution of the magnification factor ratio between the two images throughout the flaring episodes. We interpret the time variability of the ratio as a signature of the microlensing effect and derive constraints on the physical parameters of the γ-ray source by comparing the observed variability properties of the magnification factor ratio with those derived from numerical simulations of the microlensing caustics networks. Results. We find that the magnification factor ratio experienced a change characteristic for a caustic-crossing microlensing event that occurred during a 100 d flaring period in 2012. It changed again between 2012 and a recent flaring episode in 2014. We use the measurement of the maximal magnification and duration of the caustic-crossing event to derive an estimate of the projected size of the γ-ray emission region in B0218+357, R γ ∼ 10 14 −10 15 cm. This estimate is compatible with a complementary estimate found from the minimal variability time scale. The microlensing/minimal variability time scale measurements of the source size suggest that the γ-ray emission is produced at the base of the blazar jet, in the direct vicinity of the central supermassive black hole.

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THE FERMI LARGE AREA TELESCOPE ON ORBIT: EVENT CLASSIFICATION, INSTRUMENT RESPONSE FUNCTIONS, AND CALIBRATION

Cited by 482 publications

References 46 publications

Fermi-Lat Gamma-Ray Detections of Classical Novae V1369 Centauri 2013 and V5668 Sagittarii 2015

Fermi-Lat Gamma-Ray Detections of Classical Novae V1369 Centauri 2013 and V5668 Sagittarii 2015

Deep view of the Large Magellanic Cloud with six years ofFermi-LAT observations

Microlensingconstraintson the size of the gamma-ray emission region in blazar B0218+357

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