The Fermi Large Area Telescope On Orbit: Event Classification, Instrument Response Functions, and Calibration

By F. Collaboration. 2012

194 citations recorded by the source corpus.

The Fermi Large Area Telescope (Fermi -LAT, hereafter LAT), the primary instrument on the Fermi Gamma-ray Space Telescope (Fermi) mission, is an imaging, wide field-of-view, high-energy γ-ray telescope, covering the energy range from 20 MeV to more than 300 GeV. During the first years of the mission the LAT team has gained considerable insight into the in-flight performance of the instrument. Accordingly, we have updated the analysis used to reduce LAT data for public release as well as the Instrument Response Functions (IRFs), the description of the instrument performance provided for data analysis. In this paper we describe the effects that motivated these updates. Furthermore, we discuss how we originally derived IRFs from Monte Carlo simulations and later corrected those IRFs for discrepancies observed between flight and simulated data. We also give details of the validations performed using flight data and quantify the residual uncertainties in the IRFs. Finally, we describe techniques the LAT team has developed to propagate those uncertainties into estimates of the systematic errors on common measurements such as fluxes and spectra of astrophysical sources. Subject headings: instrumentation: detectors – instrumentation: miscellaneous – methods: data analysis – methods: observational – telescopes

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/e776b43b6211e9d33599024ca105dc03ccd53fba

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Citations in the corpus

THE SPECTRUM OF ISOTROPIC DIFFUSE GAMMA-RAY EMISSION BETWEEN 100 MeV AND 820 GeV (2014, methodology): “…density of H2 gas (WCO > 2.5 K km s −1) along the respective line of sight as well as lines of sight with a significant column density of Hi gas (NHI > 5×1020 cm−2) located beyond our local solar neighborhood (8 kpc < r <10 kpc) according to the gas distribution model in Ackermann et al. (2012b).”
Sensitivity of the high altitude water Cherenkov detector to sources of multi-TeV gamma rays (2013, unknown): “Quarter-decade energy bins are found by normalizing the bins in Table 1 to facilitate comparison to 50-hour IACT[3][16][17] and 3-year Fermi[18] sensitivity calculations.”
Limits on dark matter annihilation signals from the Fermi LAT 4-year measurement of the isotropic gamma-ray background (2015, methodology): “To account for bin-to-bin correlations of the systematic uncertainty of the effective area we included correlations on the scale of three adjacent energy bins [97].”
Search for gamma-ray spectral lines with the Fermi Large Area Telescope and dark matter implications (2013, unknown): “Finally, blue squares show where hits in the CAL were detected; the size of the squares corresponds to the amount of energy deposited.[31]”
In wino veritas? Indirect searches shed light on neutralino dark matter (2013, methodology): “Given the current energy resolutions of both experiments ∼ > 10 GeV, this is a reasonable approximation for m χ̃0 ≥ 200 GeV [53, 58].”
Sensitivity projections for dark matter searches with the Fermi large area telescope (2016, methodology): “The first was with “Pass 7” [79], which consists of the same event reconstruction algorithms, but updated event classification criteria to account for knowledge gained about the LAT performance and charged-particle backgrounds since launch.”