Search for neutrino emission from blazar <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mi>γ</a:mi> </a:math> -ray flares accounting for possible neutrino time delays
Abstract
We report the results of the search for the high-energy neutrino emission associated with blazar flares, accounting for a possible lag of neutrinos with respect to the electromagnetic emission, either due to the slowness of the proton energy losses in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mi>p</mml:mi> <mml:mi>γ</mml:mi> </mml:mrow> </mml:math> collisions and/or proton acceleration. We perform two tests, cross-matching neutrinos with energies <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mi>E</mml:mi> <mml:mi>ν</mml:mi> </mml:msub> <mml:mo>≳</mml:mo> <mml:mn>100</mml:mn> </mml:mrow> </mml:math> TeV from the public catalogue of neutrino alerts IceCat-1 with active galactic nuclei from two source samples based on 1) the MOJAVE database and 2) the CGRaBS catalogue, and utilising Fermi-LAT light curves from the public light curve repository. We scan over a wide range of values of the jet-frame time delay <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msubsup> <mml:mi>t</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">d</mml:mi> <mml:mi mathvariant="normal">e</mml:mi> <mml:mi mathvariant="normal">l</mml:mi> <mml:mi mathvariant="normal">a</mml:mi> <mml:mi mathvariant="normal">y</mml:mi> </mml:mrow> <mml:mi>′</mml:mi> </mml:msubsup> </mml:math> between the neutrino arrival and the time of the prior major <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>γ</mml:mi> </mml:math> -ray flare and find a pre-trial <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo>∼</mml:mo> <mml:mn>2</mml:mn> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> correlation at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msubsup> <mml:mi>t</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">d</mml:mi> <mml:mi mathvariant="normal">e</mml:mi> <mml:mi mathvariant="normal">l</mml:mi> <mml:mi mathvariant="normal">a</mml:mi> <mml:mi mathvariant="normal">y</mml:mi> </mml:mrow> <mml:mi>′</mml:mi> </mml:msubsup> <mml:mo>∼</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>3</mml:mn> </mml:msup> </mml:mrow> </mml:math> d, which is consistent ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mi>p</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">p</mml:mi> <mml:mi mathvariant="normal">o</mml:mi> <mml:mi mathvariant="normal">s</mml:mi> <mml:mi mathvariant="normal">t</mml:mi> <mml:mo mathvariant="normal">−</mml:mo> <mml:mi mathvariant="normal">t</mml:mi> <mml:mi mathvariant="normal">r</mml:mi> <mml:mi mathvariant="normal">i</mml:mi> <mml:mi mathvariant="normal">a</mml:mi> <mml:mi mathvariant="normal">l</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>0.1</mml:mn> </mml:mrow> </mml:math> ) with expectations under the null hypothesis after trial correction.