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8 results on '"Fleischhack, H"'

1. Multimessenger Gamma-Ray and Neutrino Coincidence Alerts Using HAWC and IceCube Subthreshold Data

Author

Solares, HA Ayala, Coutu, S, DeLaunay, JJ, Fox, DB, Grégoire, T, Keivani, A, Krauß, F, Mostafá, M, Murase, K, Turley, CF, Albert, A, Alfaro, R, Alvarez, C, Camacho, JR Angeles, Arteaga-Velázquez, JC, Arunbabu, KP, Rojas, D Avila, Belmont-Moreno, E, Brisbois, C, Caballero-Mora, KS, Carramiñana, A, Casanova, S, Cotti, U, De la Fuente, E, Hernandez, R Diaz, Dingus, BL, DuVernois, MA, Durocher, M, Díaz-Vélez, JC, Espinoza, C, Fan, KL, Fleischhack, H, Fraija, N, Galván-Gámez, A, Garcia, D, García-González, JA, Garfias, F, González, MM, Goodman, JA, Harding, JP, Hona, B, Huang, D, Hueyotl-Zahuantitla, F, Hüntemeyer, P, Iriarte, A, Jardin-Blicq, A, Joshi, V, Vargas, H León, Linnemann, JT, Longinotti, AL, Luis-Raya, G, Lundeen, J, Malone, K, Martinez, O, Martinez-Castellanos, I, Martínez-Castro, J, Matthews, JA, Miranda-Romagnoli, P, Moreno, E, Nellen, L, Newbold, M, Nisa, MU, Noriega-Papaqui, R, Peisker, A, Pérez-Pérez, EG, Rho, CD, Rosa-González, D, Salazar, H, Greus, F Salesa, Sandoval, A, Smith, AJ, Springer, RW, Tollefson, K, Torres, I, Torres-Escobedo, R, Ureña-Mena, F, Villaseñor, L, Weisgarber, T, Willox, E, Zepeda, A, Zhou, H, de León, C, Aartsen, MG, Abbasi, R, Ackermann, M, Adams, J, Aguilar, JA, Ahlers, M, Ahrens, M, Alispach, C, Amin, NM, Andeen, K, Anderson, T, Ansseau, I, Anton, G, Argüelles, C, Auffenberg, J, Axani, S, Bagherpour, H, and Bai, X

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, astro-ph.HE, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics, Astronomical sciences, Particle and high energy physics, Space sciences
Abstract

The High Altitude Water Cerenkov (HAWC) and IceCube observatories, through the Astrophysical Multimessenger Observatory Network (AMON) framework, have developed a multimessenger joint search for extragalactic astrophysical sources. This analysis looks for sources that emit both cosmic neutrinos and gamma rays that are produced in photohadronic or hadronic interactions. The AMON system is running continuously, receiving subthreshold data (i.e., data that are not suited on their own to do astrophysical searches) from HAWC and IceCube, and combining them in real time. Here we present the analysis algorithm, as well as results from archival data collected between 2015 June and 2018 August, with a total live time of 3.0 yr. During this period we found two coincident events that have a false-alarm rate (FAR) of

Published
2021

2. Multimessenger gamma-ray and neutrino coincidence alerts using hawc and icecube subthreshold data

Author

Solares, HAA, Coutu, S, DeLaunay, JJ, Fox, DB, Grégoire, T, Keivani, A, Krauß, F, Mostafá, M, Murase, K, Turley, CF, Albert, A, Alfaro, R, Alvarez, C, Angeles Camacho, JR, Arteaga-Velázquez, JC, Arunbabu, KP, Rojas, DA, Belmont-Moreno, E, Brisbois, C, Caballero-Mora, KS, Carramiñana, A, Casanova, S, Cotti, U, De la Fuente, E, Hernandez, RD, Dingus, BL, DuVernois, MA, Durocher, M, Díaz-Vélez, JC, Espinoza, C, Fan, KL, Fleischhack, H, Fraija, N, Galván-Gámez, A, Garcia, D, García-González, JA, Garfias, F, González, MM, Goodman, JA, Harding, JP, Hona, B, Huang, D, Hueyotl-Zahuantitla, F, Hüntemeyer, P, Iriarte, A, Jardin-Blicq, A, Joshi, V, Vargas, HL, Linnemann, JT, Longinotti, AL, Luis-Raya, G, Lundeen, J, Malone, K, Martinez, O, Martinez-Castellanos, I, Martínez-Castro, J, Matthews, JA, Miranda-Romagnoli, P, Moreno, E, Nellen, L, Newbold, M, Nisa, MU, Noriega-Papaqui, R, Peisker, A, Pérez-Pérez, EG, Rho, CD, Rosa-González, D, Salazar, H, Greus, FS, Sandoval, A, Smith, AJ, Springer, RW, Tollefson, K, Torres, I, Torres-Escobedo, R, Ureña-Mena, F, Villaseñor, L, Weisgarber, T, Willox, E, Zepeda, A, Zhou, H, de León, C, Aartsen, MG, Abbasi, R, Ackermann, M, Adams, J, Aguilar, JA, Ahlers, M, Ahrens, M, Alispach, C, Amin, NM, Andeen, K, Anderson, T, Ansseau, I, Anton, G, Argüelles, C, Auffenberg, J, Axani, S, Bagherpour, H, and Bai, X

