468 research outputs found
Search for Spectral Irregularities due to Photon–Axionlike-Particle Oscillations with the Fermi Large Area Telescope
No full textM. Ajello, A. Albert, B. Anderson, L. Baldini, G. Barbiellini, D. Bastieri, R. Bellazzini, E. Bissaldi, R. D. Blandford, E. D. Bloom, R. Bonino, E. Bottacini, J. Bregeon, P. Bruel, R. Buehler, G. A. Caliandro, R. A. Cameron, M. Caragiulo, P. A. Caraveo, C. Cecchi, A. Chekhtman, S. Ciprini, J. Cohen-Tanugi, J. Conrad, F. Costanza, F. D’Ammando, A. de Angelis, F. de Palma, R. Desiante, M. Di Mauro, L. Di Venere, A. Domínguez, P. S. Drell, C. Favuzzi, W. B. Focke, A. Franckowiak, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Giglietto, T. Glanzman, G. Godfrey, S. Guiriec, D. Horan, G. Jóhannesson, M. Katsuragawa, S. Kensei, M. Kuss, S. Larsson, L. Latronico, J. Li, L. Li, F. Longo, F. Loparco, P. Lubrano, G. M. Madejski, S. Maldera, A. Manfreda, M. Mayer, M. N. Mazziotta, M. Meyer, P. F. Michelson, N. Mirabal, T. Mizuno, M. E. Monzani, A. Morselli, I. V. Moskalenko, S. Murgia, M. Negro, E. Nuss, C. Okada, E. Orlando, J. F. Ormes, D. Paneque, J. S. Perkins, M. Pesce-Rollins, F. Piron, G. Pivato, T. A. Porter, S. Rainò, R. Rando, M. Razzano, A. Reimer, M. Sánchez-Conde, C. Sgrò,D. Simone, E. J. Siskind, F. Spada, G. Spandre, P. Spinelli, H. Takahashi, J. B. Thayer, D. F. Torres, G. Tosti, E. Troja, Y. Uchiyama, K. S. Wood, M. Wood, G. Zaharijas, and S. Zimmer.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.The Fermi-LAT Collaboration acknowledges support for LAT development, operation, and data analysis from NASA and DOE (U.S.), CEA/Irfu and IN2P3/CNRS (France), ASI and INFN (Italy), MEXT, KEK, and JAXA (Japan), and the K. A. Wallenberg Foundation, the Swedish Research Council, and the National Space Board (Sweden). Science analysis support in the operations
phase from INAF (Italy) and CNES (France) is also gratefully acknowledged. J. C. is a Wallenberg Academy Fellow. S. G. and N. M. are NASA Postdoctoral Program Fellows. M. R. is funded by Contract No. FIRB-2012-RBFR12PM1F from the Italian Ministry of Education, University and Research (MIUR).https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.16110
Characterizing the population of pulsars in the inner Galaxy with the Fermi Large Area Telescope
No full textM. AJELLO, L. BALDINI, J. BALLET, G. BARBIELLINI, D. BASTIERI, R. BELLAZZINI, E. BISSALDI, R. D. BLANDFORD, E. D. BLOOM, E. BOTTACINI, J. BREGEON, P. BRUEL, R. BUEHLER, R. A. CAMERON, R. CAPUTO, M. CARAGIULO, P. A. CARAVEO, E. CAVAZZUTI, C. CECCHI, E. CHARLES, A. CHEKHTMAN, G. CHIARO, S. CIPRINI, D. COSTANTIN, F. COSTANZA, F. D’AMMANDO, F. DE PALMA, R. DESIANTE, S. W. DIGEL, N. DI LALLA, M. DI MAURO11, L. DI VENERE, C. FAVUZZI, E. C. FERRARA, A. FRANCKOWIAK, Y. FUKAZAWA, S. FUNK, P. FUSCO, F. GARGANO, D. GASPARRINI, N. GIGLIETTO, F. GIORDANO, M. GIROLETTI, D. GREEN, L. GUILLEMOT, S. GUIRIEC, A. K. HARDING, D. HORAN, G. JOHANNESSON, M. KUSS, G. LA MURA, S. LARSSON, L. LATRONICO, J. LI, F. LONGO, F. LOPARCO, M. N. LOVELLETTE, P. LUBRANO, S. MALDERA, D. MALYSHEV, L. MARCOTULLI, P. MARTIN, M. N. MAZZIOTTA, M. MEYER, P. F. MICHELSON, N. MIRABAL, T. MIZUNO, M. E. MONZANI, A. MORSELLI, I. V. MOSKALENKO, E. NUSS, N. OMODEI, M. ORIENTI, E. ORLANDO, M. PALATIELLO, V. S. PALIYA, D. PANEQUE, J. S. PERKINS , M. PERSIC, M. PESCE-ROLLINS, F. PIRON, G. PRINCIPE, S. RAINO, R. RANDO, M. RAZZANO, A. REIMER, O. REIMER, P. M. SAZ PARKINSON, C. SGRO, E. J. SISKIND, D. A. SMITH, F. SPADA, G. SPANDRE, P. SPINELLI, H. TAJIMA, J. B. THAYER, D. J. THOMPSON, L. TIBALDO, D. F. TORRES, E. TROJA, G. VIANELLO, K. WOOD, M. WOOD, G. ZAHARIJASAn excess of γ-ray emission from the