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Sample records for first-year fermi large

  1. Fermi GBM: Highlights from the First Year

    NASA Technical Reports Server (NTRS)

    Wilson-Hodge, Colleen A.

    2009-01-01

    The Fermi Gamma ray Burst Monitor is an all-sky instrument sensitive to photons from about 8 keV to 40 MeV. I will summarize highlights from the first year, including triggered observations of gamma ray bursts, soft gamma ray repeaters, and terrestrial gamma flashes, and observations in the continuous data of X-ray binaries and accreting X-ray pulsars. GBM provides complementary observations to Swift/BAT, observing many of the same sources, but over a wider energy range.

  2. The Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived From First-Year Fermi Large Area Telescope Data

    SciTech Connect

    Abdo, A. A.

    2011-08-19

    We report on the first Fermi Large Area Telescope (LAT) measurements of the so-called 'extra-galactic' diffuse {gamma}-ray emission (EGB). This component of the diffuse {gamma}-ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modelling of the bright foreground diffuse Galactic {gamma}-ray emission (DGE), the detected LAT sources and the solar {gamma}-ray emission. We find the spectrum of the EGB is consistent with a power law with differential spectral index {gamma} = 2.41 {+-} 0.05 and intensity, I(> 100 MeV) = (1.03 {+-} 0.17) x 10{sup -5} cm{sup -2} s{sup -1} sr{sup -1}, where the error is systematics dominated. Our EGB spectrum is featureless, less intense, and softer than that derived from EGRET data.

  3. Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived from First-Year Fermi Large Area Telescope Data

    DOE PAGES

    Abdo, A. A.

    2010-03-08

    Here, we report on the first Fermi Large Area Telescope (LAT) measurements of the so-called “extragalactic” diffuse γ -ray emission (EGB). This component of the diffuse γ -ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modeling of the bright foreground diffuse Galactic γ -ray emission, the detected LAT sources, and the solar γ -ray emission. We also find the spectrum of the EGB is consistent with a power law with a differential spectral index γ =more » 2.41 ± 0.05 and intensity I ( > 100 MeV ) = ( 1.03 ± 0.17 ) × 10 - 5 cm -2 s - 1 sr - 1 , where the error is systematics dominated. The EGB spectrum, presented here, is featureless, less intense, and softer than that derived from EGRET data.« less

  4. Fermi GBM: Results from the First Year +

    NASA Technical Reports Server (NTRS)

    Wilson-Hodge, Colleen A.

    2009-01-01

    Gamma-ray Burst Monitor (GBM) has performed well in the first year+. GBM triggers 353 Gamma-ray Bursts (GRBs), 168 SGR events, 18 TGFs, and 1 solar flare to date. Short GRBs appear contracted in time and shifted to higher energy than long GRBs. Pulsed persistent emission from SGR 1550-5418 detected. TGFs are shorter, have higher average photon energies, and much higher count rates than GRBs. GBM monitoring of accreting pulsars provides long-term spin-histories. GBM Earth occultation monitoring complements Swift.

  5. A First Year View of the Galaxy with the Fermi Gamma-ray Space Telescope

    NASA Technical Reports Server (NTRS)

    Hays, Elizabeth

    2009-01-01

    After one year of survey observations and more than 70 billion triggers, Fermi is revealing an unprecedented view of the high energy gamma-ray sky. The observatory carries two instruments, the Gamma-ray Burst Monitor (GBM, 8 keV - 40 MeV) and the Large Area Telescope (LAT, 20 MeV - X300 GeV), which in combination cover over 7 orders of magnitude in energy. The LAT provides substantially more sensitivity than previous instruments in this waveband and has opened up the energy window from 10-100 GeV. This is particularly relevant for the study of gamma-ray sources in the Galaxy. The first year data have revealed new classes of Galactic emitters as well as providing spectacular detail on some old friends. I'll review the fascinating range of Galactic emission now seen - from pulsars their nebulae to X-ray binaries and supernova remnants - with particular emphasis on the impact of the Fermi pulsars.

  6. First Year Results from the Fermi Gamma-Ray Space Telescope

    NASA Technical Reports Server (NTRS)

    Hays, Elizabeth

    2009-01-01

    After one year of survey observations and more than 70 billion triggers, Fermi is revealing an unprecedented view of the high energy gamma-ray sky. The observatory .carries two instruments, the Gamma-ray Burst Monitor (GB, 8 keV - 40 MeV) and the Large Area Telescope (LAT, 20 MeV greater than or equal to 300 GeV), which in combination cover over 7 orders of magnitude in energy for transient phenomena. The LAT provides substantially more sensitivity than previous instruments in this waveband and has opened up the energy window from 10-100 GeV. The first year has produced many important results, from detections of extremely energetic and distant gamma-ray bursts, to monitoring daily variations in emission caused by massive black holes at the cores of galaxies, to identifying a new population of gamma-ray bright pulsars, to measuring the spectrum of diffuse emission from our own. Galaxy and the spectrum of the local cosmic electrons. I'll review highlights from the first year and discuss how the data are answering questions from the past and raising new ones for the future.

  7. On flipping the classroom in large first year calculus courses

    NASA Astrophysics Data System (ADS)

    Jungić, Veselin; Kaur, Harpreet; Mulholland, Jamie; Xin, Cindy

    2015-05-01

    Over the course of two years, 2012--2014, we have implemented a 'flipping' the classroom approach in three of our large enrolment first year calculus courses: differential and integral calculus for scientists and engineers. In this article we describe the details of our particular approach and share with the reader some experiences of both instructors and students.

  8. On Flipping the Classroom in Large First Year Calculus Courses

    ERIC Educational Resources Information Center

    Jungic, Veselin; Kaur, Harpreet; Mulholland, Jamie; Xin, Cindy

    2015-01-01

    Over the course of two years, 2012-2014, we have implemented a "flipping" the classroom approach in three of our large enrolment first year calculus courses: differential and integral calculus for scientists and engineers. In this article we describe the details of our particular approach and share with the reader some experiences of…

  9. On Flipping the Classroom in Large First Year Calculus Courses

    ERIC Educational Resources Information Center

    Jungic, Veselin; Kaur, Harpreet; Mulholland, Jamie; Xin, Cindy

    2015-01-01

    Over the course of two years, 2012-2014, we have implemented a "flipping" the classroom approach in three of our large enrolment first year calculus courses: differential and integral calculus for scientists and engineers. In this article we describe the details of our particular approach and share with the reader some experiences of…

  10. The vela pulsar: results from the first year of FERMI lat observations

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2010-03-18

    Here, we report on analysis of timing and spectroscopy of the Vela pulsar using 11 months of observations with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. The intrinsic brightness of Vela at GeV energies combined with the angular resolution and sensitivity of the LAT allows us to make the most detailed study to date of the energy-dependent light curves and phase-resolved spectra, using a LAT-derived timing model. The light curve consists of two peaks (P1 and P2) connected by bridge emission containing a third peak (P3). We have confirmed the strong decrease of the P1/P2 ratiomore » with increasing energy seen with EGRET and previous Fermi LAT data, and observe that P1 disappears above 20 GeV. The increase with energy of the mean phase of the P3 component can be followed with much greater detail, showing that P3 and P2 are present up to the highest energies of pulsation. We find significant pulsed emission at phases outside the main profile, indicating that magnetospheric emission exists over 80% of the pulsar period. With increased high-energy counts the phase-averaged spectrum is seen to depart from a power law with simple exponential cutoff, and is better fit with a more gradual cutoff. The spectra in fixed-count phase bins are well fit with power laws with exponential cutoffs, revealing a strong and complex phase dependence of the cutoff energy, especially in the peaks. Finally, by combining these results with predictions of the outer magnetosphere models that map emission characteristics to phase, it will be possible to probe the particle acceleration and the structure of the pulsar magnetosphere with unprecedented detail.« less

  11. Fermi's Large Area Telescope (LAT)

    NASA Image and Video Library

    Fermi’s Large Area Telescope (LAT) is the spacecraft’s main scientificinstrument. This animation shows a gamma ray (purple) entering the LAT,where it is converted into an electron (red) and a...

  12. FIRST-YEAR RESULTS OF BROADBAND SPECTROSCOPY OF THE BRIGHTEST FERMI-GBM GAMMA-RAY BURSTS

    SciTech Connect

    Bissaldi, Elisabetta; Von Kienlin, Andreas; Greiner, Jochen; Gruber, David; Lichti, Giselher; Diehl, Roland; Foley, Suzanne; Kouveliotou, Chryssa; Fishman, Gerald J.; Fitzpatrick, Gerard; Gibby, Melissa H.; Giles, Misty M.; Van der Horst, Alexander J.

    2011-06-01

    We present our results of the temporal and spectral analysis of a sample of 52 bright and hard gamma-ray bursts (GRBs) observed with the Fermi Gamma-ray Burst Monitor (GBM) during its first year of operation (2008 July-2009 July).Our sample was selected from a total of 253 GBM GRBs based on the event peak count rate measured between 0.2 and 40 MeV. The final sample comprised of 34 long and 18 short GRBs. These numbers show that the GBM sample contains a much larger fraction of short GRBs than the CGRO/BATSE data set, which we explain as the result of our (different) selection criteria, which favor collection of short, bright GRBs over BATSE. A first by-product of our selection methodology is the determination of a detection threshold from the GBM data alone, above which GRBs most likely will be detected in the MeV/GeV range with the Large Area Telescope on board Fermi. This predictor will be very useful for future multi-wavelength GRB follow-ups with ground- and space-based observatories. Further, we have estimated the burst durations up to 10 MeV and for the first time expanded the duration-energy relationship in the GRB light curves to high energies. We confirm that GRB durations decline with energy as a power law with index approximately -0.4, as was found earlier with the BATSE data and we also notice evidence of a possible cutoff or break at higher energies. Finally, we performed time-integrated spectral analysis of all 52 bursts and compared their spectral parameters with those obtained with the larger data sample of the BATSE data. We find that the two parameter data sets are similar and confirm that short GRBs are in general harder than longer ones.

  13. The Fermi Gamma-Ray Burst Monitor: Results from the first year and spectral analysis of GRB 090323 and GRB 090328

    NASA Astrophysics Data System (ADS)

    Bissaldi, Elisabetta

    2010-03-01

    In the first year since the launch of the Fermi Observatory, the Gamma-ray Burst Monitor (GBM) has detected over 250 gamma-ray bursts (GRBs). Besides GRBs, GBM has triggered on other transient sources, such as soft gamma-ray repeaters and terrestrial gamma-ray flashes. Here we present an overview of the capabilities and scientific goals of the GBM, both by itself and in conjunction with the Large Area Telescope (LAT). The wide energy coverage of the two instruments gives an unprecedented view of the broadband emission and energetics of GRBs, spanning almost 7 decades in energy. Out of a total of 9 LAT GRBs detected up to July 31, 2009, 8 showed extended emission. GBM spectral analysis results from two such events, GRBs 090323 and 090328, are discussed.

  14. Enhancing Student Engagement in Large, Non-Disciplinary First Year Survey Courses

    ERIC Educational Resources Information Center

    Baldwin, Annabelle; Koh, Ernest

    2012-01-01

    Large first year survey units pose unique challenges to both teachers and learners. Survey units are designed to deliver non-disciplinary specific knowledge about a given subject to a wide audience of learners. However, first year students in these units often find that they are unable to identify the architecture of such units, and are hence…

  15. Supernova Remnants with Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Caragiulo, M.; Di Venere, L.

    2017-03-01

    The Large Area Telescope (LAT), on-board the Fermi satellite, proved to be, after 8 years of data taking, an excellent instrument to detect and observe Supernova Remnants (SNRs) in a range of energies running from few hundred MeV up to few hundred GeV. It provides essential information on physical processes that occur at the source, involving both accelerated leptons and hadrons, in order to understand the mechanisms responsible for the primary Cosmic Ray (CR) acceleration. We show the latest results in the observation of Galactic SNRs by Fermi-LAT.

  16. Assessing Core Manipulative Skills in a Large, First-Year Laboratory

    ERIC Educational Resources Information Center

    Moni, Roger W.; Hryciw, Deanne H.; Poronnik, Philip; Lluka, Lesley J.; Moni, Karen B.

    2007-01-01

    Responding to the concern from our faculty that undergraduate students do not have robust laboratory skills, we designed and implemented a strategy to individually teach and assess the manipulative skills of students in first-year laboratories. Five core laboratory skills were selected for the course entitled Human Biology, a large, first-year…

  17. Establishing Peer Mentor-Led Writing Groups in Large First-Year Courses

    ERIC Educational Resources Information Center

    Marcoux, Sarah; Marken, Liv; Yu, Stan

    2012-01-01

    This paper describes the results of a pilot project designed to improve students' academic writing in a large (200-student) first-year Agriculture class at the University of Saskatchewan. In collaboration with the course's professor, the Writing Centre coordinator and a summer student designed curriculum for four two-hour Writing Group sessions…

  18. Biohorizons: An eConference to Assess Human Biology in Large, First-Year Classes

    ERIC Educational Resources Information Center

    Moni, Roger W.; Moni, Karen B.; Poronnik, Philip; Lluka, Lesley J.

    2007-01-01

    The authors detail the design, implementation and evaluation of an eConference entitled "Biohorizons," using a presage-process-product model to describe the development of an eLearning community. Biohorizons was a summative learning and assessment task aiming to introduce large classes of first-year Human Biology students to the practices of…

  19. Integration of Information Literacy Components into a Large First-Year Lecture-Based Chemistry Course

    ERIC Educational Resources Information Center

    Locknar, Angela; Mitchell, Rudolph; Rankin, Janet; Sadoway, Donald R.

    2012-01-01

    A first-year chemistry course is ideal for introducing students to finding and using scholarly information early in their academic careers. A four-pronged approach (lectures, homework problems, videos, and model solutions) was used to incorporate library research skills into a large lecture-based course. Pre- and post-course surveying demonstrated…

  20. Online Lecture Recordings and Lecture Attendance: Investigating Student Preferences in a Large First Year Psychology Course

    ERIC Educational Resources Information Center

    Yeung, Alexandra; Raju, Sadhana; Sharma, Manjula D.

    2016-01-01

    While blended learning has been around for some time, the interplay between lecture recordings, lecture attendance and grades needs further examination particularly for large cohorts of over 1,000 students in 500 seat lecture theatres. This paper reports on such an investigation with a cohort of 1,450 first year psychology students' who indicated…

  1. Assessing Core Manipulative Skills in a Large, First-Year Laboratory

    ERIC Educational Resources Information Center

    Moni, Roger W.; Hryciw, Deanne H.; Poronnik, Philip; Lluka, Lesley J.; Moni, Karen B.

    2007-01-01

    Responding to the concern from our faculty that undergraduate students do not have robust laboratory skills, we designed and implemented a strategy to individually teach and assess the manipulative skills of students in first-year laboratories. Five core laboratory skills were selected for the course entitled Human Biology, a large, first-year…

  2. Biohorizons: An eConference to Assess Human Biology in Large, First-Year Classes

    ERIC Educational Resources Information Center

    Moni, Roger W.; Moni, Karen B.; Poronnik, Philip; Lluka, Lesley J.

    2007-01-01

    The authors detail the design, implementation and evaluation of an eConference entitled "Biohorizons," using a presage-process-product model to describe the development of an eLearning community. Biohorizons was a summative learning and assessment task aiming to introduce large classes of first-year Human Biology students to the practices of…

  3. Fermi large area telescope second source catalog

    SciTech Connect

    Nolan, P. L.; Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Belfiore, A.; Bellazzini, R.; Berenji, B.; Bignami, G. F.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; 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.; Campana, R.; Cañadas, B.; Cannon, A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Ceccanti, M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chipaux, R.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Corbet, R.; Cutini, S.; D'Ammando, F.; Davis, D. S.; de Angelis, A.; DeCesar, M. E.; DeKlotz, M.; De Luca, A.; den Hartog, P. R.; de Palma, F.; Dermer, C. D.; Digel, S. W.; do Couto e Silva, E.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Enoto, T.; Escande, L.; Fabiani, D.; Falletti, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Iafrate, G.; Itoh, R.; Jóhannesson, G.; Johnson, R. P.; Johnson, T. E.; Johnson, A. S.; Johnson, T. J.; Kamae, T.; Katagiri, H.; Kataoka, J.; Katsuta, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Landriu, D.; Latronico, L.; Lemoine-Goumard, M.; Lionetto, A. M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Marelli, M.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Minuti, M.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Norris, J. P.; Nuss, E.; Nymark, T.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Pinchera, M.; Piron, F.; Pivato, G.; Porter, T. A.; Racusin, J. L.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rochester, L. S.; Romani, R. W.; Roth, M.; Rousseau, R.; Ryde, F.; Sadrozinski, H. F. -W.; Salvetti, D.; Sanchez, D. A.; Saz Parkinson, P. M.; Sbarra, C.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Shaw, M. S.; Shrader, C.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stephens, T. E.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Tinebra, F.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vandenbroucke, J.; Van Etten, A.; Van Klaveren, B.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Werner, M.; Winer, B. L.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.; Zimmer, S.

    2012-03-28

    Here, we present the second catalog of high-energy γ-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. Furthermore, we provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. Finally, the 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely γ-ray-producing source classes.

  4. Fermi Large Area Telescope Second Source Catalog

    NASA Technical Reports Server (NTRS)

    Nolan, P. L.; Abdo, A. A.; Ackermann, M.; Ajello, M; Allafort, A.; Antolini, E; Bonnell, J.; Cannon, A.; Celik O.; Corbet, R.; Davis, D. S.; DeCesar, M. E.; Ferrara, E. C.; Gehrels, N.; Harding, A. K.; Hays, E.; Johnson, T. E.; McConville, W.; McEnery, J. E; Perkins, J. S.; Racusin, J. L; Scargle, J. D.; Stephens, T. E.; Thompson, D. J.; Troja, E.

    2012-01-01

    We present the second catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24-month period. The Second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in 5 energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 11eV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely gamma-ray-producing source classes.

  5. FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG

    SciTech Connect

    Nolan, P. L.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Abdo, A. A.; Ackermann, M.; Antolini, E.; Bonamente, E.; Atwood, W. B.; Belfiore, A.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Ballet, J.; Bastieri, D.; Bignami, G. F. E-mail: Gino.Tosti@pg.infn.it E-mail: tburnett@u.washington.edu; and others

    2012-04-01

    We present the second catalog of high-energy {gamma}-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely {gamma}-ray-producing source classes.

  6. Fermi Large Area Telescope Second Source Catalog

    NASA Astrophysics Data System (ADS)

    Nolan, P. L.; Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Belfiore, A.; Bellazzini, R.; Berenji, B.; Bignami, G. F.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; 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.; Campana, R.; Cañadas, B.; Cannon, A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Ceccanti, M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chipaux, R.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Corbet, R.; Cutini, S.; D'Ammando, F.; Davis, D. S.; de Angelis, A.; DeCesar, M. E.; DeKlotz, M.; De Luca, A.; den Hartog, P. R.; de Palma, F.; Dermer, C. D.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Enoto, T.; Escande, L.; Fabiani, D.; Falletti, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Iafrate, G.; Itoh, R.; Jóhannesson, G.; Johnson, R. P.; Johnson, T. E.; Johnson, A. S.; Johnson, T. J.; Kamae, T.; Katagiri, H.; Kataoka, J.; Katsuta, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Landriu, D.; Latronico, L.; Lemoine-Goumard, M.; Lionetto, A. M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Marelli, M.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Minuti, M.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Norris, J. P.; Nuss, E.; Nymark, T.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Pinchera, M.; Piron, F.; Pivato, G.; Porter, T. A.; Racusin, J. L.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rochester, L. S.; Romani, R. W.; Roth, M.; Rousseau, R.; Ryde, F.; Sadrozinski, H. F.-W.; Salvetti, D.; Sanchez, D. A.; Saz Parkinson, P. M.; Sbarra, C.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Shaw, M. S.; Shrader, C.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stephens, T. E.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Tinebra, F.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vandenbroucke, J.; Van Etten, A.; Van Klaveren, B.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Werner, M.; Winer, B. L.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.; Zimmer, S.

    2012-04-01

    We present the second catalog of high-energy γ-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely γ-ray-producing source classes. We dedicate this paper to the memory of our colleague Patrick Nolan, who died on 2011 November 6. His career spanned much of the history of high-energy astronomy from space and his work on the Large Area Telescope (LAT) began nearly 20 years ago when it was just a concept. Pat was a central member in the operation of the LAT collaboration and he is greatly missed.

  7. Fermi large area telescope second source catalog

    DOE PAGES

    Nolan, P. L.; Abdo, A. A.; Ackermann, M.; ...

    2012-03-28

    Here, we present the second catalog of high-energy γ-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are fluxmore » measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. Furthermore, we provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. Finally, the 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely γ-ray-producing source classes.« less

  8. Large optical conductivity of Dirac semimetal Fermi arc surface states

    NASA Astrophysics Data System (ADS)

    Shi, Li-kun; Song, Justin C. W.

    2017-08-01

    Fermi arc surface states, a hallmark of topological Dirac semimetals, can host carriers that exhibit unusual dynamics distinct from that of their parent bulk. Here we find that Fermi arc carriers in intrinsic Dirac semimetals possess a strong and anisotropic light-matter interaction. This is characterized by a large Fermi arc optical conductivity when light is polarized transverse to the Fermi arc; when light is polarized along the Fermi arc, Fermi arc optical conductivity is significantly muted. The large surface spectral weight is locked to the wide separation between Dirac nodes and persists as a large Drude weight of Fermi arc carriers when the system is doped. As a result, large and anisotropic Fermi arc conductivity provides a novel means of optically interrogating the topological surfaces states of Dirac semimetals.

  9. Fermi Large Area Telescope First Source Catalog

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2010-05-25

    Here, we present a catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), during the first 11 months of the science phase of the mission, which began on 2008 August 4. The First Fermi-LAT catalog (1FGL) contains 1451 sources detected and characterized in the 100 MeV to 100 GeV range. Source detection was based on the average flux over the 11 month period, and the threshold likelihood Test Statistic is 25, corresponding to a significance of just over 4σ. The 1FGL catalog includes source location regions,more » defined in terms of elliptical fits to the 95% confidence regions and power-law spectral fits as well as flux measurements in five energy bands for each source. In addition, monthly light curves are provided. Using a protocol defined before launch we have tested for several populations of gamma-ray sources among the sources in the catalog. For individual LAT-detected sources we provide firm identifications or plausible associations with sources in other astronomical catalogs. Identifications are based on correlated variability with counterparts at other wavelengths, or on spin or orbital periodicity. For the catalogs and association criteria that we have selected, 630 of the sources are unassociated. In conclusion, care was taken to characterize the sensitivity of the results to the model of interstellar diffuse gamma-ray emission used to model the bright foreground, with the result that 161 sources at low Galactic latitudes and toward bright local interstellar clouds are flagged as having properties that are strongly dependent on the model or as potentially being due to incorrectly modeled structure in the Galactic diffuse emission.« less

  10. Fermi Large Area Telescope First Source Catalog

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Belli, F.; Berenji, B.; Bisello, D.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Busetto, G.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Campana, R.; Canadas, B.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Ceccanti, M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Cillis, A. N.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Corbet, R.; Davis, D. S.; DeKlotz, M.; den Hartog, P. R.; Dermer, C. D.; de Angelis, A.; de Luca, A.; de Palma, F.; Digel, S. W.; Dormody, M.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Fabiani, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giavitto, G.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Healey, S. E.; Hill, A. B.; Horan, D.; Hughes, R. E.; Iafrate, G.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Landriu, D.; Latronico, L.; Lee, S. -H.; Lemoine-Goumard, M.; Lionetto, A. M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Marangelli, B.; Marelli, M.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Michelson, P. F.; Minuti, M.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakajima, H.; Nakamori, T.; Naumann-Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paccagnella, A.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Pinchera, M.; Piron, F.; Porter, T. A.; Poupard, L.; Rainò, S.; Rando, R.; Ray, P. S.; Razzano, M.; Razzaque, S.; Rea, N.; Reimer, A.; Reimer, O.; Reposeur, T.; Ripken, J.; Ritz, S.; Rochester, L. S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Sadrozinski, H. F. -W.; Salvetti, D.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Schalk, T. L.; Scolieri, G.; Sgrò, C.; Shaw, M. S.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J. -L.; Stephens, T. E.; Striani, E.; Strickman, M. S.; Strong, A. W.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Tinebra, F.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Van Etten, A.; Vasileiou, V.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Watters, K.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ylinen, T.; Ziegler, M.

    2010-05-25

    Here, we present a catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), during the first 11 months of the science phase of the mission, which began on 2008 August 4. The First Fermi-LAT catalog (1FGL) contains 1451 sources detected and characterized in the 100 MeV to 100 GeV range. Source detection was based on the average flux over the 11 month period, and the threshold likelihood Test Statistic is 25, corresponding to a significance of just over 4σ. The 1FGL catalog includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and power-law spectral fits as well as flux measurements in five energy bands for each source. In addition, monthly light curves are provided. Using a protocol defined before launch we have tested for several populations of gamma-ray sources among the sources in the catalog. For individual LAT-detected sources we provide firm identifications or plausible associations with sources in other astronomical catalogs. Identifications are based on correlated variability with counterparts at other wavelengths, or on spin or orbital periodicity. For the catalogs and association criteria that we have selected, 630 of the sources are unassociated. In conclusion, care was taken to characterize the sensitivity of the results to the model of interstellar diffuse gamma-ray emission used to model the bright foreground, with the result that 161 sources at low Galactic latitudes and toward bright local interstellar clouds are flagged as having properties that are strongly dependent on the model or as potentially being due to incorrectly modeled structure in the Galactic diffuse emission.

  11. Fermi Large Area Telescope third source catalog

    DOE PAGES

    Acero, F.; Ackermann, M.; Ajello, M.; ...

    2015-06-12

    Here, we present the third Fermi Large Area Telescope (LAT) source catalog (3FGL) of sources in the 100 MeV–300 GeV range. Based on the first 4 yr of science data from the Fermi Gamma-ray Space Telescope mission, it is the deepest yet in this energy range. Relative to the Second Fermi LAT catalog, the 3FGL catalog incorporates twice as much data, as well as a number of analysis improvements, including improved calibrations at the event reconstruction level, an updated model for Galactic diffuse γ-ray emission, a refined procedure for source detection, and improved methods for associating LAT sources with potential counterparts at other wavelengths. The 3FGL catalog includes 3033 sources abovemore » $$4\\sigma $$ significance, with source location regions, spectral properties, and monthly light curves for each. Of these, 78 are flagged as potentially being due to imperfections in the model for Galactic diffuse emission. Twenty-five sources are modeled explicitly as spatially extended, and overall 238 sources are considered as identified based on angular extent or correlated variability (periodic or otherwise) observed at other wavelengths. For 1010 sources we have not found plausible counterparts at other wavelengths. More than 1100 of the identified or associated sources are active galaxies of the blazar class; several other classes of non-blazar active galaxies are also represented in the 3FGL. Pulsars represent the largest Galactic source class. As a result, from source counts of Galactic sources we estimate that the contribution of unresolved sources to the Galactic diffuse emission is ~3% at 1 GeV.« less

  12. Fermi Large Area Telescope First Source Catalog

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Belli, F.; Berenji, B.; Bisello, D.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Busetto, G.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Campana, R.; Canadas, B.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Ceccanti, M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Cillis, A. N.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Corbet, R.; Davis, D. S.; DeKlotz, M.; den Hartog, P. R.; Dermer, C. D.; de Angelis, A.; de Luca, A.; de Palma, F.; Digel, S. W.; Dormody, M.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Fabiani, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giavitto, G.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Healey, S. E.; Hill, A. B.; Horan, D.; Hughes, R. E.; Iafrate, G.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Landriu, D.; Latronico, L.; Lee, S.-H.; Lemoine-Goumard, M.; Lionetto, A. M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Marangelli, B.; Marelli, M.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Michelson, P. F.; Minuti, M.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakajima, H.; Nakamori, T.; Naumann-Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paccagnella, A.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Pinchera, M.; Piron, F.; Porter, T. A.; Poupard, L.; Rainò, S.; Rando, R.; Ray, P. S.; Razzano, M.; Razzaque, S.; Rea, N.; Reimer, A.; Reimer, O.; Reposeur, T.; Ripken, J.; Ritz, S.; Rochester, L. S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Sadrozinski, H. F.-W.; Salvetti, D.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Schalk, T. L.; Scolieri, G.; Sgrò, C.; Shaw, M. S.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J.-L.; Stephens, T. E.; Striani, E.; Strickman, M. S.; Strong, A. W.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Tinebra, F.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Van Etten, A.; Vasileiou, V.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Watters, K.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ylinen, T.; Ziegler, M.; Fermi LAT Collaboration

    2010-06-01

    We present a catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), during the first 11 months of the science phase of the mission, which began on 2008 August 4. The First Fermi-LAT catalog (1FGL) contains 1451 sources detected and characterized in the 100 MeV to 100 GeV range. Source detection was based on the average flux over the 11 month period, and the threshold likelihood Test Statistic is 25, corresponding to a significance of just over 4σ. The 1FGL catalog includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and power-law spectral fits as well as flux measurements in five energy bands for each source. In addition, monthly light curves are provided. Using a protocol defined before launch we have tested for several populations of gamma-ray sources among the sources in the catalog. For individual LAT-detected sources we provide firm identifications or plausible associations with sources in other astronomical catalogs. Identifications are based on correlated variability with counterparts at other wavelengths, or on spin or orbital periodicity. For the catalogs and association criteria that we have selected, 630 of the sources are unassociated. Care was taken to characterize the sensitivity of the results to the model of interstellar diffuse gamma-ray emission used to model the bright foreground, with the result that 161 sources at low Galactic latitudes and toward bright local interstellar clouds are flagged as having properties that are strongly dependent on the model or as potentially being due to incorrectly modeled structure in the Galactic diffuse emission.

  13. A First-Year Chemistry Undergraduate "Course Community" at a Large, Research-Intensive University

    ERIC Educational Resources Information Center

    De La Franier, Brian J.; Diep, Jenny; Menzies, Perry J. C.; Morra, Barbora; Koroluk, Katherine J.; Dicks, Andrew P.

    2016-01-01

    This article describes the integration of a cocurricular "Community" into a first-year undergraduate chemistry course at the University of Toronto. The Community has been in existence since 2006, with over 700 students being involved. Its broad objectives have been three-fold: to inform course members about departmental resources and…

  14. A First-Year Chemistry Undergraduate "Course Community" at a Large, Research-Intensive University

    ERIC Educational Resources Information Center

    De La Franier, Brian J.; Diep, Jenny; Menzies, Perry J. C.; Morra, Barbora; Koroluk, Katherine J.; Dicks, Andrew P.

    2016-01-01

    This article describes the integration of a cocurricular "Community" into a first-year undergraduate chemistry course at the University of Toronto. The Community has been in existence since 2006, with over 700 students being involved. Its broad objectives have been three-fold: to inform course members about departmental resources and…

  15. Applying results from Physics Education Research in a large first-year service course

    NASA Astrophysics Data System (ADS)

    Ahrensmeier, Daria

    2012-10-01

    First-year service courses are among the most challenging teaching appointments, due to factors such as lack of motivation, lack of academic preparation, and huge class size. I will describe how the Labatorial Project at the University of Calgary strives to apply results from Physics Education research on inquiry-based learning, addressing misconceptions, peer instruction etc. to the small group sections of these courses. After a brief overview of the design and implementation of the labatorials for a first-year course for engineering students, I will focus on the aspects of change management and sustainability: how one initial change led to a sequence of related modifications, from the lectures to the exams and TA training, accompanied by a natural process of faculty professional development.

  16. Applying a Linked-Course Model to Foster Inquiry and Integration across Large First-Year Courses

    ERIC Educational Resources Information Center

    Husband, Brian C.; Bettger, William J.; Murrant, Coral L.; Kirby, Kim; Wright, Patricia A.; Newmaster, Steven G.; Dawson, John F.; Gregory, T. Ryan; Mullen, Robert T.; Nejedly, April; van der Merwe, George; Yankulov, Krassimir; Wolf, Peter

    2015-01-01

    Many first-year university courses are large and content-driven, which can contribute to low student engagement and difficulty involving students in the dynamic, cross-disciplinary nature of inquiry. Learning communities can address these goals, but their implementation often poses logistical challenges, especially in large courses. Here, we apply…

  17. Designed for Learning: A Case Study in Rethinking Teaching and Learning for a Large First Year Class

    ERIC Educational Resources Information Center

    Goldacre, Lisa; Bolt, Susan; Lambiris, Michael

    2013-01-01

    This paper presents a case study in which the principles of scholarship were applied to designing an approach to learning suitable for large classes. While this case study describes an Australian first year Business Law unit, the findings presented in this paper would be relevant to a wide range of teachers faced with large enrollments in first…

  18. Fermi Large Area Telescope Bright Gamma-ray Source List

    SciTech Connect

    Abdo, Aous A.; Ackermann, M.; Ajello, M.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Ballet, J.; Band, D.L.; Barbiellini, Guido; Bastieri, Denis; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bignami, G.F.; Bloom, Elliott D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brigida, M.; Bruel, P.; Burnett, Thompson H.; /more authors..

    2009-05-15

    Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the {gamma}-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than {approx}10{sigma}) {gamma}-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) {gamma}-ray sources in the early mission data.

  19. Student Engagement in a Large Classroom: Using Technology to Generate a Hybridized Problem- Based Learning Experience in a Large First Year Undergraduate Class

    ERIC Educational Resources Information Center

    Fukuzawa, Sherry; Boyd, Cleo

    2016-01-01

    Large first year undergraduate courses have unique challenges in the promotion of student engagement and self-directed learning due to resource constraints that prohibit small group discussions with instructors. The Monthly Virtual Mystery was developed to increase student engagement in a large (N = 725) first year undergraduate class in…

  20. First-Year Students' Perceptions of Instruction in Large Lectures: The Top-10 Mistakes Made by Instructors

    ERIC Educational Resources Information Center

    Richards, K. Andrew R.; Velasquez, Juan D.

    2014-01-01

    Constructivist approaches to education embrace students' prior learning experiences and preference for learning in social environments. However, many postsecondary classes continue to embrace lecture-styles of teaching. This study sought to understand first-year students' perceptions of the mistakes instructors make in large lecture classes.…

  1. First-Year Students' Perceptions of Instruction in Large Lectures: The Top-10 Mistakes Made by Instructors

    ERIC Educational Resources Information Center

    Richards, K. Andrew R.; Velasquez, Juan D.

    2014-01-01

    Constructivist approaches to education embrace students' prior learning experiences and preference for learning in social environments. However, many postsecondary classes continue to embrace lecture-styles of teaching. This study sought to understand first-year students' perceptions of the mistakes instructors make in large lecture classes.…

  2. Technology Supported Facilitation and Assessment of Small Group Collaborative Inquiry Learning in Large First-Year Classes

    ERIC Educational Resources Information Center

    Lawrie, Gwendolyn A.; Gahan, Lawrence R.; Matthews, Kelly E.; Weaver, Gabriela C.; Bailey, Chantal; Adams, Peter; Kavanagh, Lydia J.; Long, Phillip D.; Taylor, Matthew

    2014-01-01

    Collaborative learning activities offer the potential to support mutual knowledge construction and shared understanding amongst students. Introducing collaborative tasks into large first-year undergraduate science classes to create learning environments that foster student engagement and enhance communication skills is appealing. However,…

  3. Large magnetoresistance and Fermi surface topology of PrSb

    NASA Astrophysics Data System (ADS)

    Wu, F.; Guo, C. Y.; Smidman, M.; Zhang, J. L.; Yuan, H. Q.

    2017-09-01

    We report magnetotransport measurements of PrSb in high magnetic fields. Our results show that PrSb exhibits large magnetoresistance at low temperatures. Meanwhile angle-dependent magnetoresistance measurements were used to probe the Fermi surface via Shubnikov-de Haas oscillations. We found that the angular dependence of the oscillation frequency of the α branch can be explained well by a model for a two-dimensional-like Fermi surface, whereas the effective mass of this branch as a function of angle shows a fourfold signature. The evolution of the Fermi surface with increasing magnetic field also was studied up to 32 T. A continuous increase in the oscillation frequency up to 14 T is observed before it becomes constant at higher fields. Meanwhile our analysis of the residual Landau index from the high-field data reveals a zero Berry phase and therefore trivial topology of the Fermi surface.

  4. Managing Active Learning Processes in Large First Year Physics Classes: The Advantages of an Integrated Approach

    ERIC Educational Resources Information Center

    Drinkwater, Michael J.; Gannaway, Deanne; Sheppard, Karen; Davis, Matthew J.; Wegener, Margaret J.; Bowen, Warwick P.; Corney, Joel F.

    2014-01-01

    Turning lectures into interactive, student-led question and answer sessions is known to increase learning, but enabling interaction in a large class seems an insurmountable task. This can discourage adoption of this new approach -- who has time to individualize responses, address questions from over 200 students and encourage active participation…

  5. Introducing a Learning Management System in a Large First Year Class: Impact on Lecturers and Students

    ERIC Educational Resources Information Center

    Snowball, J.; Mostert, M.

    2010-01-01

    The challenges of teaching large classes are well documented in the literature on teaching in higher education. Information and communication technologies (ICTs) have the potential to address some of these challenges, but, used inappropriately, technology can perpetuate entrenched practices and simply support performance models of teaching that…

  6. Fermi Large Area Telescope Operations: Progress Over 4 Years

    SciTech Connect

    Cameron, Robert A.; /SLAC

    2012-06-28

    The Fermi Gamma-ray Space Telescope was launched into orbit in June 2008, and is conducting a multi-year gamma-ray all-sky survey, using the main instrument on Fermi, the Large Area Telescope (LAT). Fermi began its science mission in August 2008, and has now been operating for almost 4 years. The SLAC National Accelerator Laboratory hosts the LAT Instrument Science Operations Center (ISOC), which supports the operation of the LAT in conjunction with the Mission Operations Center (MOC) and the Fermi Science Support Center (FSSC), both at NASA's Goddard Space Flight Center. The LAT has a continuous output data rate of about 1.5 Mbits per second, and data from the LAT are stored on Fermi and transmitted to the ground through TDRS and the MOC to the ISOC about 10 times per day. Several hundred computers at SLAC are used to process LAT data to perform event reconstruction, and gamma-ray photon data are subsequently delivered to the FSSC for public release with a few hours of being detected by the LAT. We summarize the current status of the LAT, and the evolution of the data processing and monitoring performed by the ISOC during the first 4 years of the Fermi mission, together with future plans for further changes to detected event data processing and instrument operations and monitoring.

  7. A method of providing engaging formative feedback to large cohort first-year physiology and anatomy students.

    PubMed

    Weston-Green, Katrina; Wallace, Margaret

    2016-09-01

    A growing body of evidence demonstrates a critical role for effective, meaningful feedback to enhance student learning. Effective feedback can become part of the learning cycle that is not only a learning opportunity for the student but can also be used to inform the teacher and ongoing curriculum development. Feedback is considered particularly important during the first year of university and can even be viewed as a retention strategy that can help attenuate student performance anxieties and solidify perceptions of academic support. Unfortunately, the provision of individualized, timely feedback can be particularly challenging in first-year courses as they tend to be large and diverse cohort classes that pose challenges of time and logistics. Various forms of generic feedback can provide rapid and cost-effect feedback to large cohorts but may be of limited benefit to students other than signaling weaknesses in knowledge. The present study describes a method that was used to provide formative task-related feedback to a large cohort of first-year physiology and anatomy students. Based on student evaluations presented in this study, this method provided feedback in a manner that engaged students, uncovered underlying misconceptions, facilitated peer discussion, and provided opportunity for new instruction while allowing the lecturer to recognize common gaps in knowledge and inform ongoing curriculum development.

  8. Searches for Axionlike Particles with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Albert, Andrea; Meyer, Manuel; Sanchez-Conde, Miguel; Wood, Matthew; LAT Collaboration

    2017-01-01

    Axionlike particles (ALPs) are dark-matter candidates that occur in a variety of extensions of the Standard Model. These particles could leave signatures in gamma rays, due to the coupling of ALPs to photons in external electromagnetic fields. To date, observations with Fermi Large Area Telescope (LAT) provide the strongest constraints on the photon-ALP coupling for ALP masses between 0.5 and 20 neV. Here, we summarize these constraints and present the sensitivity to detect an ALP induced gamma-ray burst from a Galactic core-collapse supernova. ALPs would be produced in the stellar medium via the Primakoff effect and convert into gamma rays in the Galactic magnetic field. Fermi LAT observations would be able to probe couplings where ALPs could constitute the entirety of dark matter. Below 1 neV, the Fermi-LAT sensitivity would surpass that of future laboratory experiments by one order of magnitude.

  9. Searches for cosmic-ray electron anisotropies with the Fermi Large Area Telescope

    DOE PAGES

    Ackermann, M.

    2010-11-01

    The Large Area Telescope on board the Fermi satellite (Fermi LAT) detected more than 1.6 × 106 cosmic-ray electrons/positrons with energies above 60 GeV during its first year of operation. The arrival directions of these events were searched for anisotropies of angular scale extending from ~ 10 ° up to 90°, and of minimum energy extending from 60 GeV up to 480 GeV. Two independent techniques were used to search for anisotropies, both resulting in null results. Upper limits on the degree of the anisotropy were set that depended on the analyzed energy range and on the anisotropy’s angular scale.more » The upper limits for a dipole anisotropy ranged from ~ 0.5 % to ~ 10 % .« less

  10. Searches for cosmic-ray electron anisotropies with the Fermi Large Area Telescope

    SciTech Connect

    Ackermann, M.

    2010-11-01

    The Large Area Telescope on board the Fermi satellite (Fermi LAT) detected more than 1.6 × 106 cosmic-ray electrons/positrons with energies above 60 GeV during its first year of operation. The arrival directions of these events were searched for anisotropies of angular scale extending from ~ 10 ° up to 90°, and of minimum energy extending from 60 GeV up to 480 GeV. Two independent techniques were used to search for anisotropies, both resulting in null results. Upper limits on the degree of the anisotropy were set that depended on the analyzed energy range and on the anisotropy’s angular scale. The upper limits for a dipole anisotropy ranged from ~ 0.5 % to ~ 10 % .

  11. The Fermi Large Area Telescope on Orbit: Event Classification, Instrument Response Functions, and Calibration

    DOE PAGES

    Ackermann, M.; Ajello, M.; Albert, A.; ...

    2012-10-12

    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 study, we describe the effects thatmore » 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. In conclusion, 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.« less

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

    SciTech Connect

    Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Borgland, A. W.; Bottacini, E.; Albert, A.; Atwood, W. B.; Bouvier, A.; Axelsson, M.; Baldini, L.; Ballet, J.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Bonamente, E. E-mail: luca.baldini@pi.infn.it; and others

    2012-11-15

    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 {gamma}-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.

  13. The Fermi Large Area Telescope on Orbit: Event Classification, Instrument Response Functions, and Calibration

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; hide

    2012-01-01

    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 -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.

  14. Closing the feedback loop: engaging students in large first-year mathematics test revision sessions using pen-enabled screens

    NASA Astrophysics Data System (ADS)

    Donovan, Diane; Loch, Birgit

    2013-01-01

    How can active learning, peer learning and prompt feedback be achieved in large first-year mathematics classes? Further, what technologies may support these aims? In this article, we assert that test revision sessions in first-year mathematics held in a technology-enhanced lecture theatre can be highly interactive with students solving problems, learning from each other and receiving immediate feedback. This is facilitated by pen-enabled screens and synchronization software. We argue that the educational benefits achievable through the technology do outweigh the technological distractions, and that these benefits can be achieved by focused, targeted one-off sessions and not only by a semester-long, regular approach. Repeat mid-semester test revision sessions were offered on a non-compulsory basis using pen-enabled screens for all students. Students worked practice test questions and marked solutions to mathematical problems on the screens. Students' work was then displayed anonymously for their peers to see. Answers were discussed with the whole class. We discuss outcomes from two offerings of these sessions using student feedback and lecturer reflections and show the impact of participation on self-reported student confidence. Pedagogical approaches that the technology allowed for the first time in a large class are highlighted. Students responded uniformly positively.

  15. High Energy Astrophysics with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Hays, Elizabeth

    2009-01-01

    This slide presentation reviews some of the findings of the Large Area Telescope (LAT) aboard the Fermi Observatory. It includes information about the LAT, and the Gamma-Ray Burst Monitor (GBM), detection of the quiet sun and the moon in gamma rays, Pulsars observed by the observatory, Globular Star Clusters, Active Galactic Nucleus, and Gamma-Ray Bursts, with specific information about GRB 080916C.

  16. Dark Matter Searches with the Fermi Large Area Telescope

    SciTech Connect

    Meurer, Christine

    2008-12-24

    The Fermi Gamma-Ray Space Telescope, successfully launched on June 11th, 2008, is the next generation satellite experiment for high-energy gamma-ray astronomy. The main instrument, the Fermi Large Area Telescope (LAT), with a wide field of view (>2 sr), a large effective area (>8000 cm{sup 2} at 1 GeV), sub-arcminute source localization, a large energy range (20 MeV-300 GeV) and a good energy resolution (close to 8% at 1 GeV), has excellent potential to either discover or to constrain a Dark Matter signal. The Fermi LAT team pursues complementary searches for signatures of particle Dark Matter in different search regions such as the galactic center, galactic satellites and subhalos, the milky way halo, extragalactic regions as well as the search for spectral lines. In these proceedings we examine the potential of the LAT to detect gamma-rays coming from Weakly Interacting Massive Particle annihilations in these regions with special focus on the galactic center region.

  17. The role of the iPad in collaborative learning in a large-enrollment first-year physics module

    NASA Astrophysics Data System (ADS)

    van der Ventel, Brandon; Newman, Richard; Botes, Lise; Goldberg, Alan

    2016-07-01

    The role of the iPad was investigated in the possible enhancement of collaborative learning within a tutorial setting in a large-enrollment first-year physics module. Every tutorial session was divided into an ‘iPad group’ and a ‘non-iPad group’. A set of core apps was chosen to facilitate discussion within the group. In order to maintain parity across the two groups, all the tutorial questions had to be refitted into a form suitable for use with the iPad. The results of a survey done after each tutorial indicates that, qualitatively, the iPad significantly enhanced the learning experience and strongly contributed to discussion within the group.

  18. Fermi Large Area Telescope as a Galactic Supernovae Axionscope

    DOE PAGES

    Meyer, M.; Giannotti, M.; Mirizzi, A.; ...

    2017-01-06

    In a Galactic core-collapse supernova (SN), axionlike particles (ALPs) could be emitted via the Primakoff process and eventually convert into γ rays in the magnetic field of the Milky Way. From a data-driven sensitivity estimate, we find that, for a SN exploding in our Galaxy, the Fermi Large Area Telescope (LAT) would be able to explore the photon-ALP coupling down to gaγ ≃ 2 × 10-13 GeV-1 for an ALP mass ma ≲ 10-9 eV. Also, these values are out of reach of next generation laboratory experiments. In this event, the Fermi LAT would probe large regions of the ALPmore » parameter space invoked to explain the anomalous transparency of the Universe to γ rays, stellar cooling anomalies, and cold dark matter. Lastly, if no γ-ray emission were to be detected, Fermi-LAT observations would improve current bounds derived from SN 1987A by more than 1 order of magnitude.« less

  19. Fermi Large Area Telescope as a Galactic Supernovae Axionscope

    NASA Astrophysics Data System (ADS)

    Meyer, M.; Giannotti, M.; Mirizzi, A.; Conrad, J.; Sánchez-Conde, M. A.

    2017-01-01

    In a Galactic core-collapse supernova (SN), axionlike particles (ALPs) could be emitted via the Primakoff process and eventually convert into γ rays in the magnetic field of the Milky Way. From a data-driven sensitivity estimate, we find that, for a SN exploding in our Galaxy, the Fermi Large Area Telescope (LAT) would be able to explore the photon-ALP coupling down to ga γ≃2 ×10-13 GeV-1 for an ALP mass ma≲10-9 eV . These values are out of reach of next generation laboratory experiments. In this event, the Fermi LAT would probe large regions of the ALP parameter space invoked to explain the anomalous transparency of the Universe to γ rays, stellar cooling anomalies, and cold dark matter. If no γ -ray emission were to be detected, Fermi-LAT observations would improve current bounds derived from SN 1987A by more than 1 order of magnitude.

  20. Fermi Large Area Telescope as a Galactic Supernovae Axionscope.

    PubMed

    Meyer, M; Giannotti, M; Mirizzi, A; Conrad, J; Sánchez-Conde, M A

    2017-01-06

    In a Galactic core-collapse supernova (SN), axionlike particles (ALPs) could be emitted via the Primakoff process and eventually convert into γ rays in the magnetic field of the Milky Way. From a data-driven sensitivity estimate, we find that, for a SN exploding in our Galaxy, the Fermi Large Area Telescope (LAT) would be able to explore the photon-ALP coupling down to g_{aγ}≃2×10^{-13}  GeV^{-1} for an ALP mass m_{a}≲10^{-9}  eV. These values are out of reach of next generation laboratory experiments. In this event, the Fermi LAT would probe large regions of the ALP parameter space invoked to explain the anomalous transparency of the Universe to γ rays, stellar cooling anomalies, and cold dark matter. If no γ-ray emission were to be detected, Fermi-LAT observations would improve current bounds derived from SN 1987A by more than 1 order of magnitude.

  1. Prospects for GRB science with the Fermi Large Area Telescope

    DOE PAGES

    Band, D. L.; Axelsson, M.; Baldini, L.; ...

    2009-08-04

    The Large Area Telescope (LAT) instrument on the Fermi mission will reveal the rich spectral and temporal gamma-ray burst (GRB) phenomena in the >100 MeV band. The synergy with Fermi's Gamma-ray Burst Monitor detectors will link these observations to those in the well explored 10-1000 keV range; the addition of the >100 MeV band observations will resolve theoretical uncertainties about burst emission in both the prompt and afterglow phases. Trigger algorithms will be applied to the LAT data both onboard the spacecraft and on the ground. Furthermore, the sensitivity of these triggers will differ because of the available computing resourcesmore » onboard and on the ground. Here we present the LAT's burst detection methodologies and the instrument's GRB capabilities.« less

  2. The Second Fermi Large Area Telescope GRB Catalog

    NASA Astrophysics Data System (ADS)

    Kocevski, Daniel; Fermi Large Area Telescope Collaboration

    2017-01-01

    The high-energy emission from gamma-ray bursts (GRBs) is a formidable probe of extreme physics, requiring rapid variability from highly relativistic sources. Despite the advancements in our understanding of GRBs through observations by NASA's Swift and Fermi spacecraft, many fundemental questions regarding the particle acceleration and radiative processes associated with these events remain unanswered. Here we present the most extensive search for emission from GRBs above 40 MeV performed by the Fermi Large Area Telescope (LAT). The resulting catalog includes more than 130 detections and represents an improvement in the detection efficency of GRBs at high-energies of over 50% compared to the first LAT GRB catalog. We utilize this improved sensativity to characterize the high-energy emission from GRBs and review how these observations further our understanding of the nature of these events.

  3. Assessing the First Year of a Large-Scale Salmonid River Restoration Project on the Carmel River, CA

    NASA Astrophysics Data System (ADS)

    Smith, D. P.; Chow, K.; Luna, L.; Conlen, A.; Marson, L.

    2016-12-01

    The 93 year old San Clemente Dam was removed from the Carmel River in 2015 to reduce seismic hazards and to improve steelhead migration. A new 1 km long channel was constructed with a low-gradient meandering section, and a long series of step-pools interspersed with sporadic resting pools and plane-bed reaches. Each step was constructed with approximately 1 ft drop to facilitate steelhead mobility. The channel banks were constructed of well-compacted and vegetated soil lifts encapsulated in jute geotechnical fabric. The adjacent floodplain was graded and covered with vegetated geotechnical fabric. A variety of tall large-wood structures were anchored in the floodplain for hydraulic roughness, and to capture large wood. Following one run-off season, the project shows improved fish passage, salmonids residing in new pools, robust new floodplain vegetation, a veneer of new sediment and wood on floodplain areas, and sediment transport past the former dam location. The strongest components of the project were designed to sustain flows up to the 50-yr event without significant alteration. Significant changes occurred during the first year of operation, although the flows did not exceed the 3-yr event. Many large boulders used to construct arcuate steps were dislodged into the subsequent pools. Several reaches experienced bank erosion leading to geotechnical material disturbance or removal. Several of the large wood structures were compromised by bank erosion, and some were mobilized downstream. Floodwaters locally destroyed a constructed wetland, and produced significant erosional features. If left unchecked, the floodplain alteration could lead to avulsion. Premature boulder transport may have been caused by hydraulic modeling that assumed incorrect boulder density, impact and leveraging from large wood structures liberated from the floodplain, or differences between modeled and actual boulder stacking geometry. Excessive floodplain erosion occurred where pool

  4. Fermi Large Area Telescope third source catalog

    SciTech Connect

    Acero, F.; Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Belfiore, A.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Bonino, R.; Bottacini, E.; Bregeon, J.; Britto, R. J.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caputo, R.; Caragiulo, M.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Tanugi, J. Cohen-; Cominsky, L. R.; Conrad, J.; Cutini, S.; D’Ammando, F.; Angelis, A. de; DeKlotz, M.; Palma, F. de; Desiante, R.; Digel, S. W.; Venere, L. Di; Drell, P. S.; Dubois, R.; Dumora, D.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Finke, J.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hays, E.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Iafrate, G.; Jogler, T.; Jóhannesson, G.; Johnson, R. P.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Kataoka, J.; Katsuta, J.; Kuss, M.; Mura, G. La; Landriu, D.; Larsson, S.; Latronico, L.; Goumard, M. Lemoine-; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mirabal, N.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Perkins, J. S.; Rollins, M. Pesce-; Piron, F.; Pivato, G.; Porter, T. A.; Racusin, J. L.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Rochester, L. S.; Romani, R. W.; Salvetti, D.; Conde, M. Sánchez-; Parkinson, P. M. Saz; Schulz, A.; Siskind, E. J.; Smith, D. A.; Spada, F.; Spandre, G.; Spinelli, P.; Stephens, T. E.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Torresi, E.; Tosti, G.; Troja, E.; Klaveren, B. Van; Vianello, G.; Winer, B. L.; Wood, K. S.; Wood, M.; Zimmer, S.

    2015-06-12

    Here, we present the third Fermi Large Area Telescope (LAT) source catalog (3FGL) of sources in the 100 MeV–300 GeV range. Based on the first 4 yr of science data from the Fermi Gamma-ray Space Telescope mission, it is the deepest yet in this energy range. Relative to the Second Fermi LAT catalog, the 3FGL catalog incorporates twice as much data, as well as a number of analysis improvements, including improved calibrations at the event reconstruction level, an updated model for Galactic diffuse γ-ray emission, a refined procedure for source detection, and improved methods for associating LAT sources with potential counterparts at other wavelengths. The 3FGL catalog includes 3033 sources above $4\\sigma $ significance, with source location regions, spectral properties, and monthly light curves for each. Of these, 78 are flagged as potentially being due to imperfections in the model for Galactic diffuse emission. Twenty-five sources are modeled explicitly as spatially extended, and overall 238 sources are considered as identified based on angular extent or correlated variability (periodic or otherwise) observed at other wavelengths. For 1010 sources we have not found plausible counterparts at other wavelengths. More than 1100 of the identified or associated sources are active galaxies of the blazar class; several other classes of non-blazar active galaxies are also represented in the 3FGL. Pulsars represent the largest Galactic source class. As a result, from source counts of Galactic sources we estimate that the contribution of unresolved sources to the Galactic diffuse emission is ~3% at 1 GeV.

  5. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE VELA PULSAR

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Bartelt, J.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Atwood, W. B.; Bagagli, R.; Baldini, L.; Bellardi, F.; Bellazzini, R.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bisello, D.; Baughman, B. M. E-mail: massimiliano.razzano@pi.infn.it

    2009-05-10

    The Vela pulsar is the brightest persistent source in the GeV sky and thus is the traditional first target for new {gamma}-ray observatories. We report here on initial Fermi Large Area Telescope observations during verification phase pointed exposure and early sky survey scanning. We have used the Vela signal to verify Fermi timing and angular resolution. The high-quality pulse profile, with some 32,400 pulsed photons at E {>=} 0.03 GeV, shows new features, including pulse structure as fine as 0.3 ms and a distinct third peak, which shifts in phase with energy. We examine the high-energy behavior of the pulsed emission; initial spectra suggest a phase-averaged power-law index of {gamma} = 1.51{sup +0.05} {sub -0.04} with an exponential cutoff at E{sub c} = 2.9 {+-} 0.1 GeV. Spectral fits with generalized cutoffs of the form e{sup -(E/E{sub c}){sup b}} require b {<=} 1, which is inconsistent with magnetic pair attenuation, and thus favor outer-magnetosphere emission models. Finally, we report on upper limits to any unpulsed component, as might be associated with a surrounding pulsar wind nebula.

  6. The Personal Response: A Novel Writing Assignment to Engage First Year Students in Large Human Biology Classes

    ERIC Educational Resources Information Center

    Moni, Roger W.; Moni, Karen B.; Poronnik, Philip

    2007-01-01

    The teaching of highly valued scientific writing skills in the first year of university is challenging. This report describes the design, implementation, and evaluation of a novel written assignment, "The Personal Response" and accompanying Peer Review, in the course, Human Biology (BIOL1015) at The University of Queensland. These assignments were…

  7. The Personal Response: A Novel Writing Assignment to Engage First Year Students in Large Human Biology Classes

    ERIC Educational Resources Information Center

    Moni, Roger W.; Moni, Karen B.; Poronnik, Philip

    2007-01-01

    The teaching of highly valued scientific writing skills in the first year of university is challenging. This report describes the design, implementation, and evaluation of a novel written assignment, "The Personal Response" and accompanying Peer Review, in the course, Human Biology (BIOL1015) at The University of Queensland. These assignments were…

  8. The personal response: A novel writing assignment to engage first year students in large human biology classes.

    PubMed

    Moni, Roger W; Moni, Karen B; Lluka, Lesley J; Poronnik, Philip

    2007-03-01

    The teaching of highly valued scientific writing skills in the first year of university is challenging. This report describes the design, implementation, and evaluation of a novel written assignment, The Personal Response and accompanying Peer Review, in the course, Human Biology (BIOL1015) at The University of Queensland. These assignments were the first assessment tasks of the course and were set early in the first semester of university. BIOL1015 had a diverse cohort of 319 first year students from five bachelor degree programs, primarily from Pharmacy and Human Movement Studies. Audio files in the form of interviews with eminent biomedical scientists were obtained from a leading public radio program. Students used these files as triggers to submit a short but highly structured assignment written from a personal perspective and in an expressive style. Evaluations revealed that overall, students found the task interesting and challenging. Students performed well, regardless of their background knowledge, disciplinary interest, or preference for topics within human biology. This study demonstrated that The Personal Response was an appropriate task for these first year students of human biology. It represents an alternative to traditional essay writing.

  9. SENSITIVITY OF BLIND PULSAR SEARCHES WITH THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Dormody, M.; Johnson, R. P.; Atwood, W. B.; Belfiore, A.; Razzano, M.; Saz Parkinson, P. M.; Grenier, I. A.

    2011-12-01

    We quantitatively establish the sensitivity to the detection of young to middle-aged, isolated, gamma-ray pulsars through blind searches of Fermi Large Area Telescope (LAT) data using a Monte Carlo simulation. We detail a sensitivity study of the time-differencing blind search code used to discover gamma-ray pulsars in the first year of observations. We simulate 10,000 pulsars across a broad parameter space and distribute them across the sky. We replicate the analysis in the Fermi LAT First Source Catalog to localize the sources, and the blind search analysis to find the pulsars. We analyze the results and discuss the effect of positional error and spin frequency on gamma-ray pulsar detections. Finally, we construct a formula to determine the sensitivity of the blind search and present a sensitivity map assuming a standard set of pulsar parameters. The results of this study can be applied to population studies and are useful in characterizing unidentified LAT sources.

  10. Fermi Large Area Telescope Observations Of Misaligned Active Galactic Nuclei

    DOE PAGES

    Abdo, A. A.

    2010-08-13

    Analysis is presented for 15 months of data taken with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope for 11 non-blazar active galactic nuclei (AGNs), including seven FRI radio galaxies and four FRII radio sources consisting of two FRII radio galaxies and two steep spectrum radio quasars. The broad line FRI radio galaxy 3C 120 is reported here as a γ-ray source for the first time. The analysis is based on directional associations of LAT sources with radio sources in the 3CR, 3CRR, and MS4 (collectively referred to as 3C-MS) catalogs. Seven of the eleven LAT sourcesmore » associated with 3C-MS radio sources have spectral indices larger than 2.3 and, except for the FRI radio galaxy NGC 1275 that shows possible spectral curvature, are well described by a power law. No evidence for time variability is found for any sources other than NGC 1275. The γ-ray luminosities of FRI radio galaxies are significantly smaller than those of the BL Lac objects detected by the LAT, whereas the γ-ray luminosities of the FRII sources are quite similar to those of FSRQs, which could reflect different beaming factors for the γ-ray emission. A core dominance (CD) study of the 3CRR sample indicates that sources closer to the jet axis are preferentially detected with the Fermi LAT, insofar as the γ-ray-detected misaligned AGNs have larger CD at a given average radio flux. The results are discussed in view of the AGN unification scenario.« less

  11. The Fermi Large Area Telescope on Orbit: Event Classification, Instrument Response Functions, and Calibration

    SciTech Connect

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Atwood, W. B.; Axelsson, M.; Baldini, L.; 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.; Cutini, S.; D’Ammando, F.; Davis, D. S.; de Angelis, A.; DeKlotz, M.; de Palma, F.; Dermer, C. D.; Digel, S. W.; do Couto e Silva, E.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Fukazawa, Y.; 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. E.; 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.; Lande, J.; Larsson, S.; 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.; Mehault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Naumann-Godo, M.; Nemmen, R.; Nishino, S.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; 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, A.; Reimer, O.; Reposeur, T.; Reyes, L. C.; Ritz, S.; Rochester, L. S.; Romoli, C.; Roth, M.; Sadrozinski, H. F. -W.; Sanchez, D. A.; Saz Parkinson, P. M.; Sbarra, C.; Scargle, J. D.; Sgrò, C.; Siegal-Gaskins, J.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Stephens, T. E.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Tosti, G.; Troja, E.; Usher, T. L.; Vandenbroucke, J.; Van Klaveren, B.; 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.

    2012-10-12

    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 study, 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. In conclusion, 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.

  12. FERMI LARGE AREA TELESCOPE DETECTION OF SUPERNOVA REMNANT RCW 86

    SciTech Connect

    Yuan, Qiang; Huang, Xiaoyuan; Liu, Siming; Zhang, Bing

    2014-04-20

    Using 5.4 yr Fermi Large Area Telescope data, we report the detection of GeV γ-ray emission from the shell-type supernova remnant RCW 86 (G315.4-2.3) with a significance of ∼5.1σ. The data slightly favors an extended emission of this supernova remnant. The spectral index of RCW 86 is found to be very hard, Γ ∼ 1.4, in the 0.4-300 GeV range. A one-zone leptonic model can well fit the multi-wavelength data from radio to very high energy γ-rays. The very hard GeV γ-ray spectrum and the inferred low gas density seem to disfavor a hadronic origin for the γ-rays. The γ-ray behavior of RCW 86 is very similar to several other TeV shell-type supernova remnants, e.g., RX J1713.7-3946, RX J0852.0-4622, SN 1006, and HESS J1731-347.

  13. Pulsar simulations for the Fermi Large Area Telescope

    DOE PAGES

    Razzano, M.; Harding, Alice K.; Baldini, L.; ...

    2009-05-21

    Pulsars are among the prime targets for the Large Area Telescope (LAT) aboard the recently launched Fermi observatory. The LAT will study the gamma-ray Universe between 20 MeV and 300 GeV with unprecedented detail. Increasing numbers of gamma-ray pulsars are being firmly identified, yet their emission mechanisms are far from being understood. To better investigate and exploit the LAT capabilities for pulsar science, a set of new detailed pulsar simulation tools have been developed within the LAT collaboration. The structure of the pulsar simulator package (PulsarSpectrum) is presented here. Starting from photon distributions in energy and phase obtained from theoreticalmore » calculations or phenomenological considerations, gamma-rays are generated and their arrival times at the spacecraft are determined by taking into account effects such as barycentric effects and timing noise. Pulsars in binary systems also can be simulated given orbital parameters. As a result, we present how simulations can be used for generating a realistic set of gamma-rays as observed by the LAT, focusing on some case studies that show the performance of the LAT for pulsar observations.« less

  14. Pulsar Simulations for the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Razzano, M.; Harding, A. K.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Burnett, T.; Chiang, J.; Digel, S. W.; Dubois, R.; Kuss, M. W.; hide

    2009-01-01

    Pulsars are among the prime targets for the Large Area Telescope (LAT) aboard the recently launched Fermi observatory. The LAT will study the gamma-ray Universe between 20 MeV and 300 GeV with unprecedented detail. Increasing numbers of gamma-ray pulsars are being firmly identified, yet their emission mechanisms are far from being understood. To better investigate and exploit the tAT capabilities for pulsar science. a set of new detailed pulsar simulation tools have been developed within the LAT collaboration. The structure of the pulsar simulator package (PulsarSpeccrum) is presented here. Starting from photon distributions in energy and phase obtained from theoretical calculations or phenomenological considerations, gamma-rays are generated and their arrival times at the spacecraft are determined by taking Into account effects such as barycentric effects and timing noise. Pulsars in binary systems also can be simulated given orbital parameters. We present how simulations can be used for generating a realistic set of gamma rays as observed by the LAT, focusing on some case studies that show the performance of the LAT for pulsar observations.

  15. Large and Small Scale Nitrogen and Phosporous Manipulation Experiment in a Tree-Grass Ecosystem: first year of results

    NASA Astrophysics Data System (ADS)

    Migliavacca, Mirco; Perez Priego, Oscar; El-Madany, Tarek; Guan, JinHong; Carrara, Arnaud; Fava, Francesco; Moreno, Gerardo; Kolle, Olaf; Rossini, Micol; Schrumpf, Marion; Julitta, Tommaso; Reichstein, Markus

    2015-04-01

    Recent studies have shown how human induced N/P imbalances affect essential ecosystem processes (e.g. photosynthesis, plant growth rate, respiration), and might be particularly important in water-limited ecosystems. In this contribution we will present the experimental design and the results of the first year of two nutrient manipulation experiments conducted at different spatial scale. In the first experiment a cluster of 2 eddy covariance (EC) flux towers has been set up beside a long-term EC site (Las Majadas del Tietar, Spain). Sites are selected in a way to have similar nutrient conditions, canopy structure, and stoichiometry of the different vegetation and soil pools. Two of the three footprints will be manipulated with addition of N and NP fertilizer at the beginning of 2015. The comparison of the three EC flux towers installed during the first year of the experiment (without fertilization) will be shown. We characterized the differences of the responses of carbon and water fluxes measured by the EC systems to environmental drivers, and structural and biophysical properties of the canopy. The second experiment was conducted over a Mediterranean grassland, where 16 plots of 10x10 meters that were manipulated by adding nutrient (N, P, and NP). The overall objective was to investigate the response of the gross primary productivity (GPP), assessed by using transparent transient-state canopy chambers, to different nutrient availability. The second objective was to evaluate the capability of hyperspectral data and Solar induced fluorescence to track short- and long-term GPP and light use efficiency variation under different N and P fertilization treatments. Spectral vegetation indices (VIs) were acquired manually using high resolution spectrometers (HR4000, OceanOptics, USA) along a phenological cycle. The VIs used included photochemical reflectance index (PRI), MERIS terrestrial-chlorophyll index (MTCI) and normalized difference vegetation index (NDVI). Solar

  16. Observations of the Large Magellanic Cloud with Fermi

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2010-03-18

    Context. The Large Magellanic Cloud (LMC) is to date the only normal external galaxy that has been detected in high-energy gamma rays. High-energy gamma rays trace particle acceleration processes and gamma-ray observations allow the nature and sites of acceleration to be studied. Aims. We characterise the distribution and sources of cosmic rays in the LMC from analysis of gamma-ray observations. Methods. We analyse 11 months of continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-Ray Space Telescope and compare it to tracers of the interstellar medium and models of the gamma-ray sources in the LMC. Results.more » The LMC is detected at 33σ significance. The integrated >100 MeV photon flux of the LMC amounts to (2.6 ± 0.2) × 10-7 ph cm-2 s-1 which corresponds to an energy flux of (1.6 ± 0.1) × 10-10 erg cm-2 s-1, with additional systematic uncertainties of 16%. The analysis reveals the massive star forming region 30 Doradus as a bright source of gamma-ray emission in the LMC in addition to fainter emission regions found in the northern part of the galaxy. The gamma-ray emission from the LMC shows very little correlation with gas density and is rather correlated to tracers of massive star forming regions. The close confinement of gamma-ray emission to star forming regions suggests a relatively short GeV cosmic-ray proton diffusion length. In conclusion, the close correlation between cosmic-ray density and massive star tracers supports the idea that cosmic rays are accelerated in massive star forming regions as a result of the large amounts of kinetic energy that are input by the stellar winds and supernova explosions of massive stars into the interstellar medium.« less

  17. Performance of first-year health sciences students in a large, diverse, multidisciplinary, first-semester, physiology service module.