Subjects
astro-ph.HE, Astronomy & Astrophysics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural)
Abstract

The High Altitude Water Cerenkov (HAWC) and IceCube observatories, through the Astrophysical Multimessenger Observatory Network (AMON) framework, have developed a multimessenger joint search for extragalactic astrophysical sources. This analysis looks for sources that emit both cosmic neutrinos and gamma rays that are produced in photohadronic or hadronic interactions. The AMON system is running continuously, receiving subthreshold data (i.e., data that are not suited on their own to do astrophysical searches) from HAWC and IceCube, and combining them in real time. Here we present the analysis algorithm, as well as results from archival data collected between 2015 June and 2018 August, with a total live time of 3.0 yr. During this period we found two coincident events that have a false-alarm rate (FAR) of

Published
2021

3. All-sky Measurement of the Anisotropy of Cosmic Rays at 10 TeV and Mapping of the Local Interstellar Magnetic Field

Author

Abeysekara, AU, Alfaro, R, Alvarez, C, Arceo, R, Arteaga-Velázquez, JC, Rojas, D Avila, Belmont-Moreno, E, BenZvi, SY, Brisbois, C, Capistrán, T, Carramiana, A, Casanova, S, Cotti, U, Cotzomi, J, Díaz-Vélez, JC, De León, C, De la Fuente, E, Dichiara, S, DuVernois, MA, Espinoza, C, Fiorino, DW, Fleischhack, H, Fraija, N, Galván-Gámez, A, García-González, JA, González, MM, Goodman, JA, Hampel-Arias, Z, Harding, JP, Hernandez, S, Hona, B, Hueyotl-Zahuantitla, F, Iriarte, A, Jardin-Blicq, A, Joshi, V, Lara, A, Vargas, H León, Luis-Raya, G, Malone, K, Marinelli, SS, Martínez-Castro, J, Martinez, O, Matthews, JA, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nellen, L, Newbold, M, Nisa, MU, Noriega-Papaqui, R, Pérez-Pérez, EG, Pretz, J, Ren, Z, Rho, CD, Rivière, C, Rosa-González, D, Rosenberg, M, Salazar, H, Greus, F Salesa, Sandoval, A, Schneider, M, Schoorlemmer, H, Sinnis, G, Smith, AJ, Surajbali, P, Taboada, I, Tollefson, K, Torres, I, Villaseor, L, Weisgarber, T, Wood, J, Zepeda, A, Zhou, H, Álvarez, JD, Aartsen, MG, Ackermann, M, Adams, J, Aguilar, JA, Ahlers, M, Ahrens, M, Altmann, D, Andeen, K, Anderson, T, Ansseau, I, Anton, G, Argüelles, C, Auffenberg, J, Axani, S, Backes, P, Bagherpour, H, Bai, X, Barbano, A, Barron, JP, Barwick, SW, Baum, V, Bay, R, Beatty, JJ, Tjus, J Becker, Becker, K-H, and BenZvi, S

Subjects
Particle and High Energy Physics, Astronomical Sciences, Physical Sciences, astroparticle physics, cosmic rays, ISM: magnetic fields, astro-ph.HE, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics, Astronomical sciences, Particle and high energy physics, Space sciences
Abstract