Galactic Center (GC) region with respect to predictions based on a variety of interstellar emission models and γ-ray source catalogs has been found by many groups using data from the {\it Fermi} Large Area Telescope (LAT). Several interpretations of this excess have been invoked. In this paper we search for members of an unresolved population of γ-ray pulsars located in the inner Galaxy that are predicted by the interpretation of the GC excess as being due to a population of such sources. We use cataloged LAT sources to derive criteria that efficiently select pulsars with very small contamination from blazars. We search for point sources in the inner 40∘×40∘ region of the Galaxy, derive a list of approximately 400 sources, and apply pulsar selection criteria to extract pulsar candidates among our source list. We performed the entire data analysis chain with two different interstellar emission models (IEMs), and found a total of 135 pulsar candidates, of which 66 were selected with both IEMs.MDM and EC acknowledge support by the NASA Fermi Guest Investigator Program 2014 through the Fermi multiyear Large Program N. 81303 (P.I. E. Charles). We would like to thank Richard Bartels, Dan Hooper, Tim Linden, Siddhartha Mishra-Sharma, Nicholas Rodd, Benjamin Safdi and Tracy Slatyer for helping us to identify an error in the maximum likelihood analysis of the Galactic bulge and disk PSR populations that was included in a previous version of this paper, (arXiv:1705.00009, v1). Their work is described in a note will be posted on arXiv at the same time as this draft (Bartels et al. 2017).https://arxiv.org/abs/1705.0000
Exploring Broadband GRB Behavior during γ-Ray Emission
No full textS. A. Yost, H. F. Swan, E. S. Rykoff, F. Aharonian, C. W. Akerlof, A. Alday, M. C. B. Ashley, S. Barthelmy, D. Burrows, D. L. Depoy, R. J. Dufour, J. D. Eastman, R. D. Forgey, N. Gehrels, E. GoguY, T. Guver,J. P. Halpern, L. C. Hardin, D. Horns, Ü. Kızıloǧlu, H. A. Krimm, S. Lepine, E. P. Liang,J. L. Marshall, T. A. McKay, T. Mineo, N. Mirabal, M. O zel, A. Phillips, J. L. Prieto,R. M. Quimby, P. Romano, G. Rowell, W. Rujopakarn, B. E. Schaefer, J. M. Silverman,
R. Siverd, M. Skinner, D. A. Smith, I. A. Smith, S. Tonnesen, E. Troja,W. T. Vestrand, J. C. Wheeler, J. Wren, F. Yuan, and B. ZhangThe robotic ROTSE-III telescope network detected prompt optical emission contemporaneous with the γ-ray emission of Swift events GRB 051109A and GRB 051111. Both data sets have continuous coverage at high signal-to-noise levels from the prompt phase onward, and thus the early observations are readily compared to the Swift XRT and BAT high-energy detections. In both cases, the optical afterglow is established, declining steadily during the prompt emission. For GRB 051111, there is evidence of an excess optical component during the prompt emission. The component is consistent with the flux spectrally extrapolated from the γ-rays, using the γ-ray spectral index. A compilation of spectral information from previous prompt detections shows that such a component is unusual. The existence of two prompt optical components—one connected to the high-energy emission, the other to separate afterglow flux, as indicated in GRB 051111—is not compatible with a simple "external-external" shock model for the GRB and its afterglow.ROTSE-III has been supported by NASA grant NNG04WC41G, NSF grant AST 04-07061, the Australian Research Council, the University of New South Wales, the University of Texas, and the University of Michigan. Work performed at LANL is supported through internal LDRD funding. Special thanks to the observatory staff at McDonald Observatory, especially David
Doss.
