Fermi Gamma-ray Space Telescope

Probing the high-energy emission of the very nearby CV SS Cygni: testing unification along the mass scale?

Alan Loh
Stephane Corbel, Guillaume Dubus, on behalf of the Fermi-LAT Collaboration

Abstract:

Accretion onto compact objects powers a wide range of celestial bodies in the Universe: e.g. active galactic nuclei, stellar-mass black holes, cataclysmic variables (CVs)... A global picture describing the properties of these accreting systems, coupled with their relation with their jets, has emerged these recent years. With their regular outbursts, CVs offer a good opportunity to test these unification scenarios. SS Cygni is one the brightest and best studied dwarf novae. It undergoes bright outbursts with a period of approximatively 40 days. Radio emission has been detected during these outbursts and interpreted as synchrotron radiation from jets, incorporating CVs into the scenario of ubiquitous disk/jet coupling in accreting systems. Inverse Compton gamma-ray emission from the jets of SS Cygni may be expected. Here, we will present our search for gamma-ray emission using the six years of Fermi/Large Area Telescope data. With no detection with Large Area Telescope, the high-energy upper limit provides strong constraints on the system's nearby environment as well as on the nature of the radio emission mechanisms, questioning the global picture of accreting compact objects.