We present the first full-sky analysis of the cosmic ray arrival direction distribution with data collected by the High-Altitude Water Cherenkov and IceCube observatories in the northern and southern hemispheres at the same median primary particle energy of 10 TeV. The combined sky map and angular power spectrum largely eliminate biases that result from partial sky coverage and present a key to probe into the propagation properties of TeV cosmic rays through our local interstellar medium and the interaction between the interstellar and heliospheric magnetic fields. From the map, we determine the horizontal dipole components of the anisotropy δ 0h = 9.16 ×10-4 and δ 6h = 7.25 ×10-4 (±0.04 × 10-4). In addition, we infer the direction (229.°2 ± 3.°5 R.A., 11.°4 ± 3.°0 decl.) of the interstellar magnetic field from the boundary between large-scale excess and deficit regions from which we estimate the missing corresponding vertical dipole component of the large-scale anisotropy to be δN ∼ -3.97+1.0-2.0 × 10-4.

Published
2019

4. All-sky Measurement of the Anisotropy of Cosmic Rays at 10 TeV and Mapping of the Local Interstellar Magnetic Field

Author

Collaboration, H, Collaboration, I, Abeysekara, AU, Alfaro, R, Alvarez, C, Arceo, R, Arteaga-Velázquez, JC, Rojas, DA, Belmont-Moreno, E, Benzvi, SY, Brisbois, C, Capistrán, T, Carramiana, A, Casanova, S, Cotti, U, Cotzomi, J, Diaz-Vélez, JC, De León, C, Fuente, EDL, Dichiara, S, Duvernois, MA, Espinoza, C, Fiorino, DW, Fleischhack, H, Fraija, N, Galván-Gámez, A, Garcia-González, JA, González, MM, Goodman, JA, Hampel-Arias, Z, Harding, JP, Hernandez, S, Hona, B, Hueyotl-Zahuantitla, F, Iriarte, A, Jardin-Blicq, A, Joshi, V, Lara, A, Vargas, HL, Luis-Raya, G, Malone, K, Marinelli, SS, Martinez-Castro, J, Martinez, O, Matthews, JA, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nellen, L, Newbold, M, Nisa, MU, Noriega-Papaqui, R, Pérez-Pérez, EG, Pretz, J, Ren, Z, Rho, CD, Riviere, C, Rosa-González, D, Rosenberg, M, Salazar, H, Greus, FS, Sandoval, A, Schneider, M, Schoorlemmer, H, Sinnis, G, Smith, AJ, Surajbali, P, Taboada, I, Tollefson, K, Torres, I, Villaseor, L, Weisgarber, T, Wood, J, Zepeda, A, Zhou, H, Alvarez, JD, Aartsen, MG, Ackermann, M, Adams, J, Aguilar, JA, Ahlers, M, Ahrens, M, Altmann, D, Andeen, K, Anderson, T, Ansseau, I, Anton, G, Argüelles, C, Auffenberg, J, Axani, S, Backes, P, Bagherpour, H, Bai, X, Barbano, A, Barron, JP, Barwick, SW, Baum, V, Bay, R, Beatty, JJ, and Tjus, JB

Subjects
astroparticle physics, cosmic rays, ISM: magnetic fields, astro-ph.HE, Astronomy & Astrophysics, Astronomical and Space Sciences, Organic Chemistry, Physical Chemistry, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural)
Abstract

We present the first full-sky analysis of the cosmic ray arrival direction distribution with data collected by the High-Altitude Water Cherenkov and IceCube observatories in the northern and southern hemispheres at the same median primary particle energy of 10 TeV. The combined sky map and angular power spectrum largely eliminate biases that result from partial sky coverage and present a key to probe into the propagation properties of TeV cosmic rays through our local interstellar medium and the interaction between the interstellar and heliospheric magnetic fields. From the map, we determine the horizontal dipole components of the anisotropy δ 0h = 9.16 ×10 -4 and δ 6h = 7.25 ×10 -4 (±0.04 × 10 -4 ). In addition, we infer the direction (229.°2 ± 3.°5 R.A., 11.°4 ± 3.°0 decl.) of the interstellar magnetic field from the boundary between large-scale excess and deficit regions from which we estimate the missing corresponding vertical dipole component of the large-scale anisotropy to be δN ∼ -3.97 +1.0-2.0 × 10 -4 .