    PubMed

    Higgins-Opitz, Susan B; Tufts, Mark

    2014-06-01

    Health Science students at the University of KwaZulu-Natal perform better in their professional modules compared with their physiology modules. The pass rates of physiology service modules have steadily declined over the years. While a system is in place to identify "at-risk" students, it is only activated after the first semester. As a result, it is only from the second semester of their first year studies onward that at-risk students can be formally assisted. The challenge is thus to devise an appropriate strategy to identify struggling students earlier in the semester. Using questionnaires, students were asked about attendance, financing of their studies, and relevance of physiology. After the first class test, failing students were invited to complete a second questionnaire. In addition, demographic data were also collected and analyzed. Correlation analyses were undertaken of performance indicators based on the demographical data collected. The 2011 class comprised mainly sport science students (57%). The pass rate of sport science students was lower than the pass rates of other students (42% vs. 70%, P < 0.001). Most students were positive about physiology and recognized its relevance. Key issues identified were problems understanding concepts and terminology, poor study environment and skills, and lack of matriculation biology. The results of the first class test and final module marks correlated well. It is clear from this study that student performance in the first class test is a valuable tool to identify struggling students and that appropriate testing should be held as early as possible.

  18. International Student Adaptation to a U.S. College: A Mixed Methods Exploration of the Impact of a Specialized First-Year Course at a Large Midwestern Institution

    ERIC Educational Resources Information Center

    Kovtun, Olena

    2011-01-01

    This mixed methods study assessed a first-year course for international students, entitled the U.S. Education and Culture, at a large Midwestern public institution. The quantitative results indicated that participation in the course improved students' academic skills, psychosocial development, understanding of social diversity in the U.S., use of…

  19. Putting the S(ensational) Back into Sociology--Developing Strategies for Enhancing Teaching and Learning for First Year Student Teachers in Large Classes

    ERIC Educational Resources Information Center

    Daniell, Linda; Hogan, Vivienne

    2012-01-01

    The focus of the research was to develop a model for effective learning and teaching of sociology in a large class to promote active engagement with first year undergraduate student teachers and encourage deep learning. By seeking regular feedback from students and recording their own reflections on each lecture, the teaching team and…

  20. A Large, First-Year, Introductory, Multi-Sectional Biological Concepts of Health Course Designed to Develop Skills and Enhance Deeper Learning

    ERIC Educational Resources Information Center

    Murrant, Coral L.; Dyck, David J.; Kirkland, James B.; Newton, Genevieve S.; Ritchie, Kerry L.; Tishinsky, Justine M.; Bettger, William J.; Richardson, Nicolette S.

    2015-01-01

    Large first-year biology classes, with their heavy emphasis on factual content, contribute to low student engagement and misrepresent the dynamic, interdisciplinary nature of biological science. We sought to redesign a course to deliver fundamental biology curriculum through the study of health, promote skills development, and encourage a deeper…

  1. Performance of first-year health sciences students in a large, diverse, multidisciplinary, first-semester, physiology service module

    PubMed Central

    Tufts, Mark

    2014-01-01

    Health Science students at the University of KwaZulu-Natal perform better in their professional modules compared with their physiology modules. The pass rates of physiology service modules have steadily declined over the years. While a system is in place to identify “at-risk” students, it is only activated after the first semester. As a result, it is only from the second semester of their first year studies onward that at-risk students can be formally assisted. The challenge is thus to devise an appropriate strategy to identify struggling students earlier in the semester. Using questionnaires, students were asked about attendance, financing of their studies, and relevance of physiology. After the first class test, failing students were invited to complete a second questionnaire. In addition, demographic data were also collected and analyzed. Correlation analyses were undertaken of performance indicators based on the demographical data collected. The 2011 class comprised mainly sport science students (57%). The pass rate of sport science students was lower than the pass rates of other students (42% vs. 70%, P < 0.001). Most students were positive about physiology and recognized its relevance. Key issues identified were problems understanding concepts and terminology, poor study environment and skills, and lack of matriculation biology. The results of the first class test and final module marks correlated well. It is clear from this study that student performance in the first class test is a valuable tool to identify struggling students and that appropriate testing should be held as early as possible. PMID:24913452

  2. Automated Science Processing for the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Chiang, James

    2012-03-01

    The Large Area Telescope (LAT) onboard the Fermi γ-ray Space Telescope provides high sensitivity to emission from astronomical sources over a broad energy range (20MeV to >300 GeV) and has substantially improved spatial, energy, and timing resolution compared with previous observatories at these energies [4]. One of the LAT's most innovative features is that it performs continuous monitoring of the gamma-ray sky with all-sky coverage every 3 h. This survey strategy greatly enables the search for transient behavior from both previously known and unknown sources. In addition, the constant accumulation of data allows for increasingly improved measurements of persistent sources. These include the Milky Way Galaxy itself, which produces gamma-ray emission as a result from interactions of cosmic rays with gas in the Galaxy, and potential signals from candidate dark matter particles in the Milky Way and its neighboring galaxies. The automated science processing (ASP) functionality of the Fermi Instrument Science Operations Center (ISOC) is a part of the automated data pipeline that processes the raw data arriving from the spacecraft and puts it into a form amenable to scientific analysis. ASP operates at the end of the pipeline on the processed data and is intended to detect and characterize transient behavior (e.g., short time scale increases or “flares” in the gamma-ray flux) from astronomical sources. On detection of a flaring event, ASP will alert other observatories on a timely basis so that they may train their telescopes on the flaring source in order to detect possible correlated activity in other wavelength bands. Since the data from the LAT is archived and publicly available as soon as it is processed, ASP serves mainly to provide triggers for those follow-up observations; its estimates of the properties of the flaring sources (flux, spectral index, location) need not be the best possible, as subsequent off-line analysis can provide more refined

  3. FERMI Large Area Telescope Gamma-Ray Detection of the Radio Galaxy M87

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2009-11-17

    Here, we report the Fermi Large Area Telescope (LAT) discovery of high-energy (MeV/GeV) γ-ray emission positionally consistent with the center of the radio galaxy M87, at a source significance of over 10σ in 10 months of all-sky survey data. Following the detections of Cen A and Per A, this makes M87 the third radio galaxy seen with the LAT. The faint point-like γ-ray source has a >100 MeV flux of 2.45 (±0.63) × 10–8 photons cm–2 s–1 (photon index = 2.26 ± 0.13) with no significant variability detected within the LAT observation. This flux is comparable with the previous EGRETmore » upper limit (<2.18 × 10–8 photons cm–2 s–1, 2σ), thus there is no evidence for a significant MeV/GeV flare on decade timescales. Contemporaneous Chandra and Very Long Baseline Array data indicate low activity in the unresolved X-ray and radio core relative to previous observations, suggesting M87 is in a quiescent overall level over the first year of Fermi-LAT observations. The LAT γ-ray spectrum is modeled as synchrotron self-Compton (SSC) emission from the electron population producing the radio-to-X-ray emission in the core. The resultant SSC spectrum extrapolates smoothly from the LAT band to the historical-minimum TeV emission. Lastly, alternative models for the core and possible contributions from the kiloparsec-scale jet in M87 are considered, and cannot be excluded.« less

  4. Future Multiwavelength Studies with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Thompson, David J.

    2011-01-01

    With two and a half years of experience, Fermi LAT contributions to multiwavelength studies have become an integral part of many astrophysical research projects. Future efforts will benefit from (1) Deeper LAT exposures} resulting in more sources; (2) More high-energy, high-angular resolution photons, giving better source locations and imaging; (3) Faster analysis of variability and announcements to the community; and (4) Longer time series for studies of variable source properties in comparison to other wavelengths.

  5. Fermi: The Gamma-Ray Large Area Telescope Mission Status

    NASA Technical Reports Server (NTRS)

    McEnery, Julie

    2014-01-01

    Following its launch in June 2008, high-energy gamma-ray observations by the Fermi Gamma-ray Space Telescope have unveiled over 1000 new sources and opened an important and previously unexplored window on a wide variety of phenomena. These have included the discovery of an population of pulsars pulsing only in gamma rays; the detection of photons up to 10s of GeV from gamma-ray bursts, enhancing our understanding of the astrophysics of these powerful explosions; the detection of hundreds of active galaxies; a measurement of the high energy cosmic-ray electron spectrum which may imply the presence of nearby astrophysical particle accelerators; the determination of the diffuse gamma-ray emission with unprecedented accuracy and the constraints on phenomena such as supersymmetric dark-matter annihilations and exotic relics from the Big Bang. Continuous monitoring of the high-energy gamma-ray sky has uncovered numerous outbursts from active galaxies and the discovery of transient sources in our galaxy. In this talk I will describe the current status of the Fermi observatory and review the science highlights from Fermi.

  6. Fermi: The Gamma-Ray Large Area Telescope

    NASA Technical Reports Server (NTRS)

    McEnery, Julie

    2015-01-01

    Following its launch in June 2008, high-energy gamma-ray observations by the Fermi Gamma-ray Space Telescope have unveiled over 1000 new sources and opened an important and previously unexplored window on a wide variety of phenomena. These have included the discovery of an population of pulsars pulsing only in gamma rays; the detection of photons up to 10s of GeV from gamma-ray bursts, enhancing our understanding of the astrophysics of these powerful explosions; the detection of hundreds of active galaxies; a measurement of the high energy cosmic-ray electron spectrum which may imply the presence of nearby astrophysical particle accelerators; the determination of the diffuse gamma-ray emission with unprecedented accuracy and the constraints on phenomena such as supersymmetric dark-matter annihilations and exotic relics from the Big Bang. Continuous monitoring of the high-energy gamma-ray sky has uncovered numerous outbursts from active galaxies and the discovery of transient sources in our galaxy. In this talk I will describe the current status of the Fermi observatory and review the science highlights from Fermi.

  7. Fermi: The Gamma-Ray Large Area Telescope

    NASA Technical Reports Server (NTRS)

    McEnery, Julie

    2014-01-01

    Following its launch in June 2008, high-energy gamma-ray observations by the Fermi Gamma-ray Space Telescope have unveiled over 1000 new sources and opened an important and previously unexplored window on a wide variety of phenomena. These have included the discovery of an population of pulsars pulsing only in gamma rays; the detection of photons up to 10 seconds of gigaelectronvolts from gamma-ray bursts, enhancing our understanding of the astrophysics of these powerful explosions; the detection of hundreds of active galaxies; a measurement of the high energy cosmic-ray electron spectrum which may imply the presence of nearby astrophysical particle accelerators; the determination of the diffuse gamma-ray emission with unprecedented accuracy and the constraints on phenomena such as super-symmetric dark-matter annihilations and exotic relics from the Big Bang. Continuous monitoring of the high-energy gamma-ray sky has uncovered numerous outbursts from active galaxies and the discovery of transient sources in our galaxy. In this talk I will describe the current status of the Fermi observatory and review the science highlights from Fermi.

  8. Fermi: The Gamma-Ray Large Area Space Telescope

    NASA Technical Reports Server (NTRS)

    McEnery, Julie

    2014-01-01

    Following its launch in June 2008, high-energy gamma-ray observations by the Fermi Gamma-ray Space Telescope have unveiled over 1000 new sources and opened an important and previously unexplored window on a wide variety of phenomena. These have included the discovery of an population of pulsars pulsing only in gamma rays; the detection of photons up to 10s of GeV from gamma-ray bursts, enhancing our understanding of the astrophysics of these powerful explosions; the detection of hundreds of active galaxies; a measurement of the high energy cosmic-ray electron spectrum which may imply the presence of nearby astrophysical particle accelerators; the determination of the diffuse gamma-ray emission with unprecedented accuracy and the constraints on phenomena such as supersymmetric dark-matter annihilations and exotic relics from the Big Bang. Continuous monitoring of the high-energy gamma-ray sky has uncovered numerous outbursts from active galaxies and the discovery of transient sources in our galaxy. In this talk I will describe the current status of the Fermi observatory and review the science highlights from Fermi.

  9. Fermi/Large Area Telescope Bright Gamma-Ray Source List

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Band, D. L.; Barbiellini, G.; Bastieri, D.; Battelino, M.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bignami, G. F.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Corbet, R.; Costamante, L.; Cutini, S.; Davis, D. S.; Dermer, C. D.; de Angelis, A.; de Luca, A.; de Palma, F.; Digel, S. W.; Dormody, M.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hanabata, Y.; Harding, A. K.; Hartman, R. C.; Hayashida, M.; Hays, E.; Healey, S. E.; Horan, D.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocevski, D.; Kocian, M. L.; Komin, N.; Kuehn, F.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Marelli, M.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; McGlynn, S.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Poupard, L.; Rainò, S.; Rando, R.; Ray, P. S.; Razzano, M.; Rea, N.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rochester, L. S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Schalk, T. L.; Sellerholm, A.; Sgrò, C.; Shaw, M. S.; Shrader, C.; Sierpowska-Bartosik, A.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J.-L.; Stephens, T. E.; Strickman, M. S.; Strong, A. W.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Van Etten, A.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Watters, K.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Ziegler, M.; Fermi/LAT Collaboration

    2009-07-01

    Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the γ-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than ~10σ) γ-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) γ-ray sources in the early mission data.

  10. FERMI/LARGE AREA TELESCOPE BRIGHT GAMMA-RAY SOURCE LIST

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Atwood, W. B.; Axelsson, M.; Battelino, M.; Baldini, L.; Bellazzini, R.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bignami, G. F.; Bonamente, E. E-mail: jean.ballet@cea.fr E-mail: David.J.Thompson@nasa.gov

    2009-07-15

    Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the {gamma}-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than {approx}10{sigma}) {gamma}-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) {gamma}-ray sources in the early mission data.

  11. A Characterization of Areas of Racial Tension among First Year Students: A Focus Group Follow-Up to a Large Survey.

    ERIC Educational Resources Information Center

    Grayson, J. Paul

    This study examined areas of racial tension and racial attitudes among first-year students at York University in Ontario (Canada). A survey of 1,129 first-year students in 1993-94 indicated that the vast majority believed that visible minority students had been treated equally by professors, staff, and other students. However, the first year was…

  12. The Fermi Large Area Telescope Flare Advocate Program: Rapid Sharing of Results with the Community

    NASA Astrophysics Data System (ADS)

    Thompson, David John; Ciprini, Stefano; Gasparrini, Dario; Fermi Large Area Telescope Collaboration

    2015-01-01

    The Fermi Flare Advocate (also known as Gamma-ray Sky Watcher) program provides a quick look and review of the gamma-ray sky observed daily by the Fermi Large Area Telescope (LAT) through on-duty LAT Flare Advocates and high-level software pipelines like the LAT Automatic Science Processing and the Fermi All-sky Variability Analysis. The FA-GSW service provides rapid alerts and communicates to the external scientific community potentially new gamma-ray sources, interesting transients and flares. News items are regularly posted through the Fermi multiwavelength mailing list, Astronomer's Telegrams and Gamma-ray Coordinates Network notices. A weekly digest containing the highlights about the variable LAT gamma-ray sky at E>100 MeV is published on the web ("Fermi Sky Blog"). From July 2008 to September 2014 more than 290 ATels and 90 GCNs have been published by the Fermi LAT Collaboration. Target of opportunity observing programs with other satellites and telescopes have been triggered by Flare Advocates based on gamma-ray flares from blazars and other kinds of sources.

  13. REFINING THE ASSOCIATIONS OF THE FERMI LARGE AREA TELESCOPE SOURCE CATALOGS

    SciTech Connect

    Massaro, F.; D’Abrusco, R.; Paggi, A.; Smith, Howard A.; Landoni, M.; Masetti, N.; Giroletti, M.; Otí-Floranes, H.; Jiménez-Bailón, E.; Chavushyan, V.; Patiño-Álvarez, V.; Digel, S. W.; Tosti, G.

    2015-03-15

    The Fermi-Large Area Telescope (LAT) First Source Catalog (1FGL) was released in 2010 February and the Fermi-LAT 2-Year Source Catalog (2FGL) appeared in 2012 April, based on data from 24 months of operation. Since they were released, many follow up observations of unidentified γ-ray sources have been performed and new procedures for associating γ-ray sources with potential counterparts at other wavelengths have been developed. Here we review and characterize all of the associations as published in the 1FGL and 2FGL catalogs on the basis of multifrequency archival observations. In particular, we located 177 spectra for the low-energy counterparts that were not listed in the previous Fermi catalogs, and in addition we present new spectroscopic observations of eight γ-ray blazar candidates. Based on our investigations, we introduce a new counterpart category of “candidate associations” and propose a refined classification for the candidate low-energy counterparts of the Fermi sources. We compare the 1FGL-assigned counterparts with those listed in 2FGL to determine which unassociated sources became associated in later releases of the Fermi catalogs. We also search for potential counterparts to all of the remaining unassociated Fermi sources. Finally, we prepare a refined and merged list of all of the associations of 1FGL plus 2FGL that includes 2219 unique Fermi objects. This is the most comprehensive and systematic study of all the associations collected for the γ-ray sources available to date. We conclude that 80% of the Fermi sources have at least one known plausible γ-ray emitter within their positional uncertainty regions.

  14. The Vela-X pulsar wind nebula revisited with four years of Fermi Large Area Telescope observations

    SciTech Connect

    Grondin, M. -H.; Romani, R. W.; Lemoine-Goumard, M.; Guillemot, L.; Harding, A. K.; Reposeur, T.

    2013-08-21

    Here, the Vela supernova remnant (SNR) is the closest SNR to Earth containing an active pulsar, the Vela pulsar (PSR B0833–45). This pulsar is an archetype of the middle-aged pulsar class and powers a bright pulsar wind nebula (PWN), Vela-X, spanning a region of 2° × 3° south of the pulsar and observed in the radio, X-ray, and very high energy γ-ray domains. The detection of the Vela-X PWN by the Fermi Large Area Telescope (LAT) was reported in the first year of the mission. Subsequently, we have reinvestigated this complex region and performed a detailed morphological and spectral analysis of this source using 4 yr of Fermi-LAT observations. This study lowers the threshold for morphological analysis of the nebula from 0.8 GeV to 0.3 GeV, allowing for the inspection of distinct energy bands by the LAT for the first time. We describe the recent results obtained on this PWN and discuss the origin of the newly detected spatial features.

  15. The VELA-X-Pulsar Wind Nebula Revisited with Four Years of Fermi Large Area Telescope Observations

    NASA Technical Reports Server (NTRS)

    Grondin, M. -H.; Romani, R. W.; Lemoine-Goumard, M.; Guillemot, L.; Harding, Alice K.; Reposeur, T.

    2013-01-01

    The Vela supernova remnant (SNR) is the closest SNR to Earth containing an active pulsar, the Vela pulsar (PSR B0833-45). This pulsar is an archetype of the middle-aged pulsar class and powers a bright pulsar wind nebula (PWN), Vela-X, spanning a region of 2deg × 3deg south of the pulsar and observed in the radio, X-ray, and very high energy ?-ray domains. The detection of the Vela-X PWN by the Fermi Large Area Telescope (LAT) was reported in the first year of the mission. Subsequently, we have reinvestigated this complex region and performed a detailed morphological and spectral analysis of this source using 4 yr of Fermi-LAT observations. This study lowers the threshold for morphological analysis of the nebula from 0.8 GeV to 0.3 GeV, allowing for the inspection of distinct energy bands by the LAT for the first time. We describe the recent results obtained on this PWN and discuss the origin of the newly detected spatial features.

  16. THE VELA-X PULSAR WIND NEBULA REVISITED WITH FOUR YEARS OF FERMI LARGE AREA TELESCOPE OBSERVATIONS

    SciTech Connect

    Grondin, M.-H.; Romani, R. W.; Lemoine-Goumard, M.; Reposeur, T.; Harding, A. K.

    2013-09-10

    The Vela supernova remnant (SNR) is the closest SNR to Earth containing an active pulsar, the Vela pulsar (PSR B0833-45). This pulsar is an archetype of the middle-aged pulsar class and powers a bright pulsar wind nebula (PWN), Vela-X, spanning a region of 2 Degree-Sign Multiplication-Sign 3 Degree-Sign south of the pulsar and observed in the radio, X-ray, and very high energy {gamma}-ray domains. The detection of the Vela-X PWN by the Fermi Large Area Telescope (LAT) was reported in the first year of the mission. Subsequently, we have reinvestigated this complex region and performed a detailed morphological and spectral analysis of this source using 4 yr of Fermi-LAT observations. This study lowers the threshold for morphological analysis of the nebula from 0.8 GeV to 0.3 GeV, allowing for the inspection of distinct energy bands by the LAT for the first time. We describe the recent results obtained on this PWN and discuss the origin of the newly detected spatial features.

  17. The Vela-X pulsar wind nebula revisited with four years of Fermi Large Area Telescope observations

    DOE PAGES

    Grondin, M. -H.; Romani, R. W.; Lemoine-Goumard, M.; ...

    2013-08-21

    Here, the Vela supernova remnant (SNR) is the closest SNR to Earth containing an active pulsar, the Vela pulsar (PSR B0833–45). This pulsar is an archetype of the middle-aged pulsar class and powers a bright pulsar wind nebula (PWN), Vela-X, spanning a region of 2° × 3° south of the pulsar and observed in the radio, X-ray, and very high energy γ-ray domains. The detection of the Vela-X PWN by the Fermi Large Area Telescope (LAT) was reported in the first year of the mission. Subsequently, we have reinvestigated this complex region and performed a detailed morphological and spectral analysismore » of this source using 4 yr of Fermi-LAT observations. This study lowers the threshold for morphological analysis of the nebula from 0.8 GeV to 0.3 GeV, allowing for the inspection of distinct energy bands by the LAT for the first time. We describe the recent results obtained on this PWN and discuss the origin of the newly detected spatial features.« less

  18. Indirect searches for dark matter with the Fermi large area telescope

    SciTech Connect

    Albert, Andrea

    2015-03-24

    There is overwhelming evidence that non-baryonic dark matter constitutes ~ 27% of the energy density of the Universe. Weakly Interacting Massive Particles (WIMPs) are promising dark matter candidates that may produce γ rays via annihilation or decay detectable by the Fermi Large Area Telescope (LAT). A detection of WIMPs would also indicate the existence of physics beyond the Standard Model. We present recent results from the two cleanest indirect WIMP searches by the Fermi-LAT Collaboration: searches for γ-ray spectral lines and γ-ray emission associated with Milky Way dwarf spheroidal satellite galaxies.

  19. Indirect searches for dark matter with the Fermi large area telescope

    DOE PAGES

    Albert, Andrea

    2015-03-24

    There is overwhelming evidence that non-baryonic dark matter constitutes ~ 27% of the energy density of the Universe. Weakly Interacting Massive Particles (WIMPs) are promising dark matter candidates that may produce γ rays via annihilation or decay detectable by the Fermi Large Area Telescope (LAT). A detection of WIMPs would also indicate the existence of physics beyond the Standard Model. We present recent results from the two cleanest indirect WIMP searches by the Fermi-LAT Collaboration: searches for γ-ray spectral lines and γ-ray emission associated with Milky Way dwarf spheroidal satellite galaxies.

  20. Recent Results on SNRs and PWNe from the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Hays, Elizabeth

    2010-01-01

    Topics include: Fermi LAT Collaboration groups; galactic results from LAT; a GeV, wide-field instrument; the 1FGL catalog, the Fermi LAT 1FGL source catalog, unidentified gamma-ray sources; variability in 1FGL sources; curvature in 1FGL sources; spectral-variability classification; pulsars and their wind nebulae; gamma-ray pulsars and MSPs; GeV PWN search; Crab pulsar and nebula; Vela X nebular of Vela pulsar; MSH 15-52; supernova remnants, resolved GeV sources, galactic transients, LAT unassociated transient detections; gamma rays from a nova; V407 Cyngi - a symbiotic nova; V407 Cygni: a variable star; and March 11 - a nova. Summary slides include pulsars everywhere, blazars, LAT as an electron detector, cosmic ray spectrum, the Large Area Telescope, the Fermi Observatory, LAT sensitivity with time, candidate gamma-ray events, on-orbit energy calibration and rate, a 1 year sky map, LAT automated science processing, reported GeV flares, early activity and spectacular flare, gamma-ray transients near the galactic plane , two early unassociated transients, counter part search - Fermi J0910-5404; counterpart search 3EG J0903-3531, and a new LAT transient - J1057-6027.

  1. The Fermi Large Area Telescope on Orbit: Event Classification, Instrument Response Functions, and Calibration

    DTIC Science & Technology

    2012-11-01

    All rights reserved. Printed in the U.S.A. THE FERMI LARGE AREA TELESCOPE ON ORBIT: EVENT CLASSIFICATION, INSTRUMENT RESPONSE FUNCTIONS, AND CALIBRATION...dimensional ( 3D ) imaging calorimeter. This is achieved by arranging the CsI crystals in each tower module in 8 layers, each with 12 crystal logs (with...Thus, the CAL provides a 3D image of the energy deposition for each event. Since the CAL is only 8.6 radiation lengths thick at normal incidence

  2. Active Learning in a Large First Year Biology Class: A Collaborative Resource-Based Study Project on "AIDS in Science and Society".

    ERIC Educational Resources Information Center

    Sutcliffe, Roger G.; Cogdell, Barbara; Hansell, Mike H.; McAteer, Erica

    1999-01-01

    Describes a student-directed learning program called "AIDS in Science and Society" that was developed as a resource-based, collaborative project at the University of Glasgow (United Kingdom) for a first-year biology class. Discusses materials, written assignments, oral presentations, and feedback from students and faculty, and includes a…

  3. FERMI Large Area Telescope Gamma-Ray Detection of the Radio Galaxy M87

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Caliandro, G. A.; Cameron, R. A.; Cannon, A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Çelik, Ö.; Charles, E.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Colafrancesco, S.; Conrad, J.; Costamante, L.; Cutini, S.; Davis, D. S.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Digel, S. W.; Donato, D.; Couto e Silva, E. do; Drell, P. S.; Dubois, R.; Dumora, D.; Edmonds, Y.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Finke, J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Georganopoulos, M.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Horan, D.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocian, M. L.; Kuss, M.; Lande, J.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rochester, L. S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Ryde, F.; Sadrozinski, H. F. -W.; Sambruna, R.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Sgrò, C.; Shaw, M. S.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Taylor, G. B.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vasileiou, V.; Vilchez, N.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Ziegler, M.; Harris, D. E.; Massaro, F.; Stawarz, Ł.

    2009-11-17

    Here, we report the Fermi Large Area Telescope (LAT) discovery of high-energy (MeV/GeV) γ-ray emission positionally consistent with the center of the radio galaxy M87, at a source significance of over 10σ in 10 months of all-sky survey data. Following the detections of Cen A and Per A, this makes M87 the third radio galaxy seen with the LAT. The faint point-like γ-ray source has a >100 MeV flux of 2.45 (±0.63) × 10–8 photons cm–2 s–1 (photon index = 2.26 ± 0.13) with no significant variability detected within the LAT observation. This flux is comparable with the previous EGRET upper limit (<2.18 × 10–8 photons cm–2 s–1, 2σ), thus there is no evidence for a significant MeV/GeV flare on decade timescales. Contemporaneous Chandra and Very Long Baseline Array data indicate low activity in the unresolved X-ray and radio core relative to previous observations, suggesting M87 is in a quiescent overall level over the first year of Fermi-LAT observations. The LAT γ-ray spectrum is modeled as synchrotron self-Compton (SSC) emission from the electron population producing the radio-to-X-ray emission in the core. The resultant SSC spectrum extrapolates smoothly from the LAT band to the historical-minimum TeV emission. Lastly, alternative models for the core and possible contributions from the kiloparsec-scale jet in M87 are considered, and cannot be excluded.

  4. NASA Goddard Space Flight Center, on Behalf of the Fermi Large Area Telescope Collaboration

    NASA Technical Reports Server (NTRS)

    Thompson, David J.

    2010-01-01

    Because high-energy gamma rays can be produced by processes that also produce neutrinos, the gamma-ray survey of the sky by the Fermi (Gamma-ray Space Telescope offers a view of potential targets for neutrino observations. Gamma-ray bursts. Active Galactic Nuclei, and supernova remnants are all sites where hadronic, neutrino-producing interactions are plausible. Pulsars, pulsar wind nebulae, and binary sources are all phenomena that reveal leptonic particle acceleration through their gamma-ray emission. While important to gamma-ray astrophysics, such sources are of less interest to neutrino studies. This talk will present a broad overview of the constantly changing sky seen with the Large Area Telescope (LAT)on the Fermi spacecraft.

  5. Recent Results on SNRs and PWNe from the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Hays, Elizabeth A.

    2010-01-01

    Topics include: Fermi LAT Collaboration groups; galactic results from LAT; a GeV, wide-field instrument; the 1FGL catalog, the Fermi LAT 1FGL source catalog, unidentified gamma-ray sources; variability in 1FGL sources; curvature in 1FGL sources; spectral-variability classification; gamma-ray pulsars and MSPs; GeV PWN - where to look; Crab pulsar and nebula; Vela X nebular of Vela pulsar; MSH 15-52; GeV PWNe spectra; GeV nebula limits; Nebula search of LAT pulsars; supernova remnants; SNR: GeV morphology; SNR: molecular connection; SNR: GeV breaks; SNR: young vs. old. The summary includes slides about the Large Area Telescope (LAT) and LAT sensitivity with time.

  6. Fermi Large Area Telescope observations of high-energy gamma-ray emission from Solar flares

    NASA Astrophysics Data System (ADS)

    Pesce Rollins, Melissa

    2017-01-01

    The Fermi Large Area Telescope (LAT) observations of the active Sun provide the largest sample of detected solar flares with emission greater than 30 MeV to date. These include detections of impulsive and sustained emission, extending up to 20 hours in the case of the 2012 March 7 X-class flares. These high-energy flares are coincident with GOES X-ray flares of X, M and C classes as well as very fast Coronal Mass Ejections (CME). We will present results from the First Fermi-LAT solar flare catalog covering the majority of Solar Cycle 24 including correlation studies with the associated Solar Energetic Particles (SEP) and CMEs.

  7. A tool to estimate the Fermi Large Area Telescope background for short-duration observations

    DOE PAGES

    Vasileiou, Vlasios

    2013-07-25

    Here, the proper estimation of the background is a crucial component of data analyses in astrophysics, such as source detection, temporal studies, spectroscopy, and localization. For the case of the Large Area Telescope (LAT) on board the Fermi spacecraft, approaches to estimate the background for short (≲1000 s duration) observations fail if they ignore the strong dependence of the LAT background on the continuously changing observational conditions. We present a (to be) publicly available background-estimation tool created and used by the LAT Collaboration in several analyses of Gamma Ray Bursts. This tool can accurately estimate the expected LAT background formore » any observational conditions, including, for example, observations with rapid variations of the Fermi spacecraft’s orientation occurring during automatic repointings.« less

  8. Fermi Large Area Telescope Observations of the Dark Accelerator HESS J1745-303

    NASA Astrophysics Data System (ADS)

    Yeung, Paul

    2016-12-01

    Reviewing the two MeV-GeV investigations in the field of the HESS J1745-303 performed using Fermi Large Area Telescope data, we confirmed that the emission peak comfortably coincides with ‘Region A’ in the TeV regime, which is the brightest part of this feature. The MeV–TeV spectrum can be precisely described by a single power-law. Also, recent investigation has shown that the MeV-GeV feature is elongated from ‘Region A’ toward the north-west, which is similar to the case of large- scale atomic/molecular gas distribution.

  9. Search For Gamma-Ray Emission From Magnetars With The Fermi Large Area Telescope

    DOE PAGES

    Abdo, A. A.

    2010-11-22

    We report on the search for 0.1-10 GeV emission from magnetars in 17 months of Fermi Large Area Telescope (LAT) observations. No significant evidence for gamma-ray emission from any of the currently known magnetars is found. The most stringent upper limits to date on their persistent emission in the Fermi energy range are estimated between ~10–12 and 10–10 erg s–1 cm–2, depending on the source. We also searched for gamma-ray pulsations and possible outbursts, also with no significant detection. The upper limits derived support the presence of a cutoff at an energy below a few MeV in the persistent emissionmore » of magnetars. They also show the likely need for a revision of current models of outer-gap emission from strongly magnetized pulsars, which, in some realizations, predict detectable GeV emission from magnetars at flux levels exceeding the upper limits identified here using the Fermi-LAT observations.« less

  10. Coordinate-Space Hartree-Fock-Bogoliubov Solvers for Superfluid Fermi Systems in Large Boxes

    SciTech Connect

    Pei, J. C.; Fann, George I; Harrison, Robert J; Nazarewicz, W.; Hill, Judith C; Galindo, Diego A; Jia, Jun

    2012-01-01

    The self-consistent Hartree-Fock-Bogoliubov problem in large boxes can be solved accurately in the coordinate space with the recently developed solvers HFB-AX (2D) and MADNESS-HFB (3D). This is essential for the description of superfluid Fermi systems with complicated topologies and significant spatial extend, such as fissioning nuclei, weakly-bound nuclei, nuclear matter in the neutron star rust, and ultracold Fermi atoms in elongated traps. The HFB-AX solver based on B-spline techniques uses a hybrid MPI and OpenMP programming model for parallel computation for distributed parallel computation, within a node multi-threaded LAPACK and BLAS libraries are used to further enable parallel calculations of large eigensystems. The MADNESS-HFB solver uses a novel multi-resolution analysis based adaptive pseudo-spectral techniques to enable fully parallel 3D calculations of very large systems. In this work we present benchmark results for HFB-AX and MADNESS-HFB on ultracold trapped fermions.

  11. Constraints on dark matter annihilation in clusters of galaxies with the Fermi large area telescope

    DOE PAGES

    Ackermann, M.; Ajello, M.; Allafort, A.; ...

    2010-05-20

    Nearby clusters and groups of galaxies are potentially bright sources of high-energy gamma-ray emission resulting from the pair-annihilation of dark matter particles. However, no significant gamma-ray emission has been detected so far from clusters in the first 11 months of observations with the Fermi Large Area Telescope. We interpret this non-detection in terms of constraints on dark matter particle properties. In particular for leptonic annihilation final states and particle masses greater than ~ 200 GeV, gamma-ray emission from inverse Compton scattering of CMB photons is expected to dominate the dark matter annihilation signal from clusters, and our gamma-ray limits excludemore » large regions of the parameter space that would give a good fit to the recent anomalous Pamela and Fermi-LAT electron-positron measurements. We also present constraints on the annihilation of more standard dark matter candidates, such as the lightest neutralino of supersymmetric models. The constraints are particularly strong when including the fact that clusters are known to contain substructure at least on galaxy scales, increasing the expected gamma-ray flux by a factor of ~ 5 over a smooth-halo assumption. Here, we also explore the effect of uncertainties in cluster dark matter density profiles, finding a systematic uncertainty in the constraints of roughly a factor of two, but similar overall conclusions. Finally, in this work, we focus on deriving limits on dark matter models; a more general consideration of the Fermi-LAT data on clusters and clusters as gamma-ray sources is forthcoming.« less

  12. Constraints on dark matter annihilation in clusters of galaxies with the Fermi large area telescope

    SciTech Connect

    Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Angelis, A. de; Palma, F. de; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Edmonds, Y.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Frailis, M.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Guiriec, S.; Gustafsson, M.; Harding, A. K.; Hayashida, M.; Horan, D.; Hughes, R. E.; Jeltema, T. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S. -H; Garde, M. Llena; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Mazziotta, M. N.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Panetta, J. H.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Profumo, S.; Rainò, S.; Razzano, M.; Reposeur, T.; Ritz, S.; Rodriguez, A. Y.; Roth, M.; Sadrozinski, H. F. -W; Sander, A.; Scargle, J. D.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J. -L; Strickman, M. S.; Suson, D. J.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Usher, T. L.; Vasileiou, V.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ylinen, T.; Ziegler, M.

    2010-05-20

    Nearby clusters and groups of galaxies are potentially bright sources of high-energy gamma-ray emission resulting from the pair-annihilation of dark matter particles. However, no significant gamma-ray emission has been detected so far from clusters in the first 11 months of observations with the Fermi Large Area Telescope. We interpret this non-detection in terms of constraints on dark matter particle properties. In particular for leptonic annihilation final states and particle masses greater than ~ 200 GeV, gamma-ray emission from inverse Compton scattering of CMB photons is expected to dominate the dark matter annihilation signal from clusters, and our gamma-ray limits exclude large regions of the parameter space that would give a good fit to the recent anomalous Pamela and Fermi-LAT electron-positron measurements. We also present constraints on the annihilation of more standard dark matter candidates, such as the lightest neutralino of supersymmetric models. The constraints are particularly strong when including the fact that clusters are known to contain substructure at least on galaxy scales, increasing the expected gamma-ray flux by a factor of ~ 5 over a smooth-halo assumption. Here, we also explore the effect of uncertainties in cluster dark matter density profiles, finding a systematic uncertainty in the constraints of roughly a factor of two, but similar overall conclusions. Finally, in this work, we focus on deriving limits on dark matter models; a more general consideration of the Fermi-LAT data on clusters and clusters as gamma-ray sources is forthcoming.

  13. The Radio/Gamma-Ray Connection in Active Galactic Nuclei in the Era of the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Allafort, A.; Angelakis, E.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Gehrels, N.; Hays, E.; MeEnery, J. E.; Scargle, J. D.; Thompson, D. J.

    2011-01-01

    We present a detailed statistical analysis of the correlation between radio and gamma-ray emission of the active galactic nuclei (AGNs) detected by Fermi during its first year of operation, with the largest data sets ever used for this purpose.We use both archival interferometric 8.4 GHz data (from the Very Large Array and ATCA, for the full sample of 599 sources) and concurrent single-dish 15 GHz measurements from the OwensValley RadioObservatory (OVRO, for a sub sample of 199 objects). Our unprecedentedly large sample permits us to assess with high accuracy the statistical significance of the correlation, using a surrogate data method designed to simultaneously account for common-distance bias and the effect of a limited dynamical range in the observed quantities. We find that the statistical significance of a positive correlation between the centimeter radio and the broadband (E > 100 MeV) gamma-ray energy flux is very high for the whole AGN sample, with a probability of <10(exp -7) for the correlation appearing by chance. Using the OVRO data, we find that concurrent data improve the significance of the correlation from 1.6 10(exp -6) to 9.0 10(exp -8). Our large sample size allows us to study the dependence of correlation strength and significance on specific source types and gamma-ray energy band. We find that the correlation is very significant (chance probability < 10(exp -7)) for both flat spectrum radio quasars and BL Lac objects separately; a dependence of the correlation strength on the considered gamma-ray energy band is also present, but additional data will be necessary to constrain its significance.

  14. The radio/gamma-ray connection in active galactic nuclei in the era of the Fermi Large Area Telescope

    DOE PAGES

    Ackermann, M.; Ajello, M.; Allafort, A.; ...

    2011-10-12

    We present a detailed statistical analysis of the correlation between radio and gamma-ray emission of the active galactic nuclei (AGNs) detected by Fermi during its first year of operation, with the largest data sets ever used for this purpose. We use both archival interferometric 8.4 GHz data (from the Very Large Array and ATCA, for the full sample of 599 sources) and concurrent single-dish 15 GHz measurements from the Owens Valley Radio Observatory (OVRO, for a sub sample of 199 objects). Our unprecedentedly large sample permits us to assess with high accuracy the statistical significance of the correlation, using amore » surrogate data method designed to simultaneously account for common-distance bias and the effect of a limited dynamical range in the observed quantities. We find that the statistical significance of a positive correlation between the centimeter radio and the broadband (E > 100 MeV) gamma-ray energy flux is very high for the whole AGN sample, with a probability of <10–7 for the correlation appearing by chance. Using the OVRO data, we find that concurrent data improve the significance of the correlation from 1.6 × 10–6 to 9.0 × 10–8. Our large sample size allows us to study the dependence of correlation strength and significance on specific source types and gamma-ray energy band. As a result, we find that the correlation is very significant (chance probability < 10–7) for both flat spectrum radio quasars and BL Lac objects separately; a dependence of the correlation strength on the considered gamma-ray energy band is also present, but additional data will be necessary to constrain its significance.« less

  15. The Radio/Gamma-Ray Connection in Active Galactic Nuclei in the Era of the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Allafort, A.; Angelakis, E.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; hide

    2011-01-01

    We present a detailed statistical analysis of the correlation between radio and gamma-ray emission of the active galactic nuclei (AGNs) detected by Fermi during its first year of operation, with the largest data sets ever used for this purpose.We use both archival interferometric 8.4 GHz data (from the Very Large Array and ATCA, for the full sample of 599 sources) and concurrent single-dish 15 GHz measurements from the OwensValley RadioObservatory (OVRO, for a sub sample of 199 objects). Our unprecedentedly large sample permits us to assess with high accuracy the statistical significance of the correlation, using a surrogate data method designed to simultaneously account for common-distance bias and the effect of a limited dynamical range in the observed quantities. We find that the statistical significance of a positive correlation between the centimeter radio and the broadband (E > 100 MeV) gamma-ray energy flux is very high for the whole AGN sample, with a probability of <10(exp -7) for the correlation appearing by chance. Using the OVRO data, we find that concurrent data improve the significance of the correlation from 1.6 10(exp -6) to 9.0 10(exp -8). Our large sample size allows us to study the dependence of correlation strength and significance on specific source types and gamma-ray energy band. We find that the correlation is very significant (chance probability < 10(exp -7)) for both flat spectrum radio quasars and BL Lac objects separately; a dependence of the correlation strength on the considered gamma-ray energy band is also present, but additional data will be necessary to constrain its significance.

  16. The second FERMI large area telescope catalog of gamma-ray pulsars

    SciTech Connect

    Abdo, A. A.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Belfiore, A.; Bellazzini, R.; Bhattacharyya, B.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burgay, M.; Burnett, T. H.; Busetto, G.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Camilo, F.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chaty, S.; Chaves, R. C. G.; Chekhtman, A.; Chen, A. W.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cognard, I.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; DeCesar, M. E.; De Luca, A.; den Hartog, P. R.; de Palma, F.; Dermer, C. D.; Desvignes, G.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Espinoza, C. M.; Falletti, L.; Favuzzi, C.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Freire, P. C. C.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gotthelf, E. V.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hessels, J.; Hewitt, J.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Jackson, M. S.; Janssen, G. H.; Jogler, T.; Jóhannesson, G.; Johnson, R. P.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Johnston, S.; Kamae, T.; Kataoka, J.; Keith, M.; Kerr, M.; Knödlseder, J.; Kramer, M.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Lyne, A. G.; Manchester, R. N.; Marelli, M.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; McLaughlin, M. A.; Mehault, J.; Michelson, P. F.; Mignani, R. P.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nemmen, R.; Nuss, E.; Ohno, M.; Ohsugi, T.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Pletsch, H. J.; Porter, T. A.; Possenti, A.; Rainò, S.; Rando, R.; Ransom, S. M.; Ray, P. S.; Razzano, M.; Rea, N.; Reimer, A.; Reimer, O.; Renault, N.; Reposeur, T.; Ritz, S.; Romani, R. W.; Roth, M.; Rousseau, R.; Roy, J.; Ruan, J.; Sartori, A.; Saz Parkinson, P. M.; Scargle, J. D.; Schulz, A.; Sgrò, C.; Shannon, R.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stappers, B. W.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.; Theureau, G.; Thompson, D. J.; Thorsett, S. E.; Tibaldo, L.; Tibolla, O.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Venter, C.; Vianello, G.; Vitale, V.; Wang, N.; Weltevrede, P.; Winer, B. L.; Wolff, M. T.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.

    2013-09-19

    This catalog summarizes 117 high-confidence ≥0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-peak phase intervals indicates probable pulsar wind nebula emission for four pulsars, and off-peak magnetospheric emission for several young and millisecond pulsars. We compare the gamma-ray properties with those in the radio, optical, and X-ray bands. We provide flux limits for pulsars with no observed gamma-ray emission, highlighting a small number of gamma-faint, radio-loud pulsars. The large, varied gamma-ray pulsar sample constrains emission models. Fermi's selection biases complement those of radio surveys, enhancing comparisons with predicted population distributions.

  17. THE SECOND FERMI LARGE AREA TELESCOPE CATALOG OF GAMMA-RAY PULSARS

    SciTech Connect

    Abdo, A. A.; Ajello, M.; Allafort, A.; Bloom, E. D.; Bottacini, E.; Baldini, L.; Ballet, J.; Baring, M. G.; Bastieri, D.; Belfiore, A.; Bellazzini, R.; Bregeon, J.; Bhattacharyya, B.; Bissaldi, E.; Bonamente, E.; Brandt, T. J.; Brigida, M.; and others

    2013-10-01

    This catalog summarizes 117 high-confidence ≥0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-peak phase intervals indicates probable pulsar wind nebula emission for four pulsars, and off-peak magnetospheric emission for several young and millisecond pulsars. We compare the gamma-ray properties with those in the radio, optical, and X-ray bands. We provide flux limits for pulsars with no observed gamma-ray emission, highlighting a small number of gamma-faint, radio-loud pulsars. The large, varied gamma-ray pulsar sample constrains emission models. Fermi's selection biases complement those of radio surveys, enhancing comparisons with predicted population distributions.

  18. Large-momentum distribution of a polarized Fermi gas and p -wave contacts

    NASA Astrophysics Data System (ADS)

    Peng, Shi-Guo; Liu, Xia-Ji; Hu, Hui

    2016-12-01

    We present a derivation of the adiabatic energy relations as well as the large momentum distribution of a polarized Fermi gas near p -wave Feshbach resonances. The leading asymptotic behavior k-2 and subleading behavior k-4 of the large momentum distribution have recently been predicted by Z. Yu et al. [Phys. Rev. Lett. 115, 135304 (2015), 10.1103/PhysRevLett.115.135304] and by M. Y. He et al. [Phys. Rev. Lett. 116, 045301 (2016), 10.1103/PhysRevLett.116.045301] using two different approaches. Here, we show that the subleading asymptotic behavior (˜k-4 ) cannot fully be captured by the contact defined from the adiabatic energy relation related to the p -wave effective range, and there should be an extra term resulting from the center-of-mass motion of the pairs. The omission of this extra term is perhaps a reasonable approximation at zero temperature. However, it should be taken into account at finite temperature and should have significant importance to understand the recently measured momentum distribution in a resonant p -wave Fermi gas of ultracold 40K atoms [C. Luciuk et al., Nat. Phys. 12, 599 (2016), 10.1038/nphys3670].

  19. Observing two dark accelerators around the Galactic Centre with Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Hui, C. Y.; Yeung, P. K. H.; Ng, C. W.; Lin, L. C. C.; Tam, P. H. T.; Cheng, K. S.; Kong, A. K. H.; Chernyshov, D. O.; Dogiel, V. A.

    2016-04-01

    We report the results from a detailed γ-ray investigation in the field of two `dark accelerators', HESS J1745-303 and HESS J1741-302, with 6.9 yr of data obtained by the Fermi Large Area Telescope. For HESS J1745-303, we found that its MeV-GeV emission is mainly originated from the `Region A' of the TeV feature. Its γ-ray spectrum can be modelled with a single power law with a photon index of Γ ˜ 2.5 from few hundreds MeV-TeV. Moreover, an elongated feature, which extends from `Region A' towards north-west for ˜1.3°, is discovered for the first time. The orientation of this feature is similar to that of a large-scale atomic/molecular gas distribution. For HESS J1741-302, our analysis does not yield any MeV-GeV counterpart for this unidentified TeV source. On the other hand, we have detected a new point source, Fermi J1740.1-3013, serendipitously. Its spectrum is apparently curved which resembles that of a γ-ray pulsar. This makes it possibly associated with PSR B1737-20 or PSR J1739-3023.

  20. The Second Fermi Large Area Telescope Catalog of Gamma-Ray Pulsars

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Belfiore, A.; Bellazzini, R.; Bhattacharyya, B.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burgay, M.; Burnett, T. H.; Busetto, G.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Camilo, F.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chaty, S.; Chaves, R. C. G.; Chekhtman, A.; Chen, A. W.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cognard, I.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; DeCesar, M. E.; De Luca, A.; den Hartog, P. R.; de Palma, F.; Dermer, C. D.; Desvignes, G.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Espinoza, C. M.; Falletti, L.; Favuzzi, C.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Freire, P. C. C.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gotthelf, E. V.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hessels, J.; Hewitt, J.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Jackson, M. S.; Janssen, G. H.; Jogler, T.; Jóhannesson, G.; Johnson, R. P.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Johnston, S.; Kamae, T.; Kataoka, J.; Keith, M.; Kerr, M.; Knödlseder, J.; Kramer, M.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Lyne, A. G.; Manchester, R. N.; Marelli, M.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; McLaughlin, M. A.; Mehault, J.; Michelson, P. F.; Mignani, R. P.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nemmen, R.; Nuss, E.; Ohno, M.; Ohsugi, T.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Pletsch, H. J.; Porter, T. A.; Possenti, A.; Rainò, S.; Rando, R.; Ransom, S. M.; Ray, P. S.; Razzano, M.; Rea, N.; Reimer, A.; Reimer, O.; Renault, N.; Reposeur, T.; Ritz, S.; Romani, R. W.; Roth, M.; Rousseau, R.; Roy, J.; Ruan, J.; Sartori, A.; Saz Parkinson, P. M.; Scargle, J. D.; Schulz, A.; Sgrò, C.; Shannon, R.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stappers, B. W.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.; Theureau, G.; Thompson, D. J.; Thorsett, S. E.; Tibaldo, L.; Tibolla, O.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Venter, C.; Vianello, G.; Vitale, V.; Wang, N.; Weltevrede, P.; Winer, B. L.; Wolff, M. T.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.

    2013-10-01

    This catalog summarizes 117 high-confidence >=0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-peak phase intervals indicates probable pulsar wind nebula emission for four pulsars, and off-peak magnetospheric emission for several young and millisecond pulsars. We compare the gamma-ray properties with those in the radio, optical, and X-ray bands. We provide flux limits for pulsars with no observed gamma-ray emission, highlighting a small number of gamma-faint, radio-loud pulsars. The large, varied gamma-ray pulsar sample constrains emission models. Fermi's selection biases complement those of radio surveys, enhancing comparisons with predicted population distributions.

  1. The second FERMI large area telescope catalog of gamma-ray pulsars

    SciTech Connect

    Abdo, A. A.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Belfiore, A.; Bellazzini, R.; Bhattacharyya, B.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burgay, M.; Burnett, T. H.; Busetto, G.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Camilo, F.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chaty, S.; Chaves, R. C. G.; Chekhtman, A.; Chen, A. W.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cognard, I.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; DeCesar, M. E.; De Luca, A.; den Hartog, P. R.; de Palma, F.; Dermer, C. D.; Desvignes, G.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Espinoza, C. M.; Falletti, L.; Favuzzi, C.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Freire, P. C. C.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gotthelf, E. V.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hessels, J.; Hewitt, J.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Jackson, M. S.; Janssen, G. H.; Jogler, T.; Jóhannesson, G.; Johnson, R. P.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Johnston, S.; Kamae, T.; Kataoka, J.; Keith, M.; Kerr, M.; Knödlseder, J.; Kramer, M.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Lyne, A. G.; Manchester, R. N.; Marelli, M.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; McLaughlin, M. A.; Mehault, J.; Michelson, P. F.; Mignani, R. P.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nemmen, R.; Nuss, E.; Ohno, M.; Ohsugi, T.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Pletsch, H. J.; Porter, T. A.; Possenti, A.; Rainò, S.; Rando, R.; Ransom, S. M.; Ray, P. S.; Razzano, M.; Rea, N.; Reimer, A.; Reimer, O.; Renault, N.; Reposeur, T.; Ritz, S.; Romani, R. W.; Roth, M.; Rousseau, R.; Roy, J.; Ruan, J.; Sartori, A.; Saz Parkinson, P. M.; Scargle, J. D.; Schulz, A.; Sgrò, C.; Shannon, R.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stappers, B. W.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.; Theureau, G.; Thompson, D. J.; Thorsett, S. E.; Tibaldo, L.; Tibolla, O.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Venter, C.; Vianello, G.; Vitale, V.; Wang, N.; Weltevrede, P.; Winer, B. L.; Wolff, M. T.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.

    2013-09-19

    This catalog summarizes 117 high-confidence ≥0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-peak phase intervals indicates probable pulsar wind nebula emission for four pulsars, and off-peak magnetospheric emission for several young and millisecond pulsars. We compare the gamma-ray properties with those in the radio, optical, and X-ray bands. We provide flux limits for pulsars with no observed gamma-ray emission, highlighting a small number of gamma-faint, radio-loud pulsars. The large, varied gamma-ray pulsar sample constrains emission models. Fermi's selection biases complement those of radio surveys, enhancing comparisons with predicted population distributions.

  2. The second fermi large area telescope catalog of gamma-ray pulsars

    SciTech Connect

    Abdo, A. A.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Belfiore, A.; Bellazzini, R.; Bhattacharyya, B.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burgay, M.; Burnett, T. H.; Busetto, G.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Camilo, F.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chaty, S.; Chaves, R. C. G.; Chekhtman, A.; Chen, A. W.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cognard, I.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; DeCesar, M. E.; De Luca, A.; den Hartog, P. R.; de Palma, F.; Dermer, C. D.; Desvignes, G.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Espinoza, C. M.; Falletti, L.; Favuzzi, C.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Freire, P. C. C.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gotthelf, E. V.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hessels, J.; Hewitt, J.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Jackson, M. S.; Janssen, G. H.; Jogler, T.; Jóhannesson, G.; Johnson, R. P.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Johnston, S.; Kamae, T.; Kataoka, J.; Keith, M.; Kerr, M.; Knödlseder, J.; Kramer, M.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Lyne, A. G.; Manchester, R. N.; Marelli, M.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; McLaughlin, M. A.; Mehault, J.; Michelson, P. F.; Mignani, R. P.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nemmen, R.; Nuss, E.; Ohno, M.; Ohsugi, T.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Pletsch, H. J.; Porter, T. A.; Possenti, A.; Rainò, S.; Rando, R.; Ransom, S. M.; Ray, P. S.; Razzano, M.; Rea, N.; Reimer, A.; Reimer, O.; Renault, N.; Reposeur, T.; Ritz, S.; Romani, R. W.; Roth, M.; Rousseau, R.; Roy, J.; Ruan, J.; Sartori, A.; Saz Parkinson, P. M.; Scargle, J. D.; Schulz, A.; Sgrò, C.; Shannon, R.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stappers, B. W.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.; Theureau, G.; Thompson, D. J.; Thorsett, S. E.; Tibaldo, L.; Tibolla, O.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Venter, C.; Vianello, G.; Vitale, V.; Wang, N.; Weltevrede, P.; Winer, B. L.; Wolff, M. T.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.

    2013-09-19

    This catalog summarizes 117 high-confidence ≥0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-peak phase intervals indicates probable pulsar wind nebula emission for four pulsars, and off-peak magnetospheric emission for several young and millisecond pulsars. We compare the gamma-ray properties with those in the radio, optical, and X-ray bands. We provide flux limits for pulsars with no observed gamma-ray emission, highlighting a small number of gamma-faint, radio-loud pulsars. The large, varied gamma-ray pulsar sample constrains emission models. Fermi's selection biases complement those of radio surveys, enhancing comparisons with predicted population distributions.

  3. ON THE FERMI LARGE AREA TELESCOPE SURPLUS OF DIFFUSE GALACTIC GAMMA-RAY EMISSION

    SciTech Connect

    Völk, H. J.; Berezhko, E. G.

    2013-11-10

    Recent observations of diffuse Galactic γ-ray emission (DGE) by the Fermi Large Area Telescope (Fermi-LAT) have shown significant deviations, above a few GeV to about 100 GeV, from DGE models that use the GALPROP code for the propagation of cosmic ray (CR) particles outside their sources in the Galaxy and their interaction with the target distributions of the interstellar gas and radiation fields. The surplus of radiation observed is most pronounced in the inner Galaxy, where the concentration of CR sources is strongest. The present study investigates this 'Fermi-LAT Galactic Plane Surplus' by estimating the γ-ray emission from the sources themselves, which is disregarded in the above DGE models. It is shown that the expected hard spectrum of CRs, still confined in their sources (source cosmic rays, SCRs), can indeed explain this surplus. The method is based on earlier studies regarding the so-called EGRET GeV excess, which by now is generally interpreted as an instrumental effect. The contribution from SCRs is also predicted to increasingly exceed the DGE models above 100 GeV, up to γ-ray energies of about 10 TeV, where the corresponding surplus exceeds the hadronic part of the DGE by about one order of magnitude. Above such energies, the emission surplus should decrease again with energy due to the finite lifetime of the assumed supernova remnant sources. Observations of the DGE in the inner Galaxy at 15 TeV with the ground-based Milagro γ-ray detector and, at TeV energies, with the ARGO-YBJ detector are interpreted to provide confirmation of a significant SCR contribution to the DGE.

  4. On the Fermi Large Area Telescope Surplus of Diffuse Galactic Gamma-Ray Emission

    NASA Astrophysics Data System (ADS)

    Völk, H. J.; Berezhko, E. G.

    2013-11-01

    Recent observations of diffuse Galactic γ-ray emission (DGE) by the Fermi Large Area Telescope (Fermi-LAT) have shown significant deviations, above a few GeV to about 100 GeV, from DGE models that use the GALPROP code for the propagation of cosmic ray (CR) particles outside their sources in the Galaxy and their interaction with the target distributions of the interstellar gas and radiation fields. The surplus of radiation observed is most pronounced in the inner Galaxy, where the concentration of CR sources is strongest. The present study investigates this "Fermi-LAT Galactic Plane Surplus" by estimating the γ-ray emission from the sources themselves, which is disregarded in the above DGE models. It is shown that the expected hard spectrum of CRs, still confined in their sources (source cosmic rays, SCRs), can indeed explain this surplus. The method is based on earlier studies regarding the so-called EGRET GeV excess, which by now is generally interpreted as an instrumental effect. The contribution from SCRs is also predicted to increasingly exceed the DGE models above 100 GeV, up to γ-ray energies of about 10 TeV, where the corresponding surplus exceeds the hadronic part of the DGE by about one order of magnitude. Above such energies, the emission surplus should decrease again with energy due to the finite lifetime of the assumed supernova remnant sources. Observations of the DGE in the inner Galaxy at 15 TeV with the ground-based Milagro γ-ray detector and, at TeV energies, with the ARGO-YBJ detector are interpreted to provide confirmation of a significant SCR contribution to the DGE.

  5. International Student Adaptation to a U.S. College: A Mixed Methods Exploration of the Impact of a Specialized First-Year Foundations Course at a Large Midwestern Institution

    ERIC Educational Resources Information Center

    Kovtun, Olena

    2010-01-01

    The present study assessed the effects of a specialized first-year foundations course as an intervention for international students' academic and cultural adaptation at a large, Midwestern, public research institution (very high research activity). This was a quasi-experimental, mixed methods study, consisting of two quantitative and two…

  6. Measurement of the cosmic-ray proton spectrum with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Green, David; Fermi LAT Area Telescope Collaboration Collaboration

    2017-01-01

    We present the measurement of the cosmic-ray proton spectrum between 54 GeV and 9.5 TeV using 7 years of Pass 8 flight data from the Fermi Large Area Telescope (LAT). We developed a dedicated proton event selection with an acceptance of 0.25 m2 sr. Our analysis yields a large dataset with low statistical uncertainty and low residual contamination for a spectral measurement. The systematic errors associated with the acceptance, energy measurement, GEANT4 Monte-Carlo simulations are an order of magnitude larger than the statistical uncertainty. The event selection and spectral measurement of the proton analysis create the opportunity for additional proton analyses with the LAT, such as a dedicated proton anisotropy search.

  7. Gamma-ray and radio properties of six pulsars detected by the Fermi Large Area Telescope

    DOE PAGES

    Weltevrede, P.

    2009-12-22

    Here, we report the detection of pulsed γ-rays for PSRs J0631+1036, J0659+1414, J0742-2822, J1420-6048, J1509-5850, and J1718-3825 using the Large Area Telescope on board the Fermi Gamma-ray Space Telescope (formerly known as GLAST). Although these six pulsars are diverse in terms of their spin parameters, they share an important feature: their γ-ray light curves are (at least given the current count statistics) single peaked. For two pulsars, there are hints for a double-peaked structure in the light curves. The shapes of the observed light curves of this group of pulsars are discussed in the light of models for which themore » emission originates from high up in the magnetosphere. We observed phases of the γ-ray light curves are and, in general, they are consistent with those predicted by high-altitude models, although we speculate that the γ-ray emission of PSR J0659+1414, possibly featuring the softest spectrum of all Fermi pulsars coupled with a very low efficiency, arises from relatively low down in the magnetosphere. High-quality radio polarization data are available showing that all but one have a high degree of linear polarization. Furthermore, this allows us to place some constraints on the viewing geometry and aids the comparison of the γ-ray light curves with high-energy beam models.« less

  8. Fermi Large Area Telescope observations of two gamma-ray emission components from the quiescent sun

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2011-06-06

    Here, we report the detection of high-energy γ-rays from the quiescent Sun with the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope (Fermi) during the first 18 months of the mission. These observations correspond to the recent period of low solar activity when the emission induced by cosmic rays (CRs) is brightest. For the first time, the high statistical significance of the observations allows clear separation of the two components: the point-like emission from the solar disk due to CR cascades in the solar atmosphere and extended emission from the inverse Compton (IC) scattering of CR electrons onmore » solar photons in the heliosphere. The observed integral flux (≥100 MeV) from the solar disk is (4.6 ± 0.2[statistical error]+1.0 –0.8[systematic error]) × 10–7 cm–2 s–1, which is ~7 times higher than predicted by the "nominal" model of Seckel et al. In contrast, the observed integral flux (≥100 MeV) of the extended emission from a region of 20° radius centered on the Sun, but excluding the disk itself, (6.8 ± 0.7[stat.]+0.5 – 0.4[syst.]) × 10–7 cm–2 s–1, along with the observed spectrum and the angular profile, is in good agreement with the theoretical predictions for the IC emission.« less

  9. Constraints on Lorentz invariance violation from Fermi -Large Area Telescope observations of gamma-ray bursts

    DOE PAGES

    Vasileiou, V.; Jacholkowska, A.; Piron, F.; ...

    2013-06-04

    For this research, we analyze the MeV/GeV emission from four bright gamma-ray bursts (GRBs) observed by the Fermi Large Area Telescope to produce robust, stringent constraints on a dependence of the speed of light in vacuo on the photon energy (vacuum dispersion), a form of Lorentz invariance violation (LIV) allowed by some quantum gravity (QG) theories. First, we use three different and complementary techniques to constrain the total degree of dispersion observed in the data. Additionally, using a maximally conservative set of assumptions on possible source-intrinsic, spectral-evolution effects, we constrain any vacuum dispersion solely attributed to LIV. We then derivemore » limits on the QG energy scale (the energy scale where LIV-inducing QG effects become strong, EQG) and the coefficients of the Standard Model Extension. For the subluminal case (where high-energy photons propagate more slowly than lower-energy photons) and without taking into account any source-intrinsic dispersion, our most stringent limits (at 95% C.L.) are obtained from GRB 090510 and are EQG,1 > 7.6 times the Planck energy (EPl) and EQG,2 > 1.3 × 1011 GeV for linear and quadratic leading-order LIV-induced vacuum dispersion, respectively. In conclusion, these limits improve the latest constraints by Fermi and H.E.S.S. by a factor of ~2 . Our results disfavor any class of models requiring EQG,1 ≲ EPl .« less

  10. FERMI LARGE AREA TELESCOPE CONSTRAINTS ON THE GAMMA-RAY OPACITY OF THE UNIVERSE

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bouvier, A.; Atwood, W. B.; Baldini, L.; Bellazzini, R.; Ballet, J.; Baring, M. G.; Bastieri, D.; Baughman, B. M.; Bhat, P. N.; Bonamente, E. E-mail: bouvier@stanford.ed E-mail: silvia.raino@ba.infn.i E-mail: lreyes@kicp.uchicago.ed

    2010-11-10

    The extragalactic background light (EBL) includes photons with wavelengths from ultraviolet to infrared, which are effective at attenuating gamma rays with energy above {approx}10 GeV during propagation from sources at cosmological distances. This results in a redshift- and energy-dependent attenuation of the {gamma}-ray flux of extragalactic sources such as blazars and gamma-ray bursts (GRBs). The Large Area Telescope on board Fermi detects a sample of {gamma}-ray blazars with redshift up to z {approx} 3, and GRBs with redshift up to z {approx} 4.3. Using photons above 10 GeV collected by Fermi over more than one year of observations for these sources, we investigate the effect of {gamma}-ray flux attenuation by the EBL. We place upper limits on the {gamma}-ray opacity of the universe at various energies and redshifts and compare this with predictions from well-known EBL models. We find that an EBL intensity in the optical-ultraviolet wavelengths as great as predicted by the 'baseline' model of Stecker et al. can be ruled out with high confidence.

  11. Fermi Large Area Telescope Constraints On The Gamma-Ray Opacity Of The Universe

    DOE PAGES

    Abdo, A. A.

    2010-10-19

    The extragalactic background light (EBL) includes photons with wavelengths from ultraviolet to infrared, which are effective at attenuating gamma rays with energy above ~10 GeV during propagation from sources at cosmological distances. This results in a redshift- and energy-dependent attenuation of the γ-ray flux of extragalactic sources such as blazars and gamma-ray bursts (GRBs). The Large Area Telescope on board Fermi detects a sample of γ-ray blazars with redshift up to z ~ 3, and GRBs with redshift up to z ~ 4.3. Using photons above 10 GeV collected by Fermi over more than one year of observations for thesemore » sources, we investigate the effect of γ-ray flux attenuation by the EBL. We place upper limits on the γ-ray opacity of the universe at various energies and redshifts and compare this with predictions from well-known EBL models. We find that an EBL intensity in the optical-ultraviolet wavelengths as great as predicted by the "baseline" model of Stecker et al. can be ruled out with high confidence.« less

  12. Gamma-ray and radio properties of six pulsars detected by the Fermi Large Area Telescope

    SciTech Connect

    Weltevrede, P.

    2009-12-22

    Here, we report the detection of pulsed γ-rays for PSRs J0631+1036, J0659+1414, J0742-2822, J1420-6048, J1509-5850, and J1718-3825 using the Large Area Telescope on board the Fermi Gamma-ray Space Telescope (formerly known as GLAST). Although these six pulsars are diverse in terms of their spin parameters, they share an important feature: their γ-ray light curves are (at least given the current count statistics) single peaked. For two pulsars, there are hints for a double-peaked structure in the light curves. The shapes of the observed light curves of this group of pulsars are discussed in the light of models for which the emission originates from high up in the magnetosphere. We observed phases of the γ-ray light curves are and, in general, they are consistent with those predicted by high-altitude models, although we speculate that the γ-ray emission of PSR J0659+1414, possibly featuring the softest spectrum of all Fermi pulsars coupled with a very low efficiency, arises from relatively low down in the magnetosphere. High-quality radio polarization data are available showing that all but one have a high degree of linear polarization. Furthermore, this allows us to place some constraints on the viewing geometry and aids the comparison of the γ-ray light curves with high-energy beam models.

