Ojha, R.Mirabal, N.et al.2020-05-082020-05-082015-12-15M. L. Ahnen et al., VERY HIGH ENERGY γ-RAYS FROM THE UNIVERSE'S MIDDLE AGE: DETECTION OF THE z = 0.940 BLAZAR PKS 1441+25 WITH MAGIC, The Astrophysical Journal Letters, Volume 815, Number 2, doi: https://doi.org/10.1088%2F2041-8205%2F815%2F2%2Fl23https://doi.org/10.1088%2F2041-8205%2F815%2F2%2Fl23http://hdl.handle.net/11603/18511http://simbad.u-strasbg.fr/simbad/sim-ref?querymethod=bib&simbo=on&submit=submit+bibcode&bibcode=2015ApJ...815L..23Ahttps://ned.ipac.caltech.edu/cgi-bin/objsearch?search_type=Search&refcode=2015ApJ...815L..23Ahttps://heasarc.gsfc.nasa.gov/xamin/xamin.jsp?bibcode=2015ApJ%2E%2E%2E815L%2E%2E23AAuthors: "M. L. Ahnen and S. Ansoldi and L. A. Antonelli and P. Antoranz and A. Babic and B. Banerjee and P. Bangale and U. Barres de Almeida and J. A. Barrio and W. Bednarek and E. Bernardini and B. Biasuzzi and A. Biland and O. Blanch and S. Bonnefoy and G. Bonnoli and F. Borracci and T. Bretz and E. Carmona and A. Carosi and A. Chatterjee and R. Clavero and P. Colin and E. Colombo and J. L. Contreras and J. Cortina and S. Covino and P. Da Vela and F. Dazzi and A. De Angelis and B. De Lotto and E. de O{\~{n}}a Wilhelmi and C. Delgado Mendez and F. Di Pierro and D. Dominis Prester and D. Dorner and M. Doro and S. Einecke and D. Eisenacher Glawion and D. Elsaesser and A. Fern{\'{a}}ndez-Barral and D. Fidalgo and M. V. Fonseca and L. Font and K. Frantzen and C. Fruck and D. Galindo and R. J. Garc{\'{\i}}a L{\'{o}}pez and M. Garczarczyk and D. Garrido Terrats and M. Gaug and P. Giammaria and N. Godinovi{\'{c}} and A. Gonz{\'{a}}lez Mu{\~{n}}oz and D. Guberman and A. Hahn and Y. Hanabata and M. Hayashida and J. Herrera and J. Hose and D. Hrupec and G. Hughes and W. Idec and K. Kodani and Y. Konno and H. Kubo and J. Kushida and A. La Barbera and D. Lelas and E. Lindfors and S. Lombardi and M. L{\'{o}}pez and R. L{\'{o}}pez-Coto and A. L{\'{o}}pez-Oramas and E. Lorenz and P. Majumdar and M. Makariev and K. Mallot and G. Maneva and M. Manganaro and K. Mannheim and L. Maraschi and B. Marcote and M. Mariotti and M. Mart{\'{\i}}nez and D. Mazin and U. Menzel and J. M. Miranda and R. Mirzoyan and A. Moralejo and E. Moretti and D. Nakajima and V. Neustroev and A. Niedzwiecki and M. Nievas Rosillo and K. Nilsson and K. Nishijima and K. Noda and R. Orito and A. Overkemping and S. Paiano and J. Palacio and M. Palatiello and D. Paneque and R. Paoletti and J. M. Paredes and X. Paredes-Fortuny and M. Persic and J. Poutanen and P. G. Prada Moroni and E. Prandini and I. Puljak and W. Rhode and M. Rib{\'{o}} and J. Rico and J. Rodriguez Garcia and T. Saito and K. Satalecka and C. Schultz and T. Schweizer and S. N. Shore and A. Sillanpää and J. Sitarek and I. Snidaric and D. Sobczynska and A. Stamerra and T. Steinbring and M. Strzys and L. Takalo and H. Takami and F. Tavecchio and P. Temnikov and T. Terzi{\'{c}} and D. Tescaro and M. Teshima and J. Thaele and D. F. Torres and T. Toyama and A. Treves and V. Verguilov and I. Vovk and J. E. Ward and M. Will and M. H. Wu and R. Zanin and M. Ajello and L. Baldini and G. Barbiellini and D. Bastieri and J. Becerra Gonz{\'{a}}lez and R. Bellazzini and E. Bissaldi and R. D. Blandford and R. Bonino and J. Bregeon and P. Bruel and S. Buson and G. A. Caliandro and R. A. Cameron and M. Caragiulo and P. A. Caraveo and E. Cavazzuti and J. Chiang and G. Chiaro and S. Ciprini and F. D'Ammando and F. de Palma and R. Desiante and L. Di Venere and A. Dom{\'{\i}}nguez and P. Fusco and F. Gargano and D. Gasparrini and N. Giglietto and F. Giordano and M. Giroletti and I. A. Grenier and S. Guiriec and E. Hays and J. W. Hewitt and T. Jogler and M. Kuss and S. Larsson and J. Li and L. Li and F. Longo and F. Loparco and M. N. Lovellette and P. Lubrano and S. Maldera and M. Mayer and M. N. Mazziotta and J. E. McEnery and N. Mirabal and T. Mizuno and M. E. Monzani and A. Morselli and I. V. Moskalenko and E. Nuss and R. Ojha and T. Ohsugi and N. Omodei and E. Orlando and J. S. Perkins and M. Pesce-Rollins and F. Piron and G. Pivato and T. A. Porter and S. Raino and R. Rando and M. Razzano and A. Reimer and O. Reimer and C. Sgro and E. J. Siskind and F. Spada and G. Spandre and P. Spinelli and H. Tajima and H. Takahashi and J. B. Thayer and D. J. Thompson and E. Troja and K. S. Wood and M. Balokovic and A. Berdyugin and A. Carraminana and L. Carrasco and V. Chavushyan and V. Fallah Ramazani and M. Feige and S. Haarto and P. Haeusner and T. Hovatta and J. Kania and J. Klamt and A. Lähteenmäki and J. Leon-Tavares and C. Lorey and L. Pacciani and A. Porras and E. Recillas and R. Reinthal and M. Tornikoski and D. Wolfert and N. Zottmann"The flat-spectrum radio quasar PKS 1441+25 at a redshift of z = 0.940 is detected between 40 and 250 GeV with a significance of 25.5σ using the MAGIC telescopes. Together with the gravitationally lensed blazar QSO B0218+357 (z = 0.944), PKS 1441+25 is the most distant very high energy (VHE) blazar detected to date. The observations were triggered by an outburst in 2015 April seen at GeV energies with the Large Area Telescope on board Fermi. Multi-wavelength observations suggest a subdivision of the high state into two distinct flux states. In the band covered by MAGIC, the variability timescale is estimated to be 6.4 ± 1.9 days. Modeling the broadband spectral energy distribution with an external Compton model, the location of the emitting region is understood as originating in the jet outside the broad-line region (BLR) during the period of high activity, while being partially within the BLR during the period of low (typical) activity. The observed VHE spectrum during the highest activity is used to probe the extragalactic background light at an unprecedented distance scale for ground-based gamma-ray astronomy.8 pagesen-USThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.Public Domain Mark 1.0This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. LawText