XRT work is supported at Observatorio Astronomica di Brera and INAF-IASF Palermo by ASI grant I/R/039/04 The MDM work has been supported by the National Science Foundation under grant 0206051 to J. P. H..https://iopscience.iop.org/article/10.1086/51089
MINUTE-TIMESCALE >100 MeV γ-RAY VARIABILITY DURING THE GIANT OUTBURST OF QUASAR 3C 279 OBSERVED BY FERMI-LAT IN 2015 JUNE
No full textM. Ackermann, R. Anantua, K. Asano, L. Baldini, G. Barbiellini, D. Bastieri, J. Becerra Gonzalez, R. Bellazzini, E. Bissaldi, R. D. Blandford, E. D. Bloom, R. Bonino, E. Bottacini, P. Bruel, R. Buehler, G. A. Caliandro, R. A. Cameron, M. Caragiulo, P. A. Caraveo, E. Cavazzuti, C. Cecchi, C. C. Cheung, J. Chiang, G. Chiaro, S. Ciprini, J. Cohen-Tanugi, F. Costanza, S. Cutini, F. D’Ammando, F. de Palma, R. Desiante, S. W. Digel, N. Di Lalla, M. Di Mauro, L. Di Venere, P. S. Drell, C. Favuzzi, S. J. Fegan, E. C. Ferrara, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Giglietto, F. Giordano, M. Giroletti, I. A. Grenier, L. Guillemot, S. Guiriec, M. Hayashida, E. Hays, D. Horan, G. JÓhannesson, S. Kensei, D. Kocevski, M. Kuss, G. La Mura, S. Larsson, L. Latronico, J. Li, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, G. M. Madejski, J. D. Magill, S. Maldera, A. Manfreda, M. Mayer, M. N. Mazziotta, P. F. Michelson, N. Mirabal, T. Mizuno, M. E. Monzani, A. Morselli, I. V. Moskalenko, K. Nalewajko, M. Negro, E. Nuss, T. Ohsugi, E. Orlando, D. Paneque, J. S. Perkins, M. Pesce-Rollins, F. Piron, G. Pivato, T. A. Porter, G. Principe, R. Rando, M. Razzano, S. Razzaque, A. Reimer, J. D. Scargle, C. Sgrò, M. Sikora, D. Simone, E. J. Siskind, F. Spada, P. Spinelli, L. Stawarz, J. B. Thayer, D. J. Thompson, D. F. Torres, E. Troja, Y. Uchiyama, Y. Yuan, and S. ZimmerOn 2015 June 16, Fermi-LAT observed a giant outburst from the flat spectrum radio quasar 3C 279 with a peak >100 MeV flux of ~3.6 × 10⁻⁵ photons cm⁻² s⁻¹, averaged over orbital period intervals. It is historically the highest γ-ray flux observed from the source, including past EGRET observations, with the γ-ray isotropic luminosity reaching ~10⁴⁹ erg s⁻¹. During the outburst, the Fermi spacecraft, which has an orbital period of 95.4 minutes, was operated in a special pointing mode to optimize the exposure for 3C 279. For the first time, significant flux variability at sub-orbital timescales was found in blazar observations by Fermi-LAT. The source flux variability was resolved down to 2-minute binned timescales, with flux doubling times of less than 5 minutes. The observed minute-scale variability suggests a very compact emission region at hundreds of Schwarzschild radii from the central engine in conical jet models. A minimum bulk jet Lorentz factor (Γ) of 35 is necessary to avoid both internal γ-ray absorption and super-Eddington jet power. In the standard external radiation Comptonization scenario, Γ should be at least 50 to avoid overproducing the synchrotron self-Compton component. However, this predicts extremely low magnetization (~5 × 10⁻⁴). Equipartition requires Γ as high as 120, unless the emitting region is a small fraction of the dissipation region. Alternatively, we consider γ rays originating as synchrotron radiation of γ e ~ 1.6 × 10⁶ electrons, in a magnetic field B ~ 1.3 kG, accelerated by strong electric fields E ~ B in the process of magnetoluminescence. At such short distance scales, one cannot immediately exclude the production of γ-rays in hadronic processes.The Fermi-LAT Collaboration acknowledges support for LAT development, operation, and data analysis from NASA and DOE (United States), CEA/Irfu and IN2P3/CNRS (France), ASI and INFN (Italy), MEXT, KEK, and JAXA (Japan), and the K.A. Wallenberg Foundation, the Swedish Research Council and the National Space Board (Sweden). Science analysis support in the operations phase from INAF (Italy) and CNES (France) is also gratefully acknowledged. M.H. acknowledges support by JSPS KAKENHI grant number JP15K17640.https://iopscience.iop.org/article/10.3847/2041-8205/824/2/L2
Detailed optical and near-infrared polarimetry, spectroscopy and broad-band photometry of the afterglow of GRB 091018 : polarization evolution