  13. The Fermi Large Area Telescope Thrid Gamma-ray Source Catalog

    NASA Astrophysics Data System (ADS)

    Stephens, Thomas E.; Ballet, Jean; Burnett, Toby; Cavazzuti, Elisabetta; Digel, Seth William; Fermi LAT Collaboration

    2015-01-01

    We present an overview of the third Fermi Large Area Telescope source catalog (3FGL) of sources in the 100 MeV - 300 GeV range. Based on the first four years of science data from the Fermi Gamma-ray Space Telescope mission, it is the deepest yet in this energy range. Relative to the 2FGL catalog (Nolan et al. 2012, ApJS 199, 31), the 3FGL catalog incorporates twice as much data as well as a number of analysis improvements, including improved calibrations at the event reconstruction level, an updated model for Galactic diffuse gamma-ray emission, a refined procedure for source detection, and improved methods for associating LAT sources with potential counterparts at other wavelengths. The 3FGL catalog includes 3033 sources, with source location regions, spectral properties, and monthly light curves for each. For approximately one-third of the sources we have not found counterparts at other wavelengths. More than 1100 of the identified or associated sources are active galaxies of the blazar class; several other classes of non-blazar active galaxies are also represented in the 3FGL. Pulsars represent the largest Galactic source class. From source counts of Galactic sources we estimate the contribution of unresolved sources to the Galactic diffuse emission.

  14. Search for Large Extra Dimensions Based on Observations of Neutron Stars with the Fermi-LAT

    SciTech Connect

    Berenji, Bijan

    2012-09-19

    Large extra dimensions (LED) have been proposed to account for the apparent weakness of gravitation. These theories also indicate that the postulated massive Kaluza-Klein (KK) gravitons may be produced by nucleon-nucleon bremsstrahlung in the course of core collapse of supernovae. Hannestad and Raffelt have predicted energy spectra of gamma ray emission from the decay of KK gravitons trapped by the gravity of the remnant neutron stars (NS). These and other authors have used EGRET data on NS to obtain stringent limits on LED. Fermi-LAT is observing radio pulsar positions obtained from radio and x-ray catalogs. NS with certain characteristics are unlikely emitter of gamma rays, and emit in radio and perhaps x-rays. This talk will focus on the blind analysis we plan to perform, which has been developed using the 1st 2 months of all sky data and Monte Carlo simulations, to obtain limits on LED based on about 1 year of Fermi-LAT data. Preliminary limits from this analysis using these first 2 months of data will be also be discussed.

  15. Limits on Large Extra Dimensions Based on Observations of Neutron Stars with the Fermi-LAT

    NASA Technical Reports Server (NTRS)

    Ferrara, E. C.; Scargle, J. D.; Troja, E.

    2012-01-01

    We present limits for the compactification scale in the theory of Large Extra Dimensions (LED) proposed by Arkani-Hamed, Dimopoulos, and Dvali. We use 11 months of data from the Fermi Large Area Telescope (Fermi-LAT) to set gamma ray flux limits for 6 gamma-ray faint neutron stars (NS). To set limits on LED we use the model of Hannestad and Raffelt (HR) that calculates the Kaluza-Klein (KK) graviton production in supernova cores and the large fraction subsequently gravitationally bound around the resulting NS. The predicted decay of the bound KK gravitons to should contribute to the flux from NSs. Considering 2 to 7 extra dimensions of the same size in the context of the HR model, we use Monte Carlo techniques to calculate the expected differential flux of gamma-rays arising from these KK gravitons, including the effects of the age of the NS, graviton orbit, and absorption of gamma-rays in the magnetosphere of the NS. We compare our Monte Carlo-based differential flux to the experimental differential flux using maximum likelihood techniques to obtain our limits on LED. Our limits are more restrictive than past EGRET-based optimistic limits that do not include these important corrections. Additionally, our limits are more stringent than LHC based limits for 3 or fewer LED, and comparable for 4 LED. We conclude that if the effective Planck scale is around a TeV, then for 2 or 3 LED the compactification topology must be more complicated than a torus.

  16. Limits on Large Extra Dimensions Based on Observations of Neutron Stars with the Fermi-LAT

    SciTech Connect

    Ajello, M.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E.D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G.A.; Cameron, R.A.; Caraveo, P.A.; Casandjian, J.M.; Cecchi, C.; Charles, E.; /more authors..

    2012-08-17

    We present limits for the compactification scale in the theory of Large Extra Dimensions (LED) proposed by Arkani-Hamed, Dimopoulos, and Dvali. We use 11 months of data from the Fermi Large Area Telescope (Fermi-LAT) to set gamma ray flux limits for 6 gamma-ray faint neutron stars (NS). To set limits on LED we use the model of Hannestad and Raffelt (HR) that calculates the Kaluza-Klein (KK) graviton production in supernova cores and the large fraction subsequently gravitationally bound around the resulting NS. The predicted decay of the bound KK gravitons to {gamma}{gamma} should contribute to the flux from NSs. Considering 2 to 7 extra dimensions of the same size in the context of the HR model, we use Monte Carlo techniques to calculate the expected differential flux of gamma-rays arising from these KK gravitons, including the effects of the age of the NS, graviton orbit, and absorption of gamma-rays in the magnetosphere of the NS. We compare our Monte Carlo-based differential flux to the experimental differential flux using maximum likelihood techniques to obtain our limits on LED. Our limits are more restrictive than past EGRET-based optimistic limits that do not include these important corrections. Additionally, our limits are more stringent than LHC based limits for 3 or fewer LED, and comparable for 4 LED. We conclude that if the effective Planck scale is around a TeV, then for 2 or 3 LED the compactification topology must be more complicated than a torus.

  17. Limits on large extra dimensions based on observations of neutron stars with the Fermi-LAT

    SciTech Connect

    Ajello, M.

    2012-02-01

    We present limits for the compactification scale in the theory of Large Extra Dimensions (LED) proposed by Arkani-Hamed, Dimopoulos, and Dvali. We use 11 months of data from the Fermi Large Area Telescope (Fermi-LAT) to set gamma ray flux limits for 6 gamma-ray faint neutron stars (NS). To set limits on LED we use the model of Hannestad and Raffelt (HR) that calculates the Kaluza-Klein (KK) graviton production in supernova cores and the large fraction subsequently gravitationally bound around the resulting NS. The predicted decay of the bound KK gravitons to γγ should contribute to the flux from NSs. Considering 2 to 7 extra dimensions of the same size in the context of the HR model, we use Monte Carlo techniques to calculate the expected differential flux of gamma-rays arising from these KK gravitons, including the effects of the age of the NS, graviton orbit, and absorption of gamma-rays in the magnetosphere of the NS. We compare our Monte Carlo-based differential flux to the experimental differential flux using maximum likelihood techniques to obtain our limits on LED. Our limits are more restrictive than past EGRET-based optimistic limits that do not include these important corrections. Additionally, our limits are more stringent than LHC based limits for 3 or fewer LED, and comparable for 4 LED. We conclude that if the effective Planck scale is around a TeV, then for 2 or 3 LED the compactification topology must be more complicated than a torus.

  18. Limits on large extra dimensions based on observations of neutron stars with the Fermi-LAT

    SciTech Connect

    Ajello, M.; Bechtol, K.; Berenji, B.; Bloom, E.D.; Borgland, A.W.; Buehler, R.; Cameron, R.A.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Barbiellini, G.; Bastieri, D.; Buson, S.; Bonamente, E.; Cecchi, C.; Brigida, M.; Bruel, P.; Caraveo, P.A.; Casandjian, J.M. E-mail: elliott@slac.stanford.edu [Laboratoire AIM, CEA-IRFU Collaboration: Fermi-LAT collaboration; and others

    2012-02-01

    We present limits for the compactification scale in the theory of Large Extra Dimensions (LED) proposed by Arkani-Hamed, Dimopoulos, and Dvali. We use 11 months of data from the Fermi Large Area Telescope (Fermi-LAT) to set gamma ray flux limits for 6 gamma-ray faint neutron stars (NS). To set limits on LED we use the model of Hannestad and Raffelt (HR) that calculates the Kaluza-Klein (KK) graviton production in supernova cores and the large fraction subsequently gravitationally bound around the resulting NS. The predicted decay of the bound KK gravitons to γγ should contribute to the flux from NSs. Considering 2 to 7 extra dimensions of the same size in the context of the HR model, we use Monte Carlo techniques to calculate the expected differential flux of gamma-rays arising from these KK gravitons, including the effects of the age of the NS, graviton orbit, and absorption of gamma-rays in the magnetosphere of the NS. We compare our Monte Carlo-based differential flux to the experimental differential flux using maximum likelihood techniques to obtain our limits on LED. Our limits are more restrictive than past EGRET-based optimistic limits that do not include these important corrections. Additionally, our limits are more stringent than LHC based limits for 3 or fewer LED, and comparable for 4 LED. We conclude that if the effective Planck scale is around a TeV, then for 2 or 3 LED the compactification topology must be more complicated than a torus.

  19. Limits on large extra dimensions based on observations of neutron stars with the Fermi-LAT

    DOE PAGES

    Ajello, M.

    2012-02-01

    We present limits for the compactification scale in the theory of Large Extra Dimensions (LED) proposed by Arkani-Hamed, Dimopoulos, and Dvali. We use 11 months of data from the Fermi Large Area Telescope (Fermi-LAT) to set gamma ray flux limits for 6 gamma-ray faint neutron stars (NS). To set limits on LED we use the model of Hannestad and Raffelt (HR) that calculates the Kaluza-Klein (KK) graviton production in supernova cores and the large fraction subsequently gravitationally bound around the resulting NS. The predicted decay of the bound KK gravitons to γγ should contribute to the flux from NSs. Consideringmore » 2 to 7 extra dimensions of the same size in the context of the HR model, we use Monte Carlo techniques to calculate the expected differential flux of gamma-rays arising from these KK gravitons, including the effects of the age of the NS, graviton orbit, and absorption of gamma-rays in the magnetosphere of the NS. We compare our Monte Carlo-based differential flux to the experimental differential flux using maximum likelihood techniques to obtain our limits on LED. Our limits are more restrictive than past EGRET-based optimistic limits that do not include these important corrections. Additionally, our limits are more stringent than LHC based limits for 3 or fewer LED, and comparable for 4 LED. We conclude that if the effective Planck scale is around a TeV, then for 2 or 3 LED the compactification topology must be more complicated than a torus.« less

  20. The Large Area Telescope on the Fermi Gamma-Ray Space Telescope Mission

    NASA Astrophysics Data System (ADS)

    Atwood, W. B.; Abdo, A. A.; Ackermann, M.; Althouse, W.; Anderson, B.; Axelsson, M.; Baldini, L.; Ballet, J.; Band, D. L.; Barbiellini, G.; Bartelt, J.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bédérède, D.; Bellardi, F.; Bellazzini, R.; Berenji, B.; Bignami, G. F.; Bisello, D.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Bonamente, E.; Bonnell, J.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Busetto, G.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Carius, S.; Carlson, P.; Casandjian, J. M.; Cavazzuti, E.; Ceccanti, M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chipaux, R.; Cillis, A. N.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Condamoor, S.; Conrad, J.; Corbet, R.; Corucci, L.; Costamante, L.; Cutini, S.; Davis, D. S.; Decotigny, D.; DeKlotz, M.; Dermer, C. D.; de Angelis, A.; Digel, S. W.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Edmonds, Y.; Fabiani, D.; Farnier, C.; Favuzzi, C.; Flath, D. L.; Fleury, P.; Focke, W. B.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Gentit, F.-X.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Haller, G.; Harding, A. K.; Hart, P. A.; Hays, E.; Healey, S. E.; Hirayama, M.; Hjalmarsdotter, L.; Horn, R.; Hughes, R. E.; Jóhannesson, G.; Johansson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kavelaars, A.; Kawai, N.; Kelly, H.; Kerr, M.; Klamra, W.; Knödlseder, J.; Kocian, M. L.; Komin, N.; Kuehn, F.; Kuss, M.; Landriu, D.; Latronico, L.; Lee, B.; Lee, S.-H.; Lemoine-Goumard, M.; Lionetto, A. M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Marangelli, B.; Massai, M. M.; Mazziotta, M. N.; McEnery, J. E.; Menon, N.; Meurer, C.; Michelson, P. F.; Minuti, M.; Mirizzi, N.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nishino, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paccagnella, A.; Paneque, D.; Panetta, J. H.; Parent, D.; Pearce, M.; Pepe, M.; Perazzo, A.; Pesce-Rollins, M.; Picozza, P.; Pieri, L.; Pinchera, M.; Piron, F.; Porter, T. A.; Poupard, L.; Rainò, S.; Rando, R.; Rapposelli, E.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Reyes, L. C.; Ritz, S.; Rochester, L. S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Russell, J. J.; Ryde, F.; Sabatini, S.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Sapozhnikov, L.; Parkinson, P. M. Saz; Scargle, J. D.; Schalk, T. L.; Scolieri, G.; Sgrò, C.; Share, G. H.; Shaw, M.; Shimokawabe, T.; Shrader, C.; Sierpowska-Bartosik, A.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J.-L.; Stephens, T. E.; Strickman, M. S.; Strong, A. W.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Tenze, A.; Tether, S.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Tosti, G.; Tramacere, A.; Turri, M.; Usher, T. L.; Vilchez, N.; Vitale, V.; Wang, P.; Watters, K.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Ziegler, M.

    2009-06-01

    The 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 (FoV), high-energy γ-ray telescope, covering the energy range from below 20 MeV to more than 300 GeV. The LAT was built by an international collaboration with contributions from space agencies, high-energy particle physics institutes, and universities in France, Italy, Japan, Sweden, and the United States. This paper describes the LAT, its preflight expected performance, and summarizes the key science objectives that will be addressed. On-orbit performance will be presented in detail in a subsequent paper. The LAT is a pair-conversion telescope with a precision tracker and calorimeter, each consisting of a 4 × 4 array of 16 modules, a segmented anticoincidence detector that covers the tracker array, and a programmable trigger and data acquisition system. Each tracker module has a vertical stack of 18 (x, y) tracking planes, including two layers (x and y) of single-sided silicon strip detectors and high-Z converter material (tungsten) per tray. Every calorimeter module has 96 CsI(Tl) crystals, arranged in an eight-layer hodoscopic configuration with a total depth of 8.6 radiation lengths, giving both longitudinal and transverse information about the energy deposition pattern. The calorimeter's depth and segmentation enable the high-energy reach of the LAT and contribute significantly to background rejection. The aspect ratio of the tracker (height/width) is 0.4, allowing a large FoV (2.4 sr) and ensuring that most pair-conversion showers initiated in the tracker will pass into the calorimeter for energy measurement. Data obtained with the LAT are intended to (1) permit rapid notification of high-energy γ-ray bursts and transients and facilitate monitoring of variable sources, (2) yield an extensive catalog of several thousand high-energy sources obtained from an all-sky survey, (3) measure spectra

  1. The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission

    SciTech Connect

    Atwood, W.B.; Abdo, Aous A.; Ackermann, M.; Anderson, B. Axelsson, M.; Baldini, L.; Ballet, J.; Band, D.L.; Barbiellini, Guido; Bartelt, J.; Bastieri, Denis; Baughman, B.M.; Bechtol, K.; Bederede, D.; Bellardi, F.; Bellazzini, R.; Berenji, B.; Bignami, G.F.; Bisello, D.; Bissaldi, E.; Blandford, R.D.; /more authors..

    2009-05-15

    The 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 (FoV), high-energy {gamma}-ray telescope, covering the energy range from below 20 MeV to more than 300 GeV. The LAT was built by an international collaboration with contributions from space agencies, high-energy particle physics institutes, and universities in France, Italy, Japan, Sweden, and the United States. This paper describes the LAT, its preflight expected performance, and summarizes the key science objectives that will be addressed. On-orbit performance will be presented in detail in a subsequent paper. The LAT is a pair-conversion telescope with a precision tracker and calorimeter, each consisting of a 4 x 4 array of 16 modules, a segmented anticoincidence detector that covers the tracker array, and a programmable trigger and data acquisition system. Each tracker module has a vertical stack of 18 (x, y) tracking planes, including two layers (x and y) of single-sided silicon strip detectors and high-Z converter material (tungsten) per tray. Every calorimeter module has 96 CsI(Tl) crystals, arranged in an eight-layer hodoscopic configuration with a total depth of 8.6 radiation lengths, giving both longitudinal and transverse information about the energy deposition pattern. The calorimeter's depth and segmentation enable the high-energy reach of the LAT and contribute significantly to background rejection. The aspect ratio of the tracker (height/width) is 0.4, allowing a large FoV (2.4 sr) and ensuring that most pair-conversion showers initiated in the tracker will pass into the calorimeter for energy measurement. Data obtained with the LAT are intended to (1) permit rapid notification of high-energy {gamma}-ray bursts and transients and facilitate monitoring of variable sources, (2) yield an extensive catalog of several thousand high-energy sources obtained from an all-sky survey, (3) measure

  2. Fermi Observations of Resolved Large-Scale Jets: Testing the IC/CMB Model

    NASA Astrophysics Data System (ADS)

    Breiding, Peter; Meyer, Eileen T.; Georganopoulos, Markos

    2017-01-01

    It has been observed with the Chandra X-ray Observatory since the early 2000s that many powerful quasar jets show X-ray emission on the kpc scale (Harris & Krawczynski, 2006). In many cases these X-rays cannot be explained by the extension of the radio-optical spectrum produced by synchrotron emitting electrons in the jet, since the observed X-ray flux is too high and the X-ray spectral index too hard. A widely accepted model for the X-ray emission first proposed by Celotti et al. 2001 and Tavecchio et al. 2000 posits that the X-rays are produced when relativistic electrons in the jet up-scatter ambient cosmic microwave background (CMB) photons via inverse Compton scattering from microwave to X-ray energies (the IC/CMB model). However, explaining the X-ray emission for these jets with the IC/CMB model requires high levels of IC/CMB γ-ray emission (Georganopoulos et al., 2006), which we are looking for using the FERMI/LAT γ-ray space telescope. Another viable model for the large scale jet X-ray emission favored by the results of Meyer et al. 2015 and Meyer & Georganopoulos 2014 is an alternate population of synchrotron emitting electrons. In contrast with the second synchrotron interpretation; the IC/CMB model requires jets with high kinetic powers which can exceed the Eddington luminsoity (Dermer & Atoyan 2004 and Atoyan & Dermer 2004) and be very fast on the kpc scale with a Γ~10 (Celotti et al. 2001 and Tavecchio et al. 2000). New results from data obtained with the Fermi/LAT will be shown for several quasars not in the Fermi/LAT 3FGL catalog whose large scale X-ray jets are attributed to IC/CMB. Additionally, recent work on the γ-ray bright blazar AP Librae will be shown which helps to constrain some models attempting to explain the high energy component of its SED, which extends from X-ray to TeV energies (e.g., Zacharias & Wagner 2016 & Petropoulou et al. 2016).

  3. Measurement of Separate Cosmic-Ray Electron and Positron Spectra with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ferrara, E. C.; Harding, A. K.; McEnery, J. E.; Moiseev, A. A.; Ackemann, M.

    2012-01-01

    We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because the instrument does not have an onboard magnet, we distinguish the two species by exploiting Earth's shadow, which, is offset in opposite directions for opposite charges due to Earth's magnetic field. We estimate and subtract the cosmic-ray proton background using two different methods that produce consistent results. We report the electron-only spectrum, the positron-only spectrum, and the positron fraction between 20 and 200 Ge V. We confirm that the fraction rises with energy in the 20-100 Ge V range. The three new spectral points between 100 and 200 GeV are consistent with a fraction that is continuing to rise with energy.

  4. Measurement of Separate Cosmic-Ray Electron and Positron Spectra with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; hide

    2011-01-01

    We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because the instrument does not have an onboard magnet, we distinguish the two species by exploiting the Earth's shadow, which is offset in opposite directions for opposite charges due to the Earth's magnetic field. We estimate and subtract the cosmic-ray proton background using two different methods that produce consistent results. We report the electron-only spectrum, the positron-only spectrum, and the positron fraction between 20 GeV and 200 GeV, We confirm that the fraction rises with energy in the 20-100 GeV range and determine for the first time that it continues to rise between 100 and 200 GeV,

  5. Search for the γ-ray emission from M33 with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Fu, L.; Xia, Z. Q.; Shen, Z. Q.

    2017-10-01

    We searched for the γ-ray signal from M33, one of the largest galaxies in the Local Group, using the Pass8 data from the Fermi Large Area Telescope (LAT). No statistically significant γ-ray emission has been detected in the direction of M33, and we report a new upper limit of the high-energy ( > 100 MeV) photon flux of 2.3 × 10- 9 ph cm- 2 s- 1, which is stricter than previous constraints and implies a cosmic ray density for M33 that is lower than that suggested previously. The current limit is still, however, in agreement with the correlation of star formation rate and γ-ray luminosity inferred from the Local group galaxies and a few nearby starburst galaxies.

  6. Cosmic Ray Studies with the Fermi Gamma-ray Space Telescope Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Baldini, L.; Uchiyama, Y.

    2011-01-01

    The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope provides both direct and indirect measurements of Galactic cosmic rays (CR). The LAT high-statistics observations of the 7 GeV - 1 TcV electron plus positron spectrum and limits on spatial anisotropy constrain models for this cosmic-ray component. On a Galactic scale, the LAT observations indicate that cosmic-ray sources may be more plentiful in the outer Galaxy than expected or that the scale height of the cosmic-ray diffusive halo is larger than conventional models. Production of cosmic rays in supernova remnants (SNR) is supported by the LAT gamma-ray studies of several of these, both young SNR and those interacting with molecular clouds.

  7. Cosmic Ray Studies with the Fermi Gamma-ray Space Telescope Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Thompson, David J.; Baldini, L.; Uchiyama, Y.

    2012-01-01

    The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope provides both direct and indirect measurements of galactic cosmic rays (CR). The LAT high-statistics observations of the 7 GeV - 1 TeV electron plus positron spectrum and limits on spatial anisotropy constrain models for this cosmic-ray component. On a galactic scale, the LAT observations indicate that cosmic-ray sources may be more plentiful in the outer Galaxy than expected or that the scale height of the cosmic-ray diffusive halo is larger than conventional models. Production of cosmic rays in supernova remnants (SNR) is supported by the LAT gamma-ray studies of several of these, both young SNR and those interacting with molecular clouds.

  8. The On-Orbit Calibrations for the Fermi Large Area Telescope

    SciTech Connect

    Abdo, Aous A.; Ackermann, M.; Ajello, M.; Ampe, J.; Anderson, B.; Atwood, W.B.; Axelsson, M.; Bagagli, R.; Baldini, L.; Ballet, J.; Barbiellini, Guido; Bartelt, J.; Bastieri, Denis; Baughman, B.M.; Bechtol, K.; Bederede, D.; Bellardi, F.; Bellazzini, R.; Belli, F.; Berenji, B.; Bisello, D.; /more authors..

    2011-11-17

    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope began its on-orbit operations on June 23, 2008. Calibrations, defined in a generic sense, correspond to synchronization of trigger signals, optimization of delays for latching data, determination of detector thresholds, gains and responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA), measurements of live time, of absolute time, and internal and spacecraft boresight alignments. Here we describe on-orbit calibration results obtained using known astrophysical sources, galactic cosmic rays, and charge injection into the front-end electronics of each detector. Instrument response functions will be described in a separate publication. This paper demonstrates the stability of calibrations and describes minor changes observed since launch. These results have been used to calibrate the LAT datasets to be publicly released in August 2009.

  9. A population of gamma-ray millisecond pulsars seen with the Fermi Large Area Telescope.

    PubMed

    Abdo, A A; Ackermann, M; Ajello, M; Atwood, W B; Axelsson, M; Baldini, L; Ballet, J; Barbiellini, G; Baring, M G; Bastieri, D; Baughman, B M; Bechtol, K; Bellazzini, R; Berenji, B; Bignami, G F; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Burnett, T H; Caliandro, G A; Cameron, R A; Camilo, F; Caraveo, P A; Carlson, P; Casandjian, J M; Cecchi, C; Celik, O; Charles, E; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cognard, I; Cohen-Tanugi, J; Cominsky, L R; Conrad, J; Corbet, R; Cutini, S; Dermer, C D; Desvignes, G; de Angelis, A; de Luca, A; de Palma, F; Digel, S W; Dormody, M; do Couto e Silva, E; Drell, P S; Dubois, R; Dumora, D; Edmonds, Y; Farnier, C; Favuzzi, C; Fegan, S J; Focke, W B; Frailis, M; Freire, P C C; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giebels, B; Giglietto, N; Giordano, F; Glanzman, T; Godfrey, G; Grenier, I A; Grondin, M H; Grove, J E; Guillemot, L; Guiriec, S; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hobbs, G; Hughes, R E; Jóhannesson, G; Johnson, A S; Johnson, R P; Johnson, T J; Johnson, W N; Johnston, S; Kamae, T; Katagiri, H; Kataoka, J; Kawai, N; Kerr, M; Knödlseder, J; Kocian, M L; Kramer, M; Kuss, M; Lande, J; Latronico, L; Lemoine-Goumard, M; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Manchester, R N; Marelli, M; Mazziotta, M N; McConville, W; McEnery, J E; McLaughlin, M A; Meurer, C; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nolan, P L; Norris, J P; Nuss, E; Ohsugi, T; Omodei, N; Orlando, E; Ormes, J F; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Ransom, S M; Ray, P S; Razzano, M; Rea, N; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Rochester, L S; Rodriguez, A Y; Romani, R W; Roth, M; Ryde, F; Sadrozinski, H F W; Sanchez, D; Sander, A; Saz Parkinson, P M; Scargle, J D; Schalk, T L; Sgrò, C; Siskind, E J; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Stappers, B W; Starck, J L; Striani, E; Strickman, M S; Suson, D J; Tajima, H; Takahashi, H; Tanaka, T; Thayer, J B; Thayer, J G; Theureau, G; Thompson, D J; Thorsett, S E; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Uchiyama, Y; Usher, T L; Van Etten, A; Vasileiou, V; Venter, C; Vilchez, N; Vitale, V; Waite, A P; Wallace, E; Wang, P; Watters, K; Webb, N; Weltevrede, P; Winer, B L; Wood, K S; Ylinen, T; Ziegler, M

    2009-08-14

    Pulsars are born with subsecond spin periods and slow by electromagnetic braking for several tens of millions of years, when detectable radiation ceases. A second life can occur for neutron stars in binary systems. They can acquire mass and angular momentum from their companions, to be spun up to millisecond periods and begin radiating again. We searched Fermi Large Area Telescope data for pulsations from all known millisecond pulsars (MSPs) outside of globular clusters, using rotation parameters from radio telescopes. Strong gamma-ray pulsations were detected for eight MSPs. The gamma-ray pulse profiles and spectral properties resemble those of young gamma-ray pulsars. The basic emission mechanism seems to be the same for MSPs and young pulsars, with the emission originating in regions far from the neutron star surface.

  10. Measurement of Separate Cosmic-Ray Electron and Positron Spectra with the Fermi Large Area Telescope

    DOE PAGES

    Ackermann, M.

    2012-01-05

    We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because the instrument does not have an onboard magnet, we distinguish the two species by exploiting the Earth’s shadow, which is offset in opposite directions for opposite charges due to the Earth’s magnetic field. We estimate and subtract the cosmic-ray proton background using two different methods that produce consistent results. We report the electron-only spectrum, the positron-only spectrum, and the positron fraction between 20 GeV and 200 GeV. We confirm that the fraction rises with energy in the 20–100 GeV range. The three new spectral pointsmore » between 100 and 200 GeV are consistent with a fraction that is continuing to rise with energy.« less

  11. Measurement of Separate Cosmic-Ray Electron and Positron Spectra with the Fermi Large Area Telescope

    SciTech Connect

    Ackermann, M.

    2012-01-05

    We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because the instrument does not have an onboard magnet, we distinguish the two species by exploiting the Earth’s shadow, which is offset in opposite directions for opposite charges due to the Earth’s magnetic field. We estimate and subtract the cosmic-ray proton background using two different methods that produce consistent results. We report the electron-only spectrum, the positron-only spectrum, and the positron fraction between 20 GeV and 200 GeV. We confirm that the fraction rises with energy in the 20–100 GeV range. The three new spectral points between 100 and 200 GeV are consistent with a fraction that is continuing to rise with energy.

  12. Correlation Investigation of Radio and Optical Variations in a Large Sample of Fermi Blazars

    NASA Astrophysics Data System (ADS)

    Zhang, B. K.; Zhao, X. Y.; Zhang, L.; Dai, B. Z.

    2017-08-01

    We have performed a correlation analysis of radio and optical variations in a large sample of Fermi blazars, of which there are 36 flat spectrum radio quasars and 34 BL Lacertae objects. The discrete cross-correlation function (DCF) method has been employed to investigate the correlation and the possible time lag. A clear correlation has been found in 55 sources (78.6% of the sample sources). It is confirmed that the variations in optical bands lead those in radio bands by several days to several hundred days. In four cases, optical flares are found to occur simultaneously with the radio flares. A jet-in-shock model has been used to explain these results. We estimate that the lag between the radio and optical bands may range from 3 days to 2.4 years. The DCF analysis results are consistent with expectations.

  13. The on-orbit calibration of the Fermi Large Area Telescope

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Ampe, J.; Anderson, B.; Atwood, W. B.; Axelsson, M.; Bagagli, R.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bartelt, J.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bédérède, D.; Bellardi, F.; Bellazzini, R.; Belli, F.; Berenji, B.; Bisello, D.; Bissaldi, E.; Bloom, E. D.; Bogaert, G.; Bogart, J. R.; Bonamente, E.; Borgland, A. W.; Bourgeois, P.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Busetto, G.; Caliandro, G. A.; Cameron, R. A.; Campell, M.; Caraveo, P. A.; Carius, S.; Carlson, P.; Casandjian, J. M.; Cavazzuti, E.; Ceccanti, M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chipaux, R.; Cillis, A. N.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Condamoor, S.; Conrad, J.; Corbet, R.; Cutini, S.; Davis, D. S.; DeKlotz, M.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Digel, S. W.; Dizon, P.; Dormody, M.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Edmonds, Y.; Fabiani, D.; Farnier, C.; Favuzzi, C.; Ferrara, E. C.; Ferreira, O.; Fewtrell, Z.; Flath, D. L.; Fleury, P.; Focke, W. B.; Fouts, K.; Frailis, M.; Freytag, D.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Goodman, J.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hakimi, M.; Haller, G.; Hanabata, Y.; Hart, P. A.; Hascall, P.; Hays, E.; Huffer, M.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kavelaars, A.; Kelly, H.; Kerr, M.; Klamra, W.; Knödlseder, J.; Kocian, M. L.; Kuehn, F.; Kuss, M.; Latronico, L.; Lavalley, C.; Leas, B.; Lee, B.; Lee, S. -H.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Lung, D. K.; Madejski, G. M.; Makeev, A.; Marangelli, B.; Marchetti, M.; Massai, M. M.; May, D.; Mazzenga, G.; Mazziotta, M. N.; McEnery, J. E.; McGlynn, S.; Meurer, C.; Michelson, P. F.; Minuti, M.; Mirizzi, N.; Mitra, P.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nelson, D.; Nilsson, L.; Nishino, S.; Nolan, P. L.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paccagnella, A.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Picozza, P.; Pinchera, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Rapposelli, E.; Raynor, W.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Reyes, L. C.; Ritz, S.; Robinson, S.; Rochester, L. S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Ryde, F.; Sacchetti, A.; Sadrozinski, H. F. -W.; Saggini, N.; Sanchez, D.; Sander, A.; Sapozhnikov, L.; Saxton, O. H.; Saz Parkinson, P. M.; Sellerholm, A.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J. -L.; Stephens, T. E.; Strickman, M. S.; Strong, A. W.; Sugizaki, M.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Tenze, A.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Tosti, G.; Tramacere, A.; Turri, M.; Usher, T. L.; Vilchez, N.; Virmani, N.; Vitale, V.; Wai, L. L.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, D. L.; Wood, K. S.; Yasuda, H.; Ylinen, T.; Ziegler, M.

    2009-09-06

    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope began its on-orbit operations on June 23, 2008. Calibrations, defined in a generic sense, correspond to synchronization of trigger signals, optimization of delays for latching data, determination of detector thresholds, gains and responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA), measurements of live time, of absolute time, and internal and spacecraft boresight alignments. Here in this work, we describe on-orbit calibration results obtained using known astrophysical sources, galactic cosmic rays, and charge injection into the front-end electronics of each detector. Instrument response functions will be described in a separate publication. This paper demonstrates the stability of calibrations and describes minor changes observed since launch. Lastly, these results have been used to calibrate the LAT datasets to be publicly released in August 2009.

  14. The on-orbit calibration of the Fermi Large Area Telescope

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2009-09-06

    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope began its on-orbit operations on June 23, 2008. Calibrations, defined in a generic sense, correspond to synchronization of trigger signals, optimization of delays for latching data, determination of detector thresholds, gains and responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA), measurements of live time, of absolute time, and internal and spacecraft boresight alignments. Here in this work, we describe on-orbit calibration results obtained using known astrophysical sources, galactic cosmic rays, and charge injection into the front-end electronics of each detector. Instrument response functions will be describedmore » in a separate publication. This paper demonstrates the stability of calibrations and describes minor changes observed since launch. Lastly, these results have been used to calibrate the LAT datasets to be publicly released in August 2009.« less

  15. Fermi Large Area Telescope Observations of the Cosmic-Ray Induced

    SciTech Connect

    Abdo, A.

    2012-02-29

    We report on measurements of the cosmic-ray induced {gamma}-ray emission of Earth's atmosphere by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope. The LAT has observed the Earth during its commissioning phase and with a dedicated Earth-limb following observation in September 2008. These measurements yielded {approx} 6.4 x 10{sup 6} photons with energies > 100 MeV and {approx} 250 hours total livetime for the highest quality data selection. This allows the study of the spatial and spectral distributions of these photons with unprecedented detail. The spectrum of the emission - often referred to as Earth albedo gamma-ray emission - has a power-law shape up to 500 GeV with spectral index {Lambda} = 2.79 {+-} 0.06.

  16. The First Year and Beyond.

    ERIC Educational Resources Information Center

    Schroeder, Charles

    2003-01-01

    John Gardner reflects on everything from current efforts to improve the first-year experience to the assessment movement, student expectations of college, professional preparation for student affairs, and more. (Author)

  17. GeV Observations of star-forming galaxies with the Fermi large area telescope

    DOE PAGES

    Ackermann, M.; Ajello, M.; Allafort, A.; ...

    2012-08-07

    Some recent detections of the starburst galaxies M82 and NGC 253 by gamma-ray telescopes suggest that galaxies rapidly forming massive stars are more luminous at gamma-ray energies compared to their quiescent relatives. Building upon those results, we examine a sample of 69 dwarf, spiral, and luminous and ultraluminous infrared galaxies at photon energies 0.1-100 GeV using 3 years of data collected by the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (Fermi). Measured fluxes from significantly detected sources and flux upper limits for the remaining galaxies are used to explore the physics of cosmic rays in galaxies. Here,more » we find further evidence for quasi-linear scaling relations between gamma-ray luminosity and both radio continuum luminosity and total infrared luminosity which apply both to quiescent galaxies of the Local Group and low-redshift starburst galaxies (conservative P-values ≲ 0.05 accounting for statistical and systematic uncertainties). The normalizations of these scaling relations correspond to luminosity ratios of log (L 0.1-100 GeV/L 1.4 GHz) = 1.7 ± 0.1(statistical) ± 0.2(dispersion) and log (L 0.1-100 GeV/L 8-1000 μm) = –4.3 ± 0.1(statistical) ± 0.2(dispersion) for a galaxy with a star formation rate of 1 M ⊙yr–1, assuming a Chabrier initial mass function. Using the relationship between infrared luminosity and gamma-ray luminosity, the collective intensity of unresolved star-forming galaxies at redshifts 0 < z < 2.5 above 0.1 GeV is estimated to be 0.4-2.4 × 10–6 ph cm–2 s–1 sr–1 (4%-23% of the intensity of the isotropic diffuse component measured with the LAT). Furthermore, we anticipate that ~10 galaxies could be detected by their cosmic-ray-induced gamma-ray emission during a 10 year Fermi mission.« less

  18. Fermi Large Area Telescope observations of Markarian 421: The missing piece of its spectral energy distribution

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2011-07-15

    Here, we report on the γ-ray activity of the high-synchrotron-peaked BL Lacertae object Markarian 421 (Mrk 421) during the first 1.5 years of Fermi operation, from 2008 August 5 to 2010 March 12. We find that the Large Area Telescope (LAT) γ-ray spectrum above 0.3 GeV can be well described by a power-law function with photon index Γ = 1.78 ± 0.02 and average photon flux F(> 0.3 GeV) = (7.23 ± 0.16) × 10–8 ph cm–2 s–1. Over this time period, the Fermi-LAT spectrum above 0.3 GeV was evaluated on seven-day-long time intervals, showing significant variations in the photonmore » flux (up to a factor ~3 from the minimum to the maximum flux) but mild spectral variations. The variability amplitude at X-ray frequencies measured by RXTE/ASM and Swift/BAT is substantially larger than that in γ-rays measured by Fermi-LAT, and these two energy ranges are not significantly correlated. We also present the first results from the 4.5 month long multifrequency campaign on Mrk 421, which included the VLBA, Swift, RXTE, MAGIC, the F-GAMMA, GASP-WEBT, and other collaborations and instruments that provided excellent temporal and energy coverage of the source throughout the entire campaign (2009 January 19 to 2009 June 1). During this campaign, Mrk 421 showed a low activity at all wavebands. The extensive multi-instrument (radio to TeV) data set provides an unprecedented, complete look at the quiescent spectral energy distribution (SED) for this source. The broadband SED was reproduced with a leptonic (one-zone synchrotron self-Compton) and a hadronic model (synchrotron proton blazar). Both frameworks are able to describe the average SED reasonably well, implying comparable jet powers but very different characteristics for the blazar emission site.« less

  19. γ-ray spectral evolution of NGC 1275 observed with FERMI large area telescope

    SciTech Connect

    Kataoka, J.; Stawarz, Ł.; Cheung, C. C.; Tosti, G.; Cavazzuti, E.; Celotti, A.; Nishino, S.; Fukazawa, Y.; Thompson, D. J.; McConville, W. F.

    2010-04-29

    Here, we report on a detailed investigation of the high-energy γ-ray emission from NGC 1275, a well-known radio galaxy hosted by a giant elliptical located at the center of the nearby Perseus cluster. With the increased photon statistics, the center of the γ-ray-emitting region is now measured to be separated by only 0.46 arcmin from the nucleus of NGC 1275, well within the 95% confidence error circle with radius ≃1.5 arcmin. Early Fermi Large Area Telescope (LAT) observations revealed a significant decade-timescale brightening of NGC 1275 at GeV photon energies, with a flux about 7 times higher than the one implied by the upper limit from previous EGRET observations. With the accumulation of one year of Fermi-LAT all-sky-survey exposure, we now detect flux and spectral variations of this source on month timescales, as reported in this paper. The average >100 MeV γ-ray spectrum of NGC 1275 shows a possible deviation from a simple power-law shape, indicating a spectral cutoff around an observed photon energy of εγ = 42.2 ± 19.6 GeV, with an average flux of Fγ = (2.31 ± 0.13) × 10–7 photons cm–2 s–1 and a power-law photon index, Γγ = 2.13 ± 0.02. The largest γ-ray flaring event was observed in 2009 April-May and was accompanied by significant spectral variability above εγ ≳ 1-2 GeV. The γ-ray activity of NGC 1275 during this flare can be described by a hysteresis behavior in the flux versus photon index plane. The highest energy photon associated with the γ-ray source was detected at the very end of the observation, with the observed energy of εγ = 67.4 GeV and an angular separation of about 2.4 arcmin from the nucleus. In this paper we present the details of the Fermi-LAT data analysis, and briefly discuss the implications of the observed γ-ray spectral evolution of NGC 1275 in the context of γ-ray blazar sources in general.

  20. GeV Observations of star-forming galaxies with the Fermi large area telescope

    SciTech Connect

    Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Cillis, A. N.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; de Palma, F.; Dermer, C. D.; Digel, S. W.; do Couto e Silva, E.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Fortin, P.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hayashida, M.; Hays, E.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Martin, P.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nishino, S.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ozaki, M.; Parent, D.; Persic, M.; Pesce-Rollins, M.; Petrosian, V.; Pierbattista, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Ritz, S.; Roth, M.; Sbarra, C.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Stawarz, Łukasz; Strong, A. W.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vandenbroucke, J.; Vianello, G.; Vitale, V.; Waite, A. P.; Wood, M.; Yang, Z.

    2012-08-07

    Some recent detections of the starburst galaxies M82 and NGC 253 by gamma-ray telescopes suggest that galaxies rapidly forming massive stars are more luminous at gamma-ray energies compared to their quiescent relatives. Building upon those results, we examine a sample of 69 dwarf, spiral, and luminous and ultraluminous infrared galaxies at photon energies 0.1-100 GeV using 3 years of data collected by the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (Fermi). Measured fluxes from significantly detected sources and flux upper limits for the remaining galaxies are used to explore the physics of cosmic rays in galaxies. Here, we find further evidence for quasi-linear scaling relations between gamma-ray luminosity and both radio continuum luminosity and total infrared luminosity which apply both to quiescent galaxies of the Local Group and low-redshift starburst galaxies (conservative P-values ≲ 0.05 accounting for statistical and systematic uncertainties). The normalizations of these scaling relations correspond to luminosity ratios of log (L 0.1-100 GeV/L 1.4 GHz) = 1.7 ± 0.1(statistical) ± 0.2(dispersion) and log (L 0.1-100 GeV/L 8-1000 μm) = –4.3 ± 0.1(statistical) ± 0.2(dispersion) for a galaxy with a star formation rate of 1 M ⊙yr–1, assuming a Chabrier initial mass function. Using the relationship between infrared luminosity and gamma-ray luminosity, the collective intensity of unresolved star-forming galaxies at redshifts 0 < z < 2.5 above 0.1 GeV is estimated to be 0.4-2.4 × 10–6 ph cm–2 s–1 sr–1 (4%-23% of the intensity of the isotropic diffuse component measured with the LAT). Furthermore, we anticipate that ~10 galaxies could be detected by their cosmic-ray-induced gamma-ray emission during a 10 year Fermi mission.

  1. GeV Observations of star-forming glaxies with the FERMI Large Area Telescope

    SciTech Connect

    Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Cillis, A. N.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; de Palma, F.; Dermer, C. D.; Digel, S. W.; do Couto e Silva, E.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Fortin, P.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hayashida, M.; Hays, E.; Hughes, R. E.; J?hannesson, G.; Johnson, A. S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kn?dlseder, J.; Kuss, M.; Lande, J.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Martin, P.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nishino, S.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ozaki, M.; Parent, D.; Persic, M.; Pesce-Rollins, M.; Petrosian, V.; Pierbattista, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rain?, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Ritz, S.; Roth, M.; Sbarra, C.; Sgr?, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Stawarz, ?ukasz; Strong, A. W.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vandenbroucke, J.; Vianello, G.; Vitale, V.; Waite, A. P.; Wood, M.; Yang, Z.

    2012-08-07

    Recent detections of the starburst galaxies M82 and NGC 253 by gamma-ray telescopes suggest that galaxies rapidly forming massive stars are more luminous at gamma-ray energies compared to their quiescent relatives. Building upon those results, we examine a sample of 69 dwarf, spiral, and luminous and ultraluminous infrared galaxies at photon energies 0.1-100 GeV using 3 years of data collected by the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (Fermi). Measured fluxes from significantly detected sources and flux upper limits for the remaining galaxies are used to explore the physics of cosmic rays in galaxies. We find further evidence for quasi-linear scaling relations between gamma-ray luminosity and both radio continuum luminosity and total infrared luminosity which apply both to quiescent galaxies of the Local Group and low-redshift starburst galaxies (conservative P-values lesssim 0.05 accounting for statistical and systematic uncertainties). The normalizations of these scaling relations correspond to luminosity ratios of log (L 0.1-100 GeV/L 1.4 GHz) = 1.7 ± 0.1(statistical) ± 0.2(dispersion) and log (L 0.1-100 GeV/L 8-1000 μm) = –4.3 ± 0.1(statistical) ± 0.2(dispersion) for a galaxy with a star formation rate of 1 M ⊙ yr–1, assuming a Chabrier initial mass function. Using the relationship between infrared luminosity and gamma-ray luminosity, the collective intensity of unresolved star-forming galaxies at redshifts 0 < z < 2.5 above 0.1 GeV is estimated to be 0.4-2.4 × 10–6 ph cm–2 s–1 sr–1 (4%-23% of the intensity of the isotropic diffuse component measured with the LAT). We anticipate that ~10 galaxies could be detected by their cosmic-ray-induced gamma-ray emission during a 10 year Fermi mission.

  2. Fermi Large Area Telescope Observations of Markarian 421: The Missing Piece of its Spectral Energy Distribution

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cannon, A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Escande, L.; Favuzzi, C.; Fegan, S. J.; Finke, J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fuhrmann, L.; Fukazawa, Y.; Fukuyama, T.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Georganopoulos, M.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Guiriec, S.; Hadasch, D.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kadler, M.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Max-Moerbeck, W.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Nishino, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pavlidou, V.; Pearson, T. J.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Readhead, A.; Reimer, A.; Reimer, O.; Reyes, L. C.; Richards, J. L.; Ritz, S.; Roth, M.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stawarz, Ł.; Stevenson, M.; Strickman, M. S.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Troja, E.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Wehrle, A. E.; Winer, B. L.; Wood, K. S.; Yang, Z.; Yatsu, Y.; Ylinen, T.; Zensus, J. A.; Ziegler, M.; Fermi LAT Collaboration; Aleksić, J.; Antonelli, L. A.; Antoranz, P.; Backes, M.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Berdyugin, A.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnoli, G.; Bordas, P.; Borla Tridon, D.; Bosch-Ramon, V.; Bose, D.; Braun, I.; Bretz, T.; Camara, M.; Carmona, E.; Carosi, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Dazzi, F.; de Angelis, A.; De Cea del Pozo, E.; Delgado Mendez, C.; De Lotto, B.; De Maria, M.; De Sabata, F.; Diago Ortega, A.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Elsaesser, D.; Ferenc, D.; Fonseca, M. V.; Font, L.; García López, R. J.; Garczarczyk, M.; Gaug, M.; Giavitto, G.; Godinovi, N.; Hadasch, D.; Herrero, A.; Hildebrand, D.; Höhne-Mönch, D.; Hose, J.; Hrupec, D.; Jogler, T.; Klepser, S.; Krähenbühl, T.; Kranich, D.; Krause, J.; La Barbera, A.; Leonardo, E.; Lindfors, E.; Lombardi, S.; López, M.; Lorenz, E.; Majumdar, P.; Makariev, E.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Miyamoto, H.; Moldón, J.; Moralejo, A.; Nieto, D.; Nilsson, K.; Orito, R.; Oya, I.; Paoletti, R.; Paredes, J. M.; Partini, S.; Pasanen, M.; Pauss, F.; Pegna, R. G.; Perez-Torres, M. A.; Persic, M.; Peruzzo, J.; Pochon, J.; Prada, F.; Prada Moroni, P. G.; Prandini, E.; Puchades, N.; Puljak, I.; Reichardt, T.; Rhode, W.; Ribó, M.; Rico, J.; Rissi, M.; Rügamer, S.; Saggion, A.; Saito, K.; Saito, T. Y.; Salvati, M.; Sánchez-Conde, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shayduk, M.; Shore, S. N.; Sierpowska-Bartosik, A.; Sillanpää, A.; Sitarek, J.; Sobczynska, D.; Spanier, F.; Spiro, S.; Stamerra, A.; Steinke, B.; Storz, J.; Strah, N.; Struebig, J. C.; Suric, T.; Takalo, L. O.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Vankov, H.; Wagner, R. M.; Weitzel, Q.; Zabalza, V.; Zandanel, F.; Zanin, R.; MAGIC Collaboration; Villata, M.; Raiteri, C.; Aller, H. D.; Aller, M. F.; Chen, W. P.; Jordan, B.; Koptelova, E.; Kurtanidze, O. M.; Lähteenmäki, A.; McBreen, B.; Larionov, V. M.; Lin, C. S.; Nikolashvili, M. G.; Reinthal, R.; Angelakis, E.; Capalbi, M.; Carramiñana, A.; Carrasco, L.; Cassaro, P.; Cesarini, A.; Falcone, A.; Gurwell, M. A.; Hovatta, T.; Kovalev, Yu. A.; Kovalev, Y. Y.; Krichbaum, T. P.; Krimm, H. A.; Lister, M. L.; Moody, J. W.; Maccaferri, G.; Mori, Y.; Nestoras, I.; Orlati, A.; Pace, C.; Pagani, C.; Pearson, R.; Perri, M.; Piner, B. G.; Ros, E.; Sadun, A. C.; Sakamoto, T.; Tammi, J.; Zook, A.

    2011-08-01

    We report on the γ-ray activity of the high-synchrotron-peaked BL Lacertae object Markarian 421 (Mrk 421) during the first 1.5 years of Fermi operation, from 2008 August 5 to 2010 March 12. We find that the Large Area Telescope (LAT) γ-ray spectrum above 0.3 GeV can be well described by a power-law function with photon index Γ = 1.78 ± 0.02 and average photon flux F(> 0.3 GeV) = (7.23 ± 0.16) × 10-8 ph cm-2 s-1. Over this time period, the Fermi-LAT spectrum above 0.3 GeV was evaluated on seven-day-long time intervals, showing significant variations in the photon flux (up to a factor ~3 from the minimum to the maximum flux) but mild spectral variations. The variability amplitude at X-ray frequencies measured by RXTE/ASM and Swift/BAT is substantially larger than that in γ-rays measured by Fermi-LAT, and these two energy ranges are not significantly correlated. We also present the first results from the 4.5 month long multifrequency campaign on Mrk 421, which included the VLBA, Swift, RXTE, MAGIC, the F-GAMMA, GASP-WEBT, and other collaborations and instruments that provided excellent temporal and energy coverage of the source throughout the entire campaign (2009 January 19 to 2009 June 1). During this campaign, Mrk 421 showed a low activity at all wavebands. The extensive multi-instrument (radio to TeV) data set provides an unprecedented, complete look at the quiescent spectral energy distribution (SED) for this source. The broadband SED was reproduced with a leptonic (one-zone synchrotron self-Compton) and a hadronic model (synchrotron proton blazar). Both frameworks are able to describe the average SED reasonably well, implying comparable jet powers but very different characteristics for the blazar emission site.

  3. Fermi Large Area Telescope Observations Of Misaligned Active Galactic Nuclei

    SciTech Connect

    Abdo, A. A.

    2010-08-13

    Analysis is presented for 15 months of data taken with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope for 11 non-blazar active galactic nuclei (AGNs), including seven FRI radio galaxies and four FRII radio sources consisting of two FRII radio galaxies and two steep spectrum radio quasars. The broad line FRI radio galaxy 3C 120 is reported here as a γ-ray source for the first time. The analysis is based on directional associations of LAT sources with radio sources in the 3CR, 3CRR, and MS4 (collectively referred to as 3C-MS) catalogs. Seven of the eleven LAT sources associated with 3C-MS radio sources have spectral indices larger than 2.3 and, except for the FRI radio galaxy NGC 1275 that shows possible spectral curvature, are well described by a power law. No evidence for time variability is found for any sources other than NGC 1275. The γ-ray luminosities of FRI radio galaxies are significantly smaller than those of the BL Lac objects detected by the LAT, whereas the γ-ray luminosities of the FRII sources are quite similar to those of FSRQs, which could reflect different beaming factors for the γ-ray emission. A core dominance (CD) study of the 3CRR sample indicates that sources closer to the jet axis are preferentially detected with the Fermi LAT, insofar as the γ-ray-detected misaligned AGNs have larger CD at a given average radio flux. The results are discussed in view of the AGN unification scenario.

  4. Constraints on Lorentz Invariance Violation from Fermi -Large Area Telescope Observations of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Vasileiou, V.; Jacholkowska, A.; Piron, F.; Bolmont, J.; Courturier, C.; Granot, J.; Stecker, Floyd William; Cohen-Tanugi, J.; Longo, F.

    2013-01-01

    We analyze the MeV/GeV emission from four bright Gamma-Ray Bursts (GRBs) observed by the Fermi-Large Area Telescope to produce robust, stringent constraints on a dependence of the speed of light in vacuo on the photon energy (vacuum dispersion), a form of Lorentz invariance violation (LIV) allowed by some Quantum Gravity (QG) theories. First, we use three different and complementary techniques to constrain the total degree of dispersion observed in the data. Additionally, using a maximally conservative set of assumptions on possible source-intrinsic spectral-evolution effects, we constrain any vacuum dispersion solely attributed to LIV. We then derive limits on the "QG energy scale" (the energy scale that LIV-inducing QG effects become important, E(sub QG)) and the coefficients of the Standard Model Extension. For the subluminal case (where high energy photons propagate more slowly than lower energy photons) and without taking into account any source-intrinsic dispersion, our most stringent limits (at 95% CL) are obtained from GRB 090510 and are E(sub QG,1) > 7.6 times the Planck energy (E(sub Pl)) and E(sub QG,2) > 1.3×10(exp 11) GeV for linear and quadratic leading order LIV-induced vacuum dispersion, respectively. These limits improve the latest constraints by Fermi and H.E.S.S. by a factor of approx. 2. Our results disfavor any class of models requiring E(sub QG,1) < or approx. E(sub Pl)

  5. Jet Emission in Young Radio Sources: A Fermi Large Area Telescope Gamma-Ray View

    NASA Astrophysics Data System (ADS)

    Migliori, G.; Siemiginowska, A.; Kelly, B. C.; Stawarz, Ł.; Celotti, A.; Begelman, M. C.

    2014-01-01

    We investigate the contribution of the beamed jet component to the high-energy emission in young and compact extragalactic radio sources, focusing for the first time on the γ-ray band. We derive predictions on the γ-ray luminosities associated with the relativistic jet assuming a leptonic radiative model. The high-energy emission is produced via Compton scattering by the relativistic electrons in a spherical region at the considered scales (lsim10 kpc). Simulations show a wide range of γ-ray luminosities, with intensities up to ~1046-1048 erg s-1 depending on the assumed jet parameters. We find a highly linear relation between the simulated X-ray and γ-ray luminosities that can be used to select candidates for γ-ray detection. We compare the simulated luminosity distributions in the radio, X-ray, and γ-ray regimes with observations for the largest sample of X-ray-detected young radio quasars. Our analysis of ~4-yr Fermi Large Area Telescope (LAT) data does not yield any statistically significant detections. However, the majority of the model-predicted γ-ray fluxes for the sample are near or below the current Fermi-LAT flux threshold and compatible with the derived upper limits. Our study gives constraints on the minimum jet power (L jet, kin/L disk > 0.01) of a potential jet contribution to the X-ray emission in the most compact sources (lsim 1 kpc) and on the particle-to-magnetic field energy density ratio that are in broad agreement with equipartition assumptions.

  6. Electromagnetic counterparts to Gravitational Wave events with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Vianello, Giacomo; Omodei, Nicola; Racusin, Judith L.; McEnery, Julie E.; Chiang, James; Buson, Sara; Fermi LAT Collaboration

    2017-01-01

    At least a fraction of Gravitational Wave (GW) progenitors is expected to emit an electromagnetic (EM) signal in the form of a short gamma-ray burst (sGRB). The discovery of such a transient EM counterpart is challenging because the LIGO/VIRGO localization region is much larger (several hundreds of square degrees) than the field of view of X-ray, optical and radio telescopes. The Fermi Large Area Telescope (LAT) has a wide field of view (~ 2.4 sr), and detects ~2-3 sGRBs per year above 100 MeV. It can detect them not only during the short prompt phase but also during their long-lasting high-energy afterglow phase. If other wide-field high-energy instruments such as Fermi-GBM, Swift-BAT or INTEGRAL-ISGRI cannot detect or localize with enough precision an EM counterpart during the prompt phase, the LAT can potentially pinpoint it with < 10 arcmin accuracy during the afterglow phase. This routinely happens in the case of gamma-ray bursts. Moreover, the LAT covers the entire localization region within hours of any GW triggers during normal operations, allowing upper bounds to be evaluated. This has been demonstrated in the case of the three known GW events (GW150914, LVT151012, and GW151226). Over the coming years, as LIGO and Virgo approach design sensitivity and will soon be able to detect these mergers, LAT will continue to provide a unique capability to potentially localize and characterize gravitational wave events.

  7. Large-Scale Operations Management Test of Use of the White Amur for Control of Problem Aquatic Plants. Report 2. First Year Poststocking Results. Volume III. The Plankton and Benthos of Lake Conway, Florida,

    DTIC Science & Technology

    1981-11-01

    several exotic plant species. These include waterhyacinth (Eichhornia crassipes), Florida elodea (Hydrilla verticillata), and Eurasian watermilfoil...LARGE-SCALE OPERATIONSm o .. MANAGEMENT TEST OF USE OFI . THE WHITE AMUR FOR CONTROL OF PROBLEM AQUATIC PLANTS . Report 2 FIRST YEAR POSTSTOCKING RESULTS...OPERATIONS MANAGEMENT TEST OF USE OF THE WHITE AMUR FOR CONTROL OF PROBLEM AQUATIC PLANTS Report I: Baseline Studies Volume I: The Aquatic Macropyes of

  8. Deep View of the Large Magellanic Cloud with Six Years of Fermi-LAT Observations

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Bloom, E. D.; hide

    2016-01-01

    Context. The nearby Large Magellanic Cloud (LMC) provides a rare opportunity of a spatially resolved view of an external star-forming galaxy in gamma-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 gamma-ray emission is connected to specific objects, populations of objects, and structures in the galaxy. Methods. We revisited the gamma-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 approximately 1-100 GeV CRs with a density of approximately 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

  9. Deep view of the Large Magellanic Cloud with six years of Fermi -LAT observations

    DOE PAGES

    Ackermann, M.

    2016-01-27

    Context. The nearby Large Magellanic Cloud (LMC) provides a rare opportunity of a spatially resolved view of an external star-forming galaxy in -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 andmore » how the -ray emission is connected to specific objects, populations of objects, and structures in the galaxy. Methods. We revisited the -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 ~1–100GeV 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

  10. Deep view of the Large Magellanic Cloud with six years of Fermi-LAT observations

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Bloom, E. D.; Bonino, R.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Cohen-Tanugi, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Desiante, R.; Digel, S. W.; Drell, P. S.; Favuzzi, C.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Guillemot, L.; Guiriec, S.; Harding, A. K.; Hill, A. B.; Horan, D.; Jóhannesson, G.; Knödlseder, J.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lubrano, P.; Maldera, S.; Martin, P.; Mayer, M.; Mazziotta, M. N.; Michelson, P. F.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Murgia, S.; Nuss, E.; Ohsugi, T.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Romani, R. W.; Sánchez-Conde, M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Spada, F.; Spandre, G.; Spinelli, P.; Suson, D. J.; Takahashi, H.; Thayer, J. B.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Troja, E.; Vianello, G.; Wood, M.; Zimmer, S.

    2016-02-01

    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

  11. Fermi Large Area Telescope observations of PSR J1836+5925

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2010-03-11

    The discovery of the γ-ray pulsar PSR J1836+5925, powering the formerly unidentified EGRET source 3EG J1835+5918, was one of the early accomplishments of the Fermi Large Area Telescope (LAT). Sitting 25° off the Galactic plane, PSR J1836+5925 is a 173 ms pulsar with a characteristic age of 1.8 million years, a spindown luminosity of 1.1 × 1034 erg s–1, and a large off-peak (OP) emission component, making it quite unusual among the known γ-ray pulsar population. We present an analysis of one year of LAT data, including an updated timing solution, detailed spectral results, and a long-term light curve showingmore » no indication of variability. No evidence for a surrounding pulsar wind nebula is seen and the spectral characteristics of the OP emission indicate it is likely magnetospheric. Finally, analysis of recent XMM-Newton observations of the X-ray counterpart yields a detailed characterization of its spectrum, which, like Geminga, is consistent with that of a neutron star showing evidence for both magnetospheric and thermal emission.« less

  12. Teen Parenting: The First Year.

    ERIC Educational Resources Information Center

    McCamey, Jody

    This guide for teenage mothers discusses the needs of the mother and her child during the first year of the child's life. Information on the child's and the mother's behavior and emotions just after the child's birth is presented. Also presented is information on the following: procuring items needed for tending the baby; playing; crying; breast…

  13. Correlation of Fermi Large Area Telescope sources with the 20-GHz Australia Telescope Compact Array radio survey

    NASA Astrophysics Data System (ADS)

    Ghirlanda, G.; Ghisellini, G.; Tavecchio, F.; Foschini, L.

    2010-09-01

    We cross-correlate the Fermi 11-month survey (1FGL) catalogue with the 20-GHz Australia Telescope Compact Array (AT20G) radio survey catalogue composed of 5890 sources at declination < 0°. Among the 738 Fermi sources distributed in the southern sky, we find 230 highly probable candidate counterparts in the AT20G survey. Of these, 222 are already classified in the Fermi one-year Large Area Telescope (LAT) active galactic nucleus (AGN) catalogue (1LAC) as blazars [either flat spectrum radio quasars (FSRQs) or BL Lacertae objects (BL Lacs)], AGNs or sources of unknown class but with an associated counterpart, while eight are new associations. By studying the γ-ray and radio properties of these associations, we find a correlation between the γ-ray flux (above 100 MeV) and the 20-GHz flux density. This correlation is more than 3σ statistically significant, both for the population of BL Lacs and for FSRQs considered separately. We also find that the radio counterparts associated with the Fermi sources have, on average, flat radio spectra between 5 and 20 GHz and that Fermi γ-ray sources are not preferentially associated with `ultra-inverted spectrum' radio sources. For two of the eight new associations, we build the broad-band spectral energy distribution combining Fermi, Swift and radio observations. One of these two sources is identified with the high-redshift FSRQ Swift J1656.3-3302 (z = 2.4) and we classify the other source as a candidate new FSRQ. We also study the brightest radio source of the 46 associations without an optical classification and classify it as a new BL Lac candidate `twin' of the prototypical BL Lac OJ 287 if its redshift is larger, z ~ 0.4.

  14. FERMI Large Area Telescope View of the 1 Core of the Radio Galaxy Centaurus A

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2010-07-29

    We present γ-ray observations with the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope of the nearby radio galaxy Centaurus A (Cen A). The previous EGRET detection is confirmed, and the localization is improved using data from the first 10 months of Fermi science operation. In previous work, we presented the detection of the lobes by the LAT; in this work, we concentrate on the γ-ray core of Cen A. Flux levels as seen by the LAT are not significantly different from that found by EGRET, nor is the extremely soft LAT spectrum (Γ = 2.67 ±more » 0.10stat ± 0.08sys where the photon flux is Φ ∝ E –Γ). The LAT core spectrum, extrapolated to higher energies, is marginally consistent with the non-simultaneous HESS spectrum of the source. The LAT observations are complemented by simultaneous observations from Suzaku, the Swift Burst Alert Telescope and X-ray Telescope, and radio observations with the Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry program, along with a variety of non-simultaneous archival data from a variety of instruments and wavelengths to produce a spectral energy distribution (SED). Here, we fit this broadband data set with a single-zone synchrotron/synchrotron self-Compton model, which describes the radio through GeV emission well, but fails to account for the non-simultaneous higher energy TeV emission observed by HESS from 2004 to 2008. The fit requires a low Doppler factor, in contrast to BL Lac objects which generally require larger values to fit their broadband SEDs. This indicates that the γ-ray emission originates from a slower region than that from BL Lac objects, consistent with previous modeling results from Cen A. This slower region could be a slower moving layer around a fast spine, or a slower region farther out from the black hole in a decelerating flow. The fit parameters are also consistent with Cen A being able to accelerate ultra-high energy cosmic-rays, as hinted at by

  15. The First Fermi Large Area Telescope Catalog of Gamma-ray Pulsars

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2010-03-25

    The dramatic increase in the number of known gamma-ray pulsars since the launch of the Fermi Gamma-ray Space Telescope (formerly GLAST) offers the first opportunity to study a sizable population of these high-energy objects. This catalog summarizes 46 high-confidence pulsed detections using the first six months of data taken by the Large Area Telescope (LAT), Fermi's main instrument. Sixteen previously unknown pulsars were discovered by searching for pulsed signals at the positions of bright gamma-ray sources seen with the LAT, or at the positions of objects suspected to be neutron stars based on observations at other wavelengths. The dimmest observed flux among these gamma-ray-selected pulsars is 6.0 × 10–8 ph cm–2 s–1 (for E>100 MeV). Pulsed gamma-ray emission was discovered from 24 known pulsars by using ephemerides (timing solutions) derived from monitoring radio pulsars. Eight of these new gamma-ray pulsars are millisecond pulsars. The dimmest observed flux among the radio-selected pulsars is 1.4 × 10–8 ph cm–2 s–1 (for E>100 MeV). The remaining six gamma-ray pulsars were known since the Compton Gamma Ray Observatory mission, or before. The limiting flux for pulse detection is non-uniform over the sky owing to different background levels, especially near the Galactic plane. The pulsed energy spectra can be described by a power law with an exponential cutoff, with cutoff energies in the range ~1-5 GeV. The rotational energy-loss rate (more » $$\\dot{E}$$) of these neutron stars spans five decades, from ~3 × 1033 erg s–1 to 5 × 1038 erg s–1, and the apparent efficiencies for conversion to gamma-ray emission range from ~0.1% to ~ unity, although distance uncertainties complicate efficiency estimates. The pulse shapes show substantial diversity, but roughly 75% of the gamma-ray pulse profiles have two peaks, separated by ≳0.2 of rotational phase. For most of the pulsars, gamma-ray emission appears to come mainly from the outer magnetosphere

  16. FERMI large area telescope observations of the vela-x pulsar wind nebula

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2010-03-18

    Here, we report on gamma-ray observations in the off-pulse window of the Vela pulsar PSR B0833–45 using 11 months of survey data from the Fermi Large Area Telescope (LAT). This pulsar is located in the 8° diameter Vela supernova remnant, which contains several regions of non-thermal emission detected in the radio, X-ray, and gamma-ray bands. The gamma-ray emission detected by the LAT lies within one of these regions, the 2° × 3° area south of the pulsar known as Vela-X. The LAT flux is significantly spatially extended with a best-fit radius of 0°more » $$_.$$88 ± 0°$$_.$$12 for an assumed radially symmetric uniform disk. The 200 MeV to 20 GeV LAT spectrum of this source is well described by a power law with a spectral index of 2.41 ± 0.09 ± 0.15 and integral flux above 100 MeV of (4.73 ± 0.63 ± 1.32) × 10–7 cm–2 s–1. The first errors represent the statistical error on the fit parameters, while the second ones are the systematic uncertainties. Detailed morphological and spectral analyses give strong constraints on the energetics and magnetic field of the pulsar wind nebula system and favor a scenario with two distinct electron populations.« less

  17. Observations Of Energetic High Magnetic Field Pulsars With The Fermi Large Area Telescope

    SciTech Connect

    Parent, D.; Kerr, M.; den Hartog, P. R.; Baring, M. G.; DeCesar, M. E.; Espinoza, C. M.; Gotthelf, E. V.; Harding, A. K.; Johnston, S.; Kaspi, V. M.; Livingstone, M.; Romani, R. W.; Stappers, B. W.; Watters, K.; Weltevrede, P.; Abdo, A. A.; Burgay, M.; Camilo, F.; Craig, H. A.; Freire, P. C. C.; Giordano, F.; Guillemot, L.; Hobbs, G.; Keith, M.; Kramer, M.; Lyne, A. G.; Manchester, R. N.; Noutsos, A.; Possenti, A.; Smith, D. A.

