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@INPROCEEDINGS{Roncadelli:316737,
      author       = {Roncadelli, Marco and Galanti, Giorgio and De Angelis,
                      Alessandro and Bignami, Giovanni F.},
      title        = {{ALP}s {E}xplain the {O}bserved {R}edshift-{D}ependence of
                      {B}lazar {S}pectra},
      address      = {Hamburg},
      publisher    = {Verlag Deutsches Elektronen-Synchrotron},
      reportid     = {PUBDB-2017-00135},
      isbn         = {978-3-935702-43-0},
      series       = {DESY-PROC},
      pages        = {82-87},
      year         = {2015},
      comment      = {Roncadelli, Marco "ALPs Explain the Observed
                      Redshift-Dependence of Blazar Spectra" in Proceedings, 11th
                      Patras Workshop on Axions, WIMPs and WISPs (Axion-WIMP 2015)
                      / Irastorza, Igor G., Redondo, Javier, Carmona, José
                      Manuel, Cebrian, Susana, Dafni, Theopisti, Iguaz, Francisco
                      J., Luzon, Gloria (eds.), Verlag Deutsches
                      Elektronen-Synchrotron : 2015 ; AXION-WIMP 2015 : 11th
                      Patras Workshop on Axions, WIMPs and WISPs, 2015-06-22 -
                      2015-06-26, Zaragoza},
      booktitle     = {Roncadelli, Marco "ALPs Explain the
                       Observed Redshift-Dependence of Blazar
                       Spectra" in Proceedings, 11th Patras
                       Workshop on Axions, WIMPs and WISPs
                       (Axion-WIMP 2015) / Irastorza, Igor G.,
                       Redondo, Javier, Carmona, José Manuel,
                       Cebrian, Susana, Dafni, Theopisti,
                       Iguaz, Francisco J., Luzon, Gloria
                       (eds.), Verlag Deutsches
                       Elektronen-Synchrotron : 2015 ;
                       AXION-WIMP 2015 : 11th Patras Workshop
                       on Axions, WIMPs and WISPs, 2015-06-22
                       - 2015-06-26, Zaragoza},
      abstract     = {We considered a complete sample of blazars observed with
                      the Imaging Atmospheric Cherenkov Telescopes above $E \geq
                      80 \, {\rm GeV}$, out to $z = 0.54$ and described by
                      standard photon emission models which predict simple
                      power-law spectra to a good approximation. We first show
                      that the best-fit regression line of the emitted slope
                      distribution $\{\Gamma_{\rm em} (z) \}$ decreases with $z$,
                      in disagreement with physical intuition. Next, we
                      demonstrate that, by allowing for photon-ALP oscillations in
                      intergalactic space, for a realistic values of the
                      parameters the best-fit regression line becomes exactly
                      horizontal in the $\Gamma_{\rm em} - z$ plane. This result
                      is amazing, because it is the only possibility in agreement
                      with physical expectation, and so it can be regarded as a
                      strong hint of the existence of an ALP.},
      month         = {Jun},
      date          = {2015-06-22},
      organization  = {11th Patras Workshop on Axions, WIMPs
                       and WISPs, Zaragoza (Spain), 22 Jun
                       2015 - 26 Jun 2015},
      typ          = {PUB:(DE-HGF)8 / PUB:(DE-HGF)7},
      doi          = {10.3204/DESY-PROC-2015-02/roncadelli_marco},
      url          = {https://bib-pubdb1.desy.de/record/316737},
}