Published
2019

5. Search for Very High-energy Gamma Rays from the Northern Fermi Bubble Region with HAWC

Author

Abeysekara, AU, Albert, A, Alfaro, R, Alvarez, C, Álvarez, JD, Arceo, R, Arteaga-Velázquez, JC, Solares, HA Ayala, Barber, AS, Bautista-Elivar, N, Becerril, A, Belmont-Moreno, E, BenZvi, SY, Berley, D, Braun, J, Brisbois, C, Caballero-Mora, KS, Capistrán, T, Carramiñana, A, Casanova, S, Castillo, M, Cotti, U, Cotzomi, J, de León, S Coutiño, De León, C, De la Fuente, E, Hernandez, R Diaz, Dingus, BL, DuVernois, MA, Díaz-Vélez, JC, Ellsworth, RW, Engel, K, Fick, B, Fiorino, DW, Fleischhack, H, Fraija, N, García-González, JA, Garfias, F, Gerhardt, M, Muñoz, A González, González, MM, Goodman, JA, Hampel-Arias, Z, Harding, JP, Hernandez, S, Hernandez-Almada, A, Hinton, J, Hona, B, Hui, CM, Hüntemeyer, P, Iriarte, A, Jardin-Blicq, A, Joshi, V, Kaufmann, S, Kieda, D, Lara, A, Lauer, RJ, Lee, WH, Lennarz, D, Vargas, H León, Linnemann, JT, Longinotti, AL, Raya, G Luis, Luna-García, R, López-Coto, R, Malone, K, Marinelli, SS, Martinez, O, Martinez-Castellanos, I, Martínez-Castro, J, Martínez-Huerta, H, Matthews, JA, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nellen, L, Newbold, M, Nisa, MU, Noriega-Papaqui, R, Pelayo, R, Pretz, J, Pérez-Pérez, EG, Ren, Z, Rho, CD, Rivière, C, Rosa-González, D, Rosenberg, M, Ruiz-Velasco, E, Salazar, H, Greus, F Salesa, Sandoval, A, Schneider, M, Schoorlemmer, H, Sinnis, G, Smith, AJ, Springer, RW, Surajbali, P, Taboada, I, Tibolla, O, and Tollefson, K

Subjects
astroparticle physics, Galaxy: general, Galaxy: structure, gamma rays: diffuse background, astro-ph.HE, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics
Abstract

We present a search for very high-energy gamma-ray emission from the Northern Fermi Bubble region using data collected with the High Altitude Water Cherenkov gamma-ray observatory. The size of the data set is 290 days. No significant excess is observed in the Northern Fermi Bubble region, so upper limits above 1 TeV are calculated. The upper limits are between and . The upper limits disfavor a proton injection spectrum that extends beyond 100 TeV without being suppressed. They also disfavor a hadronic injection spectrum derived from neutrino measurements.

Published
2017

6. Search for Very High-energy Gamma Rays from the Northern Fermi Bubble Region with HAWC

Author

Abeysekara, AU, Albert, A, Alfaro, R, Alvarez, C, Alvarez, JD, Arceo, R, Arteaga-Velázquez, JC, Ayala Solares, HA, Barber, AS, Bautista-Elivar, N, Becerril, A, Belmont-Moreno, E, BenZvi, SY, Berley, D, Braun, J, Brisbois, C, Caballero-Mora, KS, Capistrán, T, Carraminana, A, Casanova, S, Castillo, M, Cotti, U, Cotzomi, J, Coutino De León, S, De León, C, De La Fuente, E, Hernandez, RD, Dingus, BL, Duvernois, MA, Diaz-Vélez, JC, Ellsworth, RW, Engel, K, Fick, B, Fiorino, DW, Fleischhack, H, Fraija, N, Garcia-González, JA, Garfias, F, Gerhardt, M, González Munoz, A, González, MM, Goodman, JA, Hampel-Arias, Z, Harding, JP, Hernandez, S, Hernandez-Almada, A, Hinton, J, Hona, B, Hui, CM, Hüntemeyer, P, Iriarte, A, Jardin-Blicq, A, Joshi, V, Kaufmann, S, Kieda, D, Lara, A, Lauer, RJ, Lee, WH, Lennarz, D, Vargas, HL, Linnemann, JT, Longinotti, AL, Raya, GL, Luna-Garcia, R, López-Coto, R, Malone, K, Marinelli, SS, Martinez, O, Martinez-Castellanos, I, Martinez-Castro, J, Martinez-Huerta, H, Matthews, JA, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nellen, L, Newbold, M, Nisa, MU, Noriega-Papaqui, R, Pelayo, R, Pretz, J, Pérez-Pérez, EG, Ren, Z, Rho, CD, Riviere, C, Rosa-González, D, Rosenberg, M, Ruiz-Velasco, E, Salazar, H, Greus, FS, Sandoval, A, Schneider, M, Schoorlemmer, H, Sinnis, G, Smith, AJ, Springer, RW, Surajbali, P, Taboada, I, Tibolla, O, and Tollefson, K