    2011-12-02

    We report the detection of γ-ray pulsations from the high-magnetic-field rotation-powered pulsar PSR J1119-6127 using data from the Fermi Large Area Telescope. The γ-ray light curve of PSR J1119-6127 shows a single, wide peak offset from the radio peak by 0.43± 0.02 in phase. Spectral analysis suggests a power law of index 1.0 ± 0.3+0.4 -0.2 with an energy cut-off at 0.8 ± 0.2+2.0 -0.5GeV. The first uncertainty is statistical and the second is systematic. We discuss the emission models of PSR J1119-6127 and demonstrate that despite the object’s high surface magnetic field—near that of magnetars—the field strength and structure in the γ-ray emitting zone are apparently similar to those of typical young pulsars. Additionally, we present upper limits on the γ-ray pulsed emission for the magnetically active PSR J1846-0258 in the supernova remnant Kesteven 75 and two other energetic high-B pulsars, PSRs J1718-3718 and J1734-3333. We explore possible explanations for the non-detection of these three objects, including peculiarities in their emission geometry.

  18. Constraints on axions and axionlike particles from Fermi Large Area Telescope observations of neutron stars

    NASA Astrophysics Data System (ADS)

    Berenji, B.; Gaskins, J.; Meyer, M.

    2016-02-01

    We present constraints on the nature of axions and axionlike particles (ALPs) by analyzing gamma-ray data from neutron stars using the Fermi Large Area Telescope. In addition to axions solving the strong C P problem of particle physics, axions and ALPs are also possible dark matter candidates. We investigate axions and ALPs produced by nucleon-nucleon bremsstrahlung within neutron stars. We derive a phenomenological model for the gamma-ray spectrum arising from subsequent axion decays. By analyzing five years of gamma-ray data (between 60 and 200 MeV) for a sample of four nearby neutron stars, we do not find evidence for an axion or ALP signal; thus we obtain a combined 95% confidence level upper limit on the axion mass of 7.9 ×10-2 eV , which corresponds to a lower limit for the Peccei-Quinn scale fa of 7.6 ×107 GeV . Our constraints are more stringent than previous results probing the same physical process, and are competitive with results probing axions and ALPs by different mechanisms.

  19. Fermi Large Area Telescope Measurements of the Diffuse Gamma-Ray Emission at Intermediate Galactic Latitudes

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2009-12-16

    We report that the diffuse galactic γ-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess γ-ray emission ≳1 GeV relative to diffuse galactic γ-ray emission models consistent with directly measured CR spectra (the so-called “EGRET GeV excess”). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse γ -ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV andmore » galactic latitudes 10° ≤ | b | ≤ 20°. Finally, the LAT spectrum for this region of the sky is well reproduced by a diffuse galactic γ-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.« less

  20. Constraints on axions and axionlike particles from Fermi Large Area Telescope observations of neutron stars

    SciTech Connect

    Berenji, B.; Gaskins, J.; Meyer, M.

    2016-02-16

    We present constraints on the nature of axions and axion–like particles (ALPs) by analyzing gamma–ray data from neutron stars using the Fermi Large Area Telescope. In addition to axions solving the strong CP problem of particle physics, axions and ALPs are also possible dark matter candidates. We investigate axions and ALPs produced by nucleon–nucleon bremsstrahlung within neutron stars. We derive a phenomenological model for the gamma–ray spectrum arising from subsequent axion decays. By analyzing 5 years of gamma-ray data (between 60 MeV and 200 MeV) for a sample of 4 nearby neutron stars, we do not find evidence for an axion or ALP signal, thus we obtain a combined 95% confidence level upper limit on the axion mass of 7.9×10-2 eV, which corresponds to a lower limit for the Peccei-Quinn scale fa of 7.6×107 GeV. Our constraints are more stringent than previous results probing the same physical process, and are competitive with results probing axions and ALPs by different mechanisms.

  1. FERMI large area telescope observations of the vela-x pulsar wind nebula

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Chekhtman, A.; Chung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; de Angelis, A.; de Palma, F.; Dormody, M.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gehrels, N.; Germani, S.; Giavitto, G.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Harding, A. K.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Johnston, S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S. -H.; Lemoine-Goumard, M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Marelli, M.; Mazziotta, M. N.; McEnery, J. E.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nolan, P. L.; Norris, J. P.; Noutsos, A.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Ray, P. S.; Rea, N.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Ryde, F.; Sadrozinski, H. F. -W.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Van Etten, A.; Vasileiou, V.; Venter, C.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Weltevrede, P.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Ziegler, M.

    2010-03-18

    Here, we report on gamma-ray observations in the off-pulse window of the Vela pulsar PSR B0833–45 using 11 months of survey data from the Fermi Large Area Telescope (LAT). This pulsar is located in the 8° diameter Vela supernova remnant, which contains several regions of non-thermal emission detected in the radio, X-ray, and gamma-ray bands. The gamma-ray emission detected by the LAT lies within one of these regions, the 2° × 3° area south of the pulsar known as Vela-X. The LAT flux is significantly spatially extended with a best-fit radius of 0°$_.$88 ± 0°$_.$12 for an assumed radially symmetric uniform disk. The 200 MeV to 20 GeV LAT spectrum of this source is well described by a power law with a spectral index of 2.41 ± 0.09 ± 0.15 and integral flux above 100 MeV of (4.73 ± 0.63 ± 1.32) × 10–7 cm–2 s–1. The first errors represent the statistical error on the fit parameters, while the second ones are the systematic uncertainties. Detailed morphological and spectral analyses give strong constraints on the energetics and magnetic field of the pulsar wind nebula system and favor a scenario with two distinct electron populations.

  2. Fermi Large Area Telescope Measurements of the Diffuse Gamma-Ray Emission at Intermediate Galactic Latitudes

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Anderson, B.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Dereli, H.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Digel, S. W.; Di Bernardo, G.; Dormody, M.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Edmonds, Y.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gaggero, D.; Gargano, F.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocian, M. L.; Kuehn, F.; Kuss, M.; Lande, J.; Latronico, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rodriguez, A. Y.; Roth, M.; Ryde, F.; Sadrozinski, H. F. -W.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Sellerholm, A.; Sgrò, C.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J. -L.; Stecker, F. W.; Striani, E.; Strickman, M. S.; Strong, A. W.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vasileiou, V.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Ziegler, M.

    2009-12-16

    We report that the diffuse galactic γ-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess γ-ray emission ≳1 GeV relative to diffuse galactic γ-ray emission models consistent with directly measured CR spectra (the so-called “EGRET GeV excess”). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse γ -ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV and galactic latitudes 10° ≤ | b | ≤ 20°. Finally, the LAT spectrum for this region of the sky is well reproduced by a diffuse galactic γ-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.

  3. Constraints on axions and axionlike particles from Fermi Large Area Telescope observations of neutron stars

    DOE PAGES

    Berenji, B.; Gaskins, J.; Meyer, M.

    2016-02-16

    We present constraints on the nature of axions and axion–like particles (ALPs) by analyzing gamma–ray data from neutron stars using the Fermi Large Area Telescope. In addition to axions solving the strong CP problem of particle physics, axions and ALPs are also possible dark matter candidates. We investigate axions and ALPs produced by nucleon–nucleon bremsstrahlung within neutron stars. We derive a phenomenological model for the gamma–ray spectrum arising from subsequent axion decays. By analyzing 5 years of gamma-ray data (between 60 MeV and 200 MeV) for a sample of 4 nearby neutron stars, we do not find evidence for anmore » axion or ALP signal, thus we obtain a combined 95% confidence level upper limit on the axion mass of 7.9×10-2 eV, which corresponds to a lower limit for the Peccei-Quinn scale fa of 7.6×107 GeV. Our constraints are more stringent than previous results probing the same physical process, and are competitive with results probing axions and ALPs by different mechanisms.« less

  4. Observations of Energetic High Magnetic Field Pulsars with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Parent, D.; Kerr, M.; DenHartog, P. R.; Baring, M. G.; DeCesar, M. E.; Espinoza, C. M.; Harding, A. K.; Romani, R. W.; Stappers, B. W.; Watters, K.; Weltevrde, P.; Abdo, A. A.; Craig, H. A.; Kramer, M.; Lyne, A. G.

    2011-01-01

    We report the detection of gamma-ray pulsations from the high-magnetic-field rotation-powered pulsar PSR J1119.6127 using data from the Fermi Large Area Telescope. The gamma-ray light curve of PSR J1119.6127 shows a single, wide peak offset from the radio peak by 0.43 +/- 0.02 in phase. Spectral analysis suggests a power law of index 1.0 +/- 0.3(+0.4 -0.2) with an energy cut-off at 0.8 +/- 0.2(+2.0 -0.5) GeV. The first uncertainty is statistical and the second is systematic. We discuss the emission models of PSR J1119.6127 and demonstrate that despite the object's high surface magnetic field--near that of magnetars -- the field strength and structure in the gamma-ray emitting zone are apparently similar to those of typical young pulsars. Additionally, we present upper limits on the gamma-ray pulsed emission for the magnetically active PSR J1846.0258 in the supernova remnant Kesteven 75 and two other energetic high-Beta pulsars, PSRs J1718.3718 and J1734.3333. We explore possible explanations for the non-detection of these three objects, including peculiarities in their emission geometry.

  5. Fermi Large Area Telescope Observations of the Cygnus Loop Supernova Remnant

    SciTech Connect

    Katagiri, H.; Tibaldo, L.; Ballet, J.; Giordano, F.; Grenier, I.A.; Porter, T.A.; Roth, M.; Tibolla, O.; Uchiyama, Y.; Yamazaki, R.; /Sagamihara, Aoyama Gakuin U.

    2011-11-08

    We present an analysis of the gamma-ray measurements by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the region of the supernova remnant (SNR) Cygnus Loop (G74.0-8.5). We detect significant gamma-ray emission associated with the SNR in the energy band 0.2-100 GeV. The gamma-ray spectrum shows a break in the range 2-3 GeV. The gamma-ray luminosity is {approx} 1 x 10{sup 33} erg s{sup -1} between 1-100 GeV, much lower than those of other GeV-emitting SNRs. The morphology is best represented by a ring shape, with inner/outer radii 0{sup o}.7 {+-} 0{sup o}.1 and 1{sup o}.6 {+-} 0{sup o}.1. Given the association among X-ray rims, H{alpha} filaments and gamma-ray emission, we argue that gamma rays originate in interactions between particles accelerated in the SNR and interstellar gas or radiation fields adjacent to the shock regions. The decay of neutral pions produced in nucleon-nucleon interactions between accelerated hadrons and interstellar gas provides a reasonable explanation for the gamma-ray spectrum.

  6. In-Flight Measurement of the Absolute Energy Scale of the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Allafort, A.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Barbielini, G; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B,; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Gehrels, N.; Hays, E.; McEnery, J. E.; Thompson, D. J.; Troja, E. J.

    2012-01-01

    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to survey the gamma-ray sky from 20 MeV to several hundreds of GeV. In this energy band there are no astronomical sources with sufficiently well known and sharp spectral features to allow an absolute calibration of the LAT energy scale. However, the geomagnetic cutoff in the cosmic ray electron- plus-positron (CRE) spectrum in low Earth orbit does provide such a spectral feature. The energy and spectral shape of this cutoff can be calculated with the aid of a numerical code tracing charged particles in the Earth's magnetic field. By comparing the cutoff value with that measured by the LAT in different geomagnetic positions, we have obtained several calibration points between approx. 6 and approx. 13 GeV with an estimated uncertainty of approx. 2%. An energy calibration with such high accuracy reduces the systematic uncertainty in LAT measurements of, for example, the spectral cutoff in the emission from gamma ray pulsars.

  7. Revisiting SNR Puppis A with Seven Years of Fermi Large Area Telescope Observations

    NASA Astrophysics Data System (ADS)

    Xin, Yu-Liang; Guo, Xiao-Lei; Liao, Neng-Hui; Yuan, Qiang; Liu, Si-Ming; Wei, Da-Ming

    2017-07-01

    Puppis A is a very famous and extensively studied supernova remnant that shows strong evidence of shock-cloud interaction. We reanalyze its GeV γ-ray emission using seven years of Pass 8 data recorded by the Fermi Large Area Telescope. The morphology of the γ-ray emission is more compatible with that of the thermal X-ray and IR emissions than the radio image, which suggests a possible correlation between the gamma-ray-emitting region and dense clouds. The γ-ray spectrum in the energy range of 1-500 GeV shows a break at 7.92 ± 1.91 GeV, with photon indices of 1.81 ± 0.08 below the break and 2.53 ± 0.12 above the break, which can naturally explain the lack of TeV γ-ray emission from Puppis A. The multi-wavelength observations favor a hadronic origin for the γ-ray emission.

  8. Pulsar simulations for the Fermi Large Area Telescope

    SciTech Connect

    Razzano, M.; Harding, Alice K.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Burnett, T.; Chiang, J.; Digel, S. W.; Dubois, R.; Kuss, M. W.; Latronico, L.; McEnery, J. E.; Omodei, N.; Pesce-Rollins, M.; Sgrò, C.; Spandre, G.; Thompson, D. J.

    2009-05-21

    Pulsars are among the prime targets for the Large Area Telescope (LAT) aboard the recently launched Fermi observatory. The LAT will study the gamma-ray Universe between 20 MeV and 300 GeV with unprecedented detail. Increasing numbers of gamma-ray pulsars are being firmly identified, yet their emission mechanisms are far from being understood. To better investigate and exploit the LAT capabilities for pulsar science, a set of new detailed pulsar simulation tools have been developed within the LAT collaboration. The structure of the pulsar simulator package (PulsarSpectrum) is presented here. Starting from photon distributions in energy and phase obtained from theoretical calculations or phenomenological considerations, gamma-rays are generated and their arrival times at the spacecraft are determined by taking into account effects such as barycentric effects and timing noise. Pulsars in binary systems also can be simulated given orbital parameters. As a result, we present how simulations can be used for generating a realistic set of gamma-rays as observed by the LAT, focusing on some case studies that show the performance of the LAT for pulsar observations.

  9. In-Flight Measurement of the Absolute Energy Scale of the Fermi Large Area Telescope

    SciTech Connect

    Ackermann, M.; Ajello, M.; Allafort, A.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E.D.; Bonamente, E.; Borgland, A.W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; /more authors..

    2012-09-20

    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to survey the gamma-ray sky from 20 MeV to several hundreds of GeV. In this energy band there are no astronomical sources with sufficiently well known and sharp spectral features to allow an absolute calibration of the LAT energy scale. However, the geomagnetic cutoff in the cosmic ray electron-plus-positron (CRE) spectrum in low Earth orbit does provide such a spectral feature. The energy and spectral shape of this cutoff can be calculated with the aid of a numerical code tracing charged particles in the Earth's magnetic field. By comparing the cutoff value with that measured by the LAT in different geomagnetic positions, we have obtained several calibration points between {approx}6 and {approx}13 GeV with an estimated uncertainty of {approx}2%. An energy calibration with such high accuracy reduces the systematic uncertainty in LAT measurements of, for example, the spectral cutoff in the emission from gamma ray pulsars.

  10. Fermi Large Area Telescope Measurements of the Diffuse Gamma-Ray Emission at Intermediate Galactic Latitudes

    SciTech Connect

    Abdo, A.A.; Ackermann, M.; Ajello, M.; Anderson, B.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B.M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R.D.; Bloom, E.D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brez, A.; Brigida, M.; /more authors..

    2012-04-11

    The diffuse galactic {gamma}-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess {gamma}-ray emission {ge}1 GeV relative to diffuse galactic {gamma}-ray emission models consistent with directly measured CR spectra (the so-called 'EGRET GeV excess'). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse {gamma}-ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV and galactic latitudes 10{sup o} {le} |b| {le} 20{sup o}. The LAT spectrum for this region of the sky is well reproduced by a diffuse galactic {gamma}-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.

  11. Observations Of Energetic High Magnetic Field Pulsars With The Fermi Large Area Telescope

    DOE PAGES

    Parent, D.; Kerr, M.; den Hartog, P. R.; ...

    2011-12-02

    We report the detection of γ-ray pulsations from the high-magnetic-field rotation-powered pulsar PSR J1119-6127 using data from the Fermi Large Area Telescope. The γ-ray light curve of PSR J1119-6127 shows a single, wide peak offset from the radio peak by 0.43± 0.02 in phase. Spectral analysis suggests a power law of index 1.0 ± 0.3+0.4 -0.2 with an energy cut-off at 0.8 ± 0.2+2.0 -0.5GeV. The first uncertainty is statistical and the second is systematic. We discuss the emission models of PSR J1119-6127 and demonstrate that despite the object’s high surface magnetic field—near that of magnetars—the field strength and structuremore » in the γ-ray emitting zone are apparently similar to those of typical young pulsars. Additionally, we present upper limits on the γ-ray pulsed emission for the magnetically active PSR J1846-0258 in the supernova remnant Kesteven 75 and two other energetic high-B pulsars, PSRs J1718-3718 and J1734-3333. We explore possible explanations for the non-detection of these three objects, including peculiarities in their emission geometry.« less

  12. OBSERVATIONS OF ENERGETIC HIGH MAGNETIC FIELD PULSARS WITH THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Parent, D.; Abdo, A. A.; Kerr, M.; Den Hartog, P. R.; Romani, R. W.; Watters, K.; Craig, H. A.; Baring, M. G.; DeCesar, M. E.; Harding, A. K.; Espinoza, C. M.; Stappers, B. W.; Weltevrede, P.; Gotthelf, E. V.; Camilo, F.; Johnston, S.; Kaspi, V. M.; Livingstone, M.; Burgay, M.; Freire, P. C. C. E-mail: kerrm@stanford.edu; and others

    2011-12-20

    We report the detection of {gamma}-ray pulsations from the high-magnetic-field rotation-powered pulsar PSR J1119-6127 using data from the Fermi Large Area Telescope. The {gamma}-ray light curve of PSR J1119-6127 shows a single, wide peak offset from the radio peak by 0.43 {+-} 0.02 in phase. Spectral analysis suggests a power law of index 1.0 {+-} 0.3{sup +0.4}{sub -0.2} with an energy cutoff at 0.8 {+-} 0.2{sup +2.0}{sub -0.5} GeV. The first uncertainty is statistical and the second is systematic. We discuss the emission models of PSR J1119-6127 and demonstrate that despite the object's high surface magnetic field-near that of magnetars-the field strength and structure in the {gamma}-ray emitting zone are apparently similar to those of typical young pulsars. Additionally, we present upper limits on the {gamma}-ray pulsed emission for the magnetically active PSR J1846-0258 in the supernova remnant Kesteven 75 and two other energetic high-B pulsars, PSRs J1718-3718 and J1734-3333. We explore possible explanations for the non-detection of these three objects, including peculiarities in their emission geometry.

  13. Fermi large area telescope measurements of the diffuse gamma-ray emission at intermediate galactic latitudes.

    PubMed

    Abdo, A A; Ackermann, M; Ajello, M; Anderson, B; Atwood, W B; Axelsson, M; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Baughman, B M; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Burnett, T H; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cecchi, C; Charles, E; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Dereli, H; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; Di Bernardo, G; Dormody, M; do Couto e Silva, E; Drell, P S; Dubois, R; Dumora, D; Edmonds, Y; Farnier, C; Favuzzi, C; Fegan, S J; Focke, W B; Frailis, M; Fukazawa, Y; Funk, S; Fusco, P; Gaggero, D; Gargano, F; Gehrels, N; Germani, S; Giebels, B; Giglietto, N; Giordano, F; Glanzman, T; Godfrey, G; Grenier, I A; Grondin, M-H; Grove, J E; Guillemot, L; Guiriec, S; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hughes, R E; Jóhannesson, G; Johnson, A S; Johnson, R P; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kawai, N; Kerr, M; Knödlseder, J; Kocian, M L; Kuehn, F; Kuss, M; Lande, J; Latronico, L; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Mazziotta, M N; McConville, W; McEnery, J E; Meurer, C; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nolan, P L; Nuss, E; Ohsugi, T; Okumura, A; Omodei, N; Orlando, E; Ormes, J F; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Razzano, M; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Rodriguez, A Y; Roth, M; Ryde, F; Sadrozinski, H F-W; Sanchez, D; Sander, A; Saz Parkinson, P M; Scargle, J D; Sellerholm, A; Sgrò, C; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Starck, J-L; Stecker, F W; Striani, E; Strickman, M S; Strong, A W; Suson, D J; Tajima, H; Takahashi, H; Tanaka, T; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Uchiyama, Y; Usher, T L; Vasileiou, V; Vilchez, N; Vitale, V; Waite, A P; Wang, P; Winer, B L; Wood, K S; Ylinen, T; Ziegler, M

    2009-12-18

    The diffuse galactic gamma-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess gamma-ray emission greater, > or approximately equal to 1 GeV relative to diffuse galactic gamma-ray emission models consistent with directly measured CR spectra (the so-called "EGRET GeV excess"). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse gamma-ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV and galactic latitudes 10 degrees < or = |b| < or = 20 degrees. The LAT spectrum for this region of the sky is well reproduced by a diffuse galactic gamma-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.

  14. Large magnetoresistance and Fermi surface study of Sb2Se2Te single crystal

    NASA Astrophysics Data System (ADS)

    Shrestha, K.; Marinova, V.; Graf, D.; Lorenz, B.; Chu, C. W.

    2017-09-01

    We have studied the magnetotransport properties of a Sb2Se2Te single crystal. Magnetoresistance (MR) is maximum when the magnetic field is perpendicular to the sample surface and reaches a value of 1100% at B = 31 T with no sign of saturation. MR shows Shubnikov de Haas (SdH) oscillations above B = 15 T. The frequency spectrum of SdH oscillations consists of three distinct peaks at α = 32 T, β = 80 T, and γ = 117 T indicating the presence of three Fermi surface pockets. Among these frequencies, β is the prominent peak in the frequency spectrum of SdH oscillations measured at different tilt angles of the sample with respect to the magnetic field. From the angle dependence β and Berry phase calculations, we have confirmed the trivial topology of the β-pocket. The cyclotron masses of charge carriers, obtained by using the Lifshitz-Kosevich formula, are found to be mβ*=0.16mo and m γ*=0.63 mo for the β and γ bands, respectively. The Large MR of Sb2Se2Te is suitable for utilization in electronic instruments such as computer hard discs, high field magnetic sensors, and memory devices.

  15. Probing Millisecond Pulsar Emission Geometry Using Light Curves From the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Venter, Christo; Harding, Alice; Guillemot, L.

    2009-01-01

    An interesting new high-energy pulsar sub-population is emerging following early discoveries of gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope (LAT). We present results from 3D emission modeling, including the Special Relativistic effects of aberration and time-of-flight delays and also rotational sweepback of 13-field lines, in the geometric context of polar cap (PC), slot gap (SG), outer gap (OG), and two-pole caustic (TPC) pulsar models. In contrast to the general belief that these very old, rapidly-rotating neutron stars (NSs) should have largely pair-starved magnetospheres due to the absence of significant pair production, we find that most of the light curves are best fit by SG and OG models, which indicates the presence of narrow accelerating gaps limited by robust pair production -- even in these pulsars with very low spin-down luminosities. The gamma-ray pulse shapes and relative phase lags with respect to the radio pulses point to high-altitude emission being dominant for all geometries. We also find exclusive differentiation of the current gamma-ray MSP population into two MSP sub-classes: light curve shapes and lags across wavebands impose either pair-starved PC (PSPC) or SG / OG-type geometries. In the first case, the radio pulse has a small lag with respect to the single gamma-ray pulse, while the (first) gamma-ray peak usually trails the radio by a large phase offset in the latter case. Finally, we find that the flux correction factor as a function of magnetic inclination and observer angles is typically of order unity for all models. Our calculation of light curves and flux correction factor f(_, _, P) for the case of MSPs is therefore complementary to the "ATLAS paper" of Watters et al. for younger pulsars.

  16. Probing Millisecond Pulsar Emission Geometry Using Light Curves From the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Venter, Christo; Harding, Alice; Guillemot, L.

    2009-01-01

    An interesting new high-energy pulsar sub-population is emerging following early discoveries of gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope (LAT). We present results from 3D emission modeling, including the Special Relativistic effects of aberration and time-of-flight delays and also rotational sweepback of 13-field lines, in the geometric context of polar cap (PC), slot gap (SG), outer gap (OG), and two-pole caustic (TPC) pulsar models. In contrast to the general belief that these very old, rapidly-rotating neutron stars (NSs) should have largely pair-starved magnetospheres due to the absence of significant pair production, we find that most of the light curves are best fit by SG and OG models, which indicates the presence of narrow accelerating gaps limited by robust pair production -- even in these pulsars with very low spin-down luminosities. The gamma-ray pulse shapes and relative phase lags with respect to the radio pulses point to high-altitude emission being dominant for all geometries. We also find exclusive differentiation of the current gamma-ray MSP population into two MSP sub-classes: light curve shapes and lags across wavebands impose either pair-starved PC (PSPC) or SG / OG-type geometries. In the first case, the radio pulse has a small lag with respect to the single gamma-ray pulse, while the (first) gamma-ray peak usually trails the radio by a large phase offset in the latter case. Finally, we find that the flux correction factor as a function of magnetic inclination and observer angles is typically of order unity for all models. Our calculation of light curves and flux correction factor f(_, _, P) for the case of MSPs is therefore complementary to the "ATLAS paper" of Watters et al. for younger pulsars.

  17. The Second Catalog Of Active Galactic Nuclei Detected By The Fermi Large Area Telescope

    DOE PAGES

    Ackermann, M.

    2011-12-02

    The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years of scientific operation is presented. The Second LAT AGN Catalog (2LAC) includes 1017 γ-ray sources located at high Galactic latitudes (|b| > 10°) that are detected with a test statistic (TS) greater than 25 and associated statistically with AGNs. However some of these are affected by analysis issues and some are associated with multiple AGNs. Consequently we define a clean sample which includes 886 AGNs, comprising 395 BL Lacertae objects (BL Lacs), 310 flat-spectrum radio quasars (FSRQs), 157 candidate blazars ofmore » unknown type (i.e., with broad-band blazar characteristics but with no optical spectral measurement yet), eight misaligned AGNs, four narrow-line Seyfert 1 (NLS1s), 10 AGNs of other types and two starburst galaxies. Where possible, the blazars have been further classified based on their spectral energy distributions (SEDs) as archival radio, optical, and X-ray data permit. While almost all FSRQs have a synchrotron-peak frequency < 1014 Hz, about half of the BL Lacs have a synchrotron-peak frequency > 1015 Hz. The 2LAC represents a significant improvement relative to the First LAT AGN Catalog (1LAC), with 52% more associated sources. The full characterization of the newly detected sources will require more broad-band data. Various properties, such as γ-ray fluxes and photon power law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities—and their correlations are presented and discussed for the different blazar classes. The general trends observed in 1LAC are confirmed.« less

  18. Sensitivity projections for dark matter dearches with the Fermi large area telescope

    DOE PAGES

    Charles, E.; M. Sanchez-Conde; Anderson, B.; ...

    2016-05-20

    The nature of dark matter is a longstanding enigma of physics; it may consist of particles beyond the Standard Model that are still elusive to experiments. Among indirect search techniques, which look for stable products from the annihilation or decay of dark matter particles, or from axions coupling to high-energy photons, observations of themore » $$\\gamma$$-ray sky have come to prominence over the last few years, because of the excellent sensitivity of the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope mission. The LAT energy range from 20 MeV to above 300 GeV is particularly well suited for searching for products of the interactions of dark matter particles. In this report we describe methods used to search for evidence of dark matter with the LAT, and review the status of searches performed with up to six years of LAT data. We also discuss the factors that determine the sensitivities of these searches, including the magnitudes of the signals and the relevant backgrounds, considering both statistical and systematic uncertainties. We project the expected sensitivities of each search method for 10 and 15 years of LAT data taking. In particular, we find that the sensitivity of searches targeting dwarf galaxies, which provide the best limits currently, will improve faster than the square root of observing time. Current LAT limits for dwarf galaxies using six years of data reach the thermal relic level for masses up to 120 GeV for the $$b\\bar{b}$$ annihilation channel for reasonable dark matter density profiles. With projected discoveries of additional dwarfs, these limits could extend to about 250 GeV. With as much as 15 years of LAT data these searches would be sensitive to dark matter annihilations at the thermal relic cross section for masses to greater than 400 GeV (200 GeV) in the $$b\\bar{b}$$ ($$\\tau^+ \\tau^-$$) annihilation channels.« less

  19. A tentative gamma-ray line from Dark Matter annihilation at the Fermi Large Area Telescope

    SciTech Connect

    Weniger, Christoph

    2012-08-01

    The observation of a gamma-ray line in the cosmic-ray fluxes would be a smoking-gun signature for dark matter annihilation or decay in the Universe. We present an improved search for such signatures in the data of the Fermi Large Area Telescope (LAT), concentrating on energies between 20 and 300 GeV. Besides updating to 43 months of data, we use a new data-driven technique to select optimized target regions depending on the profile of the Galactic dark matter halo. In regions close to the Galactic center, we find a 4.6σ indication for a gamma-ray line at E{sub γ} ≈ 130 GeV. When taking into account the look-elsewhere effect the significance of the observed excess is 3.2σ. If interpreted in terms of dark matter particles annihilating into a photon pair, the observations imply a dark matter mass of m{sub χ} = 129.8±2.4 {sup +7}{sub −13} GeV and a partial annihilation cross-section of (σv){sub χχ} {sub →} {sub γγ} = (1.27±0.32 {sup +0.18}{sub −0.28}) × 10{sup −27}cm{sup 3}s{sup −1} when using the Einasto dark matter profile. The evidence for the signal is based on about 50 photons; it will take a few years of additional data to clarify its existence.

  20. Gamma-Ray Observations of the Orion Molecular Clouds with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; hide

    2012-01-01

    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 approx 100 MeV and approx 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 approx 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 (W(sub CO)) at a 1 deg 1 deg pixel level. The correlation is found to be linear over a W(sub CO) range of approx 10-fold when divided in three regions, suggesting penetration of nuclear CRs to most of the cloud volumes. The W(sub CO)-to-mass conversion factor, X(sub CO), is found to be approx 2.3 10(exp 20) / sq cm (K km/s)(exp -1) for the high-longitude part of Orion A (l > 212 deg), approx 1.7 times higher than approx 1.3 10(exp 20) found for the rest of Orion A and B. We interpret the apparent high X(sub CO) 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.W(sub CO) decreases faster than the H2 column density in the region making the gas "darker" to W(sub CO).

  1. Gamma-ray observations of the Orion Molecular Clouds with the Fermi Large Area Telescope

    SciTech Connect

    Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; do Couto e Silva, E.; Drell, P. S.; Drlica-Wagner, A.; Enoto, T.; Falletti, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fukazawa, Y.; Fukui, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hayashi, K.; Horan, D.; Hou, X.; Hughes, R. E.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Lee, S. -H.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Makishima, K.; Mazziotta, M. N.; Mehault, J.; Mitthumsiri, W.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Nishino, S.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Orienti, M.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Razzano, M.; Reimer, A.; Reimer, O.; Roth, M.; Sadrozinski, H. F. -W.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Strong, A. W.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Tibolla, O.; Tinivella, M.; Torres, D. F.; Tramacere, A.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Zimmer, S.

    2012-08-08

    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 (W CO) at a 1° × 1° pixel level. The correlation is found to be linear over a W CO range of ~10-fold when divided in three regions, suggesting penetration of nuclear CRs to most of the cloud volumes. The W CO-to-mass conversion factor, X CO, 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 X CO 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. W CO decreases faster than the H2 column density in the region making the gas "darker" to W CO.

  2. Sensitivity projections for dark matter dearches with the Fermi large area telescope

    SciTech Connect

    Charles, E.; M. Sanchez-Conde; Anderson, B.; Caputo, R.; Cuoco, A.; Di Mauro, M.; Drlica-Wagner, A.; Gomez-Vargas, G. A.; Meyer, M.; Tibaldo, L.; Wood, M.; Zaharijas, G.; Zimmer, S.; Ajello, M.; Albert, A.; Baldini, L.; Bechtol, K.; Bloom, E. D.; Ceraudo, F.; Cohen-Tanugi, J.; Gaskins, J.; Gustafsson, M.; Mirabal, N.; Razzano, M.

    2016-05-20

    The nature of dark matter is a longstanding enigma of physics; it may consist of particles beyond the Standard Model that are still elusive to experiments. Among indirect search techniques, which look for stable products from the annihilation or decay of dark matter particles, or from axions coupling to high-energy photons, observations of the $\\gamma$-ray sky have come to prominence over the last few years, because of the excellent sensitivity of the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope mission. The LAT energy range from 20 MeV to above 300 GeV is particularly well suited for searching for products of the interactions of dark matter particles. In this report we describe methods used to search for evidence of dark matter with the LAT, and review the status of searches performed with up to six years of LAT data. We also discuss the factors that determine the sensitivities of these searches, including the magnitudes of the signals and the relevant backgrounds, considering both statistical and systematic uncertainties. We project the expected sensitivities of each search method for 10 and 15 years of LAT data taking. In particular, we find that the sensitivity of searches targeting dwarf galaxies, which provide the best limits currently, will improve faster than the square root of observing time. Current LAT limits for dwarf galaxies using six years of data reach the thermal relic level for masses up to 120 GeV for the $b\\bar{b}$ annihilation channel for reasonable dark matter density profiles. With projected discoveries of additional dwarfs, these limits could extend to about 250 GeV. With as much as 15 years of LAT data these searches would be sensitive to dark matter annihilations at the thermal relic cross section for masses to greater than 400 GeV (200 GeV) in the $b\\bar{b}$ ($\\tau^+ \\tau^-$) annihilation channels.

  3. Observation of supernova remnant IC 443 with the Fermi Large Area Telescope

    DOE PAGES

    Abdo, A. A.

    2010-03-03

    Here, we report observation of the supernova remnant (SNR) IC 443 (G189.1+3.0) with the Fermi Gamma-ray Space Telescope Large Area Telescope (LAT) in the energy band between 200 MeV and 50 GeV. IC 443 is a shell-type SNR with mixed morphology located off the outer Galactic plane where high-energy emission has been detected in the X-ray, GeV and TeV gamma-ray bands. Past observations suggest IC 443 has been interacting with surrounding interstellar matter. Proximity between dense shocked molecular clouds and GeV-TeV gamma-ray emission regions detected by EGRET, MAGIC, and VERITAS suggests an interpretation that cosmic-ray (CR) particles are accelerated by the SNR. We accurately characterize the gamma-ray emission produced by the CRs accelerated at IC 443 using the high gamma-ray statistics and broad energy coverage provided by the LAT. The emission region is extended in the energy band with θ68 = 0more » $$°\\atop{.}$$27 ± 0fdg01(stat) ± 0$$°\\atop{.}$$03(sys) for an assumed two-dimensional Gaussian profile and overlaps almost completely with the extended source region of VERITAS. Its centroid is displaced significantly from the known pulsar wind nebula (PWN) which suggests the PWN is not the major contributor in the present energy band. The observed spectrum changes its power-law slope continuously and continues smoothly to the MAGIC and VERITAS data points. Furthermore, the combined gamma-ray spectrum (200 MeV« less

  4. Observation of supernova remnant IC 443 with the Fermi Large Area Telescope

    SciTech Connect

    Abdo, A. A.

    2010-03-03

    Here, we report observation of the supernova remnant (SNR) IC 443 (G189.1+3.0) with the Fermi Gamma-ray Space Telescope Large Area Telescope (LAT) in the energy band between 200 MeV and 50 GeV. IC 443 is a shell-type SNR with mixed morphology located off the outer Galactic plane where high-energy emission has been detected in the X-ray, GeV and TeV gamma-ray bands. Past observations suggest IC 443 has been interacting with surrounding interstellar matter. Proximity between dense shocked molecular clouds and GeV-TeV gamma-ray emission regions detected by EGRET, MAGIC, and VERITAS suggests an interpretation that cosmic-ray (CR) particles are accelerated by the SNR. We accurately characterize the gamma-ray emission produced by the CRs accelerated at IC 443 using the high gamma-ray statistics and broad energy coverage provided by the LAT. The emission region is extended in the energy band with θ68 = 0$°\\atop{.}$27 ± 0fdg01(stat) ± 0$°\\atop{.}$03(sys) for an assumed two-dimensional Gaussian profile and overlaps almost completely with the extended source region of VERITAS. Its centroid is displaced significantly from the known pulsar wind nebula (PWN) which suggests the PWN is not the major contributor in the present energy band. The observed spectrum changes its power-law slope continuously and continues smoothly to the MAGIC and VERITAS data points. Furthermore, the combined gamma-ray spectrum (200 MeV

  5. Sensitivity projections for dark matter dearches with the Fermi large area telescope

    SciTech Connect

    Charles, E.; M. Sanchez-Conde; Anderson, B.; Caputo, R.; Cuoco, A.; Di Mauro, M.; Drlica-Wagner, A.; Gomez-Vargas, G. A.; Meyer, M.; Tibaldo, L.; Wood, M.; Zaharijas, G.; Zimmer, S.; Ajello, M.; Albert, A.; Baldini, L.; Bechtol, K.; Bloom, E. D.; Ceraudo, F.; Cohen-Tanugi, J.; Gaskins, J.; Gustafsson, M.; Mirabal, N.; Razzano, M.

    2016-05-20

    The nature of dark matter is a longstanding enigma of physics; it may consist of particles beyond the Standard Model that are still elusive to experiments. Among indirect search techniques, which look for stable products from the annihilation or decay of dark matter particles, or from axions coupling to high-energy photons, observations of the $\\gamma$-ray sky have come to prominence over the last few years, because of the excellent sensitivity of the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope mission. The LAT energy range from 20 MeV to above 300 GeV is particularly well suited for searching for products of the interactions of dark matter particles. In this report we describe methods used to search for evidence of dark matter with the LAT, and review the status of searches performed with up to six years of LAT data. We also discuss the factors that determine the sensitivities of these searches, including the magnitudes of the signals and the relevant backgrounds, considering both statistical and systematic uncertainties. We project the expected sensitivities of each search method for 10 and 15 years of LAT data taking. In particular, we find that the sensitivity of searches targeting dwarf galaxies, which provide the best limits currently, will improve faster than the square root of observing time. Current LAT limits for dwarf galaxies using six years of data reach the thermal relic level for masses up to 120 GeV for the $b\\bar{b}$ annihilation channel for reasonable dark matter density profiles. With projected discoveries of additional dwarfs, these limits could extend to about 250 GeV. With as much as 15 years of LAT data these searches would be sensitive to dark matter annihilations at the thermal relic cross section for masses to greater than 400 GeV (200 GeV) in the $b\\bar{b}$ ($\\tau^+ \\tau^-$) annihilation channels.

  6. THE SECOND CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bottacini, E.; Antolini, E.; Bonamente, E.; Atwood, W. B.; Bouvier, A.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Ballet, J.; Bastieri, D. E-mail: sarac@slac.stanford.edu E-mail: charles.dermer@nrl.navy.mil; and others

    2011-12-20

    The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years of scientific operation is presented. The second LAT AGN catalog (2LAC) includes 1017 {gamma}-ray sources located at high Galactic latitudes (|b| > 10 Degree-Sign ) that are detected with a test statistic (TS) greater than 25 and associated statistically with AGNs. However, some of these are affected by analysis issues and some are associated with multiple AGNs. Consequently, we define a Clean Sample which includes 886 AGNs, comprising 395 BL Lacertae objects (BL Lac objects), 310 flat-spectrum radio quasars (FSRQs), 157 candidate blazars of unknown type (i.e., with broadband blazar characteristics but with no optical spectral measurement yet), 8 misaligned AGNs, 4 narrow-line Seyfert 1 (NLS1s), 10 AGNs of other types, and 2 starburst galaxies. Where possible, the blazars have been further classified based on their spectral energy distributions (SEDs) as archival radio, optical, and X-ray data permit. While almost all FSRQs have a synchrotron-peak frequency <10{sup 14} Hz, about half of the BL Lac objects have a synchrotron-peak frequency >10{sup 15} Hz. The 2LAC represents a significant improvement relative to the first LAT AGN catalog (1LAC), with 52% more associated sources. The full characterization of the newly detected sources will require more broadband data. Various properties, such as {gamma}-ray fluxes and photon power-law spectral indices, redshifts, {gamma}-ray luminosities, variability, and archival radio luminosities and their correlations are presented and discussed for the different blazar classes. The general trends observed in 1LAC are confirmed.

  7. Probing the unified origin of dark matter and baryon asymmetry at PAMELA and Fermi Large Area Telescope

    SciTech Connect

    Kohri, Kazunori; Sahu, Narendra; Stephens, Philip; Mazumdar, Anupam

    2009-09-15

    We propose an unified model of dark matter and baryon asymmetry in a leptophilic world above the electroweak scale. We provide an example where the inflaton decay products subsequently generate a lepton asymmetry and a dark matter abundance with an unique coupling in the early Universe, while the present day decay of the dark matter through the same coupling gives rise the observed cosmic ray anomalies at PAMELA and Fermi Large Area Telescope.

  8. Observations of the Large Magellanic Cloud with Fermi

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Digel, S. W.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giavitto, G.; Giebels, B.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Gotthelf, E. V.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Jackson, M. S.; Jean, P.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocian, M. L.; Kuss, M.; Lande, J.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Marshall, F.; Martin, P.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Ryde, F.; Sadrozinski, H. F. -W.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Sellerholm, A.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J. -L.; Strickman, M. S.; Strong, A. W.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vasileiou, V.; Venter, C.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Weltevrede, P.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Ziegler, M.

    2010-03-18

    Context. The Large Magellanic Cloud (LMC) is to date the only normal external galaxy that has been detected in high-energy gamma rays. High-energy gamma rays trace particle acceleration processes and gamma-ray observations allow the nature and sites of acceleration to be studied. Aims. We characterise the distribution and sources of cosmic rays in the LMC from analysis of gamma-ray observations. Methods. We analyse 11 months of continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-Ray Space Telescope and compare it to tracers of the interstellar medium and models of the gamma-ray sources in the LMC. Results. The LMC is detected at 33σ significance. The integrated >100 MeV photon flux of the LMC amounts to (2.6 ± 0.2) × 10-7 ph cm-2 s-1 which corresponds to an energy flux of (1.6 ± 0.1) × 10-10 erg cm-2 s-1, with additional systematic uncertainties of 16%. The analysis reveals the massive star forming region 30 Doradus as a bright source of gamma-ray emission in the LMC in addition to fainter emission regions found in the northern part of the galaxy. The gamma-ray emission from the LMC shows very little correlation with gas density and is rather correlated to tracers of massive star forming regions. The close confinement of gamma-ray emission to star forming regions suggests a relatively short GeV cosmic-ray proton diffusion length. In conclusion, the close correlation between cosmic-ray density and massive star tracers supports the idea that cosmic rays are accelerated in massive star forming regions as a result of the large amounts of kinetic energy that are input by the stellar winds and supernova explosions of massive stars into the interstellar medium.

  9. The First Fermi Large Area Telescope Catalog of Gamma-ray Pulsars

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Camilo, F.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cognard, I.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Corbet, R.; Cutini, S.; den Hartog, P. R.; Dermer, C. D.; de Angelis, A.; de Luca, A.; de Palma, F.; Digel, S. W.; Dormody, M.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Espinoza, C.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Freire, P. C. C.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giavitto, G.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Glanzman, T.; Godfrey, G.; Gotthelf, E. V.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Gwon, C.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hughes, R. E.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Johnston, S.; Kamae, T.; Kanbach, G.; Kaspi, V. M.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocian, M. L.; Kramer, M.; Kuss, M.; Lande, J.; Latronico, L.; Lemoine-Goumard, M.; Livingstone, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Lyne, A. G.; Madejski, G. M.; Makeev, A.; Manchester, R. N.; Marelli, M.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; McGlynn, S.; Meurer, C.; Michelson, P. F.; Mineo, T.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nolan, P. L.; Norris, J. P.; Noutsos, A.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Ransom, S. M.; Ray, P. S.; Razzano, M.; Rea, N.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Ryde, F.; Sadrozinski, H. F. -W.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Schalk, T. L.; Sellerholm, A.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stappers, B. W.; Starck, J. -L.; Striani, E.; Strickman, M. S.; Strong, A. W.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Theureau, G.; Thompson, D. J.; Thorsett, S. E.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Van Etten, A.; Vasileiou, V.; Venter, C.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Wang, N.; Watters, K.; Weltevrede, P.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Ziegler, M.

    2010-03-25

    The dramatic increase in the number of known gamma-ray pulsars since the launch of the Fermi Gamma-ray Space Telescope (formerly GLAST) offers the first opportunity to study a sizable population of these high-energy objects. This catalog summarizes 46 high-confidence pulsed detections using the first six months of data taken by the Large Area Telescope (LAT), Fermi's main instrument. Sixteen previously unknown pulsars were discovered by searching for pulsed signals at the positions of bright gamma-ray sources seen with the LAT, or at the positions of objects suspected to be neutron stars based on observations at other wavelengths. The dimmest observed flux among these gamma-ray-selected pulsars is 6.0 × 10–8 ph cm–2 s–1 (for E>100 MeV). Pulsed gamma-ray emission was discovered from 24 known pulsars by using ephemerides (timing solutions) derived from monitoring radio pulsars. Eight of these new gamma-ray pulsars are millisecond pulsars. The dimmest observed flux among the radio-selected pulsars is 1.4 × 10–8 ph cm–2 s–1 (for E>100 MeV). The remaining six gamma-ray pulsars were known since the Compton Gamma Ray Observatory mission, or before. The limiting flux for pulse detection is non-uniform over the sky owing to different background levels, especially near the Galactic plane. The pulsed energy spectra can be described by a power law with an exponential cutoff, with cutoff energies in the range ~1-5 GeV. The rotational energy-loss rate ($\\dot{E}$) of these neutron stars spans five decades, from ~3 × 1033 erg s–1 to 5 × 1038 erg s–1, and the apparent efficiencies for conversion to gamma-ray emission range from ~0.1% to ~ unity, although distance uncertainties complicate efficiency estimates. The pulse shapes show substantial diversity, but roughly 75% of the gamma-ray pulse profiles have two peaks, separated by ≳0.2 of rotational

  10. A population of gamma-ray emitting globular clusters seen with the Fermi Large Area Telescope

    DOE PAGES

    Abdo, A. A.

    2010-11-24

    Context. Globular clusters with their large populations of millisecond pulsars (MSPs) are believed to be potential emitters of high-energy gamma-ray emission. The observation of this emission provides a powerful tool to assess the millisecond pulsar population of a cluster, is essential for understanding the importance of binary systems for the evolution of globular clusters, and provides complementary insights into magnetospheric emission processes. Aims. Our goal is to constrain the millisecond pulsar populations in globular clusters from analysis of gamma-ray observations. Methods. We use 546 days of continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-ray Spacemore » Telescope to study the gamma-ray emission towards 13 globular clusters. Results. Steady point-like high-energy gamma-ray emission has been significantly detected towards 8 globular clusters. Five of them (47 Tucanae, Omega Cen, NGC 6388, Terzan 5, and M 28) show hard spectral power indices (0.7 < Γ < 1.4) and clear evidence for an exponential cut-off in the range 1.0 - 2.6 GeV, which is the characteristic signature of magnetospheric emission from MSPs. Three of them (M 62, NGC 6440 and NGC 6652) also show hard spectral indices (1.0 < Γ < 1.7), however the presence of an exponential cut-off can not be unambiguously established. Three of them (Omega Cen, NGC 6388, NGC 6652) have no known radio or X-ray MSPs yet still exhibit MSP spectral properties. From the observed gamma-ray luminosities, we estimate the total number of MSPs that is expected to be present in these globular clusters. We show that our estimates of the MSP population correlate with the stellar encounter rate and we estimate 2600 - 4700 MSPs in Galactic globular clusters, commensurate with previous estimates. Conclusions. The observation of high-energy gamma-ray emission from globular clusters thus provides a reliable independent method to assess their millisecond pulsar populations.« less

  11. First year results from LOTIS

    NASA Astrophysics Data System (ADS)

    Williams, G. G.; Parks, H. S.; Ables, E.

    1997-11-01

    LOTIS (Livermore Optical Transient Imaging System) is a gamma-ray burst optical couterpart search experiment located near Lawrence Livermore National Laboratory in California. The system is linked to the GCN (GRB Coordinates Network) real-time coordinate distribution network and can respond to a burst trigger in 6-15 seconds. LOTIS has a total field-of-view of 17.4 degrees x 17.4 degrees with a completeness sensitivity of mv approximately 11 for a 10 second integration time. Since operations began in October 1996, LOTIS has responded to over 30 GCN/BATSE GRB triggers. Seven of these triggers are considered good events subject to the criteria of clear weather conditions, (lt) 60 S RESPONSE TIME, AND (gt)50% coverage of the final BATSE 3(sigma) error circle. We discuss results from the first year of LOTIS operations with an emphasis on the observations and analysis of GRB 971006 (BATSE trigger 6414) .

  12. Development of the Model of Galactic Interstellar Emission for Standard Point-Source Analysis of Fermi Large Area Telescope Data

    SciTech Connect

    Acero, F.

    2016-04-22

    Most of the celestial γ rays detected by the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope originate from the interstellar medium when energetic cosmic rays interact with interstellar nucleons and photons. Conventional point and extended source studies rely on the modeling of this diffuse emission for accurate characterization. We describe here the development of the Galactic Interstellar Emission Model (GIEM) that is the standard adopted by the LAT Collaboration and is publicly available. The model is based on a linear combination of maps for interstellar gas column density in Galactocentric annuli and for the inverse Compton emission produced in the Galaxy. We also include in the GIEM large-scale structures like Loop I and the Fermi bubbles. The measured gas emissivity spectra con rm that the cosmic-ray proton density decreases with Galactocentric distance beyond 5 kpc from the Galactic Center. The measurements also suggest a softening of the proton spectrum with Galactocentric distance. We observe that the Fermi bubbles have boundaries with a shape similar to a catenary at latitudes below 20° and we observe an enhanced emission toward their base extending in the North and South Galactic direction and located within ~4° of the Galactic Center.

  13. Development of the Model of Galactic Interstellar Emission for Standard Point-Source Analysis of Fermi Large Area Telescope Data

    DOE PAGES

    Acero, F.

    2016-04-22

    Most of the celestial γ rays detected by the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope originate from the interstellar medium when energetic cosmic rays interact with interstellar nucleons and photons. Conventional point and extended source studies rely on the modeling of this diffuse emission for accurate characterization. We describe here the development of the Galactic Interstellar Emission Model (GIEM) that is the standard adopted by the LAT Collaboration and is publicly available. The model is based on a linear combination of maps for interstellar gas column density in Galactocentric annuli and for the inverse Compton emissionmore » produced in the Galaxy. We also include in the GIEM large-scale structures like Loop I and the Fermi bubbles. The measured gas emissivity spectra con rm that the cosmic-ray proton density decreases with Galactocentric distance beyond 5 kpc from the Galactic Center. The measurements also suggest a softening of the proton spectrum with Galactocentric distance. We observe that the Fermi bubbles have boundaries with a shape similar to a catenary at latitudes below 20° and we observe an enhanced emission toward their base extending in the North and South Galactic direction and located within ~4° of the Galactic Center.« less

  14. Development of the Model of Galactic Interstellar Emission for Standard Point-Source Analysis of Fermi Large Area Telescope Data

    NASA Technical Reports Server (NTRS)

    Acero, F.; Ackermann, M.; Ajello, M.; Albert, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Brandt, T. J.; hide

    2016-01-01

    Most of the celestial gamma rays detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope originate from the interstellar medium when energetic cosmic rays interact with interstellar nucleons and photons. Conventional point-source and extended-source studies rely on the modeling of this diffuse emission for accurate characterization. Here, we describe the development of the Galactic Interstellar Emission Model (GIEM),which is the standard adopted by the LAT Collaboration and is publicly available. This model is based on a linear combination of maps for interstellar gas column density in Galactocentric annuli and for the inverse-Compton emission produced in the Galaxy. In the GIEM, we also include large-scale structures like Loop I and the Fermi bubbles. The measured gas emissivity spectra confirm that the cosmic-ray proton density decreases with Galactocentric distance beyond 5 kpc from the Galactic Center. The measurements also suggest a softening of the proton spectrum with Galactocentric distance. We observe that the Fermi bubbles have boundaries with a shape similar to a catenary at latitudes below 20deg and we observe an enhanced emission toward their base extending in the north and south Galactic directions and located within approximately 4deg of the Galactic Center.

  15. Development of the Model of Galactic Interstellar Emission for Standard Point-source Analysis of Fermi Large Area Telescope Data

    NASA Astrophysics Data System (ADS)

    Acero, F.; Ackermann, M.; Ajello, M.; Albert, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cuoco, A.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hayashi, K.; Hays, E.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Hou, X.; Jogler, T.; Jóhannesson, G.; Kamae, T.; Kuss, M.; Landriu, D.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Maldera, S.; Malyshev, D.; Manfreda, A.; Martin, P.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mirabal, N.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Remy, Q.; Renault, N.; Sánchez-Conde, M.; Schaal, M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Strong, A. W.; Suson, D. J.; Tajima, H.; Takahashi, H.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Vianello, G.; Werner, M.; Wood, K. S.; Wood, M.; Zaharijas, G.; Zimmer, S.

    2016-04-01

    Most of the celestial γ rays detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope originate from the interstellar medium when energetic cosmic rays interact with interstellar nucleons and photons. Conventional point-source and extended-source studies rely on the modeling of this diffuse emission for accurate characterization. Here, we describe the development of the Galactic Interstellar Emission Model (GIEM), which is the standard adopted by the LAT Collaboration and is publicly available. This model is based on a linear combination of maps for interstellar gas column density in Galactocentric annuli and for the inverse-Compton emission produced in the Galaxy. In the GIEM, we also include large-scale structures like Loop I and the Fermi bubbles. The measured gas emissivity spectra confirm that the cosmic-ray proton density decreases with Galactocentric distance beyond 5 kpc from the Galactic Center. The measurements also suggest a softening of the proton spectrum with Galactocentric distance. We observe that the Fermi bubbles have boundaries with a shape similar to a catenary at latitudes below 20° and we observe an enhanced emission toward their base extending in the north and south Galactic directions and located within ˜4° of the Galactic Center.

  16. A tool to estimate the Fermi Large Area Telescope background for short-duration observations

    SciTech Connect

    Vasileiou, Vlasios

    2013-07-25

    Here, the proper estimation of the background is a crucial component of data analyses in astrophysics, such as source detection, temporal studies, spectroscopy, and localization. For the case of the Large Area Telescope (LAT) on board the Fermi spacecraft, approaches to estimate the background for short (≲1000 s duration) observations fail if they ignore the strong dependence of the LAT background on the continuously changing observational conditions. We present a (to be) publicly available background-estimation tool created and used by the LAT Collaboration in several analyses of Gamma Ray Bursts. This tool can accurately estimate the expected LAT background for any observational conditions, including, for example, observations with rapid variations of the Fermi spacecraft’s orientation occurring during automatic repointings.

  17. AFTERGLOW OBSERVATIONS OF FERMI LARGE AREA TELESCOPE GAMMA-RAY BURSTS AND THE EMERGING CLASS OF HYPER-ENERGETIC EVENTS

    SciTech Connect

    Cenko, S. B.; Butler, N. R.; Cobb, B. E.; Cucchiara, A.; Bloom, J. S.; Perley, D. A.; Filippenko, A. V.; Frail, D. A.; Harrison, F. A.; Haislip, J. B.; Reichart, D. E.; Ivarsen, K. M.; LaCluyze, A. P.; Berger, E.; Chandra, P.; Fox, D. B.; Prochaska, J. X.; Kasliwal, M. M.; Kulkarni, S. R.

    2011-05-01

    We present broadband (radio, optical, and X-ray) light curves and spectra of the afterglows of four long-duration gamma-ray bursts (GRBs; GRBs 090323, 090328, 090902B, and 090926A) detected by the Gamma-Ray Burst Monitor and Large Area Telescope (LAT) instruments on the Fermi satellite. With its wide spectral bandpass, extending to GeV energies, Fermi is sensitive to GRBs with very large isotropic energy releases (10{sup 54} erg). Although rare, these events are particularly important for testing GRB central-engine models. When combined with spectroscopic redshifts, our afterglow data for these four events are able to constrain jet collimation angles, the density structure of the circumburst medium, and both the true radiated energy release and the kinetic energy of the outflows. In agreement with our earlier work, we find that the relativistic energy budget of at least one of these events (GRB 090926A) exceeds the canonical value of 10{sup 51} erg by an order of magnitude. Such energies pose a severe challenge for models in which the GRB is powered by a magnetar or a neutrino-driven collapsar, but remain compatible with theoretical expectations for magnetohydrodynamical collapsar models (e.g., the Blandford-Znajek mechanism). Our jet opening angles ({theta}) are similar to those found for pre-Fermi GRBs, but the large initial Lorentz factors ({Gamma}{sub 0}) inferred from the detection of GeV photons imply {theta}{Gamma}{sub 0} {approx} 70-90, values which are above those predicted in magnetohydrodynamic models of jet acceleration. Finally, we find that these Fermi-LAT events preferentially occur in a low-density circumburst environment, and we speculate that this might result from the lower mass-loss rates of their lower-metallicity progenitor stars. Future studies of Fermi-LAT afterglows at radio wavelengths with the order-of-magnitude improvement in sensitivity offered by the Extended Very Large Array should definitively establish the relativistic energy

  18. Fermi Large Area Telescope Observations of the Supernova Remnant GS.7-0.1

    NASA Technical Reports Server (NTRS)

    Ferrara, E. C.; Hays, E.; Troja, E.; Moiseev, A. A.

    2012-01-01

    We present a detailed analysis of the GeV gamma-ray emission toward the supernova remnant (SNR) G8.7-0.1 with the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope. An investigation of the relationship among G8.7-0.1 and the TeV unidentified source HESS J1804-216 provides us with an important clue on diffusion process of cosmic rays if particle acceleration operates in the SNR. The GeV gamma-ray emission is extended with most of the emission in positional coincidence with the SNR G8.7-0.1 and a lesser part located outside the western boundary of G8.7-0.1. The region of the gamma-ray emission overlaps spatially-connected molecular clouds, implying a physical connection for the gamma-ray structure. The total gamma-ray spectrum measured with LAT from 200 MeV-100 GeV can be described by a broken power-law function with a break of 2.4 +/- 0.6 (stat) +/- 1.2 (sys) GeV, and photon indices of2.10 +/- 0.06 (stat) +/- 0.10 (sys) below the break and 2.70 +/- 0.12 (stat) +/- 0.14 (sys) above the break. Given the spatial association among the gamma rays, the radio emission ofG8.7-0.1, and the molecular clouds, the decay of pions produced by particles accelerated in the SNR and hitting the molecular clouds naturally explains the GeV gamma-ray spectrum. We also find that the GeV morphology is not well represented by the TeV emission from HESS Jl804-2l6 and that the spectrum in the Ge V band is not consistent with the extrapolation of the TeV gamma-ray spectrum. The spectral index of the TeV emission is consistent with the particle spectral index predicted by a theory that assumes energy-dependent diffusion of particles accelerated in an SNR. We discuss the possibility that the TeV-spectrum originates from the interaction of particles accelerated in G8.7-0.l with molecular clouds, and we constrain the diffusion coefficient of the particles.

  19. Pulsed Gamma-Rays from PSR J2021+3651 with the Fermi Large Area Telescope

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2009-07-08

    In this paper, we report the detection of pulsed gamma-rays from the young, spin-powered radio pulsar PSR J2021+3651 using data acquired with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). The light curve consists of two narrow peaks of similar amplitude separated by 0.468 ± 0.002 in phase. The first peak lags the maximum of the 2 GHz radio pulse by 0.162 ± 0.004 ± 0.01 in phase. The integral gamma-ray photon flux above 100 MeV is (56 ± 3 ± 11) × 10–8 cm–2 s–1. The photon spectrum is well described by an exponentiallymore » cut-off power law of the form dF/dE = kE–Γe(–E/Ec), where the energy E is expressed in GeV. The photon index is Γ = 1.5 ± 0.1 ± 0.1 and the exponential cut-off is Ec = 2.4 ± 0.3 ± 0.5 GeV. The first uncertainty is statistical and the second is systematic. The integral photon flux of the bridge is approximately 10% of the pulsed emission, and the upper limit on off-pulse gamma-ray emission from a putative pulsar wind nebula is < 10% of the pulsed emission at the 95% confidence level. Radio polarization measurements yield a rotation measure of RM = 524 ± 4 rad m–2 but a poorly constrained magnetic geometry. Re-analysis of Chandra X-ray Observatory data enhanced the significance of the weak X-ray pulsations, and the first peak is roughly phase aligned with the first gamma-ray peak. We discuss the emission region and beaming geometry based on the shape and spectrum of the gamma-ray light curve combined with radio and X-ray measurements, and the implications for the pulsar distance. Finally, gamma-ray emission from the polar cap region seems unlikely for this pulsar.« less

  20. Pulsed Gamma-Rays From PSR J2021 3651 with the Fermi Large Area Telescope

    SciTech Connect

    Abdo, Aous A.; Ackermann, M.; Ajello, Marco; Atwood, William B.; Baldini, L.; Ballet, J.; Barbiellini, Guido; Bastieri, Denis; Battelino, Milan; Baughman, B.M.; Bechtol, K.; Bellazzini, Ronaldo; Berenji, Bijan; Bloom, Elliott D.; Bogaert, G.; Borgland, Anders W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, Thompson H.; /more authors..

    2011-11-30

    We report the detection of pulsed gamma-rays from the young, spin-powered radio pulsar PSR J2021+3651 using data acquired with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). The light curve consists of two narrow peaks of similar amplitude separated by 0.468 {+-} 0.002 in phase. The first peak lags the maximum of the 2 GHz radio pulse by 0.162 {+-} 0.004 {+-} 0.01 in phase. The integral gamma-ray photon flux above 100 MeV is (56 {+-} 3 {+-} 11) x 10{sup -8} cm{sup -2} s{sup -1}. The photon spectrum is well-described by an exponentially cut-off power law of the form dF/dE = kE{sup -{Gamma}}e{sup (-E/E{sub c})} where the energy E is expressed in GeV. The photon index is {Gamma} = 1.5 {+-} 0.1 {+-} 0.1 and the exponential cut-off is E{sub c} = 2.4 {+-} 0.3 {+-} 0.5 GeV. The first uncertainty is statistical and the second is systematic. The integral photon flux of the bridge is approximately 10% of the pulsed emission, and the upper limit on off-pulse gamma-ray emission from a putative pulsar wind nebula is < 10% of the pulsed emission at the 95% confidence level. Radio polarization measurements yield a rotation measure of RM = 524 {+-} 4 rad m{sup -2} but a poorly constrained magnetic geometry. Re-analysis of Chandra data enhanced the significance of the weak X-ray pulsations, and the first peak is roughly phase-aligned with the first gamma-ray peak. We discuss the emission region and beaming geometry based on the shape and spectrum of the gamma-ray light curve combined with radio and X-ray measurements, and the implications for the pulsar distance. Gamma-ray emission from the polar cap region seems unlikely for this pulsar.

  1. Fermi Large Area Telescope Observations of the Supernova Remnant G8.7-0.1

    SciTech Connect

    Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R.D.; Bloom, E.D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G.A.; Cameron, R.A.; Caraveo, P.A.; /more authors..

    2012-09-14

    We present a detailed analysis of the GeV gamma-ray emission toward the supernova remnant (SNR) G8.7-0.1 with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. An investigation of the relationship between G8.7-0.1 and the TeV unidentified source HESS J1804-216 provides us with an important clue on diffusion process of cosmic rays if particle acceleration operates in the SNR. The GeV gamma-ray emission is extended with most of the emission in positional coincidence with the SNR G8.7-0.1 and a lesser part located outside the western boundary of G8.7-0.1. The region of the gamma-ray emission overlaps spatially connected molecular clouds, implying a physical connection for the gamma-ray structure. The total gamma-ray spectrum measured with LAT from 200 MeV-100 GeV can be described by a broken power-law function with a break of 2.4 {+-} 0.6 (stat) {+-} 1.2 (sys) GeV, and photon indices of 2.10 {+-} 0.06 (stat) {+-} 0.10 (sys) below the break and 2.70 {+-} 0.12 (stat) {+-} 0.14 (sys) above the break. Given the spatial association among the gamma rays, the radio emission of G8.7-0.1, and the molecular clouds, the decay of p0s produced by particles accelerated in the SNR and hitting the molecular clouds naturally explains the GeV gamma-ray spectrum. We also find that the GeV morphology is not well represented by the TeV emission from HESS J1804-216 and that the spectrum in the GeV band is not consistent with the extrapolation of the TeV gamma-ray spectrum. The spectral index of the TeV emission is consistent with the particle spectral index predicted by a theory that assumes energy-dependent diffusion of particles accelerated in an SNR. We discuss the possibility that the TeV spectrum originates from the interaction of particles accelerated in G8.7-0.1 with molecular clouds, and we constrain the diffusion coefficient of the particles.

  2. Fermi Large Area Telescope observations of the crab pulsar and nebula

    SciTech Connect

    Abdo, A. A.

    2009-12-21

    Here, we report on γ-ray observations of the Crab Pulsar and Nebula using 8 months of survey data with the Fermi Large Area Telescope (LAT). The high quality light curve obtained using the ephemeris provided by the Nançay and Jodrell Bank radio telescopes shows two main peaks stable in phase with energy. The first γ-ray peak leads the radio main pulse by (281 ± 12 ± 21) μs, giving new constraints on the production site of non-thermal emission in pulsar magnetospheres. The first uncertainty is due to γ-ray statistics, and the second arises from the rotation parameters. The improved sensitivity and the unprecedented statistics afforded by the LAT enable precise measurement of the Crab Pulsar spectral parameters: cut-off energy at Ec = (5.8 ± 0.5 ± 1.2) GeV, spectral index of Γ = (1.97 ± 0.02 ± 0.06) and integral photon flux above 100 MeV of (2.09 ± 0.03 ± 0.18) × 10–6 cm–2 s–1. The first errors represent the statistical error on the fit parameters, while the second ones are the systematic uncertainties. Pulsed γ-ray photons are observed up to ~ 20 GeV which precludes emission near the stellar surface, below altitudes of around 4-5 stellar radii in phase intervals encompassing the two main peaks. We also performed a detailed phase-resolved spectral analysis : the hardest emission from the Crab Pulsar comes from the bridge region between the two γ-ray peaks while the softest comes from the falling edge of the second peak. Furthermore, the spectrum of the nebula in the energy range 100 MeV-300 GeV is well described by the sum of two power laws of indices Γsync = (3.99 ± 0.12 ± 0.08) and ΓIC = (1.64 ± 0.05 ± 0.07), corresponding to the falling edge of the synchrotron and the rising edge of the inverse Compton (IC) components, respectively. This latter, which links up naturally with the spectral data points of Cherenkov experiments, is well reproduced via IC scattering from

  3. Fermi Large Area Telescope Observations of the Supernova Remnant GS.7-0.1

    NASA Technical Reports Server (NTRS)

    Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; hide

    2011-01-01

    We present a detailed analysis of the GeV gamma-ray emission toward the supernova remnant (SNR) G8.7-0.1 with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. An investigation of the relationship among G8.7-0.l and the TeV unidentified source HESS J1804-216 provides us with an important clue on diffusion process of cosmic rays if particle acceleration operates in the SNR. The GeV gamma-ray emission is extended with most of the emission in positional coincidence with the SNR G8.7-0.l and a lesser part located outside the western boundary of G8.7-0.l. The region of the gamma-ray emission overlaps spatially-connected molecular clouds, implying a physical connection for the gamma-ray structure. The total gamma-ray spectrum measured with LAT from 200 MeV-100 GeV can be described by a broken power-law function with a break of 2.4 +/- 0.6 (stat) +/- 1.2 (sys) GeV, and photon indices of 2.10 +/- 0.06 (stat) +/- 0.10 (sys) below the break and 2.70 +/- 0.12 (stat) +/- 0.l4 (sys) above the break. Given the spatial association among the gamma rays, the radio emission of G8.7-0.1, and the molecular clouds, the decay of 1IoS produced by particles accelerated in the SNR and hitting the molecular clouds naturally explains the GeV gamma-ray spectrum. We also find that the GeV morphology is not well represented by the TeV emission from HESS J1804-216 and that the spectrum in the GeV band is not consistent with the extrapolation of the TeV gamma-ray spectrum. The spectral index of the TeV emission is consistent with the particle spectral index predicted by a theory that assumes energy-dependent diffusion of particles accelerated in an SNR. We discuss the possibility that the TeV spectrum originates from the interaction of particles accelerated in G8.7-0.1 with molecular clouds, and we constrain the diffusion coefficient of the particles.