No full textFollow-up observations of large numbers of gamma-ray burst (GRB) afterglows, facilitated by the Swift satellite, have produced a large sample of spectral energy distributions and light curves, from which their basic micro- and macro-physical parameters can in principle be derived. However, a number of phenomena have been observed that defy explanation by simple versions of the standard fireball model, leading to a variety of new models. Polarimetry can be a major independent diagnostic of afterglow physics, probing the magnetic field properties and internal structure of the GRB jets. In this paper we present the first high-quality multi-night polarimetric light curve of a Swift GRB afterglow, aimed at providing a well-calibrated data set of a typical afterglow to serve as a benchmark system for modelling afterglow polarization behaviour. In particular, our data set of the afterglow of GRB 091018 (at redshift z = 0.971) comprises optical linear polarimetry (R band, 0.13-2.3d after burst); circular polarimetry (R band) and near-infrared linear polarimetry (Ks band). We add to that high-quality optical and near-infrared broad-band light curves and spectral energy distributions as well as afterglow spectroscopy. The linear polarization varies between 0 and 3per cent, with both long and short time-scale variability visible. We find an achromatic break in the afterglow light curve, which corresponds to features in the polarimetric curve. We find that the data can be reproduced by jet break models only if an additional polarized component of unknown nature is present in the polarimetric curve. We probe the ordered magnetic field component in the afterglow through our deep circular polarimetry, finding P circ < 0.15per cent (2σ), the deepest limit yet for a GRB afterglow, suggesting ordered fields are weak, if at all present. Our simultaneous R- and Ks-band polarimetry shows that dust-induced polarization in the host galaxy is likely negligible
Cosmic-ray electron-positron spectrum from 7 GeV to 2 TeV with the Fermi Large Area Telescope
No full textS. Abdollahi, M. Ackermann, M. Ajello, W. B. Atwood, L. Baldini, G. Barbiellini, D. Bastieri, R. Bellazzini,E. D. Bloom, R. Bonino, T. J. Brandt, J. Bregeon, P. Bruel, R. Buehler, R. A. Cameron, R. Caputo, M. Caragiulo, D. Castro, E. Cavazzuti, C. Cecchi, A. Chekhtman, S. Ciprini, J. Cohen-Tanugi,F. Costanza, A. Cuoco, S. Cutini, F. D’Ammando, F. de Palma, R. Desiante, S. W. Digel,
N. Di Lalla, M. Di Mauro, L. Di Venere, P. S. Drell, A. Drlica-Wagner, C. Favuzzi, W. B. Focke, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Giglietto, F. Giordano, M. Giroletti, D. Green, L. Guillemot, S. Guiriec, A. K. Harding, T. Jogler, G. Jóhannesson, T. Kamae, M. Kuss, G. La Mura, L. Latronico, F. Longo, F. Loparco, P. Lubrano, S. Maldera, D. Malyshev, A. Manfreda, M. N. Mazziotta, P. F. Michelson, N. Mirabal, W. Mitthumsiri,T. Mizuno, A. A. Moiseev, M. E. Monzani, A. Morselli, I. V. Moskalenko, M. Negro, E. Nuss, E. Orlando, D. Paneque, J. S. Perkins, M. Pesce-Rollins, F. Piron, G. Pivato, T. A. Porter, G. Principe, S. Rainò, R. Rando M. Razzano, A. Reimer, O. Reimer, C. Sgrò, D. Simone, E. J. Siskind, F. Spada, G. Spandre, P. Spinelli, H. Tajima, J. B. Thayer, L. Tibaldo, D. F. Torres, E. Troja, M. Wood, A. Worley, G. Zaharijas, and S. Zimmer The Fermi-LAT CollaborationWe 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.The Fermi-LAT Collaboration acknowledges support for LAT development, operation and data analysis from NASA and DOE (United States), CEA/Irfu and IN2P3/CNRS (France), ASI and INFN (Italy), MEXT, KEK, and JAXA (Japan), and the K. A. Wallenberg Foundation, the Swedish Research Council and the National Space Board (Sweden). Science analysis support in the operations phase from INAF (Italy) and CNES (France) is also gratefully acknowledged. We would like to thank the INFN GRID Data Centers of Pisa, Trieste and CNAF-Bologna, the DOE SLAC National Accelerator Laboratory Computing Division, and
the CNRS/IN2P3 Computing Center (CC-IN2P3—Lyon/ Villeurbanne) in partnership with CEA/DSM/Irfu for their strong support in performing the massive simulations necessary for this work. W. Mitthumsiri is partially supported by the Thailand Research Fund (Grants No. TRG5880173 and No. RTA5980003).https://journals.aps.org/prd/abstract/10.1103/PhysRevD.95.08200
CONTEMPORANEOUS BROADBAND OBSERVATIONS OF THREE HIGH-REDSHIFT BL LAC OBJECTS