Subjects
astroparticle physics, Galaxy: general, Galaxy: structure, gamma rays: diffuse background, astro-ph.HE, Astronomy & Astrophysics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural)
Abstract

We present a search for very high-energy gamma-ray emission from the Northern Fermi Bubble region using data collected with the High Altitude Water Cherenkov gamma-ray observatory. The size of the data set is 290 days. No significant excess is observed in the Northern Fermi Bubble region, so upper limits above 1 TeV are calculated. The upper limits are between and . The upper limits disfavor a proton injection spectrum that extends beyond 100 TeV without being suppressed. They also disfavor a hadronic injection spectrum derived from neutrino measurements.

Published
2017

7. DEEP BROADBAND OBSERVATIONS OF THE DISTANT GAMMA-RAY BLAZAR PKS 1424+240

Author

Archambault, S, Aune, T, Behera, B, Beilicke, M, Benbow, W, Berger, K, Bird, R, Biteau, J, Bugaev, V, Byrum, K, Cardenzana, JV, Cerruti, M, Chen, X, Ciupik, L, Connolly, MP, Cui, W, Dumm, J, Errando, M, Falcone, A, Federici, S, Feng, Q, Finley, JP, Fleischhack, H, Fortson, L, Furniss, A, Galante, N, Gillanders, GH, Griffin, S, Griffiths, ST, Grube, J, Gyuk, G, Hanna, D, Holder, J, Hughes, G, Humensky, TB, Johnson, CA, Kaaret, P, Kertzman, M, Khassen, Y, Kieda, D, Krawczynski, H, Krennrich, F, Kumar, S, Lang, MJ, Madhavan, AS, Maier, G, McCann, A, Meagher, K, Moriarty, P, Mukherjee, R, Nieto, D, de Bhróithe, A O'Faoláin, Ong, RA, Otte, AN, Park, N, Pohl, M, Popkow, A, Prokoph, H, Quinn, J, Ragan, K, Rajotte, J, Reyes, LC, Reynolds, PT, Richards, GT, Roache, E, Sembroski, GH, Shahinyan, K, Staszak, D, Telezhinsky, I, Tucci, JV, Tyler, J, Varlotta, A, Vassiliev, VV, Vincent, S, Wakely, SP, Weinstein, A, Welsing, R, Wilhelm, A, Williams, DA, Ackermann, M, Ajello, M, Albert, A, Baldini, L, Bastieri, D, Bellazzini, R, Bissaldi, E, Bregeon, J, Buehler, R, Buson, S, Caliandro, GA, Cameron, RA, Caraveo, PA, Cavazzuti, E, Charles, E, Chiang, J, Ciprini, S, Claus, R, Cutini, S, D'Ammando, F, and de Angelis, A

Subjects
BL Lacertae objects: individual (PKS 1424+240)-cosmic background radiation, gamma rays: galaxies, astro-ph.HE, Astronomical and Space Sciences, Astronomy & Astrophysics
Abstract

We present deep VERITAS observations of the blazar PKS 1424+240, along with contemporaneous Fermi Large Area Telescope, Swift X-ray Telescope, and Swift UV Optical Telescope data between 2009 February 19 and 2013 June 8. This blazar resides at a redshift of z ≥ 0.6035, displaying a significantly attenuated gamma-ray flux above 100 GeV due to photon absorption via pair-production with the extragalactic background light. We present more than 100 hr of VERITAS observations over three years, a multiwavelength light curve, and the contemporaneous spectral energy distributions. The source shows a higher flux of (2.1 ± 0.3) × 10-7 photons m-2 s -1 above 120 GeV in 2009 and 2011 as compared to the flux measured in 2013, corresponding to (1.02 ± 0.08) × 10-7 photons m-2 s-1 above 120 GeV. The measured differential very high energy (VHE; E ≥ 100 GeV) spectral indices are Γ = 3.8 ± 0.3, 4.3 ± 0.6 and 4.5 ± 0.2 in 2009, 2011, and 2013, respectively. No significant spectral change across the observation epochs is detected. We find no evidence for variability at gamma-ray opacities of greater than τ = 2, where it is postulated that any variability would be small and occur on timescales longer than a year if hadronic cosmic-ray interactions with extragalactic photon fields provide a secondary VHE photon flux. The data cannot rule out such variability due to low statistics. © 2014. The American Astronomical Society. All rights reserved..