  4. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE CRAB PULSAR AND NEBULA

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Baring, M. G.; Bastieri, D.; Bonamente, E.; Brigida, M. E-mail: mazziotta@ba.infn.i E-mail: lemoine@cenbg.in2p3.f

    2010-01-10

    We report on gamma-ray observations of the Crab Pulsar and Nebula using 8 months of survey data with the Fermi Large Area Telescope (LAT). The high quality light curve obtained using the ephemeris provided by the Nancay and Jodrell Bank radio telescopes shows two main peaks stable in phase with energy. The first gamma-ray peak leads the radio main pulse by (281 +- 12 +- 21) mus, giving new constraints on the production site of non-thermal emission in pulsar magnetospheres. The first uncertainty is due to gamma-ray statistics, and the second arises from the rotation parameters. The improved sensitivity and the unprecedented statistics afforded by the LAT enable precise measurement of the Crab Pulsar spectral parameters: cut-off energy at E{sub c} = (5.8 +- 0.5 +- 1.2) GeV, spectral index of GAMMA = (1.97 +- 0.02 +- 0.06) and integral photon flux above 100 MeV of (2.09 +- 0.03 +- 0.18) x 10{sup -6} cm{sup -2} s{sup -1}. The first errors represent the statistical error on the fit parameters, while the second ones are the systematic uncertainties. Pulsed gamma-ray photons are observed up to approx 20 GeV which precludes emission near the stellar surface, below altitudes of around 4-5 stellar radii in phase intervals encompassing the two main peaks. A detailed phase-resolved spectral analysis is also performed: the hardest emission from the Crab Pulsar comes from the bridge region between the two gamma-ray peaks while the softest comes from the falling edge of the second peak. The spectrum of the nebula in the energy range 100 MeV-300 GeV is well described by the sum of two power laws of indices GAMMA{sub sync} = (3.99 +- 0.12 +- 0.08) and GAMMA{sub IC} = (1.64 +- 0.05 +- 0.07), corresponding to the falling edge of the synchrotron and the rising edge of the inverse Compton (IC) components, respectively. This latter, which links up naturally with the spectral data points of Cherenkov experiments, is well reproduced via IC scattering from standard magnetohydrodynamic

  5. PULSED GAMMA-RAYS FROM PSR J2021+3651 WITH THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Bloom, E. D.; Borgland, A. W.; Atwood, W. B.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Bastieri, D.; Battelino, M.; Baughman, B. M.; Bogaert, G.; Bruel, P. E-mail: smith@cenbg.in2p3.fr

    2009-08-01

    We report the detection of pulsed gamma-rays from the young, spin-powered radio pulsar PSR J2021+3651 using data acquired with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). The light curve consists of two narrow peaks of similar amplitude separated by 0.468 {+-} 0.002 in phase. The first peak lags the maximum of the 2 GHz radio pulse by 0.162 {+-} 0.004 {+-} 0.01 in phase. The integral gamma-ray photon flux above 100 MeV is (56 {+-} 3 {+-} 11) x 10{sup -8} cm{sup -2} s{sup -1}. The photon spectrum is well described by an exponentially cut-off power law of the form dF/dE=kE{sup -{gamma}}e{sup (-E/E{sub c})}, where the energy E is expressed in GeV. The photon index is {gamma} = 1.5 {+-} 0.1 {+-} 0.1 and the exponential cut-off is E{sub c} = 2.4 {+-} 0.3 {+-} 0.5 GeV. The first uncertainty is statistical and the second is systematic. The integral photon flux of the bridge is approximately 10% of the pulsed emission, and the upper limit on off-pulse gamma-ray emission from a putative pulsar wind nebula is < 10% of the pulsed emission at the 95% confidence level. Radio polarization measurements yield a rotation measure of RM = 524 {+-} 4 rad m{sup -2} but a poorly constrained magnetic geometry. Re-analysis of Chandra X-ray Observatory data enhanced the significance of the weak X-ray pulsations, and the first peak is roughly phase aligned with the first gamma-ray peak. We discuss the emission region and beaming geometry based on the shape and spectrum of the gamma-ray light curve combined with radio and X-ray measurements, and the implications for the pulsar distance. Gamma-ray emission from the polar cap region seems unlikely for this pulsar.

  6. Fermi Large Area Telescope observations of the crab pulsar and nebula

    DOE PAGES

    Abdo, A. A.

    2009-12-21

    Here, we report on γ-ray observations of the Crab Pulsar and Nebula using 8 months of survey data with the Fermi Large Area Telescope (LAT). The high quality light curve obtained using the ephemeris provided by the Nançay and Jodrell Bank radio telescopes shows two main peaks stable in phase with energy. The first γ-ray peak leads the radio main pulse by (281 ± 12 ± 21) μs, giving new constraints on the production site of non-thermal emission in pulsar magnetospheres. The first uncertainty is due to γ-ray statistics, and the second arises from the rotation parameters. The improved sensitivitymore » and the unprecedented statistics afforded by the LAT enable precise measurement of the Crab Pulsar spectral parameters: cut-off energy at Ec = (5.8 ± 0.5 ± 1.2) GeV, spectral index of Γ = (1.97 ± 0.02 ± 0.06) and integral photon flux above 100 MeV of (2.09 ± 0.03 ± 0.18) × 10–6 cm–2 s–1. The first errors represent the statistical error on the fit parameters, while the second ones are the systematic uncertainties. Pulsed γ-ray photons are observed up to ~ 20 GeV which precludes emission near the stellar surface, below altitudes of around 4-5 stellar radii in phase intervals encompassing the two main peaks. We also performed a detailed phase-resolved spectral analysis : the hardest emission from the Crab Pulsar comes from the bridge region between the two γ-ray peaks while the softest comes from the falling edge of the second peak. Furthermore, the spectrum of the nebula in the energy range 100 MeV-300 GeV is well described by the sum of two power laws of indices Γsync = (3.99 ± 0.12 ± 0.08) and ΓIC = (1.64 ± 0.05 ± 0.07), corresponding to the falling edge of the synchrotron and the rising edge of the inverse Compton (IC) components, respectively. This latter, which links up naturally with the spectral data points of Cherenkov experiments, is well reproduced via IC scattering from standard magnetohydrodynamic nebula models, and does not

  7. Fermi large area telescope observations of blazar 3C 279 occultations by the sun

    SciTech Connect

    Barbiellini, G.; Bastieri, D.; Buson, S.; Bechtol, K.; Blandford, R. D.; Borgland, A. W.; Buehler, R.; Cameron, R. A.; Chiang, J.; Bellazzini, R.; Bregeon, J.; Bruel, P.; Caraveo, P. A.; Cavazzuti, E.; Ciprini, S.; Cecchi, C.; Chaves, R. C. G.; Cheung, C. C. E-mail: phdmitry@stanford.edu; and others

    2014-04-01

    Observations of occultations of bright γ-ray sources by the Sun may reveal predicted pair halos around blazars and/or new physics, such as, e.g., hypothetical light dark matter particles—axions. We use Fermi Gamma-Ray Space Telescope (Fermi) data to analyze four occultations of blazar 3C 279 by the Sun on October 8 each year from 2008 to 2011. A combined analysis of the observations of these occultations allows a point-like source at the position of 3C 279 to be detected with significance of ≈3σ, but does not reveal any significant excess over the flux expected from the quiescent Sun. The likelihood ratio test rules out complete transparency of the Sun to the blazar γ-ray emission at a 3σ confidence level.

  8. Large Fermi Surface of Heavy Electrons at the Border of Mott Insulating State in NiS2

    NASA Astrophysics Data System (ADS)

    Friedemann, S.; Chang, H.; Gamża, M. B.; Reiss, P.; Chen, X.; Alireza, P.; Coniglio, W. A.; Graf, D.; Tozer, S.; Grosche, F. M.

    2016-05-01

    One early triumph of quantum physics is the explanation why some materials are metallic whereas others are insulating. While a treatment based on single electron states is correct for most materials this approach can fail spectacularly, when the electrostatic repulsion between electrons causes strong correlations. Not only can these favor new and subtle forms of matter, such as magnetism or superconductivity, they can even cause the electrons in a half-filled energy band to lock into position, producing a correlated, or Mott insulator. The transition into the Mott insulating state raises important fundamental questions. Foremost among these is the fate of the electronic Fermi surface and the associated charge carrier mass, as the Mott transition is approached. We report the first direct observation of the Fermi surface on the metallic side of a Mott insulating transition by high pressure quantum oscillatory measurements in NiS2. Our results point at a large Fermi surface consistent with Luttinger’s theorem and a strongly enhanced quasiparticle effective mass. These two findings are in line with central tenets of the Brinkman-Rice picture of the correlated metal near the Mott insulating state and rule out alternative scenarios in which the carrier concentration vanishes continuously at the metal-insulator transition.

  9. Large Fermi Surface of Heavy Electrons at the Border of Mott Insulating State in NiS2

    PubMed Central

    Friedemann, S.; Chang, H.; Gamża, M. B.; Reiss, P.; Chen, X.; Alireza, P.; Coniglio, W. A.; Graf, D.; Tozer, S.; Grosche, F. M.

    2016-01-01

    One early triumph of quantum physics is the explanation why some materials are metallic whereas others are insulating. While a treatment based on single electron states is correct for most materials this approach can fail spectacularly, when the electrostatic repulsion between electrons causes strong correlations. Not only can these favor new and subtle forms of matter, such as magnetism or superconductivity, they can even cause the electrons in a half-filled energy band to lock into position, producing a correlated, or Mott insulator. The transition into the Mott insulating state raises important fundamental questions. Foremost among these is the fate of the electronic Fermi surface and the associated charge carrier mass, as the Mott transition is approached. We report the first direct observation of the Fermi surface on the metallic side of a Mott insulating transition by high pressure quantum oscillatory measurements in NiS2. Our results point at a large Fermi surface consistent with Luttinger’s theorem and a strongly enhanced quasiparticle effective mass. These two findings are in line with central tenets of the Brinkman-Rice picture of the correlated metal near the Mott insulating state and rule out alternative scenarios in which the carrier concentration vanishes continuously at the metal-insulator transition. PMID:27174799

  10. Large Fermi Surface of Heavy Electrons at the Border of Mott Insulating State in NiS2

    DOE PAGES

    Friedemann, S.; Chang, H.; Gamża, M. B.; ...

    2016-05-12

    One early triumph of quantum physics is the explanation why some materials are metallic whereas others are insulating. While a treatment based on single electron states is correct for most materials this approach can fail spectacularly, when the electrostatic repulsion between electrons causes strong correlations. Not only can these favor new and subtle forms of matter, such as magnetism or superconductivity, they can even cause the electrons in a half-filled energy band to lock into position, producing a correlated, or Mott insulator. The transition into the Mott insulating state raises important fundamental questions. Foremost among these is the fate ofmore » the electronic Fermi surface and the associated charge carrier mass, as the Mott transition is approached. We report the first direct observation of the Fermi surface on the metallic side of a Mott insulating transition by high pressure quantum oscillatory measurements in NiS2. We find our results point at a large Fermi surface consistent with Luttinger's theorem and a strongly enhanced quasiparticle effective mass. These two findings are in line with central tenets of the Brinkman-Rice picture of the correlated metal near the Mott insulating state and rule out alternative scenarios in which the carrier concentration vanishes continuously at the metal-insulator transition.« less

  11. Gamma-Ray Observations of the Supernova Remnant RX J0852.0-4622 with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Tanaka, T.; Allafort, A.; Ballet, J.; Funk, S.; Giordano, F.; Hewitt, J.; Lemoine-Goumard, M.; Tajima, H.; Tibolla, O.; Uchiyama, Y.

    2011-01-01

    We report on gamma-ray observations of the supernova remnant (SNR) RX J0852.04622 with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. In the Fermi-LAT data, we find a spatially extended source at the location of the SNR. The extension is consistent with the SNR size seen in other wavelengths such as X-rays and TeV gamma rays, leading to the identification of the gamma-ray source with the SNR. The spectrum is well described as a power law with a photon index of = 1.85 0.06 (stat)+0.18 0.19 (sys), which smoothly connects to the H.E.S.S. spectrum in the TeV energy band. We discuss the gamma-ray emission mechanism based on multiwavelength data. The broadband data can be fit well by a model in which the gamma rays are of hadronic origin. We also consider a scenario with inverse Compton scattering of electrons as the emission mechanism of the gamma rays. Although the leptonic model predicts a harder spectrum in the Fermi-LAT energy range, the model can fit the data considering the statistical and systematic errors.

  12. Large Fermi Surface of Heavy Electrons at the Border of Mott Insulating State in NiS2

    SciTech Connect

    Friedemann, S.; Chang, H.; Gamża, M. B.; Reiss, P.; Chen, X.; Alireza, P.; Coniglio, W. A.; Graf, D.; Tozer, S.; Grosche, F. M.

    2016-05-12

    One early triumph of quantum physics is the explanation why some materials are metallic whereas others are insulating. While a treatment based on single electron states is correct for most materials this approach can fail spectacularly, when the electrostatic repulsion between electrons causes strong correlations. Not only can these favor new and subtle forms of matter, such as magnetism or superconductivity, they can even cause the electrons in a half-filled energy band to lock into position, producing a correlated, or Mott insulator. The transition into the Mott insulating state raises important fundamental questions. Foremost among these is the fate of the electronic Fermi surface and the associated charge carrier mass, as the Mott transition is approached. We report the first direct observation of the Fermi surface on the metallic side of a Mott insulating transition by high pressure quantum oscillatory measurements in NiS2. We find our results point at a large Fermi surface consistent with Luttinger's theorem and a strongly enhanced quasiparticle effective mass. These two findings are in line with central tenets of the Brinkman-Rice picture of the correlated metal near the Mott insulating state and rule out alternative scenarios in which the carrier concentration vanishes continuously at the metal-insulator transition.

  13. Gamma-Ray Observations of the Supernova Remnant RX J0852.0-4622 with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Tanaka, T.; Allafort, A.; Ballet, J.; Funk, S.; Giordano, F.; Hewitt, J.; Lemoine-Goumard, M.; Tajima, H.; Tibolla, O.; Uchiyama, Y.

    2011-01-01

    We report on gamma-ray observations of the supernova remnant (SNR) RX J0852.04622 with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. In the Fermi-LAT data, we find a spatially extended source at the location of the SNR. The extension is consistent with the SNR size seen in other wavelengths such as X-rays and TeV gamma rays, leading to the identification of the gamma-ray source with the SNR. The spectrum is well described as a power law with a photon index of = 1.85 0.06 (stat)+0.18 0.19 (sys), which smoothly connects to the H.E.S.S. spectrum in the TeV energy band. We discuss the gamma-ray emission mechanism based on multiwavelength data. The broadband data can be fit well by a model in which the gamma rays are of hadronic origin. We also consider a scenario with inverse Compton scattering of electrons as the emission mechanism of the gamma rays. Although the leptonic model predicts a harder spectrum in the Fermi-LAT energy range, the model can fit the data considering the statistical and systematic errors.

  14. Search For Gamma-Ray Emission From Magnetars With The Fermi Large Area Telescope

    SciTech Connect

    Abdo, A. A.

    2010-11-22

    We report on the search for 0.1-10 GeV emission from magnetars in 17 months of Fermi Large Area Telescope (LAT) observations. No significant evidence for gamma-ray emission from any of the currently known magnetars is found. The most stringent upper limits to date on their persistent emission in the Fermi energy range are estimated between ~10–12 and 10–10 erg s–1 cm–2, depending on the source. We also searched for gamma-ray pulsations and possible outbursts, also with no significant detection. The upper limits derived support the presence of a cutoff at an energy below a few MeV in the persistent emission of magnetars. They also show the likely need for a revision of current models of outer-gap emission from strongly magnetized pulsars, which, in some realizations, predict detectable GeV emission from magnetars at flux levels exceeding the upper limits identified here using the Fermi-LAT observations.

  15. On possible interpretations of the high energy electron–positron spectrum measured by the Fermi Large Area Telescope

    DOE PAGES

    Grasso, D.; Profumo, S.; Strong, A. W.; ...

    2009-07-11

    The Fermi-LAT experiment recently reported high precision measurements of the spectrum of cosmic-ray electrons-plus-positrons (CRE) between 20 GeV and 1 TeV. The spectrum shows no prominent spectral features, and is significantly harder than that inferred from several previous experiments. In this paper, we discuss several interpretations of the Fermi results based either on a single large scale Galactic CRE component or by invoking additional electron–positron primary sources, e.g. nearby pulsars or particle dark matter annihilation. We show that while the reported Fermi-LAT data alone can be interpreted in terms of a single component scenario, when combined with other complementary experimentalmore » results, specifically the CRE spectrum measured by H.E.S.S. and especially the positron fraction reported by PAMELA between 1 and 100 GeV, that class of models fails to provide a consistent interpretation. Rather, we find that several combinations of parameters, involving both the pulsar and dark matter scenarios, allow a consistent description of those results. Finally, we also briefly discuss the possibility of discriminating between the pulsar and dark matter interpretations by looking for a possible anisotropy in the CRE flux.« less

  16. On Possible Interpretations of the High Energy Electron-Positron Spectrum Measured by the Fermi Large Area Telescope

    SciTech Connect

    Grasso, D.; Profumo, S.; Strong, A.W.; Baldini, L.; Bellazzini, R.; Bloom, E.D.; Bregeon, J.; Di Bernardo, G.; Gaggero, D.; Giglietto, N.; Kamae, T.; Latronico, L.; Longo, F.; Mazziotta, M.N.; Moiseev, A.A.; Morselli, A.; Ormes, J.F.; Pesce-Rollins, M.; Pohl, M.; Razzano, M.; Sgro, C.

    2009-05-15

    The Fermi-LAT experiment recently reported high precision measurements of the spectrum of cosmic-ray electrons-plus-positrons (CRE) between 20 GeV and 1 TeV. The spectrum shows no prominent spectral features, and is significantly harder than that inferred from several previous experiments. Here we discuss several interpretations of the Fermi results based either on a single large scale Galactic CRE component or by invoking additional electron-positron primary sources, e.g. nearby pulsars or particle Dark Matter annihilation. We show that while the reported Fermi-LAT data alone can be interpreted in terms of a single component scenario, when combined with other complementary experimental results, specifically the CRE spectrum measured by H.E.S.S. and especially the positron fraction reported by PAMELA between 1 and 100 GeV, that class of models fails to provide a consistent interpretation. Rather, we find that several combinations of parameters, involving both the pulsar and dark matter scenarios, allow a consistent description of those results. We also briefly discuss the possibility of discriminating between the pulsar and dark matter interpretations by looking for a possible anisotropy in the CRE flux.

  17. On possible interpretations of the high energy electron–positron spectrum measured by the Fermi Large Area Telescope

    SciTech Connect

    Grasso, D.; Profumo, S.; Strong, A. W.; Baldini, L.; Bellazzini, R.; Bloom, E. D.; Bregeon, J.; Di Bernardo, G.; Gaggero, D.; Giglietto, N.; Kamae, T.; Latronico, L.; Longo, F.; Mazziotta, M. N.; Moiseev, A. A.; Morselli, A.; Ormes, J. F.; Pesce-Rollins, M.; Pohl, M.; Razzano, M.; Sgro, C.; Spandre, G.; Stephens, T. E.

    2009-07-11

    The Fermi-LAT experiment recently reported high precision measurements of the spectrum of cosmic-ray electrons-plus-positrons (CRE) between 20 GeV and 1 TeV. The spectrum shows no prominent spectral features, and is significantly harder than that inferred from several previous experiments. In this paper, we discuss several interpretations of the Fermi results based either on a single large scale Galactic CRE component or by invoking additional electron–positron primary sources, e.g. nearby pulsars or particle dark matter annihilation. We show that while the reported Fermi-LAT data alone can be interpreted in terms of a single component scenario, when combined with other complementary experimental results, specifically the CRE spectrum measured by H.E.S.S. and especially the positron fraction reported by PAMELA between 1 and 100 GeV, that class of models fails to provide a consistent interpretation. Rather, we find that several combinations of parameters, involving both the pulsar and dark matter scenarios, allow a consistent description of those results. Finally, we also briefly discuss the possibility of discriminating between the pulsar and dark matter interpretations by looking for a possible anisotropy in the CRE flux.

  18. Fermi: The Gamma-Ray Large Area Space Telescope Mission Status

    NASA Technical Reports Server (NTRS)

    McEnery, Julie E

    2014-01-01

    Following its launch in June 2008, high-energy gamma-ray observations by the Fermi Gamma-ray Space Telescope have unveiled over 1000 new sources and opened an important and previously unexplored window on a wide variety of phenomena. These have included the discovery of a population of pulsars pulsing only in gamma rays; the detection of photons up to 10s of gigaelectronvolts from gamma-ray bursts, enhancing our understanding of the astrophysics of these powerful explosions; the detection of hundreds of active galaxies; a measurement of the high energy cosmic-ray electron spectrum which may imply the presence of nearby astrophysical particle accelerators; the determination of the diffuse gamma-ray emission with unprecedented accuracy and the constraints on phenomena such as super-symmetric dark-matter annihilations and exotic relics from the Big Bang. Continuous monitoring of the high-energy gamma-ray sky has uncovered numerous outbursts from active galaxies and the discovery of transient sources in our galaxy. In this talk I will describe the current status of the Fermi observatory and review the science highlights from Fermi.

  19. A method to analyze the diffuse gamma-ray emission with the Fermi Large Area Telescope

    SciTech Connect

    Ackermann, Markus; Johannesson, Gueolaugur; Digel, Seth; Moskalenko, Igor V.; Reimer, Olaf; Porter, Troy; Strong, Andrew

    2008-12-24

    The Fermi Gamma-Ray Space Telescope with its main instrument the LAT is the most sensitive {gamma}-ray telescope in the energy region between 30 MeV and 100 GeV. One of the prime scientific goals of this mission is the measurement and interpretation of the diffuse Galactic and extragalactic {gamma}-ray emission. While not limited by photon statistics, this analysis presents several challenges: Instrumental response functions, residual background from cosmic rays as well as resolved and unresolved foreground {gamma}-ray sources have to be taken carefully into account in the interpretation of the data. Detailed modeling of the diffuse {gamma}-ray emission is being performed and will form the basis of the investigations. We present the analysis approach to be applied to the Fermi LAT data, namely the modeling of the diffuse emission components and the background contributions, followed by an all-sky maximum-likelihood fitting procedure. We also report on the performance of this method evaluated in tests on simulated Fermi LAT and real EGRET data.

  20. Fermi large area telescope study of cosmic rays and the interstellar medium in nearby molecular clouds

    DOE PAGES

    Ackermann, M.; Ajello, M.; Allafort, A.; ...

    2012-07-23

    Here, we report an analysis of the interstellar γ-ray emission from the Chamaeleon, R Coronae Australis (R CrA), and Cepheus and Polaris flare regions with the Fermi Large Area Telescope. They are among the nearest molecular cloud complexes, within ~300 pc from the solar system. The γ-ray emission produced by interactions of cosmic rays (CRs) and interstellar gas in those molecular clouds is useful to study the CR densities and distributions of molecular gas close to the solar system. The obtained γ-ray emissivities above 250 MeV are (5.9 ± 0.1stat +0.9 –1.0sys) × 10–27 photons s–1 sr–1 H-atom–1, (10.2 ±more » 0.4stat +1.2 –1.7sys) × 10–27 photons s–1 sr–1 H-atom–1, and (9.1 ± 0.3stat +1.5 –0.6sys) × 10–27 photons s–1 sr–1 H-atom–1 for the Chamaeleon, R CrA, and Cepheus and Polaris flare regions, respectively. Whereas the energy dependences of the emissivities agree well with that predicted from direct CR observations at the Earth, the measured emissivities from 250 MeV to 10 GeV indicate a variation of the CR density by ~20% in the neighborhood of the solar system, even if we consider systematic uncertainties. Furthermore, we found that the molecular mass calibrating ratio, X CO = N(H2)/W CO, was (0.96 ± 0.06stat +0.15 –0.12sys) × 1020 H2-molecule cm–2 (K km s–1)–1, (0.99 ± 0.08stat +0.18 –0.10sys) × 1020 H2-molecule cm–2 (K km s–1)–1, and (0.63 ± 0.02stat +0.09 –0.07sys) × 1020 H2-molecule cm–2 (K km s–1)–1 for the Chamaeleon, R CrA, and Cepheus and Polaris flare regions, respectively, suggesting a variation of X CO in the vicinity of the solar system. The obtained values of X CO, the masses of molecular gas traced by W CO in the Chamaeleon, R CrA, and Cepheus and Polaris flare regions are estimated to be ~5 × 103 M ,⊙ ~103 M ,⊙ and ~3.3 × 104 M ,⊙ respectively. A comparable amount of gas not traced well by standard H I and CO surveys is found in the regions investigated.« less

  1. Fermi large area telescope study of cosmic rays and the interstellar medium in nearby molecular clouds

    SciTech Connect

    Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Busetto, G.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; D’Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Digel, S. W.; do Couto e Silva, E.; Drell, P. S.; Drlica-Wagner, A.; Falletti, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fukazawa, Y.; Fukui, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashi, K.; Horan, D.; Hou, X.; Hughes, R. E.; Itoh, R.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Lee, S. -H.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Martin, P.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Naumann-Godo, M.; Nemmen, R.; Nishino, S.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Romoli, C.; Roth, M.; Sada, T.; Sadrozinski, H. F. -W.; Sanchez, D. A.; Sbarra, C.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Tinivella, M.; Torres, D. F.; Tosti, G.; Tramacere, A.; Troja, E.; Uchiyama, Y.; Uehara, T.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yamamoto, H.; Yang, Z.; Zimmer, S.

    2012-07-23

    Here, we report an analysis of the interstellar γ-ray emission from the Chamaeleon, R Coronae Australis (R CrA), and Cepheus and Polaris flare regions with the Fermi Large Area Telescope. They are among the nearest molecular cloud complexes, within ~300 pc from the solar system. The γ-ray emission produced by interactions of cosmic rays (CRs) and interstellar gas in those molecular clouds is useful to study the CR densities and distributions of molecular gas close to the solar system. The obtained γ-ray emissivities above 250 MeV are (5.9 ± 0.1stat +0.9 –1.0sys) × 10–27 photons s–1 sr–1 H-atom–1, (10.2 ± 0.4stat +1.2 –1.7sys) × 10–27 photons s–1 sr–1 H-atom–1, and (9.1 ± 0.3stat +1.5 –0.6sys) × 10–27 photons s–1 sr–1 H-atom–1 for the Chamaeleon, R CrA, and Cepheus and Polaris flare regions, respectively. Whereas the energy dependences of the emissivities agree well with that predicted from direct CR observations at the Earth, the measured emissivities from 250 MeV to 10 GeV indicate a variation of the CR density by ~20% in the neighborhood of the solar system, even if we consider systematic uncertainties. Furthermore, we found that the molecular mass calibrating ratio, X CO = N(H2)/W CO, was (0.96 ± 0.06stat +0.15 –0.12sys) × 1020 H2-molecule cm–2 (K km s–1)–1, (0.99 ± 0.08stat +0.18 –0.10sys) × 1020 H2-molecule cm–2 (K km s–1)–1, and (0.63 ± 0.02stat +0.09 –0.07sys) × 1020 H2-molecule cm–2 (K km s–1)–1 for the Chamaeleon, R CrA, and

  2. Fermi large area telescope detection of a break in the gamma-ray spectrum of the supernova remnant Cassiopeia A

    SciTech Connect

    Yuan, Yajie; Funk, Stefan; Lande, Joshua; Tibaldo, Luigi; Jóhannesson, Gülauger; Uchiyama, Yasunobu E-mail: funk@slac.stanford.edu E-mail: uchiyama@slac.stanford.edu

    2013-12-20

    We report on observations of the supernova remnant Cassiopeia A in the energy range from 100 MeV to 100 GeV using 44 months of observations from the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope. We perform a detailed spectral analysis of this source and report on a low-energy break in the spectrum at 1.72{sub −0.89}{sup +1.35} GeV. By comparing the results with models for the gamma-ray emission, we find that hadronic emission is preferred for the GeV energy range.

  3. Search for Spectral Irregularities due to Photon-Axionlike-Particle Oscillations with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Ajello, M.; Albert, A.; Anderson, B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Bregeon, J.; Bruel, P.; Buehler, R.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cecchi, C.; Chekhtman, A.; Ciprini, S.; Cohen-Tanugi, J.; Conrad, J.; Costanza, F.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Desiante, R.; Di Mauro, M.; Di Venere, L.; Domínguez, A.; Drell, P. S.; Favuzzi, C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Glanzman, T.; Godfrey, G.; Guiriec, S.; Horan, D.; Jóhannesson, G.; Katsuragawa, M.; Kensei, S.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lubrano, P.; Madejski, G. M.; Maldera, S.; Manfreda, A.; Mayer, M.; Mazziotta, M. N.; Meyer, M.; Michelson, P. F.; Mirabal, N.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Negro, M.; Nuss, E.; Okada, C.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Sánchez-Conde, M.; Sgrò, C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Takahashi, H.; Thayer, J. B.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Wood, K. S.; Wood, M.; Zaharijas, G.; Zimmer, S.; Fermi-LAT Collaboration

    2016-04-01

    We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ -ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5 ×10-12 GeV-1 for ALP masses 0.5 ≲ma≲5 neV at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ -ray opacity of the Universe.

  4. Fermi large area telescope search for photon lines from 30 to 200 GeV and dark matter implications.

    PubMed

    Abdo, A A; Ackermann, M; Ajello, M; Atwood, W B; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Bloom, E D; Bonamente, E; Borgland, A W; Bouvier, A; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Burnett, T H; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Carrigan, S; Casandjian, J M; Cecchi, C; Celik, O; Chekhtman, A; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; do Couto E Silva, E; Drell, P S; Drlica-Wagner, A; Dubois, R; Dumora, D; Edmonds, Y; Essig, R; Farnier, C; Favuzzi, C; Fegan, S J; Focke, W B; Fortin, P; Frailis, M; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giglietto, N; Giordano, F; Glanzman, T; Godfrey, G; Grenier, I A; Grove, J E; Guillemot, L; Guiriec, S; Gustafsson, M; Hadasch, D; Harding, A K; Horan, D; Hughes, R E; Jackson, M S; Jóhannesson, G; Johnson, A S; Johnson, R P; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kawai, N; Kerr, M; Knödlseder, J; Kuss, M; Lande, J; Latronico, L; Llena Garde, M; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Makeev, A; Mazziotta, M N; McEnery, J E; Meurer, C; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nolan, P L; Norris, J P; Nuss, E; Ohsugi, T; Omodei, N; Orlando, E; Ormes, J F; Ozaki, M; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Rainò, S; Rando, R; Razzano, M; Reimer, A; Reimer, O; Reposeur, T; Ripken, J; Ritz, S; Rodriguez, A Y; Roth, M; Sadrozinski, H F-W; Sander, A; Parkinson, P M Saz; Scargle, J D; Schalk, T L; Sellerholm, A; Sgrò, C; Siskind, E J; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Starck, J-L; Strickman, M S; Suson, D J; Tajima, H; Takahashi, H; Tanaka, T; Thayer, J B; Thayer, J G; Tibaldo, L; Torres, D F; Uchiyama, Y; Usher, T L; Vasileiou, V; Vilchez, N; Vitale, V; Waite, A P; Wang, P; Winer, B L; Wood, K S; Ylinen, T; Ziegler, M

    2010-03-05

    Dark matter (DM) particle annihilation or decay can produce monochromatic gamma rays readily distinguishable from astrophysical sources. gamma-ray line limits from 30 to 200 GeV obtained from 11 months of Fermi Large Area Space Telescope data from 20-300 GeV are presented using a selection based on requirements for a gamma-ray line analysis, and integrated over most of the sky. We obtain gamma-ray line flux upper limits in the range 0.6-4.5x10{-9} cm{-2} s{-1}, and give corresponding DM annihilation cross-section and decay lifetime limits. Theoretical implications are briefly discussed.

  5. The Monster Next Door: Fermi-LAT Observations of Supernova Remnant N132D in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Castro, Daniel; Hays, Elizabeth; Acero, Fabio; Slane, Patrick; Hughes, John; Plucinsky, Paul; Fermi-LAT Collaboration Collaboration

    2017-01-01

    Supernova remnant (SNR) N132D, located in the Large Magellanic Cloud, represents a unique opportunity for the study of γ-ray emission from shock accelerated cosmic rays (CRs) in another galaxy since it stands as the first and only extra-Galactic SNR detected in γ-rays. N132D is bright in the X-ray, infrared and radio bands, as well as being detected in TeV energy γ-rays, and hence, characterizing its emission in the Fermi-LAT band allows us to build a very complete picture of the properties of the system and its progenitor, and help us understand CR acceleration in SNRs.

  6. Investigating First Year Education Students' Stress Level

    ERIC Educational Resources Information Center

    Geng, Gretchen; Midford, Richard

    2015-01-01

    This paper investigated the stress levels of first-year education students who undertake teaching practicum and theory units during their first year of teacher education program. First, 139 first-year and 143 other years' education students completed the PSS-10 scale, which measures perceived level of stress. Then, 147 first-year education…

  7. Large-scale behaviour of local and entanglement entropy of the free Fermi gas at any temperature

    NASA Astrophysics Data System (ADS)

    Leschke, Hajo; Sobolev, Alexander V.; Spitzer, Wolfgang

    2016-07-01

    The leading asymptotic large-scale behaviour of the spatially bipartite entanglement entropy (EE) of the free Fermi gas infinitely extended in multidimensional Euclidean space at zero absolute temperature, T = 0, is by now well understood. Here, we present and discuss the first rigorous results for the corresponding EE of thermal equilibrium states at T\\gt 0. The leading large-scale term of this thermal EE turns out to be twice the first-order finite-size correction to the infinite-volume thermal entropy (density). Not surprisingly, this correction is just the thermal entropy on the interface of the bipartition. However, it is given by a rather complicated integral derived from a semiclassical trace formula for a certain operator on the underlying one-particle Hilbert space. But in the zero-temperature limit T\\downarrow 0, the leading large-scale term of the thermal EE considerably simplifies and displays a {ln}(1/T)-singularity which one may identify with the known logarithmic enhancement at T = 0 of the so-called area-law scaling. birthday of the ideal Fermi gas.

  8. Six faint gamma-ray pulsars seen with the Fermi Large Area Telescope: Towards a sample blending into the background

    DOE PAGES

    Hou, X.; Smith, D. A.; Guillemot, L.; ...

    2014-10-14

    Context. Here, GeV gamma-ray pulsations from over 140 pulsars have been characterized using the Fermi Large Area Telescope, enabling improved understanding of the emission regions within the neutron star magnetospheres, and the contributions of pulsars to high energy electrons and diffuse gamma rays in the Milky Way. The first gamma-ray pulsars to be detected were the most intense and/or those with narrow pulses. Aims. As the Fermi mission progresses, progressively fainter objects can be studied. In addition to more distant pulsars (thus probing a larger volume of the Galaxy), or ones in high background regions (thus improving the sampling uniformitymore » across the Galactic plane), we detect pulsars with broader pulses or lower luminosity. Adding pulsars to our catalog with inclination angles that are rare in the observed sample, and/or with lower spindown power, will reduce the bias in the currently known gamma-ray pulsar population. Methods. We use rotation ephemerides derived from radio observations to phase-fold gamma rays recorded by the Fermi Large Area Telescope, to then determine the pulse profile properties. Spectral analysis provides the luminosities and, when the signal-to-noise ratio allows, the cutoff energies. We constrain the pulsar distances by different means in order to minimize the luminosity uncertainties. Results. We present six new gamma-ray pulsars with an eclectic mix of properties. Three are young, and three are recycled. They include the farthest, the lowest power, two of the highest duty-cycle pulsars seen, and only the fourth young gamma-ray pulsar with a radio interpulse. Finally, we discuss the biases existing in the current gamma-ray pulsar catalog, and steps to be taken to mitigate the bias.« less

  9. Fermi Large Area Telescope Observation Of A Gamma-Ray Source At The Position Of Eta Carinae

    SciTech Connect

    Abdo, A. A,

    2010-10-13

    The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope detected a γ-ray source that is spatially consistent with the location of Eta Carinae. This source has been persistently bright since the beginning of the LAT survey observations (from 2008 August to 2009 July, the time interval considered here). The γ-ray signal is detected significantly throughout the LAT energy band (i.e., up to ~100 GeV). The 0.1-100 GeV energy spectrum is well represented by a combination of a cutoff power-law model (<10 GeV) and a hard power-law component (>10 GeV). The total flux (>100 MeV) is 3.7+0.3 –0.1 × 10–7 photons s–1 cm–2, with additional systematic uncertainties of 10%, and consistent with the average flux measured by AGILE. The light curve obtained by Fermi is consistent with steady emission. Our observations do not confirm the presence of a γ-ray flare in 2008 October, as reported by Tavani et al., although we cannot exclude that a flare lasting only a few hours escaped detection by the Fermi LAT. We also do not find any evidence for γ-ray variability that correlates with the large X-ray variability of Eta Carinae observed during 2008 December and 2009 January. We are thus not able to establish an unambiguous identification of the LAT source with Eta Carinae.

  10. Fermi Large Area Telescope Observation Of A Gamma-Ray Source At The Position Of Eta Carinae

    DOE PAGES

    Abdo, A. A,

    2010-10-13

    The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope detected a γ-ray source that is spatially consistent with the location of Eta Carinae. This source has been persistently bright since the beginning of the LAT survey observations (from 2008 August to 2009 July, the time interval considered here). The γ-ray signal is detected significantly throughout the LAT energy band (i.e., up to ~100 GeV). The 0.1-100 GeV energy spectrum is well represented by a combination of a cutoff power-law model (<10 GeV) and a hard power-law component (>10 GeV). The total flux (>100 MeV) is 3.7+0.3 –0.1more » × 10–7 photons s–1 cm–2, with additional systematic uncertainties of 10%, and consistent with the average flux measured by AGILE. The light curve obtained by Fermi is consistent with steady emission. Our observations do not confirm the presence of a γ-ray flare in 2008 October, as reported by Tavani et al., although we cannot exclude that a flare lasting only a few hours escaped detection by the Fermi LAT. We also do not find any evidence for γ-ray variability that correlates with the large X-ray variability of Eta Carinae observed during 2008 December and 2009 January. We are thus not able to establish an unambiguous identification of the LAT source with Eta Carinae.« less

  11. Constraints on the galactic population of TeV pulsar wind nebulae using Fermi Large Area Telescope observations

    DOE PAGES

    Acero, F.; Ackermann, M.; Ajello, M.; ...

    2013-07-29

    Pulsar wind nebulae (PWNe) have been established as the most populous class of TeV γ-ray emitters. Since launch, the Fermi Large Area Telescope (LAT) has identified five high-energy (100 MeV < E < 100 GeV) γ-ray sources as PWNe and detected a large number of PWN candidates, all powered by young and energetic pulsars. The wealth of multi-wavelength data available and the new results provided by Fermi-LAT give us an opportunity to find new PWNe and to explore the radiative processes taking place in known ones. The TeV γ-ray unidentified (UNID) sources are the best candidates for finding new PWNe.more » Using 45 months of Fermi-LAT data for energies above 10 GeV, an analysis was performed near the position of 58 TeV PWNe and UNIDs within 5° of the Galactic plane to establish new constraints on PWN properties and find new clues on the nature of UNIDs. Of the 58 sources, 30 were detected, and this work provides their γ-ray fluxes for energies above 10 GeV. The spectral energy distributions and upper limits, in the multi-wavelength context, also provide new information on the source nature and can help distinguish between emission scenarios, i.e., between classification as a pulsar candidate or as a PWN candidate. Six new GeV PWN candidates are described in detail and compared with existing models. As a result, a population study of GeV PWN candidates as a function of the pulsar/PWN system characteristics is presented.« less

  12. CONSTRAINTS ON THE GALACTIC POPULATION OF TeV PULSAR WIND NEBULAE USING FERMI LARGE AREA TELESCOPE OBSERVATIONS

    SciTech Connect

    Acero, F.; Brandt, T. J.; Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Blandford, R. D.; Bloom, E. D.; Bottacini, E.; Buehler, R.; Baldini, L.; Ballet, J.; Bastieri, D.; Buson, S.; Bellazzini, R.; Bregeon, J.; Bonamente, E.; Brigida, M.; Bruel, P. E-mail: joshualande@gmail.com E-mail: rousseau@cenbg.in2p3.fr [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS and others

    2013-08-10

    Pulsar wind nebulae (PWNe) have been established as the most populous class of TeV {gamma}-ray emitters. Since launch, the Fermi Large Area Telescope (LAT) has identified five high-energy (100 MeV < E < 100 GeV) {gamma}-ray sources as PWNe and detected a large number of PWN candidates, all powered by young and energetic pulsars. The wealth of multi-wavelength data available and the new results provided by Fermi-LAT give us an opportunity to find new PWNe and to explore the radiative processes taking place in known ones. The TeV {gamma}-ray unidentified (UNID) sources are the best candidates for finding new PWNe. Using 45 months of Fermi-LAT data for energies above 10 GeV, an analysis was performed near the position of 58 TeV PWNe and UNIDs within 5 Degree-Sign of the Galactic plane to establish new constraints on PWN properties and find new clues on the nature of UNIDs. Of the 58 sources, 30 were detected, and this work provides their {gamma}-ray fluxes for energies above 10 GeV. The spectral energy distributions and upper limits, in the multi-wavelength context, also provide new information on the source nature and can help distinguish between emission scenarios, i.e., between classification as a pulsar candidate or as a PWN candidate. Six new GeV PWN candidates are described in detail and compared with existing models. A population study of GeV PWN candidates as a function of the pulsar/PWN system characteristics is presented.

  13. The radio/gamma-ray connection in active galactic nuclei in the era of the Fermi Large Area Telescope

    SciTech Connect

    Ackermann, M.; Ajello, M.; Allafort, A.; Angelakis, E.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cannon, A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cutini, S.; de Palma, F.; Dermer, C. D.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Escande, L.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fuhrmann, L.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grandi, P.; Grenier, I. A.; Guiriec, S.; Hadasch, D.; Hayashida, M.; Hays, E.; Healey, S. E.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Lee, S. -H.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Max-Moerbeck, W.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Naumann-Godo, M.; Nishino, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Pavlidou, V.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Porter, T. A.; Rainò, S.; Razzano, M.; Readhead, A.; Reimer, A.; Reimer, O.; Richards, J. L.; Romani, R. W.; Sadrozinski, H. F. -W.; Scargle, J. D.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Suson, D. J.; Takahashi, H.; Tanaka, T.; Taylor, G. B.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Torres, D. F.; Tosti, G.; Tramacere, A.; Troja, E.; Vandenbroucke, J.; Vianello, G.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ziegler, M.

    2011-10-12

    We present a detailed statistical analysis of the correlation between radio and gamma-ray emission of the active galactic nuclei (AGNs) detected by Fermi during its first year of operation, with the largest data sets ever used for this purpose. We use both archival interferometric 8.4 GHz data (from the Very Large Array and ATCA, for the full sample of 599 sources) and concurrent single-dish 15 GHz measurements from the Owens Valley Radio Observatory (OVRO, for a sub sample of 199 objects). Our unprecedentedly large sample permits us to assess with high accuracy the statistical significance of the correlation, using a surrogate data method designed to simultaneously account for common-distance bias and the effect of a limited dynamical range in the observed quantities. We find that the statistical significance of a positive correlation between the centimeter radio and the broadband (E > 100 MeV) gamma-ray energy flux is very high for the whole AGN sample, with a probability of <10–7 for the correlation appearing by chance. Using the OVRO data, we find that concurrent data improve the significance of the correlation from 1.6 × 10–6 to 9.0 × 10–8. Our large sample size allows us to study the dependence of correlation strength and significance on specific source types and gamma-ray energy band. As a result, we find that the correlation is very significant (chance probability < 10–7) for both flat spectrum radio quasars and BL Lac objects separately; a dependence of the correlation strength on the considered gamma-ray energy band is also present, but additional data will be necessary to constrain its significance.

  14. Timing gamma-ray pulsars with the Fermi large area telescope: Timing noise and astrometry

    DOE PAGES

    Kerr, Matthew; Ray, P. S.; Johnston, S.; ...

    2015-11-25

    We have constructed timing solutions for 81 γ-ray pulsars covering more than five years of Fermi data. The sample includes 37 radio-quiet or radio-faint pulsars which cannot be timed with other telescopes. These timing solutions and the corresponding pulse times of arrival are prerequisites for further study, e.g., phase-resolved spectroscopy or searches for mode switches. Many γ-ray pulsars are strongly affected by timing noise (TN), and we present a new method for characterizing the noise process and mitigating its effects on other facets of the timing model. We present an analysis of TN over the population using a new metric for characterizing its strength and spectral shape, namely, its time-domain correlation. The dependence of the strength on ν andmore » $$\\dot{\

  15. The third catalog of active galactic nuclei detected by the Fermi large area telescope

    DOE PAGES

    Ackermann, M.; Ajello, M.; Atwood, W. B.; ...

    2015-08-25

    We present the third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC). It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic greater than 25, between 2008 August 4 and 2012 July 31. The 3LAC includes 1591 AGNs located at high Galactic latitudes (more » $$| b| \\gt 10^\\circ $$), a 71% increase over the second catalog based on 2 years of data. There are 28 duplicate associations, thus 1563 of the 2192 high-latitude gamma-ray sources of the 3FGL catalog are AGNs. Most of them (98%) are blazars. About half of the newly detected blazars are of unknown type, i.e., they lack spectroscopic information of sufficient quality to determine the strength of their emission lines. Based on their gamma-ray spectral properties, these sources are evenly split between flat-spectrum radio quasars (FSRQs) and BL Lacs. The most abundant detected BL Lacs are of the high-synchrotron-peaked (HSP) type. There were about 50% of the BL Lacs that had no measured redshifts. A few new rare outliers (HSP-FSRQs and high-luminosity HSP BL Lacs) are reported. The general properties of the 3LAC sample confirm previous findings from earlier catalogs. The fraction of 3LAC blazars in the total population of blazars listed in BZCAT remains non-negligible even at the faint ends of the BZCAT-blazar radio, optical, and X-ray flux distributions, which hints that even the faintest known blazars could eventually shine in gamma-rays at LAT-detection levels. Furthermore, the energy-flux distributions of the different blazar populations are in good agreement with extrapolation from earlier catalogs.« less

  16. The third catalog of active galactic nuclei detected by the Fermi large area telescope

    SciTech Connect

    Ackermann, M.; Ajello, M.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Gonzalez, J. Becerra; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Britto, R. J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Carpenter, B.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D’Abrusco, R.; D’Ammando, F.; Angelis, A. de; Desiante, R.; Digel, S. W.; Venere, L. Di; Drell, P. S.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Finke, J.; Focke, W. B.; Franckowiak, A.; Fuhrmann, L.; Fukazawa, Y.; Furniss, A. K.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Itoh, R.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kataoka, J.; Kawano, T.; Krauss, F.; Kuss, M.; Mura, G. La; Larsson, S.; Latronico, L.; Leto, C.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nuss, E.; Ohno, M.; Ohsugi, T.; Ojha, R.; Omodei, N.; Orienti, M.; Orlando, E.; Paggi, A.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Romani, R. W.; Salvetti, D.; Schaal, M.; Schinzel, F. K.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Sokolovsky, K. V.; Spada, F.; Spandre, G.; Spinelli, P.; Stawarz, L.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Tibaldo, L.; Torres, D. F.; Torresi, E.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vianello, G.; Winer, B. L.; Wood, K. S.; Zimmer, S.

    2015-08-25

    We present the third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC). It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic greater than 25, between 2008 August 4 and 2012 July 31. The 3LAC includes 1591 AGNs located at high Galactic latitudes ($| b| \\gt 10^\\circ $), a 71% increase over the second catalog based on 2 years of data. There are 28 duplicate associations, thus 1563 of the 2192 high-latitude gamma-ray sources of the 3FGL catalog are AGNs. Most of them (98%) are blazars. About half of the newly detected blazars are of unknown type, i.e., they lack spectroscopic information of sufficient quality to determine the strength of their emission lines. Based on their gamma-ray spectral properties, these sources are evenly split between flat-spectrum radio quasars (FSRQs) and BL Lacs. The most abundant detected BL Lacs are of the high-synchrotron-peaked (HSP) type. There were about 50% of the BL Lacs that had no measured redshifts. A few new rare outliers (HSP-FSRQs and high-luminosity HSP BL Lacs) are reported. The general properties of the 3LAC sample confirm previous findings from earlier catalogs. The fraction of 3LAC blazars in the total population of blazars listed in BZCAT remains non-negligible even at the faint ends of the BZCAT-blazar radio, optical, and X-ray flux distributions, which hints that even the faintest known blazars could eventually shine in gamma-rays at LAT-detection levels. Furthermore, the energy-flux distributions of the different blazar populations are in good agreement with extrapolation from earlier catalogs.

  17. The Third Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Becerra Gonzalez, J.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Britto, R. J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Carpenter, B.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D'Abrusco, R.; D'Ammando, F.; de Angelis, A.; Desiante, R.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Finke, J.; Focke, W. B.; Franckowiak, A.; Fuhrmann, L.; Fukazawa, Y.; Furniss, A. K.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Itoh, R.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kataoka, J.; Kawano, T.; Krauss, F.; Kuss, M.; La Mura, G.; Larsson, S.; Latronico, L.; Leto, C.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nuss, E.; Ohno, M.; Ohsugi, T.; Ojha, R.; Omodei, N.; Orienti, M.; Orlando, E.; Paggi, A.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Romani, R. W.; Salvetti, D.; Schaal, M.; Schinzel, F. K.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Sokolovsky, K. V.; Spada, F.; Spandre, G.; Spinelli, P.; Stawarz, L.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Tibaldo, L.; Torres, D. F.; Torresi, E.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vianello, G.; Winer, B. L.; Wood, K. S.; Zimmer, S.

    2015-09-01

    The third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented. It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic greater than 25, between 2008 August 4 and 2012 July 31. The 3LAC includes 1591 AGNs located at high Galactic latitudes (| b| \\gt 10^\\circ ), a 71% increase over the second catalog based on 2 years of data. There are 28 duplicate associations, thus 1563 of the 2192 high-latitude gamma-ray sources of the 3FGL catalog are AGNs. Most of them (98%) are blazars. About half of the newly detected blazars are of unknown type, i.e., they lack spectroscopic information of sufficient quality to determine the strength of their emission lines. Based on their gamma-ray spectral properties, these sources are evenly split between flat-spectrum radio quasars (FSRQs) and BL Lacs. The most abundant detected BL Lacs are of the high-synchrotron-peaked (HSP) type. About 50% of the BL Lacs have no measured redshifts. A few new rare outliers (HSP-FSRQs and high-luminosity HSP BL Lacs) are reported. The general properties of the 3LAC sample confirm previous findings from earlier catalogs. The fraction of 3LAC blazars in the total population of blazars listed in BZCAT remains non-negligible even at the faint ends of the BZCAT-blazar radio, optical, and X-ray flux distributions, which hints that even the faintest known blazars could eventually shine in gamma-rays at LAT-detection levels. The energy-flux distributions of the different blazar populations are in good agreement with extrapolation from earlier catalogs.

  18. Search for Extended Sources in the Galactic Plane Using Six Years of Fermi-Large Area Telescope Pass 8 Data above 10 GeV

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Castro, D.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiaro, G.; Ciprini, S.; Cohen, J. M.; Costantin, D.; Costanza, F.; Cutini, S.; D'Ammando, F.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Green, D.; Grenier, I. A.; Grondin, M.-H.; Guillemot, L.; Guiriec, S.; Harding, A. K.; Hays, E.; Hewitt, J. W.; Horan, D.; Hou, X.; Jóhannesson, G.; Kamae, T.; Kuss, M.; La Mura, G.; Larsson, S.; Lemoine-Goumard, M.; Li, J.; Longo, F.; Loparco, F.; Lubrano, P.; Magill, J. D.; Maldera, S.; Malyshev, D.; Manfreda, A.; Mazziotta, M. N.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Negro, M.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paliya, V. S.; Paneque, D.; Perkins, J. S.; Persic, M.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Porter, T. A.; Principe, G.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Sgrò, C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Suson, D. J.; Tak, D.; Thayer, J. B.; Thompson, D. J.; Torres, D. F.; Tosti, G.; Troja, E.; Vianello, G.; Wood, K. S.; Wood, M.

    2017-07-01

    The spatial extension of a γ-ray source is an essential ingredient to determine its spectral properties, as well as its potential multiwavelength counterpart. The capability to spatially resolve γ-ray sources is greatly improved by the newly delivered Fermi-Large Area Telescope (LAT) Pass 8 event-level analysis, which provides a greater acceptance and an improved point-spread function, two crucial factors for the detection of extended sources. Here, we present a complete search for extended sources located within 7° from the Galactic plane, using 6 yr of Fermi-LAT data above 10 GeV. We find 46 extended sources and provide their morphological and spectral characteristics. This constitutes the first catalog of hard Fermi-LAT extended sources, named the Fermi Galactic Extended Source Catalog, which allows a thorough study of the properties of the Galactic plane in the sub-TeV domain.

  19. Fermi large area telescope observations of the cosmic-ray induced γ -ray emission of the Earth’s atmosphere

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2009-12-29

    In this paper, we report on measurements of the cosmic-ray induced γ-ray emission of Earth’s atmosphere by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The Large Area Telescope has observed the Earth during its commissioning phase and with a dedicated Earth limb following observation in September 2008. These measurements yielded ~6.4 × 106 photons with energies > 100 MeV and ~ 250 hours total live time for the highest quality data selection. This allows the study of the spatial and spectral distributions of these photons with unprecedented detail. In additon, the spectrum of the emission—often referredmore » to as Earth albedo gamma-ray emission—has a power-law shape up to 500 GeV with spectral index Γ = 2.79 ± 0.06 .« less

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

    SciTech Connect

    Cheung, C. C.; Grove, J. E.; Larsson, S.; Scargle, J. D.; Amin, M. A.; Blandford, R. D.; Chiang, J.; Marshall, P. J.; Bulmash, D.; Ciprini, S.; Corbet, R. H. D.; Falco, E. E.; Wood, D. L.; Ajello, M.; Bastieri, D.; Chekhtman, A.; D'Ammando, F.; Giroletti, M.; Lott, B.; and others

    2014-02-20

    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.

  1. Fermi Large Area Telescope detection of gravitational lens delayed γ-ray flares from Blazar B0218+357

    DOE PAGES

    Cheung, C. C.; Larsson, S.; Scargle, J. D.; ...

    2014-01-30

    We report the first clear γ-ray measurement of a delay between flares from the gravitationally lensed images of a blazar, using data from the Fermi Large Area Telescope (LAT). We detected a delay 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 themore » 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.« less

  2. Fermi Large Area Telescope Constraints On The Gamma-Ray Opacity Of The Universe

    SciTech Connect

    Abdo, A. A.

    2010-10-19

    The extragalactic background light (EBL) includes photons with wavelengths from ultraviolet to infrared, which are effective at attenuating gamma rays with energy above ~10 GeV during propagation from sources at cosmological distances. This results in a redshift- and energy-dependent attenuation of the γ-ray flux of extragalactic sources such as blazars and gamma-ray bursts (GRBs). The Large Area Telescope on board Fermi detects a sample of γ-ray blazars with redshift up to z ~ 3, and GRBs with redshift up to z ~ 4.3. Using photons above 10 GeV collected by Fermi over more than one year of observations for these sources, we investigate the effect of γ-ray flux attenuation by the EBL. We place upper limits on the γ-ray opacity of the universe at various energies and redshifts and compare this with predictions from well-known EBL models. We find that an EBL intensity in the optical-ultraviolet wavelengths as great as predicted by the "baseline" model of Stecker et al. can be ruled out with high confidence.

  3. Fermi Large Area Telescope detection of gravitational lens delayed γ-ray flares from Blazar B0218+357

    SciTech Connect

    Cheung, C. C.; Larsson, S.; Scargle, J. D.; Amin, M. A.; Blandford, R. D.; Bulmash, D.; Chiang, J.; Ciprini, S.; Corbet, R. H. D.; Falco, E. E.; Marshall, P. J.; Wood, D. L.; Ajello, M.; Bastieri, D.; Chekhtman, A.; D'Ammando, F.; Giroletti, M.; Grove, J. E.; Lott, B.; Ojha, R.; Orienti, M.; Perkins, J. S.; Razzano, M.; Smith, A. W.; Thompson, D. J.; Wood, K. S.

    2014-01-30

    We report the first clear γ-ray measurement of a delay between flares from the gravitationally lensed images of a blazar, using data from the Fermi Large Area Telescope (LAT). We detected a delay 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.

  4. Timing Gamma-ray Pulsars with the Fermi Large Area Telescope: Timing Noise and Astrometry

    NASA Astrophysics Data System (ADS)

    Kerr, M.; Ray, P. S.; Johnston, S.; Shannon, R. M.; Camilo, F.

    2015-12-01

    We have constructed timing solutions for 81 γ-ray pulsars covering more than five years of Fermi data. The sample includes 37 radio-quiet or radio-faint pulsars which cannot be timed with other telescopes. These timing solutions and the corresponding pulse times of arrival are prerequisites for further study, e.g., phase-resolved spectroscopy or searches for mode switches. Many γ-ray pulsars are strongly affected by timing noise (TN), and we present a new method for characterizing the noise process and mitigating its effects on other facets of the timing model. We present an analysis of TN over the population using a new metric for characterizing its strength and spectral shape, namely, its time-domain correlation. The dependence of the strength on ν and \\dot{ν } is in good agreement with previous studies. We find that noise process power spectra S(f) for unrecycled pulsars are steep, with strong correlations over our entire data set and spectral indices S(f)\\propto {f}-α of α ˜ 5-9. One possible explanation for these results is the occurrence of unmodeled, episodic “microglitches.” Finally, we show that our treatment of TN results in robust parameter estimation, and in particular we measure a precise timing position for each pulsar. We extensively validate our results with multi-wavelength astrometry, and using our updated position, we firmly identify the X-ray counterpart of PSR J1418-6058.

  5. The Fermi Large Area Telescope: Optimizing and Then Re-Optimizing the Science Return

    NASA Astrophysics Data System (ADS)

    Atwood, W. B.

    2012-01-01

    The general concepts of how to do gamma-ray observations in space were well established and vetted by the early 1990's. In particular, the success of EGRET onboard the Compton Gamma Ray Observatory whetted the appetite for a more ambitious follow on. In parallel, advances in high-energy particle detection, spurred on by plans for the Superconducting Super Collider, provided an unprecedented opportunity for space-based detectors. The GLAST concept, now Fermi-LAT, was born at SLAC in May of 1992 and the instrument was subsequently developed by an international collaboration from France, Italy, Japan, Sweden and the United States. An overview of the original design optimization of the LAT instrument, done with the goal of imposing as few limits as possible on its applications in space, is discussed (along with some of the trials and tribulations of construction along the way to launch!). Now with over 3 years of science operations experience, the lessons-learned will be reviewed and assessed against the expectations. Finally, the ongoing re-optimization of the instrument and plans for how to extend the LAT's science window into the future are discussed.

  6. Facial Experience During the First Year

    PubMed Central

    Rennels, Jennifer L.; Simmons, Rachel E.

    2008-01-01

    Parents of 2-, 5-, 8-, and 11-month-olds used two scales we developed to provide information about their infants’ facial experience with familiar and unfamiliar individuals during one week. Results showed large discrepancies in the race, sex, and age of faces that infants experience during their first year with the majority of their facial experience being with their primary caregiver, females, and other individuals of the same race and age as their primary caregiver. The infant’s age and an unfamiliar individual’s sex were predictive of their time spent interacting with one another. Moreover, an unfamiliar individual’s sex was predictive of the attention infants allocated during social interactions. Differences in frequency and length of interactions with certain types of faces, as well as in infant attention toward certain individuals, all likely contribute to the development of expertise in processing commonly experienced face types and deficiencies in processing less commonly experienced face types. PMID:18554724

  7. Search for Spectral Irregularities due to Photon-Axionlike-Particle Oscillations with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ajello, M.; Albert, A.; Anderson, B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R.D.; Mirabal, N.; hide

    2016-01-01

    We report on the search for spectral irregularities induced by oscillations between photons and axion-like particles (ALPs) in the gamma-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5 times 10 (sup -12) per gigaelectronvolt for ALP masses less than or approximately equal to 0.5 apparent magnitude (m (sub a)) less than or approximately equal to 5 nanoelectronvolts at 95 percent confidence. The limits are competitive withthe sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain thepossibility that ALPs can reduce the gamma-ray opacity of the Universe.

  8. Search for Spectral Irregularities due to Photon–Axionlike-Particle Oscillations with the Fermi Large Area Telescope

    SciTech Connect

    Ajello, M.; Albert, A.; Anderson, B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Bregeon, J.; Bruel, P.; Buehler, R.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cecchi, C.; Chekhtman, A.; Ciprini, S.; Cohen-Tanugi, J.; Conrad, J.; Costanza, F.; D’Ammando, F.; de Angelis, A.; de Palma, F.; Desiante, R.; Di Mauro, M.; Di Venere, L.; Domínguez, A.; Drell, P. S.; Favuzzi, C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Glanzman, T.; Godfrey, G.; Guiriec, S.; Horan, D.; Jóhannesson, G.; Katsuragawa, M.; Kensei, S.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lubrano, P.; Madejski, G. M.; Maldera, S.; Manfreda, A.; Mayer, M.; Mazziotta, M. N.; Meyer, M.; Michelson, P. F.; Mirabal, N.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Negro, M.; Nuss, E.; Okada, C.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Sánchez-Conde, M.; Sgrò, C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Takahashi, H.; Thayer, J. B.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Wood, K. S.; Wood, M.; Zaharijas, G.; Zimmer, S.

    2016-04-20

    In this paper, we report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5 x 10-12 GeV-1 for ALP masses 0.5 ≲ ma ≲ 5 neV at 95% confidence. Finally, the limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ-ray opacity of the Universe.

  9. Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi Large Area Telescope Data.

    PubMed

    Ackermann, M; Albert, A; Anderson, B; Atwood, W B; Baldini, L; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Bissaldi, E; Blandford, R D; Bloom, E D; Bonino, R; Bottacini, E; Brandt, T J; Bregeon, J; Bruel, P; Buehler, R; Caliandro, G A; Cameron, R A; Caputo, R; Caragiulo, M; Caraveo, P A; Cecchi, C; Charles, E; Chekhtman, A; Chiang, J; Chiaro, G; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Cuoco, A; Cutini, S; D'Ammando, F; de Angelis, A; de Palma, F; Desiante, R; Digel, S W; Di Venere, L; Drell, P S; Drlica-Wagner, A; Essig, R; Favuzzi, C; Fegan, S J; Ferrara, E C; Focke, W B; Franckowiak, A; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Gomez-Vargas, G A; Grenier, I A; Guiriec, S; Gustafsson, M; Hays, E; Hewitt, J W; Horan, D; Jogler, T; Jóhannesson, G; Kuss, M; Larsson, S; Latronico, L; Li, J; Li, L; Llena Garde, M; Longo, F; Loparco, F; Lubrano, P; Malyshev, D; Mayer, M; Mazziotta, M N; McEnery, J E; Meyer, M; Michelson, P F; Mizuno, T; Moiseev, A A; Monzani, M E; Morselli, A; Murgia, S; Nuss, E; Ohsugi, T; Orienti, M; Orlando, E; Ormes, J F; Paneque, D; Perkins, J S; Pesce-Rollins, M; Piron, F; Pivato, G; Porter, T A; Rainò, S; Rando, R; Razzano, M; Reimer, A; Reimer, O; Ritz, S; Sánchez-Conde, M; Schulz, A; Sehgal, N; Sgrò, C; Siskind, E J; Spada, F; Spandre, G; Spinelli, P; Strigari, L; Tajima, H; Takahashi, H; Thayer, J B; Tibaldo, L; Torres, D F; Troja, E; Vianello, G; Werner, M; Winer, B L; Wood, K S; Wood, M; Zaharijas, G; Zimmer, S

    2015-12-04

    The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on γ-ray observations of Milky Way dSphs based on six years of Fermi Large Area Telescope data processed with the new Pass8 event-level analysis. None of the dSphs are significantly detected in γ rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. These constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass ≲100  GeV annihilating via quark and τ-lepton channels.

  10. Search for Spectral Irregularities due to Photon–Axionlike-Particle Oscillations with the Fermi Large Area Telescope

    DOE PAGES

    Ajello, M.; Albert, A.; Anderson, B.; ...

    2016-04-20

    In this paper, we report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5 x 10-12 GeV-1 for ALP masses 0.5 ≲ ma ≲ 5 neV at 95% confidence. Finally, the limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ-ray opacity of the Universe.

  11. Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi Large Area Telescope Data

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Albert, A.; Anderson, B.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Caliandro, G. A.; Cameron, R. A.; Caputo, R.; Caragiulo, M.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cuoco, A.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Essig, R.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Guiriec, S.; Gustafsson, M.; Hays, E.; Hewitt, J. W.; Horan, D.; Jogler, T.; Jóhannesson, G.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Llena Garde, M.; Longo, F.; Loparco, F.; Lubrano, P.; Malyshev, D.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Meyer, M.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Murgia, S.; Nuss, E.; Ohsugi, T.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Ritz, S.; Sánchez-Conde, M.; Schulz, A.; Sehgal, N.; Sgrò, C.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Strigari, L.; Tajima, H.; Takahashi, H.; Thayer, J. B.; Tibaldo, L.; Torres, D. F.; Troja, E.; Vianello, G.; Werner, M.; Winer, B. L.; Wood, K. S.; Wood, M.; Zaharijas, G.; Zimmer, S.; Fermi-LAT Collaboration

    2015-12-01

    The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on γ -ray observations of Milky Way dSphs based on six years of Fermi Large Area Telescope data processed with the new Pass8 event-level analysis. None of the dSphs are significantly detected in γ rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. These constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass ≲100 GeV annihilating via quark and τ -lepton channels.

  12. Measurement of the high-energy gamma-ray emission from the Moon with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bonino, R.; Bottacini, E.; Bregeon, J.; Bruel, P.; Buehler, R.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Costanza, F.; Cuoco, A.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Franckowiak, A.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Harding, A. K.; Hewitt, J. W.; Horan, D.; Hou, X.; Iafrate, G.; Jóhannesson, G.; Kamae, T.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Magill, J.; Maldera, S.; Manfreda, A.; Mayer, M.; Mazziotta, M. N.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Murgia, S.; Nuss, E.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Pivato, G.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Sgrò, C.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Takahashi, H.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Troja, E.; Vianello, G.; Winer, B. L.; Wood, K. S.; Yassine, M.; Cerutti, F.; Ferrari, A.; Sala, P. R.; Fermi LAT Collaboration

    2016-04-01

    We have measured the gamma-ray emission spectrum of the Moon using the data collected by the Large Area Telescope onboard the Fermi satellite during its first seven years of operation, in the energy range from 30 MeV up to a few GeV. We have also studied the time evolution of the flux, finding a correlation with the solar activity. We have developed a full Monte Carlo simulation describing the interactions of cosmic rays with the lunar surface. The results of the present analysis can be explained in the framework of this model, where the production of gamma rays is due to the interactions of cosmic-ray proton and helium nuclei with the surface of the Moon. Finally, we have used our simulation to derive the cosmic-ray proton and helium spectra near Earth from the Moon gamma-ray data.