No full textM. Ackermann, M. Ajello, H. An, L. Baldini, G. Barbiellini, D. Bastieri, R. Bellazzini, E. Bissaldi, R. D. Blandford, R. Bonino, J. Bregeon, R. J. Britto, P. Bruel, R. Buehler, G. A. Caliandro, R. A. Cameron, M. Caragiulo, P. A. Caraveo, E. Cavazzuti, C. Cecchi, E. Charles, A. Chekhtman, G. Chiaro, S. Ciprini, J. Cohen-Tanugi, F. Costanza, S. Cutini, F. D’Ammando, A. de Angelis, F. de Palma, R. Desiante, M. Di Mauro, L. Di Venere, A. Dominguez , P. S. Drell, C. Favuzzi, S. J. Fegan, E. C. Ferrara, J. Finke, P. Fusco, F. Gargano, D. Gasparrini, N. Giglietto, F. Giordano, M. Giroletti, D. Green, I. A. Grenier, S. Guiriec, D. Horan, G. JÓhannesson, M. Katsuragawa, M. Kuss, S. Larsson, L. Latronico, J. Li, L. Li, F. Longo, F. Loparco, M. N. Lovellette, P. Lubrano, J. Magill, S. Maldera, A. Manfreda, M. Mayer, M. N. Mazziotta, P. F. Michelson, N. Mirabal, W. Mitthumsiri, T. Mizuno, M. E. Monzani, A. Morselli, I. V. Moskalenko, M. Negro, E. Nuss, T. Ohsugi, C. Okada, E. Orlando, D. Paneque, M. Pesce-Rollins, F. Piron, G. Pivato, T. A. Porter, S. Rainò, R. Rando, M. Razzano, O. Reimer, A. Rau, R. W. Romani, P. Schady, C. Sgrò, D. Simone, E. J. Siskind, F. Spada, G. Spandre, P. Spinelli, D. Stern, H. Takahashi, J. B. Thayer, D. F. Torres, G. Tosti, E. Troja, G. Vianello, K. S. Wood, and M. Wood.We have collected broadband spectral energy distributions (SEDs) of three BL Lac objects 3FGL J0022.1−1855 (z = 0.689), 3FGL J0630.9−2406 (z >= 1.239), and 3FGL J0811.2−7529 (z = 0.774), detected by Fermi with relatively flat gigaelectronvolt spectra. By observing simultaneously in the near-infrared to hard X-ray band, we can well characterize the high end of the synchrotron component of the SED. Thus, fitting the SEDs to synchro-Compton models of the dominant emission from the relativistic jet, we can constrain the underlying particle properties and predict the shape of the gigaelectronvolt Compton component. Standard extragalactic background light (EBL) models explain the high-energy absorption well, with poorer fits for high-ultraviolet models. The fits show clear evidence for EBL absorption in the Fermi spectrum of our highest-redshift source 3FGL J0630.9−2406. While synchrotron self-Compton models adequately describe the SEDs, the situation may be complicated by possible external Compton components. For 3FGL J0811.2−7529, we also discover a nearby serendipitous source in the X-ray data, which is almost certainly another lower synchrotron peak frequency (u pk sy) BL Lac, that may contribute flux in the Fermi band. Since our sources are unusual high-luminosity, moderate u pk sy BL Lacs, we compare these quantities and the Compton dominance, the ratio of peak inverse Compton to peak synchrotron luminosities (Lpk IC/L pk sy), with those of the full Fermi BL Lac population.The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l'Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), the High Energy Accelerator Research Organization (KEK), and the Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council, and the Swedish National Space Board in Sweden.
Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d'Études Spatiales in France.
H.A. acknowledges support provided by the NASA-sponsored Fermi Contract NAS5-00147 and by the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC). Part of the funding for GROND (both hardware and personnel) was generously granted from the Leibniz Prize to Prof. G. Hasinger (DFG grant HA 1850/28-1).https://iopscience.iop.org/article/10.3847/0004-637X/820/1/7
Prospects for CTA observations of the young SNR RX J1713.7-3946
No full textF. Acero, R. Aloisio, J. Amans, E. Amato, L.A. Antonelli, C. Aramo, T. Armstrong, F. Arqueros, K. Asano, M. Ashley, M. Backes, C. Balazs, A. Balzer, A. Bamba, M. Barkov, J.A. Barrio, W. Benbow, K. Bernlöhr, V. Beshley, C. Bigongiari, A. Biland, A. Bilinsky, E. Bissaldi, J. Biteau, O. Blanch, P. Blasi, J. Blazek, C. Boisson, G. Bonanno, A. Bonardi, C. Bonavolontà, G. Bonnoli, C. Braiding, S. Brau-Nogué, J. Bregeon, A.M. Brown, V. Bugaev, A. Bulgarelli, T. Bulik, M. Burton, A. Burtovoi, G. Busetto, M. Böttcher, R. Cameron, M. Capalbi, A. Caproni, P. Caraveo, R. Carosi, E. Cascone, M. Cerruti, S. Chaty, A. Chen, X. Chen, M. Chernyakova, M. Chikawa, J. Chudoba, J. Cohen-Tanugi, S. Colafrancesco, V. Conforti, J.L. Contreras, A. Costa, G. Cotter, S. Covino, G. Covone, P. Cumani, G. Cusumano, F. D'Ammando, D. D'Urso, M. Daniel, F. Dazzi, A. De