Title: INTEGRAL view of Mkn 3 and Mkn 6: two Seyfert galaxies with strong absorption and radio jets
Proposal ID: 0120043
Subject category: Extragalactic Object
Principal investigator: Bassani
Institute: TESRE-CRN
Abstract
We propose to study with INTEGRAL two Seyfert galaxies, Mkn3 and Mkn6 with a single total exposure of
400
Ks; these two galaxies are in fact close enough (4.3 degrees) to fall within the fully coded field of view
of all INTEGRAL instruments. These two objects are intriguing from the point of view of AGN unification
schemes: in both objects we find highly collimated jets, ionization cones, and strong X-ray absorption. Yet
they belong to two different Seyfert classes: Mkn3 is a type 2 source while Mkn6 is a type 1.5 galaxy. Thus
unification only by means of absorbing torii is not able to explain these observational evidences in both.
The presence in each galaxy of a jet component resembling the structure seen in large scale radio galaxies,
suggests the possibility of a link with more powerful radio galaxies and so possible role of beaming
although of less magnitude. If the distinction of AGN in two classes, according to the scheme of Dermer and
Gehrels, is valid then Mkn6 and Mkn3 could be transition objects between the two classes and can be taken
as case studies to understand the role of jets in Seyfert galaxies with respect to the production of high
energy photons. Aim of the present proposal is therefore to observe these two galaxies over the broad band
range of INTEGRAL with the goal of extending their spectra to the highest possible energies. This will allow
the gamma-ray spectral characteristics to be measured and thus compared to those of gamma-quiet or loud
AGN. In particular we intend to measure the high energy cut-off in both galaxies in order to define if the
emission softens at about 100 keV as observed in gamma-quiet objects or extends into the gamma-ray regime as
measured in gamma-loud objects.