  13. Measurement of the high-energy gamma-ray emission from the Moon with the Fermi Large Area Telescope

    DOE PAGES

    Ackermann, M.; Ajello, M.; Albert, A.; ...

    2016-04-08

    We have measured the gamma-ray emission spectrum of the Moon using the data collected by the Large Area Telescope onboard the Fermi satellite during its first seven years of operation, in the energy range from 30 MeV up to a few GeV. We have also studied the time evolution of the flux, finding a correlation with the solar activity. We have developed a full Monte Carlo simulation describing the interactions of cosmic rays with the lunar surface. The results of the present analysis can be explained in the framework of this model, where the production of gamma rays is duemore » to the interactions of cosmic-ray proton and helium nuclei with the surface of the Moon. Lastly, we have used our simulation to derive the cosmic-ray proton and helium spectra near Earth from the Moon gamma-ray data.« less

  14. Search for Spectral Irregularities due to Photon-Axionlike-Particle Oscillations with the Fermi Large Area Telescope.

    PubMed

    Ajello, M; Albert, A; Anderson, B; Baldini, L; Barbiellini, G; Bastieri, D; Bellazzini, R; Bissaldi, E; Blandford, R D; Bloom, E D; Bonino, R; Bottacini, E; Bregeon, J; Bruel, P; Buehler, R; Caliandro, G A; Cameron, R A; Caragiulo, M; Caraveo, P A; Cecchi, C; Chekhtman, A; Ciprini, S; Cohen-Tanugi, J; Conrad, J; Costanza, F; D'Ammando, F; de Angelis, A; de Palma, F; Desiante, R; Di Mauro, M; Di Venere, L; Domínguez, A; Drell, P S; Favuzzi, C; Focke, W B; Franckowiak, A; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Giglietto, N; Glanzman, T; Godfrey, G; Guiriec, S; Horan, D; Jóhannesson, G; Katsuragawa, M; Kensei, S; Kuss, M; Larsson, S; Latronico, L; Li, J; Li, L; Longo, F; Loparco, F; Lubrano, P; Madejski, G M; Maldera, S; Manfreda, A; Mayer, M; Mazziotta, M N; Meyer, M; Michelson, P F; Mirabal, N; Mizuno, T; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Negro, M; Nuss, E; Okada, C; Orlando, E; Ormes, J F; Paneque, D; Perkins, J S; Pesce-Rollins, M; Piron, F; Pivato, G; Porter, T A; Rainò, S; Rando, R; Razzano, M; Reimer, A; Sánchez-Conde, M; Sgrò, C; Simone, D; Siskind, E J; Spada, F; Spandre, G; Spinelli, P; Takahashi, H; Thayer, J B; Torres, D F; Tosti, G; Troja, E; Uchiyama, Y; Wood, K S; Wood, M; Zaharijas, G; Zimmer, S

    2016-04-22

    We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5×10^{-12}  GeV^{-1} for ALP masses 0.5≲m_{a}≲5  neV at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ-ray opacity of the Universe.

  15. Measurement of the High-Energy Gamma-Ray Emission from the Moon with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; hide

    2016-01-01

    We have measured the gamma-ray emission spectrum of the Moon using the data collected by the Large Area Telescope onboard the Fermi satellite during its first seven years of operation, in the energy range from 30 MeV up to a few GeV. We have also studied the time evolution of the flux, finding a correlation with the solar activity. We have developed a full Monte Carlo simulation describing the interactions of cosmic rays with the lunar surface. The results of the present analysis can be explained in the framework of this model, where the production of gamma rays is due to the interactions of cosmic-ray proton and helium nuclei with the surface of the Moon. Finally, we have used our simulation to derive the cosmic-ray proton and helium spectra near Earth from the Moon gamma-ray data.

  16. A Report on the Implementation of the Blooming Biology Tool: Aligning Course Learning Outcomes with Assessments and Promoting Consistency in a Large Multi-Section First-Year Biology Course

    ERIC Educational Resources Information Center

    O'Neill, Angie; Birol, Gülnur; Pollock, Carol

    2010-01-01

    The objectives of this study were to investigate the alignment of exam questions with course learning outcomes in a first year biology majors course, to examine gaps and overlaps in assessment of content amongst the sections of the course, and to use this information to provide feedback to the teaching team to further improve the course. Our…

  17. Observations of M31 and M33 with the Fermi Large Area Telescope: A Galactic Center Excess in Andromeda?

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Albert, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Cameron, R. A.; Caputo, R.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiaro, G.; Ciprini, S.; Costanza, F.; Cutini, S.; D’Ammando, F.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Favuzzi, C.; Funk, S.; Fusco, P.; Gargano, F.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Green, D.; Grenier, I. A.; Guillemot, L.; Guiriec, S.; Hayashi, K.; Hou, X.; Jóhannesson, G.; Kamae, T.; Knödlseder, J.; Kong, A. K. H.; Kuss, M.; La Mura, G.; Larsson, S.; Latronico, L.; Li, J.; Longo, F.; Loparco, F.; Lubrano, P.; Maldera, S.; Malyshev, D.; Manfreda, A.; Martin, P.; Mazziotta, M. N.; Michelson, P. F.; Mirabal, N.; Mitthumsiri, W.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Negro, M.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Persic, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Principe, G.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, O.; Sánchez-Conde, M.; Sgrò, C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Tanaka, K.; Tibaldo, L.; Torres, D. F.; Troja, E.; Uchiyama, Y.; Wang, J. C.; Wood, K. S.; Wood, M.; Zaharijas, G.; Zhou, M.

    2017-02-01

    The Fermi Large Area Telescope (LAT) has opened the way for comparative studies of cosmic rays (CRs) and high-energy objects in the Milky Way (MW) and in other, external, star-forming galaxies. Using 2 yr of observations with the Fermi LAT, Local Group galaxy M31 was detected as a marginally extended gamma-ray source, while only an upper limit has been derived for the other nearby galaxy M33. We revisited the gamma-ray emission in the direction of M31 and M33 using more than 7 yr of LAT Pass 8 data in the energy range 0.1{--}100 {GeV}, presenting detailed morphological and spectral analyses. M33 remains undetected, and we computed an upper limit of 2.0× {10}-12 {erg} {{cm}}-2 {{{s}}}-1 on the 0.1{--}100 {GeV} energy flux (95% confidence level). This revised upper limit remains consistent with the observed correlation between gamma-ray luminosity and star formation rate tracers and implies an average CR density in M33 that is at most half of that of the MW. M31 is detected with a significance of nearly 10σ . Its spectrum is consistent with a power law with photon index {{Γ }}=2.4+/- {0.1}{stat+{syst}} and a 0.1{--}100 {GeV} energy flux of (5.6+/- {0.6}{stat+{syst}})× {10}-12 {erg} {{cm}}-2 {{{s}}}-1. M31 is detected to be extended with a 4σ significance. The spatial distribution of the emission is consistent with a uniform-brightness disk with a radius of 0.°4 and no offset from the center of the galaxy, but nonuniform intensity distributions cannot be excluded. The flux from M31 appears confined to the inner regions of the galaxy and does not fill the disk of the galaxy or extend far from it. The gamma-ray signal is not correlated with regions rich in gas or star formation activity, which suggests that the emission is not interstellar in origin, unless the energetic particles radiating in gamma rays do not originate in recent star formation. Alternative and nonexclusive interpretations are that the emission results from a population of millisecond pulsars

  18. Fermi Large Area Telescope observations of Markarian 421: The missing piece of its spectral energy distribution

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cannon, A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; de Angelis, A.; de Palma, F.; Dermer, C. D.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Escande, L.; Favuzzi, C.; Fegan, S. J.; Finke, J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fuhrmann, L.; Fukazawa, Y.; Fukuyama, T.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Georganopoulos, M.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Guiriec, S.; Hadasch, D.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kadler, M.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S. -H.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Max-Moerbeck, W.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Nishino, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pavlidou, V.; Pearson, T. J.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Readhead, A.; Reimer, A.; Reimer, O.; Reyes, L. C.; Richards, J. L.; Ritz, S.; Roth, M.; Sadrozinski, H. F. -W.; Sanchez, D.; Sander, A.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stawarz, Ł.; Stevenson, M.; Strickman, M. S.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Troja, E.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Wehrle, A. E.; Winer, B. L.; Wood, K. S.; Yang, Z.; Yatsu, Y.; Ylinen, T.; Zensus, J. A.; Ziegler, M.; Aleksić, J.; Antonelli, L. A.; Antoranz, P.; Backes, M.; Barrio, J. A.; González, J. Becerra; Bednarek, W.; Berdyugin, A.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnoli, G.; Bordas, P.; Tridon, D. Borla; Bosch-Ramon, V.; Bose, D.; Braun, I.; Bretz, T.; Camara, M.; Carmona, E.; Carosi, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Dazzi, F.; de Angelis, A.; De Cea del Pozo, E.; Mendez, C. Delgado; De Lotto, B.; De Maria, M.; De Sabata, F.; Ortega, A. Diago; Doert, M.; Domínguez, A.; Prester, D. Dominis; Dorner, D.; Doro, M.; Elsaesser, D.; Ferenc, D.; Fonseca, M. V.; Font, L.; López, R. J. García; Garczarczyk, M.; Gaug, M.; Giavitto, G.; Godinovi, N.; Hadasch, D.; Herrero, A.; Hildebrand, D.; Höhne-Mönch, D.; Hose, J.; Hrupec, D.; Jogler, T.; Klepser, S.; Krähenbühl, T.; Kranich, D.; Krause, J.; Barbera, A. La; Leonardo, E.; Lindfors, E.; Lombardi, S.; López, M.; Lorenz, E.; Majumdar, P.; Makariev, E.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Miyamoto, H.; Moldón, J.; Moralejo, A.; Nieto, D.; Nilsson, K.; Orito, R.; Oya, I.; Paoletti, R.; Paredes, J. M.; Partini, S.; Pasanen, M.; Pauss, F.; Pegna, R. G.; Perez-Torres, M. A.; Persic, M.; Peruzzo, J.; Pochon, J.; Prada, F.; Moroni, P. G. Prada; Prandini, E.; Puchades, N.; Puljak, I.; Reichardt, T.; Rhode, W.; Ribó, M.; Rico, J.; Rissi, M.; Rügamer, S.; Saggion, A.; Saito, K.; Saito, T. Y.; Salvati, M.; Sánchez-Conde, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shayduk, M.; Shore, S. N.; Sierpowska-Bartosik, A.; Sillanpää, A.; Sitarek, J.; Sobczynska, D.; Spanier, F.; Spiro, S.; Stamerra, A.; Steinke, B.; Storz, J.; Strah, N.; Struebig, J. C.; Suric, T.; Takalo, L. O.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Vankov, H.; Wagner, R. M.; Weitzel, Q.; Zabalza, V.; Zandanel, F.; Zanin, R.; Villata, M.; Raiteri, C.; Aller, H. D.; Aller, M. F.; Chen, W. P.; Jordan, B.; Koptelova, E.; Kurtanidze, O. M.; Lähteenmäki, A.; McBreen, B.; Larionov, V. M.; Lin, C. S.; Nikolashvili, M. G.; Reinthal, R.; Angelakis, E.; Capalbi, M.; Carramiñana, A.; Carrasco, L.; Cassaro, P.; Cesarini, A.; Falcone, A.; Gurwell, M. A.; Hovatta, T.; Kovalev, Yu. A.; Kovalev, Y. Y.; Krichbaum, T. P.; Krimm, H. A.; Lister, M. L.; Moody, J. W.; Maccaferri, G.; Mori, Y.; Nestoras, I.; Orlati, A.; Pace, C.; Pagani, C.; Pearson, R.; Perri, M.; Piner, B. G.; Ros, E.; Sadun, A. C.; Sakamoto, T.; Tammi, J.; Zook, A.

    2011-07-15

    Here, we report on the γ-ray activity of the high-synchrotron-peaked BL Lacertae object Markarian 421 (Mrk 421) during the first 1.5 years of Fermi operation, from 2008 August 5 to 2010 March 12. We find that the Large Area Telescope (LAT) γ-ray spectrum above 0.3 GeV can be well described by a power-law function with photon index Γ = 1.78 ± 0.02 and average photon flux F(> 0.3 GeV) = (7.23 ± 0.16) × 10–8 ph cm–2 s–1. Over this time period, the Fermi-LAT spectrum above 0.3 GeV was evaluated on seven-day-long time intervals, showing significant variations in the photon flux (up to a factor ~3 from the minimum to the maximum flux) but mild spectral variations. The variability amplitude at X-ray frequencies measured by RXTE/ASM and Swift/BAT is substantially larger than that in γ-rays measured by Fermi-LAT, and these two energy ranges are not significantly correlated. We also present the first results from the 4.5 month long multifrequency campaign on Mrk 421, which included the VLBA, Swift, RXTE, MAGIC, the F-GAMMA, GASP-WEBT, and other collaborations and instruments that provided excellent temporal and energy coverage of the source throughout the entire campaign (2009 January 19 to 2009 June 1). During this campaign, Mrk 421 showed a low activity at all wavebands. The extensive multi-instrument (radio to TeV) data set provides an unprecedented, complete look at the quiescent spectral energy distribution (SED) for this source. The broadband SED was reproduced with a leptonic (one-zone synchrotron self-Compton) and a hadronic model (synchrotron proton blazar). Both frameworks are able to describe the average SED reasonably well, implying comparable jet powers but very different characteristics for the blazar emission site.

  19. Discovery of millisecond pulsars in radio searches of southern Fermi Large Area Telescope sources

    DOE PAGES

    Keith, M. J.; Johnston, S.; Ray, P. S.; ...

    2011-06-08

    Using the Parkes Radio Telescope, we have carried out deep observations of 11 unassociated gamma-ray sources. Periodicity searches of these data have discovered two millisecond pulsars, PSR J1103–5403 (1FGL J1103.9–5355) and PSR J2241–5236 (1FGL J2241.9–5236), and a long-period pulsar, PSR J1604–44 (1FGL J1604.7–4443). In addition, we searched for but did not detect any radio pulsations from six gamma-ray pulsars discovered by the Fermi satellite to a level of ~0.04 mJy (for pulsars with a 10 per cent duty cycle). The timing of the millisecond pulsar PSR J1103–5403 has shown that its position is 9 arcmin from the centroid of themore » gamma-ray source. Since these observations were carried out, independent evidence has shown that 1FGL J1103.9–5355 is associated with the flat spectrum radio source PKS 1101–536. It appears certain that the pulsar is not associated with the gamma-ray source, despite the seemingly low probability of a chance detection of a radio millisecond pulsar. We consider that PSR J1604–44 is a chance discovery of a weak, long-period pulsar and is unlikely to be associated with 1FGL J1604.7–4443. PSR J2241–5236 has a spin period of 2.2 ms and orbits a very low mass companion with a 3.5-h orbital period. The relatively high flux density and low dispersion measure of PSR J2241–5236 make it an excellent candidate for high precision timing experiments. The gamma rays of 1FGL J2241.9–5236 have a spectrum that is well modelled by a power law with an exponential cut-off, and phase binning with the radio ephemeris results in a multipeaked gamma-ray pulse profile. Furthermore, observations with Chandra have identified a coincident X-ray source within 0.1 arcsec of the position of the pulsar obtained by radio timing.« less

  20. Discovery of millisecond pulsars in radio searches of southern Fermi Large Area Telescope sources

    NASA Astrophysics Data System (ADS)

    Keith, M. J.; Johnston, S.; Ray, P. S.; Ferrara, E. C.; Saz Parkinson, P. M.; Çelik, Ö.; Belfiore, A.; Donato, D.; Cheung, C. C.; Abdo, A. A.; Camilo, F.; Freire, P. C. C.; Guillemot, L.; Harding, A. K.; Kramer, M.; Michelson, P. F.; Ransom, S. M.; Romani, R. W.; Smith, D. A.; Thompson, D. J.; Weltevrede, P.; Wood, K. S.

    2011-06-01

    Using the Parkes Radio Telescope, we have carried out deep observations of 11 unassociated gamma-ray sources. Periodicity searches of these data have discovered two millisecond pulsars, PSR J1103-5403 (1FGL J1103.9-5355) and PSR J2241-5236 (1FGL J2241.9-5236), and a long-period pulsar, PSR J1604-44 (1FGL J1604.7-4443). In addition, we searched for but did not detect any radio pulsations from six gamma-ray pulsars discovered by the Fermi satellite to a level of ˜0.04 mJy (for pulsars with a 10 per cent duty cycle). The timing of the millisecond pulsar PSR J1103-5403 has shown that its position is 9 arcmin from the centroid of the gamma-ray source. Since these observations were carried out, independent evidence has shown that 1FGL J1103.9-5355 is associated with the flat spectrum radio source PKS 1101-536. It appears certain that the pulsar is not associated with the gamma-ray source, despite the seemingly low probability of a chance detection of a radio millisecond pulsar. We consider that PSR J1604-44 is a chance discovery of a weak, long-period pulsar and is unlikely to be associated with 1FGL J1604.7-4443. PSR J2241-5236 has a spin period of 2.2 ms and orbits a very low mass companion with a 3.5-h orbital period. The relatively high flux density and low dispersion measure of PSR J2241-5236 make it an excellent candidate for high precision timing experiments. The gamma rays of 1FGL J2241.9-5236 have a spectrum that is well modelled by a power law with an exponential cut-off, and phase binning with the radio ephemeris results in a multipeaked gamma-ray pulse profile. Observations with Chandra have identified a coincident X-ray source within 0.1 arcsec of the position of the pulsar obtained by radio timing.

  1. Search for gamma-ray emission from dark matter annihilation in the large magellanic cloud with the fermi large area telescope

    NASA Astrophysics Data System (ADS)

    Buckley, Matthew R.; Charles, Eric; Gaskins, Jennifer M.; Brooks, Alyson M.; Drlica-Wagner, Alex; Martin, Pierrick; Zhao, Geng

    2015-05-01

    At a distance of 50 kpc and with a dark matter mass of ˜1 010 M⊙ , the large magellanic cloud (LMC) is a natural target for indirect dark matter searches. We use five years of data from the Fermi Large Area Telescope (LAT) and updated models of the gamma-ray emission from standard astrophysical components to search for a dark matter annihilation signal from the LMC. We perform a rotation curve analysis to determine the dark matter distribution, setting a robust minimum on the amount of dark matter in the LMC, which we use to set conservative bounds on the annihilation cross section. The LMC emission is generally very well described by the standard astrophysical sources, with at most a 1 - 2 σ excess identified near the kinematic center of the LMC once systematic uncertainties are taken into account. We place competitive bounds on the dark matter annihilation cross section as a function of dark matter particle mass and annihilation channel.

  2. Six millisecond pulsars detected by the Fermi Large Area Telescope and the radio/gamma-ray connection of millisecond pulsars

    DOE PAGES

    Espinoza, C. M.; Guillemot, L.; Celik, O.; ...

    2013-01-25

    In this work, we report on the discovery of gamma-ray pulsations from five millisecond pulsars (MSPs) using the Fermi Large Area Telescope (LAT) and timing ephemerides provided by various radio observatories. We also present confirmation of the gamma-ray pulsations from a sixth source, PSR J2051-0827. Five of these six MSPs are in binary systems: PSRs J1713+0747, J1741+1351, J1600-3053 and the two black widow binary pulsars PSRs J0610-2100 and J2051-0827. The only isolated MSP is the nearby PSR J1024-0719, which is also known to emit X-rays. We present X-ray observations in the direction of PSRs J1600-3053 and J2051-0827. While PSR J2051-0827more » is firmly detected, we can only give upper limits for the X-ray flux of PSR J1600-3053. There are no dedicated X-ray observations available for the other three objects. The MSPs mentioned above, together with most of the MSPs detected by Fermi, are used to put together a sample of 30 gamma-ray MSPs. This sample is used to study the morphology and phase connection of radio and gamma-ray pulse profiles. We show that MSPs with pulsed gamma-ray emission which is phase-aligned with the radio emission present the steepest radio spectra and the largest magnetic fields at the light cylinder among all MSPs. Also, we observe a trend towards very low, or undetectable, radio linear polarization levels. These properties could be attributed to caustic radio emission produced at a range of different altitudes in the magnetosphere. In conclusion, we note that most of these characteristics are also observed in the Crab pulsar, the only other radio pulsar known to exhibit phase-aligned radio and gamma-ray emission.« less

  3. Search for gamma-ray spectral lines with the Fermi Large Area Telescope and dark matter implications

    SciTech Connect

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; D’Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Essig, R.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hayashida, M.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Inoue, Y.; Izaguirre, E.; Jogler, T.; Kamae, T.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Malyshev, D.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Romani, R. W.; Sánchez-Conde, M.; Schulz, A.; Sgrò, C.; Siegal-Gaskins, J.; Siskind, E. J.; Snyder, A.; Spandre, G.; Spinelli, P.; Suson, D. J.; Tajima, H.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.; Tibaldo, L.; Tinivella, M.; Tosti, G.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Winer, B. L.; Wood, K. S.; Wood, M.; Yang, Z.; Zaharijas, G.; Zimmer, S.

    2013-10-22

    Weakly interacting massive particles (WIMPs) are a theoretical class of particles that are excellent dark matter candidates. WIMP annihilation or decay may produce essentially monochromatic γ rays detectable by the Fermi Large Area Telescope (LAT) against the astrophysical γ -ray emission of the Galaxy. We have searched for spectral lines in the energy range 5–300 GeV using 3.7 years of data, reprocessed with updated instrument calibrations and an improved energy dispersion model compared to the previous Fermi-LAT Collaboration line searches. We searched in five regions selected to optimize sensitivity to different theoretically motivated dark matter density distributions. We did not find any globally significant lines in our a priori search regions and present 95% confidence limits for annihilation cross sections of self-conjugate WIMPs and decay lifetimes. Our most significant fit occurred at 133 GeV in our smallest search region and had a local significance of 3.3 standard deviations, which translates to a global significance of 1.5 standard deviations. We discuss potential systematic effects in this search, and examine the feature at 133 GeV in detail. We find that the use both of reprocessed data and of additional information in the energy dispersion model contributes to the reduction in significance of the linelike feature near 130 GeV relative to significances reported in other works. We also find that the feature is narrower than the LAT energy resolution at the level of 2 to 3 standard deviations, which somewhat disfavors the interpretation of the 133 GeV feature as a real WIMP signal.

  4. Fermi Large Area Telescope observations of two gamma-ray emission components from the quiescent sun

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Digel, S. W.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Fortin, P.; Frailis, M.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grillo, L.; Guiriec, S.; Hadasch, D.; Hays, E.; Hughes, R. E.; Iafrate, G.; Jóhannesson, G.; Johnson, A. S.; Johnson, T. J.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S. -H.; Lionetto, A. M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Pelassa, V.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Sadrozinski, H. F. -W.; Schalk, T. L.; Sgrò, C.; Share, G. H.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Strong, A. W.; Takahashi, H.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vilchez, N.; Vitale, V.; Vladimirov, A. E.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ziegler, M.

    2011-06-06

    Here, we report the detection of high-energy γ-rays from the quiescent Sun with the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope (Fermi) during the first 18 months of the mission. These observations correspond to the recent period of low solar activity when the emission induced by cosmic rays (CRs) is brightest. For the first time, the high statistical significance of the observations allows clear separation of the two components: the point-like emission from the solar disk due to CR cascades in the solar atmosphere and extended emission from the inverse Compton (IC) scattering of CR electrons on solar photons in the heliosphere. The observed integral flux (≥100 MeV) from the solar disk is (4.6 ± 0.2[statistical error]+1.0 –0.8[systematic error]) × 10–7 cm–2 s–1, which is ~7 times higher than predicted by the "nominal" model of Seckel et al. In contrast, the observed integral flux (≥100 MeV) of the extended emission from a region of 20° radius centered on the Sun, but excluding the disk itself, (6.8 ± 0.7[stat.]+0.5 – 0.4[syst.]) × 10–7 cm–2 s–1, along with the observed spectrum and the angular profile, is in good agreement with the theoretical predictions for the IC emission.

  5. Constraints on Lorentz invariance violation from Fermi -Large Area Telescope observations of gamma-ray bursts

    SciTech Connect

    Vasileiou, V.; Stecker, F. W.; Cohen-Tanugi, J.

    2013-06-04

    For this research, we analyze the MeV/GeV emission from four bright gamma-ray bursts (GRBs) observed by the Fermi Large Area Telescope to produce robust, stringent constraints on a dependence of the speed of light in vacuo on the photon energy (vacuum dispersion), a form of Lorentz invariance violation (LIV) allowed by some quantum gravity (QG) theories. First, we use three different and complementary techniques to constrain the total degree of dispersion observed in the data. Additionally, using a maximally conservative set of assumptions on possible source-intrinsic, spectral-evolution effects, we constrain any vacuum dispersion solely attributed to LIV. We then derive limits on the QG energy scale (the energy scale where LIV-inducing QG effects become strong, EQG) and the coefficients of the Standard Model Extension. For the subluminal case (where high-energy photons propagate more slowly than lower-energy photons) and without taking into account any source-intrinsic dispersion, our most stringent limits (at 95% C.L.) are obtained from GRB 090510 and are EQG,1 > 7.6 times the Planck energy (EPl) and EQG,2 > 1.3 × 1011 GeV for linear and quadratic leading-order LIV-induced vacuum dispersion, respectively. In conclusion, these limits improve the latest constraints by Fermi and H.E.S.S. by a factor of ~2 . Our results disfavor any class of models requiring EQG,1 ≲ EPl .

  6. Six millisecond pulsars detected by the Fermi Large Area Telescope and the radio/gamma-ray connection of millisecond pulsars

    SciTech Connect

    Espinoza, C. M.; Guillemot, L.; Celik, O.; Weltevrede, P.; Stappers, B. W.; Smith, D. A.; Kerr, M.; Zavlin, V. E.; Cognard, I.; Eatough, R. P.; Freire, P. C. C.; Janssen, G. H.; Camilo, F.; Desvignes, G.; Hewitt, J. W.; Hou, X.; Johnston, S.; Keith, M.; Kramer, M.; Lyne, A.; Manchester, R. N.; Ransom, S. M.; Ray, P. S.; Shannon, R.; Theureau, G.; Webb, N.

    2013-01-25

    In this work, we report on the discovery of gamma-ray pulsations from five millisecond pulsars (MSPs) using the Fermi Large Area Telescope (LAT) and timing ephemerides provided by various radio observatories. We also present confirmation of the gamma-ray pulsations from a sixth source, PSR J2051-0827. Five of these six MSPs are in binary systems: PSRs J1713+0747, J1741+1351, J1600-3053 and the two black widow binary pulsars PSRs J0610-2100 and J2051-0827. The only isolated MSP is the nearby PSR J1024-0719, which is also known to emit X-rays. We present X-ray observations in the direction of PSRs J1600-3053 and J2051-0827. While PSR J2051-0827 is firmly detected, we can only give upper limits for the X-ray flux of PSR J1600-3053. There are no dedicated X-ray observations available for the other three objects. The MSPs mentioned above, together with most of the MSPs detected by Fermi, are used to put together a sample of 30 gamma-ray MSPs. This sample is used to study the morphology and phase connection of radio and gamma-ray pulse profiles. We show that MSPs with pulsed gamma-ray emission which is phase-aligned with the radio emission present the steepest radio spectra and the largest magnetic fields at the light cylinder among all MSPs. Also, we observe a trend towards very low, or undetectable, radio linear polarization levels. These properties could be attributed to caustic radio emission produced at a range of different altitudes in the magnetosphere. In conclusion, we note that most of these characteristics are also observed in the Crab pulsar, the only other radio pulsar known to exhibit phase-aligned radio and gamma-ray emission.

  7. Negotiating the Curriculum: Surviving the First Year

    ERIC Educational Resources Information Center

    Poland, Molly

    2013-01-01

    Molly Poland is a first year English and Home Economics teacher who began her career in a small Far North Queensland town. In this article, she writes about her first year teaching and the last year of her degree and the challenges she faced as both teacher and student. Reading Boomer's "Negotiating the Curriculum" forced her to think a…

  8. Negotiating the Curriculum: Surviving the First Year

    ERIC Educational Resources Information Center

    Poland, Molly

    2013-01-01

    Molly Poland is a first year English and Home Economics teacher who began her career in a small Far North Queensland town. In this article, she writes about her first year teaching and the last year of her degree and the challenges she faced as both teacher and student. Reading Boomer's "Negotiating the Curriculum" forced her to think a…

  9. Riding the First-Year Roller Coaster

    ERIC Educational Resources Information Center

    Moir, Ellen

    2013-01-01

    A teacher's first year of teaching can feel like a sink-or-swim experience. Instead of making steady progress toward becoming a great teacher, in their first year, many teachers become overwhelmed by the daily demands of their own classrooms. As founder and CEO of New Teacher Center, an organization focused on understanding and meeting the…

  10. Riding the First-Year Roller Coaster

    ERIC Educational Resources Information Center

    Moir, Ellen

    2013-01-01

    A teacher's first year of teaching can feel like a sink-or-swim experience. Instead of making steady progress toward becoming a great teacher, in their first year, many teachers become overwhelmed by the daily demands of their own classrooms. As founder and CEO of New Teacher Center, an organization focused on understanding and meeting the…

  11. Supporting First-Year Writing Development Online

    ERIC Educational Resources Information Center

    Krause, Kerri-Lee

    2006-01-01

    It is imperative to identify the impact of technological advancements on the quality of student learning. This article reports first-year undergraduate students' perceptions of and experiences with a Web-based writing support program. Two research questions guided the study: (1) What is the nature of first-year students' interactions with…

  12. Deep view of the Large Magellanic Cloud with six years of Fermi -LAT observations

    SciTech Connect

    Ackermann, M.

    2016-01-27

    Context. The nearby Large Magellanic Cloud (LMC) provides a rare opportunity of a spatially resolved view of an external star-forming galaxy in -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 -ray emission is connected to specific objects, populations of objects, and structures in the galaxy. Methods. We revisited the -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 ~1–100GeV 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

  13. Radio Follow-up on All Unassociated Gamma-Ray Sources from the Third Fermi Large Area Telescope Source Catalog

    NASA Astrophysics Data System (ADS)

    Schinzel, Frank K.; Petrov, Leonid; Taylor, Gregory B.; Edwards, Philip G.

    2017-04-01

    The third Fermi Large Area Telescope γ-ray source catalog (3FGL) contains over 1000 objects for which there is no known counterpart at other wavelengths. The physical origin of the γ-ray emission from those objects is unknown. Such objects are commonly referred to as unassociated and mostly do not exhibit significant γ-ray flux variability. We performed a survey of all unassociated γ-ray sources found in 3FGL using the Australia Telescope Compact Array and Very Large Array in the range 4.0–10.0 GHz. We found 2097 radio candidates for association with γ-ray sources. The follow-up with very long baseline interferometry for a subset of those candidates yielded 142 new associations with active galactic nuclei that are γ-ray sources, provided alternative associations for seven objects, and improved positions for another 144 known associations to the milliarcsecond level of accuracy. In addition, for 245 unassociated γ-ray sources we did not find a single compact radio source above 2 mJy within 3σ of their γ-ray localization. A significant fraction of these empty fields, 39%, are located away from the Galactic plane. We also found 36 extended radio sources that are candidates for association with a corresponding γ-ray object, 19 of which are most likely supernova remnants or H ii regions, whereas 17 could be radio galaxies.

  14. Visiting The Pediatrician: The First Year

    MedlinePlus

    ... Listen Español Text Size Email Print Share Visiting The Pediatrician: The First Year Page Content Article Body Why does my baby need to see the pediatrician so often? You probably will see more ...

  15. Gamma-ray Emission from PSR J0007+7303 Using Seven Years of Fermi Large Area Telescope Observations

    NASA Astrophysics Data System (ADS)

    Li, Jian; Torres, Diego F.; de Oña Wilhelmi, Emma; Rea, Nanda; Martin, Jonatan

    2016-11-01

    Based on more than seven years of Fermi Large Area Telescope Pass 8 data, we report on a detailed analysis of the bright gamma-ray pulsar (PSR) J0007+7303. We confirm that PSR J0007+7303 is significantly detected as a point source also during the off-peak phases with a test statistic value of 262 (˜16σ). In the description of the off-peak spectrum of PSR J0007+7303, a power law with an exponential cutoff at 2.7 ± 1.2 ± 1.3 GeV (the first/second uncertainties correspond to statistical/systematic errors) is preferred over a single power law at a level of 3.5σ. The possible existence of a cutoff hints at a magnetospheric origin of the emission. In addition, no extended gamma-ray emission is detected that is compatible with either the supernova remnant (CTA 1) or the very high-energy (>100 GeV) pulsar wind nebula. A flux upper limit of 6.5 × 10-12 erg cm-2 s-1 in the energy range 10-300 GeV is reported, for an extended source assuming the morphology of the VERITAS detection. During on-peak phases, a sub-exponential cutoff is significantly preferred (˜11σ) for representing the spectral energy distribution, in both the phase-averaged and phase-resolved spectra. Three glitches are detected during the observation period and we found no flux variability at the time of the glitches or in the long-term behavior. We also report the discovery of a previously unknown gamma-ray source in the vicinity of PSR J0007+7303, Fermi J0020+7328, which we associate with the z = 1.781 quasar S5 0016+73. A concurrent analysis of this source is needed to correctly characterize the behavior of CTA 1 and it is also presented in the paper.

  16. FERMI Large Area Telescope View of the 1 Core of the Radio Galaxy Centaurus A

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cannon, A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Colafrancesco, S.; Cominsky, L. R.; Conrad, J.; Costamante, L.; Davis, D. S.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Falcone, A.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Finke, J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Georganopoulos, M.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grandi, P.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hase, Hayo; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Itoh, R.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Kadler, M.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kishishita, T.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S. -H.; Lemoine-Goumard, M.; Garde, M. Llena; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Müller, C.; Nakamori, T.; Naumann-Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Ojha, R.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Pagani, C.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Plötz, C.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ripken, J.; Ritz, S.; Rodriguez, A. Y.; Roth, M.; Ryde, F.; Sadrozinski, H. F. -W.; Sanchez, D.; Sander, A.; Scargle, J. D.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J. -L.; Stawarz, L.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ylinen, T.; Ziegler, M.

    2010-07-29

    We present γ-ray observations with the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope of the nearby radio galaxy Centaurus A (Cen A). The previous EGRET detection is confirmed, and the localization is improved using data from the first 10 months of Fermi science operation. In previous work, we presented the detection of the lobes by the LAT; in this work, we concentrate on the γ-ray core of Cen A. Flux levels as seen by the LAT are not significantly different from that found by EGRET, nor is the extremely soft LAT spectrum (Γ = 2.67 ± 0.10stat ± 0.08sys where the photon flux is Φ ∝ E –Γ). The LAT core spectrum, extrapolated to higher energies, is marginally consistent with the non-simultaneous HESS spectrum of the source. The LAT observations are complemented by simultaneous observations from Suzaku, the Swift Burst Alert Telescope and X-ray Telescope, and radio observations with the Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry program, along with a variety of non-simultaneous archival data from a variety of instruments and wavelengths to produce a spectral energy distribution (SED). Here, we fit this broadband data set with a single-zone synchrotron/synchrotron self-Compton model, which describes the radio through GeV emission well, but fails to account for the non-simultaneous higher energy TeV emission observed by HESS from 2004 to 2008. The fit requires a low Doppler factor, in contrast to BL Lac objects which generally require larger values to fit their broadband SEDs. This indicates that the γ-ray emission originates from a slower region than that from BL Lac objects, consistent with previous modeling results from Cen A. This slower region could be a slower moving layer around a fast spine, or a slower region farther out from the black hole in a decelerating flow. The fit parameters are also consistent with Cen A being able to accelerate ultra-high energy

  17. Fermi Large Area Telescope detection of bright γ-ray outbursts from the peculiar quasar 4C +21.35

    DOE PAGES

    Tanaka, Y. T.; Stawarz, Ł.; Thompson, D. J.; ...

    2011-04-29

    In this study, we report on the two-year-long Fermi-Large Area Telescope observation of the peculiar blazar 4C +21.35 (PKS 1222+216). This source was in a quiescent state from the start of the science operations of the Fermi Gamma-ray Space Telescope in 2008 August until 2009 September, and then became more active, with gradually increasing flux and some moderately bright flares. In 2010 April and June, 4C +21.35 underwent a very strong GeV outburst composed of several major flares characterized by rise and decay timescales of the order of a day. During the outburst, the GeV spectra of 4C +21.35 displayedmore » a broken power-law form with spectral breaks observed near 1-3 GeV photon energies. We demonstrate that, at least during the major flares, the jet in 4C +21.35 carried a total kinetic luminosity comparable to the total accretion power available to feed the outflow. We also discuss the origin of the break observed in the flaring spectra of 4C +21.35. We show that, in principle, a model involving annihilation of the GeV photons on the He II Lyman recombination continuum and line emission of "broad-line region" clouds may account for such. However, we also discuss the additional constraint provided by the detection of 4C +21.35 at 0.07-0.4 TeV energies by the MAGIC telescope, which coincided with one of the GeV flares of the source. We argue that there are reasons to believe that the lesssim TeV emission of 4C +21.35 (as well as the GeV emission of the source, if co-spatial) is not likely to be produced inside the broad-line region zone of highest ionization (~1017 cm from the nucleus), but instead originates further away from the active center, namely, around the characteristic scale of the hot dusty torus surrounding the 4C +21.35 nucleus (~1019 cm).« less

  18. Dark matter constraints from observations of 25 Milky Way satellite galaxies with the Fermi Large Area Telescope

    SciTech Connect

    Ackermann, M.; et al.

    2014-02-11

    The dwarf spheroidal satellite galaxies of the Milky Way are some of the most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are widely considered to be among the most promising targets for the indirect detection of dark matter via gamma rays. Here we report on gamma-ray observations of 25 Milky Way dwarf spheroidal satellite galaxies based on 4 years of Fermi Large Area Telescope (LAT) data. None of the dwarf galaxies are significantly detected in gamma rays, and we present gamma-ray flux upper limits between 500 MeV and 500 GeV. We determine the dark matter content of 18 dwarf spheroidal galaxies from stellar kinematic data and combine LAT observations of 15 dwarf galaxies to constrain the dark matter annihilation cross section. We set some of the tightest constraints to date on the the annihilation of dark matter particles with masses between 2 GeV and 10 TeV into prototypical Standard Model channels. We find these results to be robust against systematic uncertainties in the LAT instrument performance, diffuse gamma-ray background modeling, and assumed dark matter density profile.

  19. Dark matter constraints from observations of 25 Milky Way satellite galaxies with the Fermi Large Area Telescope

    SciTech Connect

    Ackermann, M.; Albert, A.; Anderson, B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; D’Ammando, F.; de Angelis, A.; Dermer, C. D.; Digel, S. W.; do Couto e Silva, E.; Drell, P. S.; Drlica-Wagner, A.; Essig, R.; Favuzzi, C.; Ferrara, E. C.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giroletti, M.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Guiriec, S.; Gustafsson, M.; Hayashida, M.; Hays, E.; Hewitt, J.; Hughes, R. E.; Jogler, T.; Kamae, T.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Larsson, S.; Latronico, L.; Llena Garde, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Martinez, G.; Mayer, M.; Mazziotta, M. N.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Orlando, E.; Ormes, J. F.; Perkins, J. S.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Ritz, S.; Sánchez-Conde, M.; Sehgal, N.; Sgrò, C.; Siskind, E. J.; Spinelli, P.; Strigari, L.; Suson, D. J.; Tajima, H.; Takahashi, H.; Thayer, J. B.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vianello, G.; Vitale, V.; Werner, M.; Winer, B. L.; Wood, K. S.; Wood, M.; Zaharijas, G.; Zimmer, S.

    2014-02-11

    The dwarf spheroidal satellite galaxies of the Milky Way are some of the most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are widely considered to be among the most promising targets for the indirect detection of dark matter via γ rays. We report on γ -ray observations of 25 Milky Way dwarf spheroidal satellite galaxies based on 4 years of Fermi Large Area Telescope (LAT) data. None of the dwarf galaxies are significantly detected in γ rays, and we present γ -ray flux upper limits between 500 MeV and 500 GeV. We determine the dark matter content of 18 dwarf spheroidal galaxies from stellar kinematic data and combine LAT observations of 15 dwarf galaxies to constrain the dark matter annihilation cross section. Furthermore, we set some of the tightest constraints to date on the annihilation of dark matter particles with masses between 2 GeV and 10 TeV into prototypical standard model channels. We also find these results to be robust against systematic uncertainties in the LAT instrument performance, diffuse γ -ray background modeling, and assumed dark matter density profile.

  20. Fermi large area telescope discovery of GeV gamma-ray emission from the vicinity of SNR W44

    SciTech Connect

    Uchiyama, Yasunobu; Funk, Stefan; Katagiri, Hideaki; Katsuta, Junichiro; Lemoine-Goumard, Marianne; Tajima, Hiroyasu; Tanaka, Takaaki; Torres, Diego F.

    2012-04-02

    Here, we report the detection of GeV γ-ray emission from the molecular cloud complex that surrounds the supernova remnant (SNR) W44 using the Large Area Telescope on board Fermi. And while the previously reported γ-ray emission from SNR W44 is likely to arise from the dense radio-emitting filaments within the remnant, the γ-ray emission that appears to come from the surrounding molecular cloud complex can be ascribed to the cosmic rays (CRs) that have escaped from W44. Furthermore, the non-detection of synchrotron radio emission associated with the molecular cloud complex suggests the decay of π0 mesons produced in hadronic collisions as the γ-ray emission mechanism. The total kinetic energy channeled into the escaping CRs is estimated to be W esc ~ (0.3-3) × 1050 erg, in broad agreement with the conjecture that SNRs are the main sources of Galactic CRs.

  1. FERMI LARGE AREA TELESCOPE DISCOVERY OF GeV GAMMA-RAY EMISSION FROM THE VICINITY OF SNR W44

    SciTech Connect

    Uchiyama, Yasunobu; Funk, Stefan; Katsuta, Junichiro; Lemoine-Goumard, Marianne; Torres, Diego F.

    2012-04-20

    We report the detection of GeV {gamma}-ray emission from the molecular cloud complex that surrounds the supernova remnant (SNR) W44 using the Large Area Telescope on board Fermi. While the previously reported {gamma}-ray emission from SNR W44 is likely to arise from the dense radio-emitting filaments within the remnant, the {gamma}-ray emission that appears to come from the surrounding molecular cloud complex can be ascribed to the cosmic rays (CRs) that have escaped from W44. The non-detection of synchrotron radio emission associated with the molecular cloud complex suggests the decay of {pi}{sup 0} mesons produced in hadronic collisions as the {gamma}-ray emission mechanism. The total kinetic energy channeled into the escaping CRs is estimated to be W{sub esc} {approx} (0.3-3) Multiplication-Sign 10{sup 50} erg, in broad agreement with the conjecture that SNRs are the main sources of Galactic CRs.

  2. Constraining dark matter models from a combined analysis of Milky Way satellites with the Fermi Large Area Telescope.

    PubMed

    Ackermann, M; Ajello, M; Albert, A; Atwood, W B; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bregeon, J; Brigida, M; Bruel, P; Buehler, R; Burnett, T H; Buson, S; Caliandro, G A; Cameron, R A; Cañadas, B; Caraveo, P A; Casandjian, J M; Cecchi, C; Charles, E; Chekhtman, A; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Cutini, S; de Angelis, A; de Palma, F; Dermer, C D; Digel, S W; do Couto e Silva, E; Drell, P S; Drlica-Wagner, A; Falletti, L; Favuzzi, C; Fegan, S J; Ferrara, E C; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Guiriec, S; Gustafsson, M; Hadasch, D; Hayashida, M; Hays, E; Hughes, R E; Jeltema, T E; Jóhannesson, G; Johnson, R P; Johnson, A S; Kamae, T; Katagiri, H; Kataoka, J; Knödlseder, J; Kuss, M; Lande, J; Latronico, L; Lionetto, A M; Llena Garde, M; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Mazziotta, M N; McEnery, J E; Mehault, J; Michelson, P F; Mitthumsiri, W; Mizuno, T; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Naumann-Godo, M; Norris, J P; Nuss, E; Ohsugi, T; Okumura, A; Omodei, N; Orlando, E; Ormes, J F; Ozaki, M; Paneque, D; Parent, D; Pesce-Rollins, M; Pierbattista, M; Piron, F; Pivato, G; Porter, T A; Profumo, S; Rainò, S; Razzano, M; Reimer, A; Reimer, O; Ritz, S; Roth, M; Sadrozinski, H F-W; Sbarra, C; Scargle, J D; Schalk, T L; Sgrò, C; Siskind, E J; Spandre, G; Spinelli, P; Strigari, L; Suson, D J; Tajima, H; Takahashi, H; Tanaka, T; Thayer, J G; Thayer, J B; Thompson, D J; Tibaldo, L; Tinivella, M; Torres, D F; Troja, E; Uchiyama, Y; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Waite, A P; Wang, P; Winer, B L; Wood, K S; Wood, M; Yang, Z; Zimmer, S; Kaplinghat, M; Martinez, G D

    2011-12-09

    Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10(-26)  cm3  s(-1) at 5 GeV to about 5×10(-23)   cm3  s(-1) at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section (∼3×10(-26)  cm3  s(-1) for a purely s-wave cross section), without assuming additional boost factors.

  3. Updated search for spectral lines from Galactic dark matter interactions with pass 8 data from the Fermi Large Area Telescope

    DOE PAGES

    Ackermann, M.; Ajello, M.; Albert, A.; ...

    2015-06-15

    Dark matter in the Milky Way may annihilate directly into γ rays, producing a monoenergetic spectral line. Therefore, detecting such a signature would be strong evidence for dark matter annihilation or decay. We search for spectral lines in the Fermi Large Area Telescope observations of the Milky Way halo in the energy range 200 MeV–500 GeV using analysis methods from our most recent line searches. The main improvements relative to previous works are our use of 5.8 years of data reprocessed with the Pass 8 event-level analysis and the additional data resulting from the modified observing strategy designed to increasemore » exposure of the Galactic center region. Furthermore, we search in five sky regions selected to optimize sensitivity to different theoretically motivated dark matter scenarios and find no significant detections. In addition to presenting the results from our search for lines, we also investigate the previously reported tentative detection of a line at 133 GeV using the new Pass 8 data.« less

  4. Dark matter constraints from observations of 25 Milky Way satellite galaxies with the Fermi Large Area Telescope

    DOE PAGES

    Ackermann, M.; Albert, A.; Anderson, B.; ...

    2014-02-11

    The dwarf spheroidal satellite galaxies of the Milky Way are some of the most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are widely considered to be among the most promising targets for the indirect detection of dark matter via γ rays. We report on γ -ray observations of 25 Milky Way dwarf spheroidal satellite galaxies based on 4 years of Fermi Large Area Telescope (LAT) data. None of the dwarf galaxies are significantly detected in γ rays, and we present γ -ray flux upper limits between 500 MeVmore » and 500 GeV. We determine the dark matter content of 18 dwarf spheroidal galaxies from stellar kinematic data and combine LAT observations of 15 dwarf galaxies to constrain the dark matter annihilation cross section. Furthermore, we set some of the tightest constraints to date on the annihilation of dark matter particles with masses between 2 GeV and 10 TeV into prototypical standard model channels. We also find these results to be robust against systematic uncertainties in the LAT instrument performance, diffuse γ -ray background modeling, and assumed dark matter density profile.« less

  5. Dark Matter Constraints from Observations of 25 Milky Way Satellite Galaxies with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Albert, A.; Anderson, B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; hide

    2013-01-01

    The dwarf spheroidal satellite galaxies of the Milky Way are some of the most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are widely considered to be among the most promising targets for the indirect detection of dark matter via gamma rays. Here we report on gamma ray observations of 25 Milky Way dwarf spheroidal satellite galaxies based on 4 years of Fermi Large Area Telescope (LAT) data. None of the dwarf galaxies are significantly detected in gamma rays, and we present gamma ray flux upper limits between 500MeV and 500 GeV. We determine the dark matter content of 18 dwarf spheroidal galaxies from stellar kinematic data and combine LAT observations of 15 dwarf galaxies to constrain the dark matter annihilation cross section. We set some of the tightest constraints to date on the annihilation of dark matter particles with masses between 2 GeV and 10TeV into prototypical standard model channels. We find these results to be robust against systematic uncertainties in the LAT instrument performance, diffuse gamma ray background modeling, and assumed dark matter density profile.

  6. Fermi large area telescope discovery of GeV gamma-ray emission from the vicinity of SNR W44

    DOE PAGES

    Uchiyama, Yasunobu; Funk, Stefan; Katagiri, Hideaki; ...

    2012-04-02

    Here, we report the detection of GeV γ-ray emission from the molecular cloud complex that surrounds the supernova remnant (SNR) W44 using the Large Area Telescope on board Fermi. And while the previously reported γ-ray emission from SNR W44 is likely to arise from the dense radio-emitting filaments within the remnant, the γ-ray emission that appears to come from the surrounding molecular cloud complex can be ascribed to the cosmic rays (CRs) that have escaped from W44. Furthermore, the non-detection of synchrotron radio emission associated with the molecular cloud complex suggests the decay of π0 mesons produced in hadronic collisionsmore » as the γ-ray emission mechanism. The total kinetic energy channeled into the escaping CRs is estimated to be W esc ~ (0.3-3) × 1050 erg, in broad agreement with the conjecture that SNRs are the main sources of Galactic CRs.« less

  7. Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; hide

    2011-01-01

    Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10(exp -26) cm(exp 3) / s at 5 GeV to about 5 X 10(exp -23) cm(exp 3)/ s at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section (approx 3 X 10(exp -26) cm(exp 3)/s for a purely s-wave cross section), without assuming additional boost factors.

  8. Search for Cosmic-Ray Electron and Positron Anisotropies with Seven Years of Fermi Large Area Telescope Data.

    PubMed

    Abdollahi, S; Ackermann, M; Ajello, M; Albert, A; Atwood, W B; Baldini, L; Barbiellini, G; Bellazzini, R; Bissaldi, E; Bloom, E D; Bonino, R; Bottacini, E; Brandt, T J; Bruel, P; Buson, S; Caragiulo, M; Cavazzuti, E; Chekhtman, A; Ciprini, S; Costanza, F; Cuoco, A; Cutini, S; D'Ammando, F; de Palma, F; Desiante, R; Digel, S W; Di Lalla, N; Di Mauro, M; Di Venere, L; Donaggio, B; Drell, P S; Favuzzi, C; Focke, W B; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Giglietto, N; Giordano, F; Giroletti, M; Green, D; Guiriec, S; Harding, A K; Jogler, T; Jóhannesson, G; Kamae, T; Kuss, M; Larsson, S; Latronico, L; Li, J; Longo, F; Loparco, F; Lubrano, P; Magill, J D; Malyshev, D; Manfreda, A; Mazziotta, M N; Meehan, M; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monzani, M E; Morselli, A; Negro, M; Nuss, E; Ohsugi, T; Omodei, N; Paneque, D; Perkins, J S; Pesce-Rollins, M; Piron, F; Pivato, G; Principe, G; Rainò, S; Rando, R; Razzano, M; Reimer, A; Reimer, O; Sgrò, C; Simone, D; Siskind, E J; Spada, F; Spandre, G; Spinelli, P; Strong, A W; Tajima, H; Thayer, J B; Torres, D F; Troja, E; Vandenbroucke, J; Zaharijas, G; Zimmer, S

    2017-03-03

    The Large Area Telescope on board the Fermi Gamma-ray Space Telescope has collected the largest ever sample of high-energy cosmic-ray electron and positron events since the beginning of its operation. Potential anisotropies in the arrival directions of cosmic-ray electrons or positrons could be a signature of the presence of nearby sources. We use almost seven years of data with energies above 42 GeV processed with the Pass 8 reconstruction. The present data sample can probe dipole anisotropies down to a level of 10^{-3}. We take into account systematic effects that could mimic true anisotropies at this level. We present a detailed study of the event selection optimization of the cosmic-ray electrons and positrons to be used for anisotropy searches. Since no significant anisotropies have been detected on any angular scale, we present upper limits on the dipole anisotropy. The present constraints are among the strongest to date probing the presence of nearby young and middle-aged sources.

  9. Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope

    SciTech Connect

    Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W.B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R.D.; Bloom, E.D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T.H.; Buson, S.; /more authors..

    2012-09-14

    Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10{sup -26} cm{sup 3} s{sup -1} at 5 GeV to about 5 x 10{sup -23} cm{sup 3} s{sup -1} at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section ({approx}3 x 10{sup -26} cm{sup 3} s{sup -1} for a purely s-wave cross section), without assuming additional boost factors.

  10. OBSERVATIONS OF THE YOUNG SUPERNOVA REMNANT RX J1713.7-3946 WITH THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Ballet, J.; Baring, M. G.; Bastieri, D.; Bonamente, E.; Bouvier, A.; Brandt, T. J.; Brigida, M.; Bruel, P. E-mail: funk@slac.stanford.edu

    2011-06-10

    We present observations of the young supernova remnant (SNR) RX J1713.7-3946 with the Fermi Large Area Telescope (LAT). We clearly detect a source positionally coincident with the SNR. The source is extended with a best-fit extension of 0.{sup 0}55 {+-} 0.{sup 0}04 matching the size of the non-thermal X-ray and TeV gamma-ray emission from the remnant. The positional coincidence and the matching extended emission allow us to identify the LAT source with SNR RX J1713.7-3946. The spectrum of the source can be described by a very hard power law with a photon index of {Gamma} = 1.5 {+-} 0.1 that coincides in normalization with the steeper H.E.S.S.-detected gamma-ray spectrum at higher energies. The broadband gamma-ray emission is consistent with a leptonic origin as the dominant mechanism for the gamma-ray emission.

  11. Inferred Cosmic-Ray Spectrum from Fermi Large Area Telescope γ-Ray Observations of Earth’s Limb

    SciTech Connect

    Ackermann, M.; et al.

    2014-04-17

    Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly-discovered features may offer a clue to the origin of high-energy CRs. We use the ${\\it Fermi}$ Large Area Telescope observations of the $\\gamma$-ray emission from the Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range $\\sim 90~$GeV-$6~$TeV (derived from a photon energy range $15~$GeV-$1~$TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index $2.68 \\pm 0.04$ and $2.61 \\pm 0.08$ above $\\sim 200~$GeV, respectively.

  12. Updated search for spectral lines from Galactic dark matter interactions with pass 8 data from the Fermi Large Area Telescope

    SciTech Connect

    Ackermann, M.; Ajello, M.; Albert, A.; Anderson, B.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caputo, R.; Caragiulo, M.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cuoco, A.; Cutini, S.; D’Ammando, F.; de Angelis, A.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Gustafsson, M.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Jóhannesson, G.; Johnson, R. P.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Malyshev, D.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Murgia, S.; Nuss, E.; Ohsugi, T.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reposeur, T.; Ritz, S.; Sánchez-Conde, M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Tajima, H.; Takahashi, H.; Thayer, J. B.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Troja, E.; Vianello, G.; Werner, M.; Winer, B. L.; Wood, K. S.; Wood, M.; Zaharijas, G.; Zimmer, S.

    2015-06-15

    Dark matter in the Milky Way may annihilate directly into γ rays, producing a monoenergetic spectral line. Therefore, detecting such a signature would be strong evidence for dark matter annihilation or decay. We search for spectral lines in the Fermi Large Area Telescope observations of the Milky Way halo in the energy range 200 MeV–500 GeV using analysis methods from our most recent line searches. The main improvements relative to previous works are our use of 5.8 years of data reprocessed with the Pass 8 event-level analysis and the additional data resulting from the modified observing strategy designed to increase exposure of the Galactic center region. Furthermore, we search in five sky regions selected to optimize sensitivity to different theoretically motivated dark matter scenarios and find no significant detections. In addition to presenting the results from our search for lines, we also investigate the previously reported tentative detection of a line at 133 GeV using the new Pass 8 data.

  13. Inferred Cosmic-Ray Spectrum from Fermi Large Area Telescope γ-Ray Observations of Earth's Limb

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Bouvier, A.; Brandt, T. J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; Dalton, M.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Digel, S. W.; Di Venere, L.; do Couto e Silva, E.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hayashi, K.; Hewitt, J. W.; Horan, D.; Hou, X.; Hughes, R. E.; Inoue, Y.; Jackson, M. S.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Kawano, T.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Okumura, A.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Ritz, S.; Roth, M.; Schaal, M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Strong, A. W.; Takahashi, H.; Takeuchi, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Tronconi, V.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Werner, M.; Winer, B. L.; Wood, K. S.; Wood, M.; Yang, Z.; Fermi LAT Collaboration

    2014-04-01

    Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the γ-ray emission from Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range ˜90 GeV-6 TeV (derived from a photon energy range 15 GeV-1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68±0.04 and 2.61±0.08 above ˜200 GeV, respectively.

  14. Search for Cosmic-Ray Electron and Positron Anisotropies with Seven Years of Fermi Large Area Telescope Data

    DOE PAGES

    Abdollahi, S.; Ackermann, M.; Ajello, M.; ...

    2017-03-01

    We present the Large Area Telescope on board the Fermi Gamma-ray Space Telescope that has collected the largest ever sample of high-energy cosmic-ray electron and positron events since the beginning of its operation. Potential anisotropies in the arrival directions of cosmic-ray electrons or positrons could be a signature of the presence of nearby sources. We use almost seven years of data with energies above 42 GeV processed with the Pass 8 reconstruction. The present data sample can probe dipole anisotropies down to a level of 10-3. We take into account systematic effects that could mimic true anisotropies at this level.more » We present a detailed study of the event selection optimization of the cosmic-ray electrons and positrons to be used for anisotropy searches. Since no significant anisotropies have been detected on any angular scale, we present upper limits on the dipole anisotropy. Lastly, the present constraints are among the strongest to date probing the presence of nearby young and middle-aged sources.« less

  15. Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope

    SciTech Connect

    Ackermann, M.

    2011-12-01

    Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% con dence level upper limits range from about 10-26 cm3s-1 at 5 GeV to about 5 X10-23 cm3s-1 at 1 TeV, depending on the dark matter annihilation nal state. For the rst time, using gamma rays, we are able to rule out models with the most generic cross section (~ 3 X 10-26 cm3s-1 for a purely s-wave cross section), without assuming additional boost factors.

  16. Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope

    DOE PAGES

    Ackermann, M.

    2011-12-01

    Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% con dence level upper limits range from about 10-26 cm3s-1 at 5 GeV to about 5 X10-23 cm3s-1 at 1 TeV,more » depending on the dark matter annihilation nal state. For the rst time, using gamma rays, we are able to rule out models with the most generic cross section (~ 3 X 10-26 cm3s-1 for a purely s-wave cross section), without assuming additional boost factors.« less

  17. Detection of the pulsar wind nebula HESS J1825-137 with the Fermi Large Area Telescope

    DOE PAGES

    Grondin, M. -H.; Funk, S.; Lemoine-Goumard, M.; ...

    2011-08-10

    Here, we announce the discovery of 1-100 GeV gamma-ray emission from the archetypal TeV pulsar wind nebula (PWN) HESS J1825–137 using 20 months of survey data from the Fermi-Large Area Telescope (LAT). The gamma-ray emission detected by the LAT is significantly spatially extended, with a best-fit rms extension of σ = 0°.56 ± 0°.07 for an assumed Gaussian model. The 1-100 GeV LAT spectrum of this source is well described by a power law with a spectral index of 1.38 ± 0.12 ± 0.16 and an integral flux above 1 GeV of (6.50 ± 0.21 ± 3.90) × 10–9 cm–2more » s–1. The first errors represent the statistical errors on the fit parameters, while the second ones are the systematic uncertainties. Detailed morphological and spectral analyses bring new constraints on the energetics and magnetic field of the PWN system. As a result, the spatial extent and hard spectrum of the GeV emission are consistent with the picture of an inverse Compton origin of the GeV-TeV emission in a cooling-limited nebula powered by the pulsar PSR J1826–1334.« less

  18. Inferred Cosmic-Ray Spectrum from Fermi Large Area Telescope γ -Ray Observations of Earth’s Limb

    DOE PAGES

    Ackermann, M.; Ajello, M.; Albert, A.; ...

    2014-04-17

    Accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA recently reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly discovered features may offer a clue to the origin of high-energy CRs. Here, we use the Fermi Large Area Telescope observations of the γ -ray emission from Earth’s limb for an indirect measurement of the local spectrum of CR protons in the energy range ~ 90 GeV –more » 6 TeV (derived from a photon energy range 15 GeV–1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68 ± 0.04 and 2.61 ± 0.08 above ~ 200 GeV , respectively.« less

  19. Optical archival spectra of blazar candidates of uncertain type in the 3rd Fermi Large Area Telescope Catalog

    NASA Astrophysics Data System (ADS)

    Álvarez Crespo, N.; Massaro, F.; D'Abrusco, R.; Landoni, M.; Masetti, N.; Chavushyan, V.; Jiménez-Bailón, E.; La Franca, F.; Milisavljevic, D.; Paggi, A.; Patiño-Álvarez, V.; Ricci, F.; Smith, Howard A.

    2016-09-01

    Despite the fact that blazars constitute the rarest class among active galactic nuclei (AGNs) they are the largest known population of associated γ-ray sources. Many of the γ-ray objects listed in the Fermi-Large Area Telescope Third Source catalog (3FGL) are classified as blazar candidates of uncertain type (BCUs), either because they show multifrequency behavior similar to blazars but lacking optical spectra in the literature, or because the quality of such spectra is too low to confirm their nature. Here we select, out of 585 BCUs in the 3FGL, 42 BCUs which we identify as probable blazars by their WISE infrared colors and which also have optical spectra that are available in the Sloan Digital Sky Survey (SDSS) and/or Six-Degree Field Galaxy Survey Database (6dFGS). We confirm the blazar nature of all of the sources. We furthermore conclude that 28 of them are BL Lacs, 8 are radio-loud quasars with flat radio spectrum and 6 are BL Lac whose emission is dominated by their host galaxy.

  20. Fermi-Large Area Telescope Observations of the Exceptional Gamma-Ray Flare from 3C 279 in 2015 June

    NASA Astrophysics Data System (ADS)

    Paliya, Vaidehi S.

    2015-08-01

    An exceptional γ-ray outburst from 3C 279 was detected by the Fermi-Large Area Telescope (LAT) in 2015 June. In the energy range of 0.1-300 GeV, the highest flux measured is (39.1 ± 2.5) × 10-6 {ph} {{cm}}-2 {{{s}}}-1, which is the highest γ-ray flux ever detected from 3C 279, exceeding the previous historically brightest flare observed by EGRET in 1996. The high activity period consists of three major flares with the last one being the brightest. All but one flare show a faster rise and slower decay pattern, and at the peak of the activity, the γ-ray spectrum is found to show a clear signature of break/curvature. The obtained spectral parameters hint that the peak of the inverse Compton emission lies in the LAT energy range (around ˜1 GeV), which is in contrast to that seen during the 2013 December and 2014 April γ-ray flares of 3C 279. From the γγ pair opacity arguments, the minimum Doppler factor is estimated to be 14, and the location of the γ-ray emitting region is found to be either at the outer edge of the broad line region or farther out from it.

  1. Observations of the young supernova remnant RX J1713.7–3946 with the Fermi Large Area Telescope

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2011-05-23

    Here, we present observations of the young supernova remnant (SNR) RX J1713.7–3946 with the Fermi Large Area Telescope (LAT). We clearly detect a source positionally coincident with the SNR. The source is extended with a best-fit extension of 0°.55 ± 0°.04 matching the size of the non-thermal X-ray and TeV gamma-ray emission from the remnant. The positional coincidence and the matching extended emission allow us to identify the LAT source with SNR RX J1713.7–3946. The spectrum of the source can be described by a very hard power law with a photon index of Γ = 1.5 ± 0.1 that coincidesmore » in normalization with the steeper H.E.S.S.-detected gamma-ray spectrum at higher energies. The broadband gamma-ray emission is consistent with a leptonic origin as the dominant mechanism for the gamma-ray emission.« less

  2. Detection of the pulsar wind nebula HESS J1825-137 with the Fermi Large Area Telescope

    SciTech Connect

    Grondin, M. -H.; Funk, S.; Lemoine-Goumard, M.; Van Etten, A.; Hinton, J. A.; Camilo, F.; Cognard, I.; Espinoza, C. M.; Freire, P. C. C.; Grove, J. E.; Guillemot, L.; Johnston, S.; Kramer, M.; Lande, J.; Michelson, P.; Possenti, A.; Romani, R. W.; Skilton, J. L.; Theureau, G.; Weltevrede, P.

    2011-08-10

    Here, we announce the discovery of 1-100 GeV gamma-ray emission from the archetypal TeV pulsar wind nebula (PWN) HESS J1825–137 using 20 months of survey data from the Fermi-Large Area Telescope (LAT). The gamma-ray emission detected by the LAT is significantly spatially extended, with a best-fit rms extension of σ = 0°.56 ± 0°.07 for an assumed Gaussian model. The 1-100 GeV LAT spectrum of this source is well described by a power law with a spectral index of 1.38 ± 0.12 ± 0.16 and an integral flux above 1 GeV of (6.50 ± 0.21 ± 3.90) × 10–9 cm–2 s–1. The first errors represent the statistical errors on the fit parameters, while the second ones are the systematic uncertainties. Detailed morphological and spectral analyses bring new constraints on the energetics and magnetic field of the PWN system. As a result, the spatial extent and hard spectrum of the GeV emission are consistent with the picture of an inverse Compton origin of the GeV-TeV emission in a cooling-limited nebula powered by the pulsar PSR J1826–1334.

  3. DETECTION OF THE PULSAR WIND NEBULA HESS J1825-137 WITH THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Grondin, M.-H.; Lemoine-Goumard, M.; Hinton, J. A.; Camilo, F.; Cognard, I.; Theureau, G.; Freire, P. C. C.; Guillemot, L.; Grove, J. E.; Johnston, S.; Possenti, A.; Skilton, J. L. E-mail: lemoine@cenbg.in2p3.fr E-mail: ave@stanford.edu

    2011-09-01

    We announce the discovery of 1-100 GeV gamma-ray emission from the archetypal TeV pulsar wind nebula (PWN) HESS J1825-137 using 20 months of survey data from the Fermi-Large Area Telescope (LAT). The gamma-ray emission detected by the LAT is significantly spatially extended, with a best-fit rms extension of {sigma} = 0.{sup 0}56 {+-} 0.{sup 0}07 for an assumed Gaussian model. The 1-100 GeV LAT spectrum of this source is well described by a power law with a spectral index of 1.38 {+-} 0.12 {+-} 0.16 and an integral flux above 1 GeV of (6.50 {+-} 0.21 {+-} 3.90) x 10{sup -9} cm{sup -2} s{sup -1}. The first errors represent the statistical errors on the fit parameters, while the second ones are the systematic uncertainties. Detailed morphological and spectral analyses bring new constraints on the energetics and magnetic field of the PWN system. The spatial extent and hard spectrum of the GeV emission are consistent with the picture of an inverse Compton origin of the GeV-TeV emission in a cooling-limited nebula powered by the pulsar PSR J1826-1334.