Angelis, G. De Cesare, A. De Franco, F. De Frondat, E.M. de Gouveia Dal Pino, C. De Lisio, R. de los Reyes Lopez, B. De Lotto, M. de Naurois, F. De Palma, M. Del Santo, C. Delgado, D. della Volpe, T. Di Girolamo, C. Di Giulio, F. Di Pierro, L. Di Venere, M. Doro, J. Dournaux, D. Dumas, V. Dwarkadas, C. Díaz, J. Ebr, K. Egberts, S. Einecke, D. Elsässer, S. Eschbach, D. Falceta-Goncalves, G. Fasola , E. Fedorova, A. Fernández-Barral, G. Ferrand, M. Fesquet, E. Fiandrini, A. Fiasson, M.D. Filipovíc, V. Fioretti, L. Font, G. Fontaine, F.J. Franco, L. Freixas Coromina, Y. Fujita, Y. Fukui, S. Funk, A. Förster, A. Gadola, R. Garcia López, M. Garczarczyk, N. Giglietto, F. Giordano, A. Giuliani, J. Glicenstein, R. Gnatyk, P. Goldoni, T. Grabarczyk, R. Graciani, J. Graham, P. Grandi, J. Granot, A.J. Green, S. Griffiths, S. Gunji, H. Hakobyan, S. Hara, T. Hassan, M. Hayashida, M. Heller, J.C. Helo, J. Hinton, B. Hnatyk, J. Huet, M. Huetten, T.B. Humensky, M. Hussein, J. Hörandel, Y. Ikeno, T. Inada, Y. Inome, S. Inoue, T. Inoue, Y. Inoue, K. Ioka, M. Iori, J. Jacquemier, P. Janecek, D. Jankowsky, I. Jung, P. Kaaret, H. Katagiri, S. Kimeswenger, S. Kimura, J. Knödlseder, B. Koch, J. Kocot, K. Kohri, N. Komin, Y. Konno, K. Kosack, S. Koyama, M. Kraus, H. Kubo, G. Kukec Mezek, J. Kushida, N. La Palombara, K. Lalik, G. Lamanna, H. Landt, J. Lapington, P. Laporte, S. Lee, J. Lees, J. Lefaucheur, J.-P. Lenain, G. Leto, E. Lindfors, T. Lohse, S. Lombardi, F. Longo, M. Lopez, F. Lucarelli, P.L. Luque-Escamilla, R. López-Coto, M.C. Maccarone, G. Maier, G. Malaguti, D. Mandat, G. Maneva, S. Mangano, A. Marcowith, J. Martí, M. Martínez, G. Martínez, S. Masuda, G. Maurin, N. Maxted, C. Melioli, T. Mineo, N. Mirabal, T. Mizuno, R. Moderski, M. Mohammed, T. Montaruli, A. Moralejo, K. Mori, G. Morlino, A. Morselli, E. Moulin, R. Mukherjee, C. Mundell, H. Muraishi, K. Murase, S. Nagataki, T. Nagayoshi, T. Naito, D. Nakajima, T. Nakamori, R. Nemmen, J. Niemiec, D. Nieto, M. Nievas-Rosillo, M. Nikołajuk, K. Nishijima, K. Noda, L. Nogues, D. Nosek, B. Novosyadlyj, S. Nozaki, Y. Ohira, M. Ohishi, S. Ohm, A. Okumura, R.A. Ong, R. Orito, A. Orlati, M. Ostrowski, I. Oya, M. Padovani, J. Palacio, M. Palatka, J.M. Paredes, S. Pavy, A. Pe'er, M. Persic, P. Petrucci, O. Petruk, A. Pisarski, M. Pohl, A. Porcelli, E. Prandini, J. Prast, G. Principe, M. Prouza, E. Pueschel, G. Pühlhofer, A. Quirrenbach, M. Rameez, O. Reimer, M. Renaud, M. Ribó, J. Rico, V. Rizi, J. Rodriguez, G. Rodriguez Fernandez, J.J. Rodríguez Vázquez, P. Romano, G. Romeo, J. Rosado, J. Rousselle, G. Rowell, B. Rudak, I. Sadeh, S. Safi-Harb, T. Saito, N. Sakaki, D. Sanchez, P. Sangiorgi, H. Sano, M. Santander, S. Sarkar, M. Sawada, E.J. Schioppa, H. Schoorlemmer, P. Schovanek, F. Schussler, O. Sergijenko, M. Servillat, A. Shalchi, R.C. Shellard, H. Siejkowski, A. Sillanpää, D. Simone, V. Sliusar, H. Sol, S. Stanič, R. Starling, Ł. Stawarz, S. Stefanik, M. Stephan, T. Stolarczyk, M. Szanecki, T. Szepieniec, G. Tagliaferri, H. Tajima, M. Takahashi, J. Takeda, M. Tanaka, S. Tanaka, L.A. Tejedor, I. Telezhinsky, P. Temnikov, Y. Terada, D. Tescaro, M. Teshima, V. Testa, S. Thoudam, F. Tokanai, D.F. Torres, E. Torresi, G. Tosti, C. Townsley, P. Travnicek, C. Trichard, M. Trifoglio, S. Tsujimoto, V. Vagelli, P. Vallania, L. Valore, W. van Driel, C. van Eldik, J. Vandenbroucke, V. Vassiliev, M. Vecchi, S. Vercellone, S. Vergani, C. Vigorito, S. Vorobiov, M. Vrastil, M.L. Vázquez Acosta, S.J. Wagner, R. Wagner, S.P. Wakely, R. Walter, J.E. Ward, J.J. Watson, A. Weinstein, M. White, R. White, A. Wierzcholska, P. Wilcox, D.A. Williams, R. Wischnewski, P. Wojcik, T. Yamamoto, H. Yamamoto, R. Yamazaki, S. Yanagita, L. Yang, T. Yoshida, M. Yoshida, S. Yoshiike, T. Yoshikoshi, M. Zacharias, L. Zampieri, R. Zanin, M. Zavrtanik, D. Zavrtanik, A. Zdziarski, A. Zech, H. Zechlin, V. Zhdanov, A. Ziegler, J. ZornWe perform simulations for future Cherenkov Telescope Array (CTA) observations of RX J1713.7−3946, a young supernova remnant (SNR) and one of the brightest sources ever discovered in very high energy (VHE) gamma rays. Special attention is