Published
2014

8. Deep broadband observations of the distant gamma-ray blazar PKS 1424+240

Author

Archambault, S, Aune, T, Behera, B, Beilicke, M, Benbow, W, Berger, K, Bird, R, Biteau, J, Bugaev, V, Byrum, K, Cardenzana, JV, Cerruti, M, Chen, X, Ciupik, L, Connolly, MP, Cui, W, Dumm, J, Errando, M, Falcone, A, Federici, S, Feng, Q, Finley, JP, Fleischhack, H, Fortson, L, Furniss, A, Galante, N, Gillanders, GH, Griffin, S, Griffiths, ST, Grube, J, Gyuk, G, Hanna, D, Holder, J, Hughes, G, Humensky, TB, Johnson, CA, Kaaret, P, Kertzman, M, Khassen, Y, Kieda, D, Krawczynski, H, Krennrich, F, Kumar, S, Lang, MJ, Madhavan, AS, Maier, G, McCann, A, Meagher, K, Moriarty, P, Mukherjee, R, Nieto, D, De Bhróithe, AOF, Ong, RA, Otte, AN, Park, N, Pohl, M, Popkow, A, Prokoph, H, Quinn, J, Ragan, K, Rajotte, J, Reyes, LC, Reynolds, PT, Richards, GT, Roache, E, Sembroski, GH, Shahinyan, K, Staszak, D, Telezhinsky, I, Tucci, JV, Tyler, J, Varlotta, A, Vassiliev, VV, Vincent, S, Wakely, SP, Weinstein, A, Welsing, R, Wilhelm, A, Williams, DA, Ackermann, M, Ajello, M, Albert, A, Baldini, L, Bastieri, D, Bellazzini, R, Bissaldi, E, Bregeon, J, Buehler, R, Buson, S, Caliandro, GA, Cameron, RA, Caraveo, PA, Cavazzuti, E, Charles, E, Chiang, J, Ciprini, S, Claus, R, Cutini, S, D'Ammando, F, and De Angelis, A

Subjects
BL Lacertae objects: individual (PKS 1424+240)-cosmic background radiation, gamma rays: galaxies, astro-ph.HE, Astronomy & Astrophysics, Astronomical and Space Sciences
Abstract

We present deep VERITAS observations of the blazar PKS 1424+240, along with contemporaneous Fermi Large Area Telescope, Swift X-ray Telescope, and Swift UV Optical Telescope data between 2009 February 19 and 2013 June 8. This blazar resides at a redshift of z ≥ 0.6035, displaying a significantly attenuated gamma-ray flux above 100 GeV due to photon absorption via pair-production with the extragalactic background light. We present more than 100 hr of VERITAS observations over three years, a multiwavelength light curve, and the contemporaneous spectral energy distributions. The source shows a higher flux of (2.1 ± 0.3) × 10-7 photons m-2 s -1 above 120 GeV in 2009 and 2011 as compared to the flux measured in 2013, corresponding to (1.02 ± 0.08) × 10-7 photons m-2 s-1 above 120 GeV. The measured differential very high energy (VHE; E ≥ 100 GeV) spectral indices are Γ = 3.8 ± 0.3, 4.3 ± 0.6 and 4.5 ± 0.2 in 2009, 2011, and 2013, respectively. No significant spectral change across the observation epochs is detected. We find no evidence for variability at gamma-ray opacities of greater than τ = 2, where it is postulated that any variability would be small and occur on timescales longer than a year if hadronic cosmic-ray interactions with extragalactic photon fields provide a secondary VHE photon flux. The data cannot rule out such variability due to low statistics. © 2014. The American Astronomical Society. All rights reserved..

Published
2014

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