  4. Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cañadas, B.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Digel, S. W.; Do Couto E Silva, E.; Drell, P. S.; Drlica-Wagner, A.; Falletti, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hayashida, M.; Hays, E.; Hughes, R. E.; Jeltema, T. E.; Jóhannesson, G.; Johnson, R. P.; Johnson, A. S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lionetto, A. M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Naumann-Godo, M.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Parent, D.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Porter, T. A.; Profumo, S.; Rainò, S.; Razzano, M.; Reimer, A.; Reimer, O.; Ritz, S.; Roth, M.; Sadrozinski, H. F.-W.; Sbarra, C.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Strigari, L.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Troja, E.; Uchiyama, Y.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Wood, M.; Yang, Z.; Zimmer, S.; Kaplinghat, M.; Martinez, G. D.

    2011-12-01

    Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10-26cm3s-1 at 5 GeV to about 5×10-23cm3s-1 at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section (˜3×10-26cm3s-1 for a purely s-wave cross section), without assuming additional boost factors.

  5. Search for Cosmic-Ray Electron and Positron Anisotropies with Seven Years of Fermi Large Area Telescope Data

    NASA Astrophysics Data System (ADS)

    Abdollahi, S.; Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bellazzini, R.; Bissaldi, E.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bruel, P.; Buson, S.; Caragiulo, M.; Cavazzuti, E.; Chekhtman, A.; Ciprini, S.; Costanza, F.; Cuoco, A.; Cutini, S.; D'Ammando, F.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Donaggio, B.; Drell, P. S.; Favuzzi, C.; Focke, W. B.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Green, D.; Guiriec, S.; Harding, A. K.; Jogler, T.; Jóhannesson, G.; Kamae, T.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Longo, F.; Loparco, F.; Lubrano, P.; Magill, J. D.; Malyshev, D.; Manfreda, A.; Mazziotta, M. N.; Meehan, M.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Negro, M.; Nuss, E.; Ohsugi, T.; Omodei, N.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Principe, G.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Sgrò, C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Strong, A. W.; Tajima, H.; Thayer, J. B.; Torres, D. F.; Troja, E.; Vandenbroucke, J.; Zaharijas, G.; Zimmer, S.; Fermi-LAT Collaboration

    2017-03-01

    The Large Area Telescope on board the Fermi Gamma-ray Space Telescope has collected the largest ever sample of high-energy cosmic-ray electron and positron events since the beginning of its operation. Potential anisotropies in the arrival directions of cosmic-ray electrons or positrons could be a signature of the presence of nearby sources. We use almost seven years of data with energies above 42 GeV processed with the Pass 8 reconstruction. The present data sample can probe dipole anisotropies down to a level of 10-3 . We take into account systematic effects that could mimic true anisotropies at this level. We present a detailed study of the event selection optimization of the cosmic-ray electrons and positrons to be used for anisotropy searches. Since no significant anisotropies have been detected on any angular scale, we present upper limits on the dipole anisotropy. The present constraints are among the strongest to date probing the presence of nearby young and middle-aged sources.

  6. Inferred cosmic-ray spectrum from Fermi large area telescope γ-ray observations of Earth's limb.

    PubMed

    Ackermann, M; Ajello, M; Albert, A; Allafort, A; Baldini, L; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Blandford, R D; Bloom, E D; Bonamente, E; Bottacini, E; Bouvier, A; Brandt, T J; Brigida, M; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Cecchi, C; Charles, E; Chaves, R C G; Chekhtman, A; Chiang, J; Chiaro, G; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Cutini, S; Dalton, M; D'Ammando, F; de Angelis, A; de Palma, F; Dermer, C D; Digel, S W; Di Venere, L; do Couto e Silva, E; Drell, P S; Drlica-Wagner, A; Favuzzi, C; Fegan, S J; Ferrara, E C; Focke, W B; Franckowiak, A; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Gomez-Vargas, G A; Grenier, I A; Grove, J E; Guiriec, S; Gustafsson, M; Hadasch, D; Hanabata, Y; Harding, A K; Hayashida, M; Hayashi, K; Hewitt, J W; Horan, D; Hou, X; Hughes, R E; Inoue, Y; Jackson, M S; Jogler, T; Jóhannesson, G; Johnson, A S; Kamae, T; Kawano, T; Knödlseder, J; Kuss, M; Lande, J; Larsson, S; Latronico, L; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Mayer, M; Mazziotta, M N; McEnery, J E; Mehault, J; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nemmen, R; Nuss, E; Ohsugi, T; Okumura, A; Orienti, M; Orlando, E; Ormes, J F; Paneque, D; Panetta, J H; Perkins, J S; Pesce-Rollins, M; Piron, F; Pivato, G; Porter, T A; Rainò, S; Rando, R; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Ritz, S; Roth, M; Schaal, M; Schulz, A; Sgrò, C; Siskind, E J; Spandre, G; Spinelli, P; Strong, A W; Takahashi, H; Takeuchi, Y; Thayer, J G; Thayer, J B; Thompson, D J; Tibaldo, L; Tinivella, M; Torres, D F; Tosti, G; Troja, E; Tronconi, V; Usher, T L; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Werner, M; Winer, B L; Wood, K S; Wood, M; Yang, Z

    2014-04-18

    Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the γ-ray emission from Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range ∼90  GeV-6  TeV (derived from a photon energy range 15 GeV-1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68±0.04 and 2.61±0.08 above ∼200  GeV, respectively.

  7. Observations of M31 and M33 with the Fermi Large Area Telescope: A Galactic Center Excess in Andromeda?

    DOE PAGES

    Ackermann, M.; Ajello, M.; Albert, A.; ...

    2017-02-23

    We report the Fermi Large Area Telescope (LAT) has opened the way for comparative studies of cosmic rays (CRs) and high-energy objects in the Milky Way (MW) and in other, external, star-forming galaxies. Using 2 yr of observations with the Fermi LAT, Local Group galaxy M31 was detected as a marginally extended gamma-ray source, while only an upper limit has been derived for the other nearby galaxy M33. We revisited the gamma-ray emission in the direction of M31 and M33 using more than 7 yr of LAT Pass 8 data in the energy rangemore » $$0.1\\mbox{--}100\\,\\mathrm{GeV}$$, presenting detailed morphological and spectral analyses. M33 remains undetected, and we computed an upper limit of $$2.0\\times {10}^{-12}\\,\\mathrm{erg}\\,{\\mathrm{cm}}^{-2}\\,{{\\rm{s}}}^{-1}\\,$$ on the $$0.1\\mbox{--}100\\,\\mathrm{GeV}$$ energy flux (95% confidence level). This revised upper limit remains consistent with the observed correlation between gamma-ray luminosity and star formation rate tracers and implies an average CR density in M33 that is at most half of that of the MW. M31 is detected with a significance of nearly $$10\\sigma $$. Its spectrum is consistent with a power law with photon index $${\\rm{\\Gamma }}=2.4\\pm {0.1}_{\\mathrm{stat}+\\mathrm{syst}}$$ and a $$0.1\\mbox{--}100\\,\\mathrm{GeV}$$ energy flux of $$(5.6\\pm {0.6}_{\\mathrm{stat}+\\mathrm{syst}})\\times {10}^{-12}\\,\\mathrm{erg}\\,{\\mathrm{cm}}^{-2}\\,{{\\rm{s}}}^{-1}$$. M31 is detected to be extended with a $$4\\sigma $$ significance. The spatial distribution of the emission is consistent with a uniform-brightness disk with a radius of 0fdg4 and no offset from the center of the galaxy, but nonuniform intensity distributions cannot be excluded. The flux from M31 appears confined to the inner regions of the galaxy and does not fill the disk of the galaxy or extend far from it. The gamma-ray signal is not correlated with regions rich in gas or star formation activity, which suggests that the emission is not

  8. The First Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cannon, A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Çelik, Ö.; Celotti, A.; Charles, E.; Chekhtman, A.; Chen, A. W.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Costamante, L.; Cotter, G.; Cutini, S.; D'Elia, V.; Dermer, C. D.; de Angelis, A.; de Palma, F.; De Rosa, A.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Escande, L.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grandi, P.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hayashida, M.; Hays, E.; Healey, S. E.; Hill, A. B.; Horan, D.; Hughes, R. E.; Iafrate, G.; Itoh, R.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lavalley, C.; Lemoine-Goumard, M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Malaguti, G.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; McGlynn, S.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piranomonte, S.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ripken, J.; Ritz, S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Sgrò, C.; Shaw, M. S.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J.-L.; Stawarz, Ł.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Taylor, G. B.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Ubertini, P.; Uchiyama, Y.; Usher, T. L.; Vasileiou, V.; Vilchez, N.; Villata, M.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ylinen, T.; Ziegler, M.

    2010-05-01

    We present the first catalog of active galactic nuclei (AGNs) detected by the Large Area Telescope (LAT), corresponding to 11 months of data collected in scientific operation mode. The First LAT AGN Catalog (1LAC) includes 671 γ-ray sources located at high Galactic latitudes (|b|>10°) that are detected with a test statistic greater than 25 and associated statistically with AGNs. Some LAT sources are associated with multiple AGNs, and consequently, the catalog includes 709 AGNs, comprising 300 BL Lacertae objects, 296 flat-spectrum radio quasars, 41 AGNs of other types, and 72 AGNs of unknown type. We also classify the blazars based on their spectral energy distributions as archival radio, optical, and X-ray data permit. In addition to the formal 1LAC sample, we provide AGN associations for 51 low-latitude LAT sources and AGN "affiliations" (unquantified counterpart candidates) for 104 high-latitude LAT sources without AGN associations. The overlap of the 1LAC with existing γ-ray AGN catalogs (LBAS, EGRET, AGILE, Swift, INTEGRAL, TeVCat) is briefly discussed. Various properties—such as γ-ray fluxes and photon power-law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities—and their correlations are presented and discussed for the different blazar classes. We compare the 1LAC results with predictions regarding the γ-ray AGN populations, and we comment on the power of the sample to address the question of the blazar sequence.

  9. The first catalog of active galactic nuclei detected by the FERMI large area telescope

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2010-04-29

    Here, we present the first catalog of active galactic nuclei (AGNs) detected by the Large Area Telescope (LAT), corresponding to 11 months of data collected in scientific operation mode. The First LAT AGN Catalog (1LAC) includes 671 γ-ray sources located at high Galactic latitudes (|b|>10°) that are detected with a test statistic greater than 25 and associated statistically with AGNs. Some LAT sources are associated with multiple AGNs, and consequently, the catalog includes 709 AGNs, comprising 300 BL Lacertae objects, 296 flat-spectrum radio quasars, 41 AGNs of other types, and 72 AGNs of unknown type. We also classify the blazarsmore » based on their spectral energy distributions as archival radio, optical, and X-ray data permit. In addition to the formal 1LAC sample, we provide AGN associations for 51 low-latitude LAT sources and AGN "affiliations" (unquantified counterpart candidates) for 104 high-latitude LAT sources without AGN associations. The overlap of the 1LAC with existing γ-ray AGN catalogs (LBAS, EGRET, AGILE, Swift, INTEGRAL, TeVCat) is briefly discussed. Various properties—such as γ-ray fluxes and photon power-law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities—and their correlations are presented and discussed for the different blazar classes. Lastly, we compare the 1LAC results with predictions regarding the γ-ray AGN populations, and we comment on the power of the sample to address the question of the blazar sequence.« less

  10. Fermi Large Area Telescope detection of a break in the gamma-ray spectrum of the supernova remnant Cassiopeia A [Fermi-LAT detection of a break in the gamma-ray spectrum of the supernova remnant Cassiopeia A

    DOE PAGES

    Yuan, Yajie; Funk, Stefan; Jóhannesson, Gülauger; ...

    2013-12-02

    Here, we report on observations of the supernova remnant Cassiopeia A in the energy range from 100 MeV to 100 GeV using 44 months of observations from the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope. We perform a detailed spectral analysis of this source and report on a low-energy break in the spectrum atmore » $$1.72^{+1.35}_{-0.89}$$ GeV. By comparing the results with models for the gamma-ray emission, we find that hadronic emission is preferred for the GeV energy range.« less

  11. Search for Extended Sources in the Galactic Plane Using Six Years of Fermi-Large Area Telescope Pass 8 Data above 10 GeV

    DOE PAGES

    Ackermann, M.; Ajello, M.; Baldini, L.; ...

    2017-07-10

    The spatial extension of a γ-ray source is an essential ingredient to determine its spectral properties, as well as its potential multiwavelength counterpart. The capability to spatially resolve γ-ray sources is greatly improved by the newly delivered Fermi-Large Area Telescope (LAT) Pass 8 event-level analysis, which provides a greater acceptance and an improved point-spread function, two crucial factors for the detection of extended sources. Here, we present a complete search for extended sources located within 7° from the Galactic plane, using 6 yr of Fermi-LAT data above 10 GeV. We find 46 extended sources and provide their morphological and spectralmore » characteristics. As a result, this constitutes the first catalog of hard Fermi-LAT extended sources, named the Fermi Galactic Extended Source Catalog, which allows a thorough study of the properties of the Galactic plane in the sub-TeV domain.« less

  12. Search for gamma-ray emission from dark matter annihilation in the large magellanic cloud with the fermi large area telescope

    DOE PAGES

    Buckley, Matthew R.; Charles, Eric; Gaskins, Jennifer M.; ...

    2015-05-05

    At a distance of 50 kpc and with a dark matter mass of ~1010 M⊙, the large magellanic cloud (LMC) is a natural target for indirect dark matter searches. We use five years of data from the Fermi Large Area Telescope (LAT) and updated models of the gamma-ray emission from standard astrophysical components to search for a dark matter annihilation signal from the LMC. We perform a rotation curve analysis to determine the dark matter distribution, setting a robust minimum on the amount of dark matter in the LMC, which we use to set conservative bounds on the annihilation cross section.more » The LMC emission is generally very well described by the standard astrophysical sources, with at most a 1–2σ excess identified near the kinematic center of the LMC once systematic uncertainties are taken into account. As a result, we place competitive bounds on the dark matter annihilation cross section as a function of dark matter particle mass and annihilation channel.« less

  13. Search for gamma-ray emission from dark matter annihilation in the large magellanic cloud with the fermi large area telescope

    SciTech Connect

    Buckley, Matthew R.; Charles, Eric; Gaskins, Jennifer M.; Brooks, Alyson M.; Drlica-Wagner, Alex; Martin, Pierrick; Zhao, Geng

    2015-05-05

    At a distance of 50 kpc and with a dark matter mass of ~1010 M, the large magellanic cloud (LMC) is a natural target for indirect dark matter searches. We use five years of data from the Fermi Large Area Telescope (LAT) and updated models of the gamma-ray emission from standard astrophysical components to search for a dark matter annihilation signal from the LMC. We perform a rotation curve analysis to determine the dark matter distribution, setting a robust minimum on the amount of dark matter in the LMC, which we use to set conservative bounds on the annihilation cross section. The LMC emission is generally very well described by the standard astrophysical sources, with at most a 1–2σ excess identified near the kinematic center of the LMC once systematic uncertainties are taken into account. As a result, we place competitive bounds on the dark matter annihilation cross section as a function of dark matter particle mass and annihilation channel.

  14. Pulsed Gamma-Rays From the Millisecond Pulsar J0030+0451 with the Fermi Large Area Telescope

    SciTech Connect

    Abdo, Aous A.; Ackermann, M.; Atwood, W.B.; Axelsson, M. Baldini, L.; Ballet, J.; Barbiellini, Guido; Bastieri, Denis; Battelino, M.; Baughman, B.M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, Elliott D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, Thompson H.; /more authors..

    2011-11-17

    We report the discovery of gamma-ray pulsations from the nearby isolated millisecond pulsar PSR J0030+0451 with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). This discovery makes PSR J0030+0451 the second millisecond pulsar to be detected in gamma-rays after PSR J0218+4232, observed by the EGRET instrument on the Compton Gamma Ray Observatory. The spin-down power {dot E} = 3.5 x 10{sup 33} ergs s{sup -1} is an order of magnitude lower than the empirical lower bound of previously known gamma-ray pulsars. The emission profile is characterized by two narrow peaks, respectively 0.07 {+-} 0.01 and 0.08 {+-} 0.02 wide, separated by 0.44 {+-} 0.02 in phase. The first gamma-ray peak falls 0.15 {+-} 0.01 after the main radio peak. The pulse shape is similar to that of the 'normal' gamma-ray pulsars. An exponentially cut-off power-law fit of the emission spectrum leads to an integral photon flux above 100 MeV of (6.76 {+-} 1.05 {+-} 1.35) x 10{sup -8} cm{sup -2} s{sup -1} with cut-off energy (1.7 {+-} 0.4 {+-} 0.5) GeV. Based on its parallax distance of (300 {+-} 90) pc, we obtain a gamma-ray efficiency L{sub {gamma}}/{dot E} {approx_equal} 15% for the conversion of spin-down energy rate into gamma-ray radiation, assuming isotropic emission.

  15. Fermi Large Area Telescope Detection of Extended Gamma-Ray Emission from the Radio Galaxy Fornax A

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiaro, G.; Ciprini, S.; Cohen, J. M.; Cohen-Tanugi, J.; Costanza, F.; Cutini, S.; D'Ammando, F.; Davis, D. S.; de Angelis, A.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Georganopoulos, M.; Giglietto, N.; Giordano, F.; Giroletti, M.; Godfrey, G.; Green, D.; Grenier, I. A.; Guiriec, S.; Hays, E.; Hewitt, J. W.; Hill, A. B.; Jogler, T.; Jóhannesson, G.; Kensei, S.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lubrano, P.; Magill, J. D.; Maldera, S.; Manfreda, A.; Mayer, M.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Negro, M.; Nuss, E.; Ohno, M.; Ohsugi, T.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Schmid, J.; Sgrò, C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Stawarz, Ł.; Takahashi, H.; Thayer, J. B.; Thompson, D. J.; Torres, D. F.; Tosti, G.; Troja, E.; Vianello, G.; Wood, K. S.; Wood, M.; Zimmer, S.; Fermi LAT Collaboration

    2016-07-01

    We report the Fermi Large Area Telescope detection of extended γ-ray emission from the lobes of the radio galaxy Fornax A using 6.1 years of Pass 8 data. After Centaurus A, this is now the second example of an extended γ-ray source attributed to a radio galaxy. Both an extended flat disk morphology and a morphology following the extended radio lobes were preferred over a point-source description, and the core contribution was constrained to be < 14% of the total γ-ray flux. A preferred alignment of the γ-ray elongation with the radio lobes was demonstrated by rotating the radio lobes template. We found no significant evidence for variability on ˜0.5 year timescales. Taken together, these results strongly suggest a lobe origin for the γ-rays. With the extended nature of the > 100 MeV γ-ray emission established, we model the source broadband emission considering currently available total lobe radio and millimeter flux measurements, as well as X-ray detections attributed to inverse Compton (IC) emission off the cosmic microwave background (CMB). Unlike the Centaurus A case, we find that a leptonic model involving IC scattering of CMB and extragalactic background light (EBL) photons underpredicts the γ-ray fluxes by factors of about ˜2-3, depending on the EBL model adopted. An additional γ-ray spectral component is thus required, and could be due to hadronic emission arising from proton-proton collisions of cosmic rays with thermal plasma within the radio lobes.

  16. Searching for dwarf spheroidal galaxies and other galactic dark matter substructures with the Fermi large area telescope

    SciTech Connect

    Drlica-Wagner, Alex

    2013-08-01

    Over the past century, it has become clear that about a quarter of the known universe is composed of an invisible, massive component termed ''dark matter''. Some of the most popular theories of physics beyond the Standard Model suggest that dark matter may be a new fundamental particle that could self-annihilate to produce γ rays. Nearby over-densities in the dark matter halo of our Milky Way present some of the most promising targets for detecting the annihilation of dark matter. We used the Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope to search for γ rays produced by dark matter annihilation in Galactic dark matter substructures. We searched for γ-ray emission coincident with Milky Way dwarf spheroidal satellite galaxies, which trace the most massive Galactic dark matter substructures. We also sought to identify nearby dark matter substructures that lack all astrophysical tracers and would be detectable only through γ-ray emission from dark matter annihilation. We found no conclusive evidence for γ-ray emission from dark matter annihilation, and we set stringent and robust constraints on the dark matter annihilation cross section. While γ-ray searches for dark matter substructure are currently the most sensitive and robust probes of dark matter annihilation, they are just beginning to intersect the theoretically preferred region of dark matter parameter space. Thus, we consider future prospects for increasing the sensitivity of γ-ray searches through improvements to the LAT instrument performance and through upcoming wide- field optical surveys.

  17. Fermi large area telescope detection of extended gamma-ray emission from the radio galaxy fornax A

    SciTech Connect

    Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiaro, G.; Ciprini, S.; Cohen, J. M.; Cohen-Tanugi, J.; Costanza, F.; Cutini, S.; D’Ammando, F.; Davis, D. S.; Angelis, A. de; Palma, F. de; Desiante, R.; Digel, S. W.; Lalla, N. Di; Mauro, M. Di; Venere, L. Di; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Georganopoulos, M.; Giglietto, N.; Giordano, F.; Giroletti, M.; Godfrey, G.; Green, D.; Grenier, I. A.; Guiriec, S.; Hays, E.; Hewitt, J. W.; Hill, A. B.; Jogler, T.; Jóhannesson, G.; Kensei, S.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lubrano, P.; Magill, J. D.; Maldera, S.; Manfreda, A.; Mayer, M.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Negro, M.; Nuss, E.; Ohno, M.; Ohsugi, T.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Schmid, J.; Sgrò, C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Stawarz, Ł.; Takahashi, H.; Thayer, J. B.; Thompson, D. J.; Torres, D. F.; Tosti, G.; Troja, E.; Vianello, G.; Wood, K. S.; Wood, M.; Zimmer, S.

    2016-07-14

    Here, we report the Fermi Large Area Telescope detection of extended γ-ray emission from the lobes of the radio galaxy Fornax A using 6.1 years of Pass 8 data. After Centaurus A, this is now the second example of an extended γ-ray source attributed to a radio galaxy. Both an extended flat disk morphology and a morphology following the extended radio lobes were preferred over a point-source description, and the core contribution was constrained to be $\\lt 14$% of the total γ-ray flux. We also demonstrated a preferred alignment of the γ-ray elongation with the radio lobes by rotating the radio lobes template. We found no significant evidence for variability on ~0.5 year timescales. Taken together, these results strongly suggest a lobe origin for the γ-rays. Furthermore, with the extended nature of the $\\gt 100\\;{\\rm{MeV}}$ γ-ray emission established, we model the source broadband emission considering currently available total lobe radio and millimeter flux measurements, as well as X-ray detections attributed to inverse Compton (IC) emission off the cosmic microwave background (CMB). Unlike the Centaurus A case, we find that a leptonic model involving IC scattering of CMB and extragalactic background light (EBL) photons underpredicts the γ-ray fluxes by factors of about ~2–3, depending on the EBL model adopted. An additional γ-ray spectral component is thus required, and could be due to hadronic emission arising from proton–proton collisions of cosmic rays with thermal plasma within the radio lobes.

  18. DISCOVERY OF NINE GAMMA-RAY PULSARS IN FERMI LARGE AREA TELESCOPE DATA USING A NEW BLIND SEARCH METHOD

    SciTech Connect

    Pletsch, H. J.; Allen, B.; Aulbert, C.; Fehrmann, H.; Guillemot, L.; Kramer, M.; Barr, E. D.; Champion, D. J.; Eatough, R. P.; Freire, P. C. C.; Ray, P. S.; Belfiore, A.; Dormody, M.; Camilo, F.; Caraveo, P. A.; Celik, Oe.; Ferrara, E. C.; Hessels, J. W. T.; Keith, M.; Kerr, M. E-mail: guillemo@mpifr-bonn.mpg.de; and others

    2012-01-10

    We report the discovery of nine previously unknown gamma-ray pulsars in a blind search of data from the Fermi Large Area Telescope (LAT). The pulsars were found with a novel hierarchical search method originally developed for detecting continuous gravitational waves from rapidly rotating neutron stars. Designed to find isolated pulsars spinning at up to kHz frequencies, the new method is computationally efficient and incorporates several advances, including a metric-based gridding of the search parameter space (frequency, frequency derivative, and sky location) and the use of photon probability weights. The nine pulsars have spin frequencies between 3 and 12 Hz, and characteristic ages ranging from 17 kyr to 3 Myr. Two of them, PSRs J1803-2149 and J2111+ 4606, are young and energetic Galactic-plane pulsars (spin-down power above 6 Multiplication-Sign 10{sup 35} erg s{sup -1} and ages below 100 kyr). The seven remaining pulsars, PSRs J0106+4855, J0622+3749, J1620-4927, J1746-3239, J2028+3332, J2030+4415, and J2139+4716, are older and less energetic; two of them are located at higher Galactic latitudes (|b| > 10 Degree-Sign ). PSR J0106+4855 has the largest characteristic age (3 Myr) and the smallest surface magnetic field (2 Multiplication-Sign 10{sup 11} G) of all LAT blind-search pulsars. PSR J2139+4716 has the lowest spin-down power (3 Multiplication-Sign 10{sup 33} erg s{sup -1}) among all non-recycled gamma-ray pulsars ever found. Despite extensive multi-frequency observations, only PSR J0106+4855 has detectable pulsations in the radio band. The other eight pulsars belong to the increasing population of radio-quiet gamma-ray pulsars.

  19. The Second Catalog Of Active Galactic Nuclei Detected By The Fermi Large Area Telescope

    SciTech Connect

    Ackermann, M.

    2011-12-02

    The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years of scientific operation is presented. The Second LAT AGN Catalog (2LAC) includes 1017 γ-ray sources located at high Galactic latitudes (|b| > 10°) that are detected with a test statistic (TS) greater than 25 and associated statistically with AGNs. However some of these are affected by analysis issues and some are associated with multiple AGNs. Consequently we define a clean sample which includes 886 AGNs, comprising 395 BL Lacertae objects (BL Lacs), 310 flat-spectrum radio quasars (FSRQs), 157 candidate blazars of unknown type (i.e., with broad-band blazar characteristics but with no optical spectral measurement yet), eight misaligned AGNs, four narrow-line Seyfert 1 (NLS1s), 10 AGNs of other types and two starburst galaxies. Where possible, the blazars have been further classified based on their spectral energy distributions (SEDs) as archival radio, optical, and X-ray data permit. While almost all FSRQs have a synchrotron-peak frequency < 1014 Hz, about half of the BL Lacs have a synchrotron-peak frequency > 1015 Hz. The 2LAC represents a significant improvement relative to the First LAT AGN Catalog (1LAC), with 52% more associated sources. The full characterization of the newly detected sources will require more broad-band data. Various properties, such as γ-ray fluxes and photon power law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities—and their correlations are presented and discussed for the different blazar classes. The general trends observed in 1LAC are confirmed.

  20. Fermi large area telescope detection of extended gamma-ray emission from the radio galaxy fornax A

    DOE PAGES

    Ackermann, M.; Ajello, M.; Baldini, L.; ...

    2016-07-14

    Here, we report the Fermi Large Area Telescope detection of extended γ-ray emission from the lobes of the radio galaxy Fornax A using 6.1 years of Pass 8 data. After Centaurus A, this is now the second example of an extended γ-ray source attributed to a radio galaxy. Both an extended flat disk morphology and a morphology following the extended radio lobes were preferred over a point-source description, and the core contribution was constrained to bemore » $$\\lt 14$$% of the total γ-ray flux. We also demonstrated a preferred alignment of the γ-ray elongation with the radio lobes by rotating the radio lobes template. We found no significant evidence for variability on ~0.5 year timescales. Taken together, these results strongly suggest a lobe origin for the γ-rays. Furthermore, with the extended nature of the $$\\gt 100\\;{\\rm{MeV}}$$ γ-ray emission established, we model the source broadband emission considering currently available total lobe radio and millimeter flux measurements, as well as X-ray detections attributed to inverse Compton (IC) emission off the cosmic microwave background (CMB). Unlike the Centaurus A case, we find that a leptonic model involving IC scattering of CMB and extragalactic background light (EBL) photons underpredicts the γ-ray fluxes by factors of about ~2–3, depending on the EBL model adopted. An additional γ-ray spectral component is thus required, and could be due to hadronic emission arising from proton–proton collisions of cosmic rays with thermal plasma within the radio lobes.« less

  1. Resolving the Extragalactic γ-Ray Background above 50 GeV with the Fermi Large Area Telescope

    DOE PAGES

    Ackermann, M.; Ajello, M.; Albert, A.; ...

    2016-04-14

    The Fermi Large Area Telescope (LAT) Collaboration has recently released a catalog of 360 sources detected above 50 GeV (2FHL). This catalog was obtained using 80 months of data re-processed with Pass 8, the newest event-level analysis, which significantly improves the acceptance and angular resolution of the instrument. Most of the 2FHL sources at high Galactic latitude are blazars. In this paper, using detailed Monte Carlo simulations, we measure, for the first time, the source count distribution, dN/dS, of extragalactic γ-ray sources at E > 50 GeV and find that it is compatible with a Euclidean distribution down to the lowest measured source flux in the 2FHL (~8 x 10-12 ph cm-2s-1). We employ a one-point photon fluctuation analysis to constrain the behavior of dN/dS below the source detection threshold. Overall, the source count distribution is constrained over three decades in flux and found compatible with a broken power law with a break flux, Sb, in the range [8 x 10-12, 1.5 x 10-11] ph cm-2s-1 and power-law indices below and above the break of α2 ϵ [1.60, 1.75] and α1 = 2.49 ± 0.12, respectively. Integration of dN/dS shows that point sources account for at least 86more » $$+16\\atop{-14}$$ % of the total extragalactic γ-ray background. The simple form of the derived source count distribution is consistent with a single population (i.e., blazars) dominating the source counts to the minimum flux explored by this analysis. Finally, we estimate the density of sources detectable in blind surveys that will be performed in the coming years by the Cherenkov Telescope Array.« less

  2. Pulsed Gamma Rays from the Millisecond Pulsar J0030+0451 with the Fermi Large Area Telescope

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Battelino, M.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cognard, I.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Digel, S. W.; Dormody, M.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocian, M. L.; Komin, N.; Kuehn, F.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S. -H.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Marelli, M.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Pancrazi, B.; Paneque, D.; Panetta, J. H.; Parent, D.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rochester, L. S.; Rodriguez, A. Y.; Romani, R. W.; Ryde, F.; Sadrozinski, H. F. -W.; Sanchez, D.; Sander, A.; Parkinson, P. M. Saz; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J. -L.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Theureau, G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Van Etten, A.; Vilchez, N.; Vitale, V.; Waite, A. P.; Watters, K.; Webb, N.; Wood, K. S.; Ylinen, T.; Ziegler, M.

    2009-06-19

    In this paper, we report the discovery of gamma-ray pulsations from the nearby isolated millisecond pulsar (MSP) PSR J0030+0451 with the Large Area Telescope on the Fermi Gamma-ray Space Telescope (formerly GLAST). This discovery makes PSR J0030+0451 the second MSP to be detected in gamma rays after PSR J0218+4232, observed by the EGRET instrument on the Compton Gamma-Ray Observatory. The spin-down power E(dotabove) = 3.5 x 1033 erg s-1 is an order of magnitude lower than the empirical lower bound of previously known gamma-ray pulsars. The emission profile is characterized by two narrow peaks, 0.07 ± 0.01 and 0.08 ± 0.02 wide, respectively, separated by 0.44 ± 0.02 in phase. The first gamma-ray peak falls 0.15 ± 0.01 after the main radio peak. The pulse shape is similar to that of the "normal" gamma-ray pulsars. An exponentially cutoff power-law fit of the emission spectrum leads to an integral photon flux above 100 MeV of (6.76 ± 1.05 ± 1.35) × 10–8 cm–2 s–1 with cutoff energy (1.7 ± 0.4 ± 0.5) GeV. Finally, based on its parallax distance of (300 ± 90) pc, we obtain a gamma-ray efficiency Lγ/E(dotabove) ≃ 15% for the conversion of spin-down energy rate into gamma-ray radiation, assuming isotropic emission.

  3. Resolving the Extragalactic γ -Ray Background above 50 GeV with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bregeon, J.; Britto, R. J.; Bruel, P.; Buehler, R.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Cohen-Tanugi, J.; Cominsky, L. R.; Costanza, F.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Mauro, M.; Di Venere, L.; Domínguez, A.; Drell, P. S.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Godfrey, G.; Green, D.; Grenier, I. A.; Guiriec, S.; Hays, E.; Horan, D.; Iafrate, G.; Jogler, T.; Jóhannesson, G.; Kuss, M.; La Mura, G.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Magill, J.; Maldera, S.; Manfreda, A.; Mayer, M.; Mazziotta, M. N.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Negro, M.; Nuss, E.; Ohsugi, T.; Okada, C.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Romani, R. W.; Sánchez-Conde, M.; Schmid, J.; Schulz, A.; Sgrò, C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Suson, D. J.; Takahashi, H.; Thayer, J. B.; Tibaldo, L.; Torres, D. F.; Troja, E.; Vianello, G.; Yassine, M.; Zimmer, S.

    2016-04-01

    The Fermi Large Area Telescope (LAT) Collaboration has recently released a catalog of 360 sources detected above 50 GeV (2FHL). This catalog was obtained using 80 months of data re-processed with Pass 8, the newest event-level analysis, which significantly improves the acceptance and angular resolution of the instrument. Most of the 2FHL sources at high Galactic latitude are blazars. Using detailed Monte Carlo simulations, we measure, for the first time, the source count distribution, d N /d S , of extragalactic γ -ray sources at E >50 GeV and find that it is compatible with a Euclidean distribution down to the lowest measured source flux in the 2FHL (˜8 ×10-12 ph cm-2 s-1 ). We employ a one-point photon fluctuation analysis to constrain the behavior of d N /d S below the source detection threshold. Overall, the source count distribution is constrained over three decades in flux and found compatible with a broken power law with a break flux, Sb, in the range [8 ×10-12,1.5 ×10-11] ph cm-2 s-1 and power-law indices below and above the break of α2∈[1.60 ,1.75 ] and α1=2.49 ±0.12 , respectively. Integration of d N /d S shows that point sources account for at least 8 6-14+16% of the total extragalactic γ -ray background. The simple form of the derived source count distribution is consistent with a single population (i.e., blazars) dominating the source counts to the minimum flux explored by this analysis. We estimate the density of sources detectable in blind surveys that will be performed in the coming years by the Cherenkov Telescope Array.

  4. Discovery Of Nine Gamma-Ray Pulsars In Fermi Large Area Telescope Data Using A New Blind Search Method

    DOE PAGES

    Pletsch, H. J.; Guillemot, L.; Allen, B.; ...

    2011-12-20

    We report the discovery of nine previously unknown gamma-ray pulsars in a blind search of data from the Fermi Large Area Telescope (LAT). The pulsars were found with a novel hierarchical search method originally developed for detecting continuous gravitational waves from rapidly rotating neutron stars. Designed to find isolated pulsars spinning at up to kHz frequencies, the new method is computationally efficient, and incorporates several advances, including a metric-based gridding of the search parameter space (frequency, frequency derivative and sky location) and the use of photon probability weights. The nine pulsars have spin frequencies between 3 and 12 Hz, andmore » characteristic ages ranging from 17 kyr to 3 Myr. Two of them, PSRs J1803–2149 and J2111+4606, are young and energetic Galactic-plane pulsars (spin-down power above 6X1035 erg s-1 and ages below 100 kyr). The seven remaining pulsars, PSRs J0106+4855, J0622+3749, J1620–4927, J1746–3239, J2028+3332, J2030+4415, J2139+4716, are older and less energetic; two of them are located at higher Galactic latitudes (jbj > 10°). PSR J0106+4855 has the largest characteristic age (3 Myr) and the smallest surface magnetic field (2X1011G) of all LAT blind-search pulsars. PSR J2139+4716 has the lowest spin-down power (3X1033 erg s-1) among all non-recycled gamma-ray pulsars ever found. Despite extensive multi-frequency observations, only PSR J0106+4855 has detectable pulsations in the radio band. The other eight pulsars belong to the increasing population of radio-quiet gamma-ray pulsars.« less

  5. Pulsed Gamma Rays from the Millisecond Pulsar J0030+0451 with the Fermi Large Area Telescope

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Atwood, W. B.; ...

    2009-06-19

    In this paper, we report the discovery of gamma-ray pulsations from the nearby isolated millisecond pulsar (MSP) PSR J0030+0451 with the Large Area Telescope on the Fermi Gamma-ray Space Telescope (formerly GLAST). This discovery makes PSR J0030+0451 the second MSP to be detected in gamma rays after PSR J0218+4232, observed by the EGRET instrument on the Compton Gamma-Ray Observatory. The spin-down power E(dotabove) = 3.5 x 1033 erg s-1 is an order of magnitude lower than the empirical lower bound of previously known gamma-ray pulsars. The emission profile is characterized by two narrow peaks, 0.07 ± 0.01 and 0.08 ±more » 0.02 wide, respectively, separated by 0.44 ± 0.02 in phase. The first gamma-ray peak falls 0.15 ± 0.01 after the main radio peak. The pulse shape is similar to that of the "normal" gamma-ray pulsars. An exponentially cutoff power-law fit of the emission spectrum leads to an integral photon flux above 100 MeV of (6.76 ± 1.05 ± 1.35) × 10–8 cm–2 s–1 with cutoff energy (1.7 ± 0.4 ± 0.5) GeV. Finally, based on its parallax distance of (300 ± 90) pc, we obtain a gamma-ray efficiency Lγ/E(dotabove) ≃ 15% for the conversion of spin-down energy rate into gamma-ray radiation, assuming isotropic emission.« less

  6. GRB 090926A AND BRIGHT LATE-TIME FERMI LARGE AREA TELESCOPE GAMMA-RAY BURST AFTERGLOWS

    SciTech Connect

    Swenson, C. A.; Roming, P. W. A.; Vetere, L.; Kennea, J. A.; Maxham, A.; Zhang, B. B.; Zhang, B.; Schady, P.; Holland, S. T.; Kuin, N. P. M.; Oates, S. R.; De Pasquale, M.; Page, K. L.

    2010-07-20

    GRB 090926A was detected by both the Gamma-ray Burst Monitor and Large Area Telescope (LAT) instruments on board the Fermi Gamma-ray Space Telescope. Swift follow-up observations began {approx}13 hr after the initial trigger. The optical afterglow was detected for nearly 23 days post trigger, placing it in the long-lived category. The afterglow is of particular interest due to its brightness at late times, as well as the presence of optical flares at T0+10{sup 5} s and later, which may indicate late-time central engine activity. The LAT has detected a total of 16 gamma-ray bursts; nine of these bursts, including GRB 090926A, also have been observed by Swift. Of the nine Swift-observed LAT bursts, six were detected by UVOT, with five of the bursts having bright, long-lived optical afterglows. In comparison, Swift has been operating for five years and has detected nearly 500 bursts, but has only seen {approx}30% of bursts with optical afterglows that live longer than 10{sup 5} s. We have calculated the predicted gamma-ray fluence, as would have been seen by the Burst Alert Telescope (BAT) on board Swift, of the LAT bursts to determine whether this high percentage of long-lived optical afterglows is unique, when compared to BAT-triggered bursts. We find that, with the exception of the short burst GRB 090510A, the predicted BAT fluences indicate that the LAT bursts are more energetic than 88% of all Swift bursts and also have brighter than average X-ray and optical afterglows.

  7. Resolving the Extragalactic γ-Ray Background above 50 GeV with the Fermi Large Area Telescope.

    PubMed

    Ackermann, M; Ajello, M; Albert, A; Atwood, W B; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Bissaldi, E; Blandford, R D; Bloom, E D; Bonino, R; Bregeon, J; Britto, R J; Bruel, P; Buehler, R; Caliandro, G A; Cameron, R A; Caragiulo, M; Caraveo, P A; Cavazzuti, E; Cecchi, C; Charles, E; Chekhtman, A; Chiang, J; Chiaro, G; Ciprini, S; Cohen-Tanugi, J; Cominsky, L R; Costanza, F; Cutini, S; D'Ammando, F; de Angelis, A; de Palma, F; Desiante, R; Digel, S W; Di Mauro, M; Di Venere, L; Domínguez, A; Drell, P S; Favuzzi, C; Fegan, S J; Ferrara, E C; Franckowiak, A; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Giglietto, N; Giommi, P; Giordano, F; Giroletti, M; Godfrey, G; Green, D; Grenier, I A; Guiriec, S; Hays, E; Horan, D; Iafrate, G; Jogler, T; Jóhannesson, G; Kuss, M; La Mura, G; Larsson, S; Latronico, L; Li, J; Li, L; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Magill, J; Maldera, S; Manfreda, A; Mayer, M; Mazziotta, M N; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Negro, M; Nuss, E; Ohsugi, T; Okada, C; Omodei, N; Orlando, E; Ormes, J F; Paneque, D; Perkins, J S; Pesce-Rollins, M; Petrosian, V; Piron, F; Pivato, G; Porter, T A; Rainò, S; Rando, R; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Reposeur, T; Romani, R W; Sánchez-Conde, M; Schmid, J; Schulz, A; Sgrò, C; Simone, D; Siskind, E J; Spada, F; Spandre, G; Spinelli, P; Suson, D J; Takahashi, H; Thayer, J B; Tibaldo, L; Torres, D F; Troja, E; Vianello, G; Yassine, M; Zimmer, S

    2016-04-15

    The Fermi Large Area Telescope (LAT) Collaboration has recently released a catalog of 360 sources detected above 50 GeV (2FHL). This catalog was obtained using 80 months of data re-processed with Pass 8, the newest event-level analysis, which significantly improves the acceptance and angular resolution of the instrument. Most of the 2FHL sources at high Galactic latitude are blazars. Using detailed Monte Carlo simulations, we measure, for the first time, the source count distribution, dN/dS, of extragalactic γ-ray sources at E>50  GeV and find that it is compatible with a Euclidean distribution down to the lowest measured source flux in the 2FHL (∼8×10^{-12}  ph cm^{-2} s^{-1}). We employ a one-point photon fluctuation analysis to constrain the behavior of dN/dS below the source detection threshold. Overall, the source count distribution is constrained over three decades in flux and found compatible with a broken power law with a break flux, S_{b}, in the range [8×10^{-12},1.5×10^{-11}]  ph cm^{-2} s^{-1} and power-law indices below and above the break of α_{2}∈[1.60,1.75] and α_{1}=2.49±0.12, respectively. Integration of dN/dS shows that point sources account for at least 86_{-14}^{+16}% of the total extragalactic γ-ray background. The simple form of the derived source count distribution is consistent with a single population (i.e., blazars) dominating the source counts to the minimum flux explored by this analysis. We estimate the density of sources detectable in blind surveys that will be performed in the coming years by the Cherenkov Telescope Array.

  8. Project Laboratory for First-Year Students

    ERIC Educational Resources Information Center

    Planinsic, Gorazd

    2007-01-01

    This paper reports the modification of an existing experimental subject into a project laboratory for first-year physics students studying in the first cycle of university level and at a higher professional level. The subject is aimed at developing important science-related competences and skills through concrete steps under circumstances that are…

  9. Milwaukee Parental Choice Program. First Year Report.

    ERIC Educational Resources Information Center

    Witte, John F.

    A preliminary evaluation and report were conducted of the Milwaukee (Wisconsin) Public Schools' (MPS) Parental Choice Program (PCP) following its first year of operation. The state legislated program provides an opportunity for students meeting specific criteria to attend private, non-sectarian schools in Milwaukee. A payment from public funds…

  10. Strategies for Teaching First-Year Composition.

    ERIC Educational Resources Information Center

    Roen, Duane, Ed.; Pantoja, Veronica, Ed.; Yena, Lauren, Ed.; Miller, Susan K., Ed.; Waggoner, Eric, Ed.

    This book presents 93 essays that offer guidance, reassurance, and commentary on the many activities leading up to and surrounding classroom instruction in first-year composition. Essays in the book are written by instructors who teach in community colleges, liberal arts colleges, state university systems, and research institutions. The 14 section…

  11. Twelve Steps to a Winning First Year

    ERIC Educational Resources Information Center

    Hodges, Karen

    2009-01-01

    This article offers 12 steps to jumpstart a new school librarian's career. Being the information specialist will be both challenging and rewarding as one undertakes a myriad of activities. These 12 steps will help a new school librarian's first year successful.

  12. Anti-Semitism in First Year Composition

    ERIC Educational Resources Information Center

    Levy, Matthew; Myers, Gerald M.

    2011-01-01

    Robert Cohen, Assistant Professor English at Fairbanks University, has just completed a contentious meeting of his First Year Composition class, which had discussed a paper written by one of the students. Joe Anderson's paper contained statements that have been historically used as anti-Semitic slogans. Cohen attempted to avoid embarrassing…

  13. SerVermont--The First Year. 1986.

    ERIC Educational Resources Information Center

    Parsons, Cynthia

    SerVermont is a volunteer program for high school students. The program stresses public service in the community and is intended to teach students the value of personal volunteer service to their local communities. During SerVermont's first year of operation, 11 high schools were awarded minigrants to be used in developing programs in which…

  14. Individualized Cooperative Education (First Year). Teacher Edition.

    ERIC Educational Resources Information Center

    Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This document contains teacher's materials for competencies to be taught to all Oklahoma first-year cooperative education students. Teachers of general cooperative programs (such as individualized cooperative education) may want to use the document as their basic text, but teachers in other vocational areas may prefer to use it as a supplement.…

  15. Sustainability and First-Year Programs

    ERIC Educational Resources Information Center

    Messineo, Melinda

    2012-01-01

    To truly impact sustainability practices, campuses need to influence the overall campus culture, including that which is fostered through first-year programs. Institutions of higher education have made a commitment to make a difference for sustainability, not only by changing curriculum, but by changing the entire institutional culture. This…

  16. Learning Styles in First Year Medical Students.

    ERIC Educational Resources Information Center

    Chessell, Gwen

    1986-01-01

    Reports on a study done at Aberdeen University (England) which assessed the learning styles of first-year medical students. Results indicated that these students scored higher than other students in achievement (including study methods and competitiveness) and prediction for success. Includes the instrument used. (TW)

  17. Sustainability and First-Year Programs

    ERIC Educational Resources Information Center

    Messineo, Melinda

    2012-01-01

    To truly impact sustainability practices, campuses need to influence the overall campus culture, including that which is fostered through first-year programs. Institutions of higher education have made a commitment to make a difference for sustainability, not only by changing curriculum, but by changing the entire institutional culture. This…

  18. What To Expect the First Year.

    ERIC Educational Resources Information Center

    Eisenberg, Arlene; And Others

    This book is a comprehensive month-by-month guide covering parents' questions about the first year with a new baby. It includes an illustrated baby care primer, a first-aid guide, and recipes. It also contains special sections on the older sibling, selecting the right physician, seasonal concerns and traveling with baby, managing childhood…

  19. The first year of routine Herschel observations

    NASA Astrophysics Data System (ADS)

    2011-06-01

    MEETING REPORT The successful completion of the first year of routine science operations of ESA's Herschel Space Observatory was marked by a Specialist Discussion Meeting of the RAS held in January 2011. A few of the early science highlights from the mission were presented. Derek Ward-Thompson and David Clements summarize.

  20. New ALMA and Fermi/LAT Observations of the Large-scale Jet of PKS 0637‑752 Strengthen the Case Against the IC/CMB Model

    NASA Astrophysics Data System (ADS)

    Meyer, Eileen T.; Breiding, Peter; Georganopoulos, Markos; Oteo, Iván; Zwaan, Martin A.; Laing, Robert; Godfrey, Leith; Ivison, R. J.

    2017-02-01

    The Chandra X-ray observatory has discovered several dozen anomalously X-ray-bright jets associated with powerful quasars. A popular explanation for the X-ray flux from the knots in these jets is that relativistic synchrotron-emitting electrons inverse-Compton scatter cosmic microwave background (CMB) photons to X-ray energies (the IC/CMB model). This model predicts a high gamma-ray flux that should be detectable by the Fermi/Large Area Telescope (LAT) for many sources. GeV-band upper limits from Fermi/LAT for the well-known anomalous X-ray jet in PKS 0637‑752 were previously shown in Meyer et al. to violate the predictions of the IC/CMB model. Previously, measurements of the jet synchrotron spectrum, important for accurately predicting the gamma-ray flux level, were lacking between radio and infrared wavelengths. Here, we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of the large-scale jet at 100, 233, and 319 GHz, which further constrain the synchrotron spectrum, supporting the previously published empirical model. We also present updated limits from the Fermi/LAT using the new “Pass 8” calibration and approximately 30% more time on source. With these deeper limits, we rule out the IC/CMB model at the 8.7σ level. Finally, we demonstrate that complete knowledge of the synchrotron SED is critical in evaluating the IC/CMB model.

  1. Fermi at Six Months

    NASA Technical Reports Server (NTRS)

    Hays, Elizabeth

    2009-01-01

    An overview of the Fermi Gamma-ray Space Telescope's first 6 months in operation is provided. The Fermi Gamma-ray Space Telescope, formerly called GLAST, is a mission to measure the cosmic gamma-ray flux in the energy rage 20 MeV to more than 300 GeV, with supporting measurements for gamma-ray bursts from 8 keV to 30 MeV. It contains a Large Area Telescope capable of viewing the entire sky every 3 hours and a Gamma-ray Burst Monitor for viewing the entire unocculted sky. Since its launch on June 11, 2008 Fermi has provided information on pulsars, gamma ray bursts, relativistic jets, the active galactic nucleus, and a globular star cluster. This presentation describes Fermi's development, mission, instruments and recent findings.

  2. Fermi Large Area Telescope observations of Local Group galaxies: detection of M 31 and search for M 33

    DOE PAGES

    Abdo, A. A.

    2010-11-01

    Context. Cosmic rays (CRs) can be studied through the galaxy-wide gamma-ray emission that they generate when propagating in the interstellar medium. The comparison of the diffuse signals from different systems may inform us about the key parameters in CR acceleration and transport. Aims. We aim to determine and compare the properties of the cosmic-ray-induced gamma-ray emission of several Local Group galaxies. Methods. We use 2 years of nearly continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope to search for gamma-ray emission from M 31 and M 33. We compare the results with thosemore » for the Large Magellanic Cloud, the Small Magellanic Cloud, the Milky Way, and the starburst galaxies M 82 and NGC 253. Results. We detect a gamma-ray signal at 5σ significance in the energy range 200 MeV–20 GeV that is consistent with originating from M 31. The integral photon flux above 100 MeV amounts to (9.1 ± 1.9stat ± 1.0sys) × 10-9 ph cm-2 s-1. We find no evidence for emission from M 33 and derive an upper limit on the photon flux >100 MeV of 5.1 × 10-9 ph cm-2 s-1 (2σ). Comparing these results to the properties of other Local Group galaxies, we find indications of a correlation between star formation rate and gamma-ray luminosity that also holds for the starburst galaxies. Conclusions. The gamma-ray luminosity of M 31 is about half that of the Milky Way, which implies that the ratio between the average CR densities in M 31 and the Milky Way amounts to ξ = 0.35 ± 0.25. The observed correlation between gamma-ray luminosity and star formation rate suggests that the flux of M 33 is not far below the current upper limit from the LAT observations.« less

  3. Fermi Large Area Telescope observations of Local Group galaxies: detection of M 31 and search for M 33

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cannon, A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Digel, S. W.; Silva, E. Do Couto E.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Harding, A. K.; Hayashi, K.; Hayashida, M.; Hays, E.; Healey, S. E.; Jean, P.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Martin, P.; Mazziotta, M. N.; Mehault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Naumann-Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pepe, M.; Persic, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Ritz, S.; Romani, R. W.; Sadrozinski, H. F.-W.; Saz Parkinson, P. M.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Strigari, L.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vianello, G.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ziegler, M.

    2010-11-01

    Context. Cosmic rays (CRs) can be studied through the galaxy-wide gamma-ray emission that they generate when propagating in the interstellar medium. The comparison of the diffuse signals from different systems may inform us about the key parameters in CR acceleration and transport. Aims: We aim to determine and compare the properties of the cosmic-ray-induced gamma-ray emission of several Local Group galaxies. Methods: We use 2 years of nearly continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope to search for gamma-ray emission from M 31 and M 33. We compare the results with those for the Large Magellanic Cloud, the Small Magellanic Cloud, the Milky Way, and the starburst galaxies M 82 and NGC 253. Results: We detect a gamma-ray signal at 5σ significance in the energy range 200 MeV-20 GeV that is consistent with originating from M 31. The integral photon flux above 100 MeV amounts to (9.1 ± 1.9stat ± 1.0sys) × 10-9 ph cm-2 s-1. We find no evidence for emission from M 33 and derive an upper limit on the photon flux >100 MeV of 5.1 × 10-9 ph cm-2 s-1 (2σ). Comparing these results to the properties of other Local Group galaxies, we find indications of a correlation between star formation rate and gamma-ray luminosity that also holds for the starburst galaxies. Conclusions: The gamma-ray luminosity of M 31 is about half that of the Milky Way, which implies that the ratio between the average CR densities in M 31 and the Milky Way amounts to ξ = 0.35 ± 0.25. The observed correlation between gamma-ray luminosity and star formation rate suggests that the flux of M 33 is not far below the current upper limit from the LAT observations. Appendix A is only available in electronic form at http://www.aanda.org

  4. A population of gamma-ray emitting globular clusters seen with the Fermi Large Area Telescope

    SciTech Connect

    Abdo, A. A.

    2010-11-24

    Context. Globular clusters with their large populations of millisecond pulsars (MSPs) are believed to be potential emitters of high-energy gamma-ray emission. The observation of this emission provides a powerful tool to assess the millisecond pulsar population of a cluster, is essential for understanding the importance of binary systems for the evolution of globular clusters, and provides complementary insights into magnetospheric emission processes. Aims. Our goal is to constrain the millisecond pulsar populations in globular clusters from analysis of gamma-ray observations. Methods. We use 546 days of continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope to study the gamma-ray emission towards 13 globular clusters. Results. Steady point-like high-energy gamma-ray emission has been significantly detected towards 8 globular clusters. Five of them (47 Tucanae, Omega Cen, NGC 6388, Terzan 5, and M 28) show hard spectral power indices (0.7 < Γ < 1.4) and clear evidence for an exponential cut-off in the range 1.0 - 2.6 GeV, which is the characteristic signature of magnetospheric emission from MSPs. Three of them (M 62, NGC 6440 and NGC 6652) also show hard spectral indices (1.0 < Γ < 1.7), however the presence of an exponential cut-off can not be unambiguously established. Three of them (Omega Cen, NGC 6388, NGC 6652) have no known radio or X-ray MSPs yet still exhibit MSP spectral properties. From the observed gamma-ray luminosities, we estimate the total number of MSPs that is expected to be present in these globular clusters. We show that our estimates of the MSP population correlate with the stellar encounter rate and we estimate 2600 - 4700 MSPs in Galactic globular clusters, commensurate with previous estimates. Conclusions. The observation of high-energy gamma-ray emission from globular clusters thus provides a reliable independent method to assess their millisecond pulsar populations.

  5. Skills, Learning Styles and Success of First-Year Undergraduates

    ERIC Educational Resources Information Center

    Goldfinch, Judy; Hughes, Moira

    2007-01-01

    This study investigates the relationships between students' confidence in their generic skills on entry to university, their learning styles and their academic performance in first year. Research based on a large cohort of Scottish undergraduates found that students generally entered university feeling very confident that they already possessed…

  6. Integrated Chemistry and Biology for First-Year College Students

    ERIC Educational Resources Information Center

    Abdella, Beth R. J.; Walczak, Mary M.; Kandl, Kim A.; Schwinefus, Jeffrey J.

    2011-01-01

    A three-course sequence for first-year students that integrates beginning concepts in biology and chemistry has been designed. The first two courses that emphasize chemistry and its capacity to inform biological applications are described here. The content of the first course moves from small to large particles with an emphasis on membrane…

  7. Final Report on the Evaluation of Project Upswing's First Year.

    ERIC Educational Resources Information Center

    Plantec, P.; And Others

    This technical report describes the evaluation of the first year of Project Upswing, a 2-year experimental study to determine the potential contribution of volunteers in helping young children overcome learning difficulties. The three large groups of first grade children involved received tutoring either from specially trained volunteers,…

  8. An Innovative Learning Model for Computation in First Year Mathematics

    ERIC Educational Resources Information Center

    Tonkes, E. J.; Loch, B. I.; Stace, A. W.

    2005-01-01

    MATLAB is a sophisticated software tool for numerical analysis and visualization. The University of Queensland has adopted Matlab as its official teaching package across large first year mathematics courses. In the past, the package has met severe resistance from students who have not appreciated their computational experience. Several main…

  9. Integrated Chemistry and Biology for First-Year College Students

    ERIC Educational Resources Information Center

    Abdella, Beth R. J.; Walczak, Mary M.; Kandl, Kim A.; Schwinefus, Jeffrey J.

    2011-01-01

    A three-course sequence for first-year students that integrates beginning concepts in biology and chemistry has been designed. The first two courses that emphasize chemistry and its capacity to inform biological applications are described here. The content of the first course moves from small to large particles with an emphasis on membrane…

  10. An Innovative Learning Model for Computation in First Year Mathematics

    ERIC Educational Resources Information Center

    Tonkes, E. J.; Loch, B. I.; Stace, A. W.

    2005-01-01

    MATLAB is a sophisticated software tool for numerical analysis and visualization. The University of Queensland has adopted Matlab as its official teaching package across large first year mathematics courses. In the past, the package has met severe resistance from students who have not appreciated their computational experience. Several main…

  11. Nebraska wind resource assessment first year results

    SciTech Connect

    Hurley, P.J.F.; Vilhauer, R.; Stooksbury, D.

    1996-12-31

    This paper presents the preliminary results from a wind resource assessment program in Nebraska sponsored by the Nebraska Power Association. During the first year the measured annual wind speed at 40 meters ranged from 6.5 - 7.5 m/s (14.6 - 16.8 mph) at eight stations across the state. The site selection process is discussed as well as an overview of the site characteristics at the monitoring locations. Results from the first year monitoring period including data recovery rate, directionality, average wind speeds, wind shear, and turbulence intensity are presented. Results from the eight sites are qualitatively compared with other midwest and west coast locations. 5 figs., 2 tabs.

  12. SPEAR 3: the First Year of Operation

    SciTech Connect

    Hettel, R.O.; /SLAC

    2006-02-10

    The first electrons were accumulated in the newly completed 3-GeV SPEAR 3 storage ring on December 15, 2003, five days after the beginning of commissioning. By mid-January of 2004, 100 mA were stored, the maximum current allowed in the first phase of SPEAR 3 operation, and ring characterization and tuning continued until early March when the first photon beam line was opened for users. After the first year of operation the SPEAR 3 beam properties and ring performance had been extensively measured. These include micron stability using slow orbit feedback, an emittance coupling of {approx}0.1% and 50-h lifetimes. The performance of SPEAR 3 during its first year of commissioning and operation and the improvement plans are described.

  13. Remembering Fermi

    SciTech Connect

    Cronin, James

    2005-03-30

    A combination of the discovery of nuclear fission and the circumstances of the 2nd World War brought Enrico Fermi to Chicago, where he led the team that produced the first controlled, self-sustained nuclear chain reaction. Following the war in 1945 Chancellor Hutchins, William Zachariasen, and Walter Bartky convinced Fermi to accept a professorship at the University of Chicago, where the Institute for Nuclear Studies was established. Fermi served as the leading figure in surely the greatest collection of scientists the world has ever seen. Fermi's tenure at Chicago was cut short by his death in 1954. My talk will concentrate on the years 1945-54. Examples of his research notebooks, his speeches, his teaching, and his correspondence will be discussed.

  14. Large-Scale Operations Management Test of Use of the White Amur for Control of Problem Aquatic Plants. Report 2. First Year Poststocking Results. Volume II. The Fish, Mammals, and Waterfowl of Lake Conway, Florida.

    DTIC Science & Technology

    1982-02-01

    waterfowl and wading birds , and aquatic mammal populations on Lake Conway were surveyed for 1 year after the introduction of the herbivorous fish, white...of a series of reports documenting a large-scale operations management test of use of the white amur for control of problem aquatic plants in Lake... Manager of the Aquatic Plant Control Research Program, EL. The study was under the general supervision of Mr. B. 0. Benn, Chief, Environmental Systems

  15. First Year Experience: How We Can Better Assist First-Year International Students in Higher Education

    ERIC Educational Resources Information Center

    Yan, Zi; Sendall, Patricia

    2016-01-01

    While many American colleges and universities are providing a First Year Experience (FYE) course or program for their first year students, those programs are not often customized to take into account international students' (IS) unique challenges. Using quantitative and qualitative methods, this study evaluated a FYE course that was customized for…

  16. Recursive sequences in first-year calculus

    NASA Astrophysics Data System (ADS)

    Krainer, Thomas

    2016-02-01

    This article provides ready-to-use supplementary material on recursive sequences for a second-semester calculus class. It equips first-year calculus students with a basic methodical procedure based on which they can conduct a rigorous convergence or divergence analysis of many simple recursive sequences on their own without the need to invoke inductive arguments as is typically required in calculus textbooks. The sequences that are accessible to this kind of analysis are predominantly (eventually) monotonic, but also certain recursive sequences that alternate around their limit point as they converge can be considered.

  17. Purposeful Engagement of First-Year Division I Student-Athletes

    ERIC Educational Resources Information Center

    Comeaux, Eddie; Speer, Laura; Taustine, Maria; Harrison, C. Keith

    2011-01-01

    This study examined the extent to which transitioning, first-year student-athletes engage in educationally sound activities in college. The sample included 147 revenue and nonrevenue first-year student-athletes who were surveyed at four large Division 1-A universities. Findings revealed that revenue and nonrevenue first-year student athletes…

  18. First year results from the HAWC observatory

    NASA Astrophysics Data System (ADS)

    Casanova, Sabrina

    2017-03-01

    The High Altitude Water Cherenkov Observatory is an all-sky surveying instrument sensitive to gamma rays and cosmic rays from 100GeV to 100TeV. With its 2sr instantaneous field of view and a duty cycle of > 95%, HAWC is carrying out an unbiased survey of the Northern sky and is monitoring known flaring sources and searching for transients. HAWC operation began mid-2013 with a partially-completed detector. The array was terminated in 2015. We here summarize the status of the observatory, and highlight its first scientific results, resulting from the first year of data taking after completion of the detector. In particular, we will present the HAWC map of the sky at tens of TeV.

  19. Cosmic-ray electron-positron spectrum from 7 GeV to 2 TeV with the Fermi Large Area Telescope

    DOE PAGES

    Abdollahi, S.; Ackermann, M.; Ajello, M.; ...

    2017-04-15

    Here, we present a measurement of the cosmic-ray electron+positron spectrum between 7 GeV and 2 TeV performed with almost seven years of data collected with the Fermi Large Area Telescope. We find that the spectrum is well fit by a broken power law with a break energy at about 50 GeV. Above 50 GeV, the spectrum is well described by a single power law with a spectral index of 3.07 ± 0.02(stat + syst) ± 0.04(energy measurement). An exponential cutoff lower than 1.8 TeV is excluded at 95% CL.

  20. Cosmic-ray electron-positron spectrum from 7 GeV to 2 TeV with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Abdollahi, S.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bloom, E. D.; Bonino, R.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Cameron, R. A.; Caputo, R.; Caragiulo, M.; Castro, D.; Cavazzuti, E.; Cecchi, C.; Chekhtman, A.; Ciprini, S.; Cohen-Tanugi, J.; Costanza, F.; Cuoco, A.; Cutini, S.; D'Ammando, F.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Focke, W. B.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Green, D.; Guillemot, L.; Guiriec, S.; Harding, A. K.; Jogler, T.; Jóhannesson, G.; Kamae, T.; Kuss, M.; La Mura, G.; Latronico, L.; Longo, F.; Loparco, F.; Lubrano, P.; Maldera, S.; Malyshev, D.; Manfreda, A.; Mazziotta, M. N.; Michelson, P. F.; Mirabal, N.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Negro, M.; Nuss, E.; Orlando, E.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Principe, G.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Sgrò, C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Tajima, H.; Thayer, J. B.; Tibaldo, L.; Torres, D. F.; Troja, E.; Wood, M.; Worley, A.; Zaharijas, G.; Zimmer, S.; Fermi-LAT Collaboration

    2017-04-01

    We present a measurement of the cosmic-ray electron +positron spectrum between 7 GeV and 2 TeV performed with almost seven years of data collected with the Fermi Large Area Telescope. We find that the spectrum is well fit by a broken power law with a break energy at about 50 GeV. Above 50 GeV, the spectrum is well described by a single power law with a spectral index of 3.07 ±0.02 (stat +syst )±0.04 (energy measurement) . An exponential cutoff lower than 1.8 TeV is excluded at 95% CL.

  1. Chiral non-Fermi liquids

    NASA Astrophysics Data System (ADS)

    Sur, Shouvik; Lee, Sung-Sik

    2014-07-01

    A non-Fermi liquid state without time-reversal and parity symmetries arises when a chiral Fermi surface is coupled with a soft collective mode in two space dimensions. The full Fermi surface is described by a direct sum of chiral patch theories, which are decoupled from each other in the low-energy limit. Each patch includes low-energy excitations near a set of points on the Fermi surface with a common tangent vector. General patch theories are classified by the local shape of the Fermi surface, the dispersion of the critical boson, and the symmetry group, which form the data for distinct universality classes. We prove that a large class of chiral non-Fermi liquid states exists as stable critical states of matter. For this, we use a renormalization group scheme where low-energy excitations of the Fermi surface are interpreted as a collection of (1+1)-dimensional chiral fermions with a continuous flavor labeling the momentum along the Fermi surface. Due to chirality, the Wilsonian effective action is strictly UV finite. This allows one to extract the exact scaling exponents although the theories flow to strongly interacting field theories at low energies. In general, the low-energy effective theory of the full Fermi surface includes patch theories of more than one universality classes. As a result, physical responses include multiple universal components at low temperatures. We also point out that, in quantum field theories with extended Fermi surface, a noncommutative structure naturally emerges between a coordinate and a momentum which are orthogonal to each other. We show that the invalidity of patch description for Fermi liquid states is tied with the presence of UV/IR mixing associated with the emergent noncommutativity. On the other hand, UV/IR mixing is suppressed in non-Fermi liquid states due to UV insensitivity, and the patch description is valid.

  2. Fermi Large Area Telescope Observations of High-Energy Gamma-ray Emission From Behind-the-limb Solar Flares

    NASA Astrophysics Data System (ADS)

    Omodei, Nicola; Pesce-Rollins, Melissa; Petrosian, Vahe; Liu, Wei; Rubio da Costa, Fatima; Golenetskii, Sergei; Kashapova, Larisa; Krucker, Sam; Palshin, Valentin; Fermi Large Area Telescope Collaboration

    2017-01-01

    Fermi LAT >30 MeV observations of the active Sun have increased the number of detected solar flares by almost a factor of 10 with respect to previous space observations. Of particular interest are the recent detections of three solar flares whose position behind the limb was confirmed by the STEREO-B spacecraft. These observations sample flares from active regions originating from behind both the eastern and western limbs and include an event associated with the second ground level enhancement event (GLE) of the 24th Solar Cycle. While gamma-ray emission up to tens of MeV resulting from proton interactions has been detected before from occulted solar flares, the significance of these particular events lies in the fact that these are the first detections of >100 MeV gamma-ray emission from footpoint-occulted flares. These detections present an unique opportunity to diagnose the mechanisms of high-energy emission and particle acceleration and transport in solar flares. We will present the Fermi-LAT, RHESSI and STEREO observations of these flares and discuss the various emission scenarios for these sources.

  3. Six faint gamma-ray pulsars seen with the Fermi Large Area Telescope: Towards a sample blending into the background

    SciTech Connect

    Hou, X.; Smith, D. A.; Guillemot, L.; Cheung, C. C.; Cognard, I.; Craig, H. A.; Espinoza, C. M.; Johnston, S.; Kramer, M.; Reimer, O.; Reposeur, T.; Shannon, R.; Stappers, B. W.; Weltevrede, P.