paid to exploring possible spatial (anti)correlations of gamma rays with emission at other wavelengths, in particular X-rays and CO/H i emission. We present a series of simulated images of RX J1713.7−3946 for CTA based on a set of observationally motivated models for the gamma-ray emission. In these models, VHE gamma rays produced by high-energy electrons are assumed to trace the nonthermal X-ray emission observed by XMM-Newton, whereas those originating from relativistic protons delineate the local gas distributions. The local atomic and molecular gas distributions are deduced by the NANTEN team from CO and H i observations. Our primary goal is to show how one can distinguish the emission mechanism(s) of the gamma rays (i.e., hadronic versus leptonic, or a mixture of the two) through information provided by their spatial distribution, spectra, and time variation. This work is the first attempt to quantitatively evaluate the capabilities of CTA to achieve various proposed scientific goals by observing this important cosmic particle accelerator.The research leading to these results has received funding from the European Union’s Seventh Framework Programme
(FP7/2007-2013) under grant agreement no 262053.
We thank S. Katsuda for providing the original XMM-Newton imagehttps://iopscience.iop.org/article/10.3847/1538-4357/aa6d6
The WEBT Campaign on the Blazar 3C 279 in 2006
No full textM. Böttcher, S. Basu, M. Joshi, M. Villata, A. Arai, N. Aryan, I. M. Asfandiyarov, U. Bach, R. Bachev, A. Berduygin, M. Blaek, C. Buemi, A. J. Castro-Tirado, A. De Ugarte Postigo, A. Frasca, L. Fuhrmann, V. A. Hagen-Thorn, G. Henson, T. Hovatta, R. Hudec, M. Ibrahimov, Y. Ishii, R. Ivanidze, M. Jelínek, M. Kamada, B. Kapanadze, M. Katsuura, D. Kotaka, Y. Y. Kovalev, Yu. A. Kovalev, P. Kubánek, M. Kurosaki, O. Kurtanidze, A. Lähteenmäki, L. Lanteri, V. M. Larionov, L. Larionova, C.-U. Lee, P. Leto, E. Lindfors, E. Marilli, K. Marshall, H. R. Miller, M. G. Mingaliev, N. Mirabal, S. Mizoguchi, K. Nakamura, E. Nieppola, M. Nikolashvili, K. Nilsson, S. Nishiyama, J. Ohlert, M. A. Osterman, S. Pak, M. Pasanen, C. S. Peters, T. Pursimo, C. M. Raiteri, J. Robertson, T. Robertson, W. T. Ryle, K. Sadakane, A. Sadun, L. Sigua, B.-W. Sohn, A. Strigachev, N. Sumitomo, L. O. Takalo, Y. Tamesue, K. Tanaka, J. R. Thorstensen, G. Tosti, C. Trigilio, G. Umana, S. Vennes, S. Vitek, A. Volvach, J. Webb, M. Yamanaka, and H.-S. Yim.The quasar 3C 279 was the target of an extensive multiwavelength monitoring campaign from 2006 January through April. An optical-IR-radio monitoring campaign by the Whole Earth Blazar Telescope (WEBT) collaboration was organized around target-of-opportunity X-ray and soft γ-ray observations with Chandra and INTEGRAL in 2006 mid-January, with additional X-ray coverage by RXTE and Swift XRT. In this paper we focus on the results of the WEBT campaign. The source exhibited substantial variability of optical flux and spectral shape, with a characteristic timescale of a few days. The variability patterns throughout the optical BVRI bands were very closely correlated with each other, while there was no obvious correlation between the optical and radio variability. After the ToO trigger, the optical flux underwent a remarkably clean quasi-exponential decay by about 1 mag, with a decay timescale of τd ~ 12.8 days. In intriguing contrast to other (in particular, BL Lac type) blazars, we find a lag of shorter wavelength behind longer wavelength variability throughout the RVB wavelength ranges, with a time delay increasing with increasing frequency. Spectral hardening during flares appears delayed with respect to a rising optical flux. This, in combination with the very steep IR-optical continuum spectral index of α0 ~ 1.5-2.0, may indicate a highly oblique magnetic field configuration near the base of the jet, leading to inefficient particle acceleration and a very steep electron injection spectrum. An alternative explanation through a slow (timescale of several days) acceleration mechanism would require an unusually low magnetic field of B lesssim 0.2 G, about an order of magnitude lower than inferred from previous analyses of simultaneous SEDs of 3C 279 and other flat-spectrum radio quasars with similar properties.The work of M. B¨ottcher and S. Basu was partially supported by NASA through INTEGRAL GO grant award NNG 06GD57G and the Chandra GO program (administered by the Smithsonian Astrophysical Observatory) through award no. GO6-7101A. The Mets¨ahovi team acknowledges the support from the Academy of Finland. YYK is a research fellow of the Alexamder von Humboldt Foundation. RATAN-600 observations were partly supported by the Russian Foundation for Basic Research (project 05-02-17377). The St. Petersburg team was supported by the Russian Foundation for Basic Research through grant 05-02-17562.https://iopscience.iop.org/article/10.1086/52258