    2014-10-14

    Context. Here, GeV gamma-ray pulsations from over 140 pulsars have been characterized using the Fermi Large Area Telescope, enabling improved understanding of the emission regions within the neutron star magnetospheres, and the contributions of pulsars to high energy electrons and diffuse gamma rays in the Milky Way. The first gamma-ray pulsars to be detected were the most intense and/or those with narrow pulses. Aims. As the Fermi mission progresses, progressively fainter objects can be studied. In addition to more distant pulsars (thus probing a larger volume of the Galaxy), or ones in high background regions (thus improving the sampling uniformity across the Galactic plane), we detect pulsars with broader pulses or lower luminosity. Adding pulsars to our catalog with inclination angles that are rare in the observed sample, and/or with lower spindown power, will reduce the bias in the currently known gamma-ray pulsar population. Methods. We use rotation ephemerides derived from radio observations to phase-fold gamma rays recorded by the Fermi Large Area Telescope, to then determine the pulse profile properties. Spectral analysis provides the luminosities and, when the signal-to-noise ratio allows, the cutoff energies. We constrain the pulsar distances by different means in order to minimize the luminosity uncertainties. Results. We present six new gamma-ray pulsars with an eclectic mix of properties. Three are young, and three are recycled. They include the farthest, the lowest power, two of the highest duty-cycle pulsars seen, and only the fourth young gamma-ray pulsar with a radio interpulse. Finally, we discuss the biases existing in the current gamma-ray pulsar catalog, and steps to be taken to mitigate the bias.

  4. Constraints on the galactic population of TeV pulsar wind nebulae using Fermi Large Area Telescope observations

    SciTech Connect

    Acero, F.; Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; Dalton, M.; D'Ammando, F.; de Palma, F.; Dermer, C. D.; Venere, L. Di; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Falletti, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grégoire, T.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hayashi, K.; Hays, E.; Hewitt, J.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Inoue, Y.; Jackson, M. S.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Kawano, T.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Marelli, M.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Okumura, A.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Roth, M.; Rousseau, R.; Saz Parkinson, P. M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Suson, D. J.; Takahashi, H.; Takeuchi, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Werner, M.; Winer, B. L.; Wood, K. S.; Yang, Z.

    2013-07-29

    Pulsar wind nebulae (PWNe) have been established as the most populous class of TeV γ-ray emitters. Since launch, the Fermi Large Area Telescope (LAT) has identified five high-energy (100 MeV < E < 100 GeV) γ-ray sources as PWNe and detected a large number of PWN candidates, all powered by young and energetic pulsars. The wealth of multi-wavelength data available and the new results provided by Fermi-LAT give us an opportunity to find new PWNe and to explore the radiative processes taking place in known ones. The TeV γ-ray unidentified (UNID) sources are the best candidates for finding new PWNe. Using 45 months of Fermi-LAT data for energies above 10 GeV, an analysis was performed near the position of 58 TeV PWNe and UNIDs within 5° of the Galactic plane to establish new constraints on PWN properties and find new clues on the nature of UNIDs. Of the 58 sources, 30 were detected, and this work provides their γ-ray fluxes for energies above 10 GeV. The spectral energy distributions and upper limits, in the multi-wavelength context, also provide new information on the source nature and can help distinguish between emission scenarios, i.e., between classification as a pulsar candidate or as a PWN candidate. Six new GeV PWN candidates are described in detail and compared with existing models. As a result, a population study of GeV PWN candidates as a function of the pulsar/PWN system characteristics is presented.

  5. Simulation workshops with first year midwifery students.

    PubMed

    Catling, Christine; Hogan, Rosemarie; Fox, Deborah; Cummins, Allison; Kelly, Michelle; Sheehan, Athena

    2016-03-01

    Simulated teaching methods enable a safe learning environment that are structured, constructive and reflective. We prepared a 2-day simulation project to help prepare students for their first clinical practice. A quasi-experimental pre-test - post-test design was conducted. Qualitative data from the open-ended survey questions were analysed using content analysis. Confidence intervals and p-values were calculated to demonstrate the changes in participants' levels of understanding/ability or confidence in clinical midwifery skills included in the simulation. 71 midwifery students participated. Students rated their understanding, confidence, and abilities as higher after the simulation workshop, and higher still after their clinical experience. There were five main themes arising from the qualitative data: having a learning experience, building confidence, identifying learning needs, developing communication skills and putting skills into practise. First year midwifery students felt well prepared for the clinical workplace following the simulation workshops. Self-rated understanding, confidence and abilities in clinical midwifery skills were significantly higher following consolidation during clinical placement. Longitudinal studies on the relationship between simulation activities and student's overall clinical experience, their intentions to remain in midwifery, and facility feedback, would be desirable. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. ISS GN and C - First Year Surprises

    NASA Technical Reports Server (NTRS)

    Begley, Michael

    2002-01-01

    Assembly of the International Space Station (ISS) began in late 1998 with the joining of the first two US and Russ ian elements. For more than two years, the outpost was served by two Russian Guidance, Navigation, and Control (GN&C) systems. The station requires orbital translation and attitude control functions for its 100+ configurations, from the nascent two-module station to the half million kilogram completed station owned and operated by seventeen nations. With the launch of the US Laboratory module in February 2001, the integration of the US GN&C system with its Russian counterpart laid the foundation for such a robust system. In its first year of combined operation, the ISS GN&C system has performed admirably, even better than many expected, but there have been surprises. Loss of command capability, loss of communication between segments, a control system force-fight, and "non-propulsive vents" that weren't - such events have repeatedly underscored the importance of thorough program integration, testing, and operation, both across subsystem boundaries and across international borders.

  7. Timing gamma-ray pulsars with the Fermi large area telescope: Timing noise and astrometry

    SciTech Connect

    Kerr, Matthew; Ray, P. S.; Johnston, S.; Shannon, R. M.; Camilo, F.

    2015-11-25

    We have constructed timing solutions for 81 γ-ray pulsars covering more than five years of Fermi data. The sample includes 37 radio-quiet or radio-faint pulsars which cannot be timed with other telescopes. These timing solutions and the corresponding pulse times of arrival are prerequisites for further study, e.g., phase-resolved spectroscopy or searches for mode switches. Many γ-ray pulsars are strongly affected by timing noise (TN), and we present a new method for characterizing the noise process and mitigating its effects on other facets of the timing model. We present an analysis of TN over the population using a new metric for characterizing its strength and spectral shape, namely, its time-domain correlation. The dependence of the strength on ν and $\\dot{\

  8. Phase diagram of a one-dimensional spin-full Bose-Fermi mixture at large boson densities

    NASA Astrophysics Data System (ADS)

    Nocera, Alberto; Lutchyn, Roman M.; Feiguin, Adrian E.

    2014-03-01

    We determine the ground state phase diagram of a one dimensional Bose-Fermi Hubbard model with spin-full fermions using the Density Matrix Renormalization Group (DMRG) method. We focus on the regime with one fermion per site, and deep into the superfluid phase. We study the effects of the boson-fermion interaction on the fermionic pairing, as a function of the interaction strength, hopping, and bosonic density. We identify the regime in which fermionic superfluidity dominates, and a phase with coexisting CDW and bosonic superfluidity. At high boson densities we find a fermionic Wigner crystal coexisting with bosonic superfluidity. We analyze the structure of the Cooper pairs and the bosonic cloud that acts as the glue.

  9. Latest Observations of M31 with the Fermi Large Area Telescope: A Galactic Center Excess in Andromeda?

    NASA Astrophysics Data System (ADS)

    Hou, Xian; Martin, Pierrick

    2017-08-01

    The Fermi LAT has opened the way for comparative studies of cosmic rays (CRs) and high-energy objects in the Milky Way (MW) and in other, external, star-forming galaxies. We revisited the gamma-ray emission in the direction of M31 using more than 7 yr of LAT Pass 8 data in the energy range 0.1-100 GeV. M31 is detected with a significance of nearly 10 sigma and the source is observed to be extended with a 4 sigma significance. Its spectrum is consistent with a power law. The spatial distribution of the emission is consistent with a uniform brightness disk over the plane of sky and no offset from the center of M31, but nonuniform intensity distributions cannot be excluded. The flux from M31 appears confined to the inner regions of the galaxy and does not fill the plane of the galaxy or extend far from it. The gamma-ray signal is not correlated with regions rich in gas or star-formation activity suggesting that the emission is not interstellar in origin, unless the energetic particles radiating in gamma rays do not originate in recent star formation. Alternative and nonexclusive interpretations are that the emission results from a population of millisecond pulsars dispersed in the bulge and disk of M31 by disrupted globular clusters or from the decay or annihilation of dark matter particles, similar to what has been proposed to account for the so-called Galactic center excess found in Fermi-LAT observations of the MW.

  10. Fermi Sees the Gamma Ray Sky

    NASA Image and Video Library

    2017-09-28

    This view of the gamma-ray sky constructed from one year of Fermi LAT observations is the best view of the extreme universe to date. The map shows the rate at which the LAT detects gamma rays with energies above 300 million electron volts -- about 120 million times the energy of visible light -- from different sky directions. Brighter colors equal higher rates. Credit: NASA/DOE/Fermi LAT Collaboration Full story: www.nasa.gov/mission_pages/GLAST/news/first_year.html

  11. Why Do First-Year Students of German Lose Motivation during their First Year at University?

    ERIC Educational Resources Information Center

    Busse, Vera

    2013-01-01

    This article explores motivational changes of first-year students enrolled on German degree courses at two major UK universities. It reports on the qualitative data obtained by a longitudinal mixed-methods study, and focuses on the interplay between students' motivation and the higher education learning environment. In particular, the article aims…

  12. Why Do First-Year Students of German Lose Motivation during their First Year at University?

    ERIC Educational Resources Information Center

    Busse, Vera

    2013-01-01

    This article explores motivational changes of first-year students enrolled on German degree courses at two major UK universities. It reports on the qualitative data obtained by a longitudinal mixed-methods study, and focuses on the interplay between students' motivation and the higher education learning environment. In particular, the article aims…

  13. First-Year Seminar Intervention: Enhancing First-Year Mathematics Performance at the University of Johannesburg

    ERIC Educational Resources Information Center

    Jacobs, Melanie; Pretorius, Estherna

    2016-01-01

    South Africa has opened up access to higher education over the past 20 years. The massive increase in enrolments (with almost 70% first-generation students) substantially affects progress and graduation rates in Science programmes in higher education. First-year students in Science realise that university mathematics requires knowledge and skills…

  14. First-Year Undergraduate Induction: Who Attends and How Important Is Induction for First Year Attainment?

    ERIC Educational Resources Information Center

    Murtagh, S.; Ridley, A.; Frings, D.; Kerr-Pertic, S.

    2017-01-01

    The first year of study in higher education is a time of major transition for students. While the importance of induction has been widely demonstrated, there is evidence to suggest that not all students benefit equally from participation in induction. This study examined attendance rates at induction, the relationship between induction attendance…

  15. FERMI RULES OUT THE INVERSE COMPTON/CMB MODEL FOR THE LARGE-SCALE JET X-RAY EMISSION OF 3C 273

    SciTech Connect

    Meyer, Eileen T.; Georganopoulos, Markos

    2014-01-10

    The X-ray emission mechanism in large-scale jets of powerful radio quasars has been a source of debate in recent years, with two competing interpretations: either the X-rays are of synchrotron origin, arising from a different electron energy distribution than that producing the radio to optical synchrotron component, or they are due to inverse Compton scattering of cosmic microwave background photons (IC/CMB) by relativistic electrons in a powerful relativistic jet with bulk Lorentz factor Γ ∼ 10-20. These two models imply radically different conditions in the large-scale jet in terms of jet speed, kinetic power, and maximum energy of the particle acceleration mechanism, with important implications for the impact of the jet on the large-scale environment. A large part of the X-ray origin debate has centered on the well-studied source 3C 273. Here we present new observations from Fermi which put an upper limit on the gamma-ray flux from the large-scale jet of 3C 273 that violates at a confidence greater that 99.9% the flux expected from the IC/CMB X-ray model found by extrapolation of the UV to X-ray spectrum of knot A, thus ruling out the IC/CMB interpretation entirely for this source when combined with previous work. Further, this upper limit from Fermi puts a limit on the Doppler beaming factor of at least δ < 9, assuming equipartition fields, and possibly as low as δ < 5, assuming no major deceleration of the jet from knots A through D1.

  16. Discovery of GeV emission from the Circinus galaxy with the Fermi Large Area Telescope [Discovery of GeV emission from the Circinus galaxy with the Fermi-LAT

    SciTech Connect

    Hayashida, Masaaki; Stawarz, Łukasz; Cheung, Chi C.; Bechtol, Keith; Madejski, Greg M.; Ajello, Marco; Massaro, Francesco; Moskalenko, Igor V.; Strong, Andrew; Tibaldo, Luigi

    2013-12-03

    We report the discovery of γ-ray emission from the Circinus galaxy using the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. Circinus is a nearby (~4 Mpc) starburst with a heavily obscured Seyfert-type active nucleus, bipolar radio lobes perpendicular to the spiral disk, and kpc-scale jet-like structures. Our analysis of 0.1-100 GeV events collected during 4 yr of LAT observations reveals a significant (≃ 7.3σ) excess above the background. We find no indications of variability or spatial extension beyond the LAT point-spread function. A power-law model used to describe the 0.1-100 GeV γ-ray spectrum yields a flux of (18.8 ± 5.8) × 10–9 photon cm–2 s–1 and photon index 2.19 ± 0.12, corresponding to an isotropic γ-ray luminosity of 3 × 1040 erg s–1. This observed γ-ray luminosity exceeds the luminosity expected from cosmic-ray interactions in the interstellar medium and inverse Compton radiation from the radio lobes. Furthermore, the origin of the GeV excess requires further investigation.

  17. Discovery of GeV emission from the Circinus galaxy with the Fermi Large Area Telescope [Discovery of GeV emission from the Circinus galaxy with the Fermi-LAT

    DOE PAGES

    Hayashida, Masaaki; Stawarz, Łukasz; Cheung, Chi C.; ...

    2013-12-03

    We report the discovery of γ-ray emission from the Circinus galaxy using the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. Circinus is a nearby (~4 Mpc) starburst with a heavily obscured Seyfert-type active nucleus, bipolar radio lobes perpendicular to the spiral disk, and kpc-scale jet-like structures. Our analysis of 0.1-100 GeV events collected during 4 yr of LAT observations reveals a significant (≃ 7.3σ) excess above the background. We find no indications of variability or spatial extension beyond the LAT point-spread function. A power-law model used to describe the 0.1-100 GeV γ-ray spectrum yields a fluxmore » of (18.8 ± 5.8) × 10–9 photon cm–2 s–1 and photon index 2.19 ± 0.12, corresponding to an isotropic γ-ray luminosity of 3 × 1040 erg s–1. This observed γ-ray luminosity exceeds the luminosity expected from cosmic-ray interactions in the interstellar medium and inverse Compton radiation from the radio lobes. Furthermore, the origin of the GeV excess requires further investigation.« less

  18. Fermi large area telescope observations of the cosmic-ray induced γ -ray emission of the Earth’s atmosphere

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; de Palma, F.; Digel, S. W.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hays, E.; Horan, D.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McEnery, J. E.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Rochester, L. S.; Rodriguez, A. Y.; Roth, M.; Sadrozinski, H. F. -W.; Sander, A.; Saz Parkinson, P. M.; Sgrò, C.; Share, G. H.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Suson, D. J.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vasileiou, V.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Ziegler, M.

    2009-12-29

    In this paper, we report on measurements of the cosmic-ray induced γ-ray emission of Earth’s atmosphere by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The Large Area Telescope has observed the Earth during its commissioning phase and with a dedicated Earth limb following observation in September 2008. These measurements yielded ~6.4 × 106 photons with energies > 100 MeV and ~ 250 hours total live time for the highest quality data selection. This allows the study of the spatial and spectral distributions of these photons with unprecedented detail. In additon, the spectrum of the emission—often referred to as Earth albedo gamma-ray emission—has a power-law shape up to 500 GeV with spectral index Γ = 2.79 ± 0.06 .

  19. Measurement of the Cosmic Ray e++e- Spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope

    DOE PAGES

    Abdo, A. A.

    2009-05-04

    Designed as a high-sensitivity gamma-ray observatory, the Fermi Large Area Telescope is also an electron detector with a large acceptance exceeding 2 m2 sr at 300 GeV. Building on the gamma-ray analysis, we have developed in this paper an efficient electron detection strategy which provides sufficient background rejection for measurement of the steeply falling electron spectrum up to 1 TeV. Our high precision data show that the electron spectrum falls with energy as E-3.0 and does not exhibit prominent spectral features. Finally, interpretations in terms of a conventional diffusive model as well as a potential local extra component are brieflymore » discussed.« less

  20. Measurement of the Cosmic Ray e+ plus e- Spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope

    SciTech Connect

    Abdo, Aous A.; Ackermann, M.; Ajello, M.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, Guido; Bastieri, Denis; Battelino, M.; Baughman, B.M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R.D.; Bloom, Elliott D.; Bogaert, G.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brez, A.; /more authors..

    2012-05-14

    Designed as a high-sensitivity gamma-ray observatory, the Fermi Large Area Telescope is also an electron detector with a large acceptance exceeding 2 m{sup 2}sr at 300 GeV. Building on the gamma-ray analysis, we have developed an efficient electron detection strategy which provides sufficient background rejection for measurement of the steeply-falling electron spectrum up to 1 TeV. Our high precision data show that the electron spectrum falls with energy as E{sup -3.0} and does not exhibit prominent spectral features. Interpretations in terms of a conventional diffusive model as well as a potential local extra component are briefly discussed.

  1. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE ACTIVE GALAXY 4C +55.17: STEADY, HARD GAMMA-RAY EMISSION AND ITS IMPLICATIONS

    SciTech Connect

    McConville, W.; McEnery, J. E.; Ostorero, L.; Moderski, R.; Stawarz, L.; Cheung, C. C.; Ajello, M.; Monzani, M. E.; Bouvier, A.; Bregeon, J.; Donato, D.; Finke, J.; Furniss, A.; Williams, D. A.; Orienti, M.; Reyes, L. C.; Rossetti, A. E-mail: stawarz@astro.isas.jaxa.jp

    2011-09-10

    We report Fermi Large Area Telescope (LAT) observations and broadband spectral modeling of the radio-loud active galaxy 4C +55.17 (z = 0.896), formally classified as a flat-spectrum radio quasar. Using 19 months of all-sky survey Fermi-LAT data, we detect a {gamma}-ray continuum extending up to an observed energy of 145 GeV, and furthermore we find no evidence of {gamma}-ray variability in the source over its observed history. We illustrate the implications of these results in two different domains. First, we investigate the origin of the steady {gamma}-ray emission, where we re-examine the common classification of 4C +55.17 as a quasar-hosted blazar and consider instead its possible nature as a young radio source. We analyze and compare constraints on the source physical parameters in both blazar and young radio source scenarios by means of a detailed multiwavelength analysis and theoretical modeling of its broadband spectrum. Second, we show that the {gamma}-ray spectrum may be formally extrapolated into the very high energy (VHE, {>=}100 GeV) range at a flux level detectable by the current generation of ground-based Cherenkov telescopes. This enables us to place constraints on models of extragalactic background light within LAT energies and features the source as a promising candidate for VHE studies of the universe at an unprecedented redshift of z = 0.896.

  2. Discovery of Pulsed Gamma Rays from the Young Radio Pulsar PSR J1028-5819 with the Fermi Large Area Telescope

    SciTech Connect

    Abdo, Aous A.; Ackermann, M.; Atwood, W.B.; Baldini, L.; Ballet, J.; Barbiellini, Guido; Baring, Matthew G.; Bastieri, Denis; Baughman, B.M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, Elliott D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, Thompson H.; Caliandro, G.A.; /more authors..

    2009-05-15

    Radio pulsar PSR J1028-5819 was recently discovered in a high-frequency search (at 3.1 GHz) in the error circle of the Energetic Gamma-Ray Experiment Telescope (EGRET) source 3EG J1027-5817. The spin-down power of this young pulsar is great enough to make it very likely the counterpart for the EGRET source. We report here the discovery of {gamma}-ray pulsations from PSR J1028-5819 in early observations by the Large Area Telescope (LAT) on the Fermi Gamma-Ray Space Telescope. The {gamma}-ray light curve shows two sharp peaks having phase separation of 0.460 {+-} 0.004, trailing the very narrow radio pulse by 0.200 {+-} 0.003 in phase, very similar to that of other known {gamma}-ray pulsars. The measured {gamma}-ray flux gives an efficiency for the pulsar of {approx}10-20% (for outer magnetosphere beam models). No evidence of a surrounding pulsar wind nebula is seen in the current Fermi data but limits on associated emission are weak because the source lies in a crowded region with high background emission. However, the improved angular resolution afforded by the LAT enables the disentanglement of the previous COS-B and EGRET source detections into at least two distinct sources, one of which is now identified as PSR J1028-5819.

  3. Fermi Large Area Telescope observations of the active galaxy 4C +55.17: Steady, hard gamma-ray emission and its implications

    SciTech Connect

    McConville, W.; Ostorero, L.; Moderski, R.; Stawarz, Ł.; Cheung, C. C.; Ajello, M.; Bouvier, A.; Bregeon, J.; Donato, D.; Finke, J.; Furniss, A.; McEnery, J. E.; Monzani, M. E.; Orienti, M.; Reyes, L. C.; Rossetti, A.; Williams, D. A.

    2011-08-19

    Here, we report Fermi Large Area Telescope (LAT) observations and broadband spectral modeling of the radio-loud active galaxy 4C +55.17 (z = 0.896), formally classified as a flat-spectrum radio quasar. Using 19 months of all-sky survey Fermi-LAT data, we detect a γ-ray continuum extending up to an observed energy of 145 GeV, and furthermore we find no evidence of γ-ray variability in the source over its observed history. We illustrate the implications of these results in two different domains. First, we investigate the origin of the steady γ-ray emission, where we re-examine the common classification of 4C +55.17 as a quasar-hosted blazar and consider instead its possible nature as a young radio source. We analyze and compare constraints on the source physical parameters in both blazar and young radio source scenarios by means of a detailed multiwavelength analysis and theoretical modeling of its broadband spectrum. Second, we show that the γ-ray spectrum may be formally extrapolated into the very high energy (VHE, ≥100 GeV) range at a flux level detectable by the current generation of ground-based Cherenkov telescopes. This enables us to place constraints on models of extragalactic background light within LAT energies and features the source as a promising candidate for VHE studies of the universe at an unprecedented redshift of z = 0.896.

  4. Anisotropic Fermi couplings due to large unquenched orbital angular momentum: Q-band (1)H, (14)N, and (11)B ENDOR of bis(trispyrazolylborate) cobalt(II).

    PubMed

    Myers, William K; Scholes, Charles P; Tierney, David L

    2009-08-05

    We report Q-band ENDOR of (1)H, (14)N, and (11)B at the g( parallel) extreme of the EPR spectrum of bis(trispyrazolylborate) cobalt(II) [Co(Tp)(2)] and two structural analogs. This trigonally symmetric, high-spin (hs) S = 3/2 Co(II) complex shows large unquenched ground-state orbital angular momentum, which leads to highly anisotropic electronic g-values (g( parallel) = 8.48, g( perpendicular) = 1.02). The large g-anisotropy is shown to result in large dipolar couplings near g( parallel) and uniquely anisotropic (14)N Fermi couplings, which arise from spin transferred to the nitrogen 2s orbital (2.2%) via antibonding interactions with singly occupied metal d(x(2)-y(2)) and d(z(2)) orbitals. Large, well-resolved (1)H and (11)B dipolar couplings were also observed. Taken in concert with our previous X-band ENDOR measurements at g( perpendicular) ( Myers, W. K.; et al. Inorg. Chem. 2008, 47, 6701-6710 ), the present data allow a detailed analysis of the dipolar hyperfine tensors of two of the four symmetry distinct protons in the parent molecule. In the substituted analogs, changes in hyperfine coupling due to altered metal-proton distances give further evidence of an anisotropic Fermi contact interaction. For the pyrazolyl 3H proton, the data indicate a 0.2 MHz anisotropic contact interaction and approximately 4% transfer of spin away from Co(II). Dipolar coupling also dominates for the axial boron atoms, consistent with their distance from the Co(II) ion, and resolved (11)B quadrupolar coupling showed approximately 30% electronic inequivalence between the B-H and B-C sp(3) bonds. This is the first comprehensive ENDOR study of any hs Co(II) species and lays the foundation for future development.

  5. High-redshift Fermi blazars

    NASA Astrophysics Data System (ADS)

    Ghisellini, G.; Tagliaferri, G.; Foschini, L.; Ghirlanda, G.; Tavecchio, F.; Della Ceca, R.; Haardt, F.; Volonteri, M.; Gehrels, N.

    2011-02-01

    With the release of the first-year Fermi catalogue, the number of blazars detected above 100 MeV lying at high redshift has been largely increased. There are 28 blazars at z > 2 in the `clean' sample. All of them are flat spectrum radio quasars. We study and model their overall spectral energy distribution in order to find the physical parameters of the jet-emitting region, and for all of them, we estimate their black hole masses and accretion rates. We then compare the jet with the accretion disc properties, setting these sources in the broader context of all the other bright γ-ray or hard X-ray blazars. We confirm that the jet power correlates with the accretion luminosity. We find that the high-energy emission peak shifts to smaller frequencies as the observed luminosity increases, according to the blazar sequence, making the hard X-ray band the most suitable for searching the most-luminous and distant blazars.

  6. Enrico Fermi

    NASA Astrophysics Data System (ADS)

    Yang, Chen Ning

    2013-05-01

    Enrico Fermi was, of all the great physicists of the 20th century, among the most respected and admired. He was respected and admired because of his contributions to both theoretical and experimental physics, because of his leadership in discovering for mankind a powerful new source of energy, and above all, because of his personal character. He was always reliable and trustworthy. He had both of his feet on the ground all the time. He had great strength, but never threw his weight around. He did not play to the gallery. He did not practise one-up-manship. He exemplified, I always believe, the perfect Confucian gentleman...

  7. Searching for dark matter annihilation from Milky Way dwarf spheroidal galaxies with six years of Fermi Large Area Telescope data

    DOE PAGES

    Ackermann, M.

    2015-11-30

    The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on γ-ray observations of Milky Way dSphs based on six years of Fermi Large Area Telescope data processed with the new Pass8 event-level analysis. None of the dSphs are significantly detected in γ rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. As a result, these constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DMmore » of mass ≲100 GeV annihilating via quark and τ-lepton channels.« less

  8. Searching for dark matter annihilation from Milky Way dwarf spheroidal galaxies with six years of Fermi Large Area Telescope data

    SciTech Connect

    Ackermann, M.

    2015-11-30

    The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on γ-ray observations of Milky Way dSphs based on six years of Fermi Large Area Telescope data processed with the new Pass8 event-level analysis. None of the dSphs are significantly detected in γ rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. As a result, these constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass ≲100 GeV annihilating via quark and τ-lepton channels.

  9. Fermi Large Area Telescope Observations Of Gamma-Ray Pulsars PSR J1057–5226, J1709–4429, And J1952+3252

    SciTech Connect

    Abdo, A. A.

    2010-08-05

    The Fermi Large Area Telescope (LAT) data have confirmed the pulsed emission from all six high-confidence gamma-ray pulsars previously known from the EGRET observations. We report results obtained from the analysis of 13 months of LAT data for three of these pulsars (PSR J1057–5226, PSR J1709–4429, and PSR J1952+3252) each of which had some unique feature among the EGRET pulsars. The excellent sensitivity of LAT allows more detailed analysis of the evolution of the pulse profile with energy and also of the variation of the spectral shape with phase. We measure the cutoff energy of the pulsed emission from these pulsars for the first time and provide a more complete picture of the emission mechanism. The results confirm some, but not all, of the features seen in the EGRET data.

  10. Fermi Large Area Telescope Observations Of Gamma-Ray Pulsars PSR J1057–5226, J1709–4429, And J1952+3252

    DOE PAGES

    Abdo, A. A.

    2010-08-05

    The Fermi Large Area Telescope (LAT) data have confirmed the pulsed emission from all six high-confidence gamma-ray pulsars previously known from the EGRET observations. We report results obtained from the analysis of 13 months of LAT data for three of these pulsars (PSR J1057–5226, PSR J1709–4429, and PSR J1952+3252) each of which had some unique feature among the EGRET pulsars. The excellent sensitivity of LAT allows more detailed analysis of the evolution of the pulse profile with energy and also of the variation of the spectral shape with phase. We measure the cutoff energy of the pulsed emission from thesemore » pulsars for the first time and provide a more complete picture of the emission mechanism. The results confirm some, but not all, of the features seen in the EGRET data.« less

  11. Detection of gamma-ray emission from the Starburst Galaxies M82 and NGC 253 with the Large Area Telescope on Fermi

    DOE PAGES

    Abdo, A. A.

    2010-01-14

    Here, we report the detection of high-energy γ-ray emission from two starburst galaxies using data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Furthermore, we detected a steady point-like emission above 200 MeV at significance levels of 6.8σ and 4.8σ, respectively, from sources positionally coincident with locations of the starburst galaxies M82 and NGC 253. The total fluxes of the sources are consistent with γ-ray emission originating from the interaction of cosmic rays with local interstellar gas and radiation fields and constitute evidence for a link between massive star formation and γ-ray emission in star-formingmore » galaxies.« less

  12. Detection of gamma-ray emission from the Starburst Galaxies M82 and NGC 253 with the Large Area Telescope on Fermi

    SciTech Connect

    Abdo, A. A.

    2010-01-14

    Here, we report the detection of high-energy γ-ray emission from two starburst galaxies using data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Furthermore, we detected a steady point-like emission above 200 MeV at significance levels of 6.8σ and 4.8σ, respectively, from sources positionally coincident with locations of the starburst galaxies M82 and NGC 253. The total fluxes of the sources are consistent with γ-ray emission originating from the interaction of cosmic rays with local interstellar gas and radiation fields and constitute evidence for a link between massive star formation and γ-ray emission in star-forming galaxies.

  13. Discovery of millisecond pulsars in radio searches of southern Fermi Large Area Telescope sources

    SciTech Connect

    Keith, M. J.; Johnston, S.; Ray, P. S.; Ferrara, E. C.; Saz Parkinson, P. M.; Çelik, Ö.; Belfiore, A.; Donato, D.; Cheung, C. C.; Abdo, A. A.; Camilo, F.; Freire, P. C. C.; Guillemot, L.; Harding, A. K.; Kramer, M.; Michelson, P. F.; Ransom, S. M.; Romani, R. W.; Smith, D. A.; Thompson, D. J.; Weltevrede, P.; Wood, K. S.

    2011-06-08

    Using the Parkes Radio Telescope, we have carried out deep observations of 11 unassociated gamma-ray sources. Periodicity searches of these data have discovered two millisecond pulsars, PSR J1103–5403 (1FGL J1103.9–5355) and PSR J2241–5236 (1FGL J2241.9–5236), and a long-period pulsar, PSR J1604–44 (1FGL J1604.7–4443). In addition, we searched for but did not detect any radio pulsations from six gamma-ray pulsars discovered by the Fermi satellite to a level of ~0.04 mJy (for pulsars with a 10 per cent duty cycle). The timing of the millisecond pulsar PSR J1103–5403 has shown that its position is 9 arcmin from the centroid of the gamma-ray source. Since these observations were carried out, independent evidence has shown that 1FGL J1103.9–5355 is associated with the flat spectrum radio source PKS 1101–536. It appears certain that the pulsar is not associated with the gamma-ray source, despite the seemingly low probability of a chance detection of a radio millisecond pulsar. We consider that PSR J1604–44 is a chance discovery of a weak, long-period pulsar and is unlikely to be associated with 1FGL J1604.7–4443. PSR J2241–5236 has a spin period of 2.2 ms and orbits a very low mass companion with a 3.5-h orbital period. The relatively high flux density and low dispersion measure of PSR J2241–5236 make it an excellent candidate for high precision timing experiments. The gamma rays of 1FGL J2241.9–5236 have a spectrum that is well modelled by a power law with an exponential cut-off, and phase binning with the radio ephemeris results in a multipeaked gamma-ray pulse profile. Furthermore, observations with Chandra have identified a coincident X-ray source within 0.1 arcsec of the position of the pulsar obtained by radio timing.

  14. Fermi/Large Area Telescope Discovery of Gamma-Ray Emission from a Relativistic Jet in the Narrow-Line Quasar PMN J0948+0022

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2009-06-17

    In this paper, we report the discovery by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope of high-energy γ-ray emission from the peculiar quasar PMN J0948+0022 (z = 0.5846). The optical spectrum of this object exhibits rather narrow Hβ (FWHM(Hβ) ~1500 km s–1), weak forbidden lines, and is therefore classified as a narrow-line type I quasar. This class of objects is thought to have relatively small black hole mass and to accrete at a high Eddington ratio. The radio loudness and variability of the compact radio core indicate the presence of a relativistic jet. Quasi-simultaneous radio/optical/X-ray andmore » γ-ray observations are presented. Both radio and γ-ray emissions (observed over five months) are strongly variable. The simultaneous optical and X-ray data from Swift show a blue continuum attributed to the accretion disk and a hard X-ray spectrum attributed to the jet. The resulting broadband spectral energy distribution (SED) and, in particular, the γ-ray spectrum measured by Fermi are similar to those of more powerful Flat-Spectrum Radio Quasars (FSRQs). A comparison of the radio and γ-ray characteristics of PMN J0948+0022 with the other blazars detected by LAT shows that this source has a relatively low radio and γ-ray power with respect to other FSRQs. The physical parameters obtained from modeling the SED also fall at the low power end of the FSRQ parameter region discussed in Celotti & Ghisellini. Finally, we suggest that the similarity of the SED of PMN J0948+0022 to that of more massive and more powerful quasars can be understood in a scenario in which the SED properties depend on the Eddington ratio rather than on the absolute power.« less

  15. High-energy gamma-ray emission from solar flares: Summary of Fermi large area telescope detections and analysis of two m-class flares

    DOE PAGES

    Ackermann, M.; Ajello, M.; Albert, A.; ...

    2014-04-29

    Here, we present the detections of 18 solar flares detected in high-energy γ-rays (above 100 MeV) with the Fermi Large Area Telescope (LAT) during its first 4 yr of operation. Our work suggests that particle acceleration up to very high energies in solar flares is more common than previously thought, occurring even in modest flares, and for longer durations. Interestingly, all these flares are associated with fairly fast coronal mass ejections (CMEs). We then describe the detailed temporal, spatial, and spectral characteristics of the first two long-lasting events: the 2011 March 7 flare, a moderate (M3.7) impulsive flare followed bymore » slowly varying γ-ray emission over 13 hr, and the 2011 June 7 M2.5 flare, which was followed by γ-ray emission lasting for 2 hr. We compare the Fermi LAT data with X-ray and proton data measurements from GOES and RHESSI. We argue that the γ-rays are more likely produced through pion decay than electron bremsstrahlung, and we find that the energy spectrum of the proton distribution softens during the extended emission of the 2011 March 7 flare. Furthermore, this would disfavor a trapping scenario for particles accelerated during the impulsive phase of the flare and point to a continuous acceleration process at play for the duration of the flares. CME shocks are known for accelerating the solar energetic particles (SEPs) observed in situ on similar timescales, but it might be challenging to explain the production of γ-rays at the surface of the Sun while the CME is halfway to the Earth. A stochastic turbulence acceleration process occurring in the solar corona is another likely scenario. Detailed comparison of characteristics of SEPs and γ-ray-emitting particles for several flares will be helpful to distinguish between these two possibilities.« less

  16. High-energy gamma-ray emission from solar flares: Summary of Fermi large area telescope detections and analysis of two m-class flares

    SciTech Connect

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Bonamente, E.; Bottacini, E.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chen, Q.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Desiante, R.; Digel, S. W.; Di Venere, L.; do Couto e Silva, E.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; 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.; Hughes, R. E.; Inoue, Y.; Jackson, M. S.; Jogler, T.; Jóhannesson, G.; Johnson, W. N.; Kamae, T.; Kawano, T.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Murphy, R.; Nemmen, R.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Perkins, J. S.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Ritz, S.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Takahashi, H.; Takeuchi, Y.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Tosti, G.; Troja, E.; Tronconi, V.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Werner, M.; Winer, B. L.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.

    2014-04-29

    Here, we present the detections of 18 solar flares detected in high-energy γ-rays (above 100 MeV) with the Fermi Large Area Telescope (LAT) during its first 4 yr of operation. Our work suggests that particle acceleration up to very high energies in solar flares is more common than previously thought, occurring even in modest flares, and for longer durations. Interestingly, all these flares are associated with fairly fast coronal mass ejections (CMEs). We then describe the detailed temporal, spatial, and spectral characteristics of the first two long-lasting events: the 2011 March 7 flare, a moderate (M3.7) impulsive flare followed by slowly varying γ-ray emission over 13 hr, and the 2011 June 7 M2.5 flare, which was followed by γ-ray emission lasting for 2 hr. We compare the Fermi LAT data with X-ray and proton data measurements from GOES and RHESSI. We argue that the γ-rays are more likely produced through pion decay than electron bremsstrahlung, and we find that the energy spectrum of the proton distribution softens during the extended emission of the 2011 March 7 flare. Furthermore, this would disfavor a trapping scenario for particles accelerated during the impulsive phase of the flare and point to a continuous acceleration process at play for the duration of the flares. CME shocks are known for accelerating the solar energetic particles (SEPs) observed in situ on similar timescales, but it might be challenging to explain the production of γ-rays at the surface of the Sun while the CME is halfway to the Earth. A stochastic turbulence acceleration process occurring in the solar corona is another likely scenario. Detailed comparison of characteristics of SEPs and γ-ray-emitting particles for several flares will be helpful to distinguish between these two possibilities.

  17. Fermi/Large Area Telescope Discovery of Gamma-Ray Emission from a Relativistic Jet in the Narrow-Line Quasar PMN J0948+0022

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Battelino, M.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Collmar, W.; Conrad, J.; Costamante, L.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Focke, W. B.; Foschini, L.; Frailis, M.; Fuhrmann, L.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hanabata, Y.; Harding, A. K.; Hartman, R. C.; Hayashida, M.; Hays, E.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kerr, M.; Knödlseder, J.; Kuehn, F.; Kuss, M.; Lande, J.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Max-Moerbeck, W.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Pavlidou, V.; Pearson, T. J.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Readhead, A.; Reimer, A.; Reimer, O.; Reposeur, T.; Richards, J. L.; Ritz, S.; Rodriguez, A. Y.; Romani, R. W.; Ryde, F.; Sadrozinski, H. F. -W.; Sambruna, R.; Sanchez, D.; Sander, A.; Parkinson, P. M. Saz; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Smith, D. A.; Spandre, G.; Spinelli, P.; Starck, J. -L.; Stevenson, M.; Strickman, M. S.; Suson, D. J.; Tagliaferri, G.; Takahashi, H.; Tanaka, T.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vilchez, N.; Vitale, V.; Waite, A. P.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Zensus, J. A.; Ziegler, M.; Ghisellini, G.; Maraschi, L.; Tavecchio, F.; Angelakis, E.

    2009-06-17

    In this paper, we report the discovery by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope of high-energy γ-ray emission from the peculiar quasar PMN J0948+0022 (z = 0.5846). The optical spectrum of this object exhibits rather narrow Hβ (FWHM(Hβ) ~1500 km s–1), weak forbidden lines, and is therefore classified as a narrow-line type I quasar. This class of objects is thought to have relatively small black hole mass and to accrete at a high Eddington ratio. The radio loudness and variability of the compact radio core indicate the presence of a relativistic jet. Quasi-simultaneous radio/optical/X-ray and γ-ray observations are presented. Both radio and γ-ray emissions (observed over five months) are strongly variable. The simultaneous optical and X-ray data from Swift show a blue continuum attributed to the accretion disk and a hard X-ray spectrum attributed to the jet. The resulting broadband spectral energy distribution (SED) and, in particular, the γ-ray spectrum measured by Fermi are similar to those of more powerful Flat-Spectrum Radio Quasars (FSRQs). A comparison of the radio and γ-ray characteristics of PMN J0948+0022 with the other blazars detected by LAT shows that this source has a relatively low radio and γ-ray power with respect to other FSRQs. The physical parameters obtained from modeling the SED also fall at the low power end of the FSRQ parameter region discussed in Celotti & Ghisellini. Finally, we suggest that the similarity of the SED of PMN J0948+0022 to that of more massive and more powerful quasars can be understood in a scenario in which the SED properties depend on the Eddington ratio rather than on the absolute power.

  18. Fermi Large Area Telescope observations of the active galaxy 4C +55.17: Steady, hard gamma-ray emission and its implications

    DOE PAGES

    McConville, W.; Ostorero, L.; Moderski, R.; ...

    2011-08-19

    Here, we report Fermi Large Area Telescope (LAT) observations and broadband spectral modeling of the radio-loud active galaxy 4C +55.17 (z = 0.896), formally classified as a flat-spectrum radio quasar. Using 19 months of all-sky survey Fermi-LAT data, we detect a γ-ray continuum extending up to an observed energy of 145 GeV, and furthermore we find no evidence of γ-ray variability in the source over its observed history. We illustrate the implications of these results in two different domains. First, we investigate the origin of the steady γ-ray emission, where we re-examine the common classification of 4C +55.17 as amore » quasar-hosted blazar and consider instead its possible nature as a young radio source. We analyze and compare constraints on the source physical parameters in both blazar and young radio source scenarios by means of a detailed multiwavelength analysis and theoretical modeling of its broadband spectrum. Second, we show that the γ-ray spectrum may be formally extrapolated into the very high energy (VHE, ≥100 GeV) range at a flux level detectable by the current generation of ground-based Cherenkov telescopes. This enables us to place constraints on models of extragalactic background light within LAT energies and features the source as a promising candidate for VHE studies of the universe at an unprecedented redshift of z = 0.896.« less

  19. GAMMA-RAY LOUDNESS, SYNCHROTRON PEAK FREQUENCY, AND PARSEC-SCALE PROPERTIES OF BLAZARS DETECTED BY THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Linford, J. D.; Taylor, G. B.; Schinzel, F. K.

    2012-09-20

    The parsec-scale radio properties of 232 active galactic nuclei, most of which are blazars, detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed contemporaneously by the Very Long Baseline Array (VLBA) at 5 GHz. Data from both the first 11 months (1FGL) and the first 2 years (2FGL) of the Fermi mission were used to investigate these sources' {gamma}-ray properties. We use the ratio of the {gamma}-ray-to-radio luminosity as a measure of {gamma}-ray loudness. We investigate the relationship of several radio properties to {gamma}-ray loudness and to the synchrotron peak frequency. There is a tentative correlation between {gamma}-ray loudness and synchrotron peak frequency for BL Lac objects in both 1FGL and 2FGL, and for flat-spectrum radio quasars (FSRQs) in 2FGL. We find that the apparent opening angle tentatively correlates with {gamma}-ray loudness for FSRQs, but only when we use the 2FGL data. We also find that the total VLBA flux density correlates with the synchrotron peak frequency for BL Lac objects and FSRQs. The core brightness temperature also correlates with synchrotron peak frequency, but only for the BL Lac objects. The low-synchrotron-peaked (LSP) BL Lac object sample shows indications of contamination by FSRQs which happen to have undetectable emission lines. There is evidence that the LSP BL Lac objects are more strongly beamed than the rest of the BL Lac object population.

  20. High-energy Gamma-Ray Emission from Solar Flares: Summary of Fermi Large Area Telescope Detections and Analysis of Two M-class Flares

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Bonamente, E.; Bottacini, E.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chen, Q.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Desiante, R.; Digel, S. W.; Di Venere, L.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; 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.; Hughes, R. E.; Inoue, Y.; Jackson, M. S.; Jogler, T.; Jóhannesson, G.; Johnson, W. N.; Kamae, T.; Kawano, T.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Murphy, R.; Nemmen, R.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Perkins, J. S.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Ritz, S.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Takahashi, H.; Takeuchi, Y.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Tosti, G.; Troja, E.; Tronconi, V.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Werner, M.; Winer, B. L.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.; Fermi LAT Collaboration

    2014-05-01

    We present the detections of 18 solar flares detected in high-energy γ-rays (above 100 MeV) with the Fermi Large Area Telescope (LAT) during its first 4 yr of operation. This work suggests that particle acceleration up to very high energies in solar flares is more common than previously thought, occurring even in modest flares, and for longer durations. Interestingly, all these flares are associated with fairly fast coronal mass ejections (CMEs). We then describe the detailed temporal, spatial, and spectral characteristics of the first two long-lasting events: the 2011 March 7 flare, a moderate (M3.7) impulsive flare followed by slowly varying γ-ray emission over 13 hr, and the 2011 June 7 M2.5 flare, which was followed by γ-ray emission lasting for 2 hr. We compare the Fermi LAT data with X-ray and proton data measurements from GOES and RHESSI. We argue that the γ-rays are more likely produced through pion decay than electron bremsstrahlung, and we find that the energy spectrum of the proton distribution softens during the extended emission of the 2011 March 7 flare. This would disfavor a trapping scenario for particles accelerated during the impulsive phase of the flare and point to a continuous acceleration process at play for the duration of the flares. CME shocks are known for accelerating the solar energetic particles (SEPs) observed in situ on similar timescales, but it might be challenging to explain the production of γ-rays at the surface of the Sun while the CME is halfway to the Earth. A stochastic turbulence acceleration process occurring in the solar corona is another likely scenario. Detailed comparison of characteristics of SEPs and γ-ray-emitting particles for several flares will be helpful to distinguish between these two possibilities.

  1. High-energy gamma-ray emission from solar flares: Summary of Fermi large area telescope detections and analysis of two M-class flares

    SciTech Connect

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Bechtol, K.; Bottacini, E.; Buehler, R.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Buson, S.; Bellazzini, R.; Bregeon, J.; Bissaldi, E.; Bonamente, E.; Bouvier, A.; Brandt, T. J.; Brigida, M.; Bruel, P.; and others

    2014-05-20

    We present the detections of 18 solar flares detected in high-energy γ-rays (above 100 MeV) with the Fermi Large Area Telescope (LAT) during its first 4 yr of operation. This work suggests that particle acceleration up to very high energies in solar flares is more common than previously thought, occurring even in modest flares, and for longer durations. Interestingly, all these flares are associated with fairly fast coronal mass ejections (CMEs). We then describe the detailed temporal, spatial, and spectral characteristics of the first two long-lasting events: the 2011 March 7 flare, a moderate (M3.7) impulsive flare followed by slowly varying γ-ray emission over 13 hr, and the 2011 June 7 M2.5 flare, which was followed by γ-ray emission lasting for 2 hr. We compare the Fermi LAT data with X-ray and proton data measurements from GOES and RHESSI. We argue that the γ-rays are more likely produced through pion decay than electron bremsstrahlung, and we find that the energy spectrum of the proton distribution softens during the extended emission of the 2011 March 7 flare. This would disfavor a trapping scenario for particles accelerated during the impulsive phase of the flare and point to a continuous acceleration process at play for the duration of the flares. CME shocks are known for accelerating the solar energetic particles (SEPs) observed in situ on similar timescales, but it might be challenging to explain the production of γ-rays at the surface of the Sun while the CME is halfway to the Earth. A stochastic turbulence acceleration process occurring in the solar corona is another likely scenario. Detailed comparison of characteristics of SEPs and γ-ray-emitting particles for several flares will be helpful to distinguish between these two possibilities.

  2. Motivational Project-Based Laboratory for a Common First Year Electrical Engineering Course

    ERIC Educational Resources Information Center

    Nedic, Zorica; Nafalski, Andrew; Machotka, Jan

    2010-01-01

    Over the past few years many universities worldwide have introduced a common first year for all engineering disciplines. This is despite the opinion of many academics that large classes have negative effects on the learning outcomes of first year students. The University of South Australia is also faced with low motivation amongst engineering…

  3. Learning Communities: Foundations for First-Year Students' Development of Pluralistic Outcomes

    ERIC Educational Resources Information Center

    Soria, Krista M.; Mitchell, Tania D.

    2015-01-01

    The purpose of this study was to investigate the associations between first-year undergraduates' (n = 1,701) participation in learning communities and their development of leadership and multicultural competence. The sample included first-year students who were enrolled at six large, public research universities in 2012 and completed the Student…

  4. Maintaining Positive Attitudes toward Science and Technology in First-Year Female Undergraduates: Peril and Promise

    ERIC Educational Resources Information Center

    Machina, Kenton; Gokhale, Anu

    2010-01-01

    This study investigated attitude changes of 18-year-old first-year college students at a large state-operated institution in the USA during their initial semester in college. Attitudes of 375 students enrolled in a non-science first-year student seminar during the Fall of 2004 were measured, using a new instrument designed to focus on five…

  5. Motivational Project-Based Laboratory for a Common First Year Electrical Engineering Course

    ERIC Educational Resources Information Center

    Nedic, Zorica; Nafalski, Andrew; Machotka, Jan

    2010-01-01

    Over the past few years many universities worldwide have introduced a common first year for all engineering disciplines. This is despite the opinion of many academics that large classes have negative effects on the learning outcomes of first year students. The University of South Australia is also faced with low motivation amongst engineering…

  6. Assessing the Effectiveness of an Adventure-Based First-Year Experience Class

    ERIC Educational Resources Information Center

    Bell, Brent J.

    2012-01-01

    This study compares a first-year experience (FYE) course utilizing outdoor adventure experiences to a more traditional FYE class at a large mid-Atlantic university. This study compares the quantitative differences between responses by participants in the two classes using the First Year Initiative Survey (FYI), a measure of FYE outcomes related to…

  7. How Do Learning Communities Affect First-Year Latino Students?

    ERIC Educational Resources Information Center

    Huerta, Juan Carlos; Bray, Jennifer J.

    2013-01-01

    Do learning communities with pedagogies of active learning, collaborative learning, and integration of course material affect the learning, achievement, and persistence of first-year Latino university students? The data for this project was obtained from a survey of 1,330 first-year students in the First-Year Learning Community Program at Texas…

  8. The intergalactic magnetic field constrained by Fermi/Large Area Telescope observations of the TeV blazar 1ES0229+200

    NASA Astrophysics Data System (ADS)

    Tavecchio, F.; Ghisellini, G.; Foschini, L.; Bonnoli, G.; Ghirlanda, G.; Coppi, P.

    2010-07-01

    TeV photons from blazars at relatively large distances, interacting with the optical-infrared cosmic background, are efficiently converted into electron-positron pairs. The produced pairs are extremely relativistic (Lorentz factors of the order of 106- 107) and promptly lose their energy through inverse Compton scatterings with the photons of the microwave cosmic background, producing emission in the GeV band. The spectrum and the flux level of this reprocessed emission are critically dependent on the intensity of the intergalactic magnetic field, B, that can deflect the pairs diluting the intrinsic emission over a large solid angle. We derive a simple relation for the reprocessed spectrum expected from a steady source. We apply this treatment to the blazar 1ES0229+200, whose intrinsic, very hard TeV spectrum is expected to be approximately steady. Comparing the predicted reprocessed emission with the upper limits measured by the Fermi/Large Area Telescope, we constrain the value of the intergalactic magnetic field to be larger than B ~= 5 × 10-15 G, depending on the model of extragalactic background light.

  9. Searching the Gamma-Ray Sky for Counterparts to Gravitational Wave Sources: FERMI Gamma Ray Burst MONITOR and Large Area Telescope Observations of LVT151012 and GW151226

    DOE PAGES

    Racusin, J. L.; Burns, E.; Goldstein, A.; ...

    2017-01-19

    Here, we present the Fermi Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) observations of the LIGO binary black hole merger event GW151226 and candidate LVT151012. At the time of the LIGO triggers on LVT151012 and GW151226, GBM was observing 68% and 83% of the localization regions, and LAT was observing 47% and 32%, respectively. No candidate electromagnetic counterparts were detected by either the GBM or LAT. We present a detailed analysis of the GBM and LAT data over a range of timescales from seconds to years, using automated pipelines and new techniques for characterizing the flux upper boundsmore » across large areas of the sky. Finally, due to the partial GBM and LAT coverage of the large LIGO localization regions at the trigger times for both events, differences in source distances and masses, as well as the uncertain degree to which emission from these sources could be beamed, these non-detections cannot be used to constrain the variety of theoretical models recently applied to explain the candidate GBM counterpart to GW150914.« less

  10. Challenges for the CMS computing model in the first year

    SciTech Connect

    Fisk, I.; /Fermilab

    2009-05-01

    CMS is in the process of commissioning a complex detector and a globally distributed computing infrastructure simultaneously. This represents a unique challenge. Even at the beginning there is not sufficient analysis or organized processing resources at CERN alone. In this presentation we discuss the unique computing challenges CMS expects to face during the first year of running and how they influence the baseline computing model decisions. During the early accelerator commissioning periods, CMS will attempt to collect as many events as possible when the beam is on in order to provide adequate early commissioning data. Some of these plans involve overdriving the Tier-0 infrastructure during data collection with recovery when the beam is off. In addition to the larger number of triggered events, there will be pressure in the first year to collect and analyze more complete data formats as the summarized formats mature. The large event formats impact the required storage, bandwidth, and processing capacity across all the computing centers. While the understanding of the detector and the event selections is being improved, there will likely be a larger number of reconstruction passes and skims performed by both central operations and individual users. We discuss how these additional stresses impact the allocation of resources and the changes from the baseline computing model.

  11. First-Year Village: Experimenting with an African Model for First-Year Adjustment and Support in South Africa

    ERIC Educational Resources Information Center

    Speckman, McGlory

    2016-01-01

    Predicated on the principles of success and contextuality, this chapter shares an African perspective on a first-year adjustment programme, known as First-Year Village, including its potential and challenges in establishing it.

  12. First-Year Village: Experimenting with an African Model for First-Year Adjustment and Support in South Africa

    ERIC Educational Resources Information Center

    Speckman, McGlory

    2016-01-01

    Predicated on the principles of success and contextuality, this chapter shares an African perspective on a first-year adjustment programme, known as First-Year Village, including its potential and challenges in establishing it.

  13. Challenging and Supporting the First-Year Student: A Handbook for Improving the First Year of College

    ERIC Educational Resources Information Center

    Upcraft, M. Lee, Ed.; Gardner, John N., Ed.; Barefoot, Betsy O., Ed.

    2004-01-01

    An authoritative, comprehensive guide to the first year of college, this book includes the most current information about the policies, strategies, programs, and services designed to help first-year students make a successful transition to college and fulfill their educational and personal goals. Following the introduction, "The First Year of…

  14. Challenging and Supporting the First-Year Student: A Handbook for Improving the First Year of College

    ERIC Educational Resources Information Center

    Upcraft, M. Lee, Ed.; Gardner, John N., Ed.; Barefoot, Betsy O., Ed.

    2004-01-01

    An authoritative, comprehensive guide to the first year of college, this book includes the most current information about the policies, strategies, programs, and services designed to help first-year students make a successful transition to college and fulfill their educational and personal goals. Following the introduction, "The First Year of…

  15. Search for gamma-ray emission from dark matter annihilation in the Small Magellanic Cloud with the Fermi Large Area Telescope

    SciTech Connect

    Caputo, Regina; Buckley, Matthew R.; Martin, Pierrick; Charles, Eric; Brooks, Alyson M.; Drlica-Wagner, Alex; Gaskins, Jennifer M.; Wood, Matthew

    2016-03-22

    The Small Magellanic Cloud (SMC) is the second-largest satellite galaxy of the Milky Way and is only 60 kpc away. As a nearby, massive, and dense object with relatively low astrophysical backgrounds, it is a natural target for dark matter indirect detection searches. In this work, we use six years of Pass 8 data from the Fermi Large Area Telescope to search for gamma-ray signals of dark matter annihilation in the SMC. Using data-driven fits to the gamma-ray backgrounds, and a combination of N-body simulations and direct measurements of rotation curves to estimate the SMC DM density profile, we found that the SMC was well described by standard astrophysical sources, and no signal from dark matter annihilation was detected. We set conservative upper limits on the dark matter annihilation cross section. Furthermore, these constraints are in agreement with stronger constraints set by searches in the Large Magellanic Cloud and approach the canonical thermal relic cross section at dark matter masses lower than 10 GeV in the bb¯ and τ+τ- channels.

  16. Search for gamma-ray emission from dark matter annihilation in the Small Magellanic Cloud with the Fermi Large Area Telescope

    DOE PAGES

    Caputo, Regina; Buckley, Matthew R.; Martin, Pierrick; ...

    2016-03-22

    The Small Magellanic Cloud (SMC) is the second-largest satellite galaxy of the Milky Way and is only 60 kpc away. As a nearby, massive, and dense object with relatively low astrophysical backgrounds, it is a natural target for dark matter indirect detection searches. In this work, we use six years of Pass 8 data from the Fermi Large Area Telescope to search for gamma-ray signals of dark matter annihilation in the SMC. Using data-driven fits to the gamma-ray backgrounds, and a combination of N-body simulations and direct measurements of rotation curves to estimate the SMC DM density profile, we found that themore » SMC was well described by standard astrophysical sources, and no signal from dark matter annihilation was detected. We set conservative upper limits on the dark matter annihilation cross section. Furthermore, these constraints are in agreement with stronger constraints set by searches in the Large Magellanic Cloud and approach the canonical thermal relic cross section at dark matter masses lower than 10 GeV in the bb¯ and τ+τ- channels.« less

  17. Gamma-Ray Emission of the Kes 73/1E 1841-045 Region Observed with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Yeung, Paul K. H.; Kong, Albert K. H.; Tam, P. H. Thomas; Hui, C. Y.; Takata, Jumpei; Cheng, K. S.

    2017-03-01

    The supernova remnant (SNR) Kes 73 and/or the magnetar 1E 1841-045 at its center can deposit a large amount of energy to the surroundings and is potentially responsible for particle acceleration. Using the data taken with the Fermi Large Area Telescope (LAT), we confirmed the presence of an extended source whose centroid position is highly consistent with this magnetar/SNR pair. Its emission is intense from 100 MeV to >100 GeV. Its LAT spectrum can be decoupled into two components, which are respectively governed by two different mechanisms. According to the young age of this system, the magnetar is seemingly a necessary and sufficient source for the downward-curved spectrum below 10 GeV, as the observed <10 GeV flux is too high for the SNR to account for. On the other hand, the SNR is reasonably responsible for the hard spectrum above 10 GeV. Further studies of this region in the TeV regime is required so that we can perform physically meaningful comparisons of the >10 GeV spectrum and the TeV spectrum.

  18. German contribution to the validation of SCIAMACHY - the first year

    NASA Astrophysics Data System (ADS)

    Bramstedt, K.; Kirchhoff, B.

    2003-04-01

    An adequate validation of SCIAMACHY data products is a prerequisite for a successful completion of the SCIAMACHY mission. The German validation team, consisting of 23 different projects with more than 60 scientists, contributes with a wide range of instrument types as important part of the international validation community. A global network of ground-based stations with DOAS, FTIR, microwave instruments and ozone sondes has been build. Satellite inter-comparisons utilize the measurements of independent space-born sensors. Balloon-borne instruments participate in the Envisat Stratospheric Aircraft and Balloon validation campaigns and the German FALCON research aircraft has undertaken large flights from the Arctic to the Tropics. Here an overview of the GERMAN activities during the first year of SCIAMACHY lifetime is given.

  19. Pulsar Timing with the Fermi LAT

    DTIC Science & Technology

    2010-12-01

    Pulsar Timing with the Fermi LAT Paul S. Ray∗, Matthew Kerr†, Damien Parent∗∗ and the Fermi PSC‡ ∗Naval Research Laboratory, 4555 Overlook Ave., SW...Laboratory, Washington, DC 20375, USA ‡Fermi Pulsar Search Consortium Abstract. We present an overview of precise pulsar timing using data from the Large...unbinned photon data. In addition to determining the spindown behavior of the pulsars and detecting glitches and timing noise, such timing analyses al

  20. Fermi Large Area Telescope detection of bright γ-ray outbursts from the peculiar quasar 4C +21.35

    SciTech Connect

    Tanaka, Y. T.; Stawarz, Ł.; Thompson, D. J.; D'Ammando, F.; Fegan, S. J.; Lott, B.; Wood, D. L.; Cheung, C. C.; Finke, J.; Buson, S.; Escande, L.; Saito, S.; Ohno, M.; Takahashi, T.; Donato, D.; Chiang, J.; Giroletti, M.; Schinzel, F. K.; Iafrate, G.; Longo, F.; Ciprini, S.

    2011-04-29

    In this study, we report on the two-year-long Fermi-Large Area Telescope observation of the peculiar blazar 4C +21.35 (PKS 1222+216). This source was in a quiescent state from the start of the science operations of the Fermi Gamma-ray Space Telescope in 2008 August until 2009 September, and then became more active, with gradually increasing flux and some moderately bright flares. In 2010 April and June, 4C +21.35 underwent a very strong GeV outburst composed of several major flares characterized by rise and decay timescales of the order of a day. During the outburst, the GeV spectra of 4C +21.35 displayed a broken power-law form with spectral breaks observed near 1-3 GeV photon energies. We demonstrate that, at least during the major flares, the jet in 4C +21.35 carried a total kinetic luminosity comparable to the total accretion power available to feed the outflow. We also discuss the origin of the break observed in the flaring spectra of 4C +21.35. We show that, in principle, a model involving annihilation of the GeV photons on the He II Lyman recombination continuum and line emission of "broad-line region" clouds may account for such. However, we also discuss the additional constraint provided by the detection of 4C +21.35 at 0.07-0.4 TeV energies by the MAGIC telescope, which coincided with one of the GeV flares of the source. We argue that there are reasons to believe that the lesssim TeV emission of 4C +21.35 (as well as the GeV emission of the source, if co-spatial) is not likely to be produced inside the broad-line region zone of highest ionization (~1017 cm from the nucleus), but instead originates further away from the active center, namely, around the characteristic scale of the hot dusty torus surrounding the 4C +21.35 nucleus (~1019 cm).

  1. A model-independent analysis of the Fermi Large Area Telescope gamma-ray data from the Milky Way dwarf galaxies and halo to constrain dark matter scenarios

    DOE PAGES

    Mazziotta, M. N.; Loparco, F.; de Palma, F.; ...

    2012-07-22

    Here, we implemented a novel technique to perform the collective spectral analysis of sets of multiple gamma-ray point sources using the data collected by the Large Area Telescope onboard the Fermi satellite. The energy spectra of the sources are reconstructed starting from the photon counts and without assuming any spectral model for both the sources and the background. In case of faint sources, upper limits on their fluxes are evaluated with a Bayesian approach. Our analysis technique is very useful when several sources with similar spectral features are studied, such as sources of gamma rays from annihilation of dark mattermore » particles. We also present the results obtained by applying this analysis to a sample of dwarf spheroidal galaxies and to the Milky Way dark matter halo. The analysis of dwarf spheroidal galaxies yields upper limits on the product of the dark matter pair annihilation cross section and the relative velocity of annihilating particles that are well below those predicted by the canonical thermal relic scenario in a mass range from a few GeV to a few tens of GeV for some annihilation channels.« less

  2. A model-independent analysis of the Fermi Large Area Telescope gamma-ray data from the Milky Way dwarf galaxies and halo to constrain dark matter scenarios

    SciTech Connect

    Mazziotta, M. N.; Loparco, F.; de Palma, F.; Giglietto, N.

    2012-07-22

    Here, we implemented a novel technique to perform the collective spectral analysis of sets of multiple gamma-ray point sources using the data collected by the Large Area Telescope onboard the Fermi satellite. The energy spectra of the sources are reconstructed starting from the photon counts and without assuming any spectral model for both the sources and the background. In case of faint sources, upper limits on their fluxes are evaluated with a Bayesian approach. Our analysis technique is very useful when several sources with similar spectral features are studied, such as sources of gamma rays from annihilation of dark matter particles. We also present the results obtained by applying this analysis to a sample of dwarf spheroidal galaxies and to the Milky Way dark matter halo. The analysis of dwarf spheroidal galaxies yields upper limits on the product of the dark matter pair annihilation cross section and the relative velocity of annihilating particles that are well below those predicted by the canonical thermal relic scenario in a mass range from a few GeV to a few tens of GeV for some annihilation channels.

  3. Observations of the gamma-ray emission from the Quiescent Sun with Fermi Large Area Telescope during the first 7 years in orbit

    NASA Astrophysics Data System (ADS)

    Rainó, S.; Giglietto, N.; Moskalenko, I.; Orlando, E.; Strong, A. W.

    2017-03-01

    The high energy gamma-ray emission from the quiescent Sun is due to the interactions of cosmic ray (CR) protons and electrons with matter and photons in the solar environment. Such interactions lead to two component gamma-ray emission: a disk-like emission due to the nuclear interactions of CR protons and nuclei in the solar atmosphere and a space extended emission due to the inverse Compton (IC) scattering of CR electrons off solar photons in the whole heliosphere. The observation of these two solar emission components may give useful information about the evolution of the solar cycle by probing two different CR components (proton and electrons) in regions not directly accessible by direct observations. We present the results of the observations of the Sun with Fermi-LAT in the first 7 years on orbit, with the exception of the flaring periods. Significantly large photon statistics and improved processing performance with respect to previous analysis allow us to explore both components of the emission in greater details and perform better comparisons of data with current models of the IC component. This allows us to probe CR electrons in the inner heliosphere which is not possible by other methods. Moreover, the longer period of observations allows us to study the variations of the emission between the maximum and the minimum of the solar cycle.

  4. Determination of the Point-Spread Function for the FERMI Large Area Telescope from On-Orbit Data and Limits on Pair Halos of Active Galactic Nuclei

    DOE PAGES

    Ackermann, M.; Ajello, M.; Allafort, A.; ...

    2013-02-15

    We present the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to detect photons with energies from ≈20 MeV to >300 GeV. The pre-launch response functions of the LAT were determined through extensive Monte Carlo simulations and beam tests. The point-spread function (PSF) characterizing the angular distribution of reconstructed photons as a function of energy and geometry in the detector is determined here from two years of on-orbit data by examining the distributions of γ rays from pulsars and active galactic nuclei (AGNs). Above 3 GeV, the PSF is found to be broadermore » than the pre-launch PSF. We checked for dependence of the PSF on the class of γ-ray source and observation epoch and found none. We also investigated several possible spatial models for pair-halo emission around BL Lac AGNs. Finally, we found no evidence for a component with spatial extension larger than the PSF and set upper limits on the amplitude of halo emission in stacked images of low- and high-redshift BL Lac AGNs and the TeV blazars 1ES0229+200 and 1ES0347–121.« less

  5. Angular power spectrum of the diffuse gamma-ray emission as measured by the Fermi Large Area Telescope and constraints on its dark matter interpretation

    SciTech Connect

    Fornasa, Mattia; Cuoco, Alessandro; Zavala, Jesús; Gaskins, Jennifer M.; Sánchez-Conde, Miguel A.; Gomez-Vargas, German; Komatsu, Eiichiro; Linden, Tim; Prada, Francisco; Zandanel, Fabio; Morselli, Aldo

    2016-12-09

    The isotropic gamma-ray background arises from the contribution of unresolved sources, including members of confirmed source classes and proposed gamma-ray emitters such as the radiation induced by dark matter annihilation and decay. Clues about the properties of the contributing sources are imprinted in the anisotropy characteristics of the gamma-ray background. We use 81 months of Pass 7 Reprocessed data from the Fermi Large Area Telescope to perform a measurement of the anisotropy angular power spectrum of the gamma-ray background. Here, we analyze energies between 0.5 and 500 GeV, extending the range considered in the previous measurement based on 22 months of data. We also compute, for the first time, the cross-correlation angular power spectrum between different energy bins. The derived angular spectra are compatible with being Poissonian, i.e. constant in multipole. Furthermore, the energy dependence of the anisotropy suggests that the signal is due to two populations of sources, contributing, respectively, below and above ~ 2 GeV . Finally, using data from state-of-the-art numerical simulations to model the dark matter distribution, we constrain the contribution from dark matter annihilation and decay in Galactic and extra-Galactic structures to the measured anisotropy. These constraints