3FHL: The Third Catalog of Hard Fermi-LAT Sources
No full textM. Ajello , W. B. Atwood, L. Baldini , J. Ballet, G. Barbiellini, D. Bastieri, R. Bellazzini, E. Bissaldi,
R. D. Blandford, E. D. Bloom, R. Bonino, J. Bregeon, R. J. Britto, P. Bruel, R. Buehler, S. Buson,
R. A. Cameron, R. Caputo, M. Caragiulo, P. A. Caraveo, E. Cavazzuti, C. Cecchi, E. Charles,
A. Chekhtman, C. C. Cheung, G. Chiaro, S. Ciprini, J. M. Cohen, D. Costantin, F. Costanza, A. Cuoco,
S. Cutini, F. D’Ammando, F. de Palma, R. Desiante, S. W. Digel, N. Di Lalla, M. Di Mauro, L. Di Venere, A.Domínguez , P. S. Drell, D. Dumora, C. Favuzzi, S. J. Fegan, E. C. Ferrara, P. Fortin, A. Franckowiak, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Giglietto, P. Giommi,F. Giordano, M. Giroletti, T. Glanzman, D. Green, I. A. Grenier, M.-H. Grondin, J. E. Grove,L. Guillemot, S. Guiriec, A. K. Harding, E. Hays, J. W. Hewitt, D. Horan, G. Jóhannesson, S. Kensei, M. Kuss, G. La Mura, S. Larsson, L. Latronico, M. Lemoine-Goumard, J. Li, F. Longo, F. Loparco, B. Lott, P. Lubrano, J. D. Magill, S. Maldera , A. Manfreda, M. N. Mazziotta, J. E. McEnery, M. Meyer,P. F. Michelson, N. Mirabal, W. Mitthumsiri, T. Mizuno , A. A. Moiseev, M. E. Monzani, A. Morselli, I. V. Moskalenko, M. Negro, E. Nuss, T. Ohsugi, N. Omodei , M. Orienti, E. Orlando, M. Palatiello, V. S. Paliya, D. Paneque, J. S. Perkins, M. Persic, M. Pesce-Rollins, F. Piron, T. A. Porter, G. Principe, S. Rainò, R. Rando, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, T. Reposeur, P. M. Saz Parkinson, C. Sgrò, D. Simone, E. J. Siskind, F. Spada
, G. Spandre, P. Spinelli, L. Stawarz, D. J. Suson, M. Takahashi, D. Tak, J. G. Thayer, J. B. Thayer, D. J. Thompson, D. F. Torres, E. Torresi, E. Troja, G. Vianello, K. Wood, and M. Wood.We present a catalog of sources detected above 10 GeV by the Fermi Large Area Telescope (LAT) in the first 7 years of data using the Pass 8 event-level analysis. This is the Third Catalog of Hard Fermi-LAT Sources (3FHL), containing 1556 objects characterized in the 10 GeV–2 TeV energy range. The sensitivity and angular resolution are improved by factors of 3 and 2 relative to the previous LAT catalog at the same energies (1FHL). The vast majority of detected sources (79%) are associated with extragalactic counterparts at other wavelengths, including 16 sources located at very high redshift (z > 2). Of the sources, 8% have Galactic counterparts and 13% are unassociated (or associated with a source of unknown nature). The high-latitude sky and the Galactic plane are observed with a flux sensitivity of 4.4 to 9.5 × 10⁻¹¹ ph cm⁻² s⁻¹, respectively (this is approximately 0.5% and 1% of the Crab Nebula flux above 10 GeV). The catalog includes 214 new γ-ray sources. The substantial increase in the number of photons (more than 4 times relative to 1FHL and 10 times to 2FHL) also allows us to measure significant spectral curvature for 32 sources and find flux variability for 163 of them. Furthermore, we estimate that for the same flux limit of 10⁻¹² erg cm⁻² s⁻¹, the energy range above 10 GeV has twice as many sources as the range above 50 GeV, highlighting the importance, for future Cherenkov telescopes, of lowering the energy threshold as much as possible.The authors thank Harold Peña-Herazo for providing some redshifts before their publication. The Fermi-LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l'Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK) and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d'Études Spatiales in France. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France.https://iopscience.iop.org/article/10.3847/1538-4365/aa822
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