Abstract
Microvariability (intra-night variability) is a low amplitude flux change at short time scales (i.e. hours). It has been detected in unobscured type 1 AGNs and blazars. However in type 2 AGNs, the detection is hampered by the low contrast between the presumably variable nucleus and the host galaxy. In this paper, we present a search for microvariability in a sample of four type 2 quasars as an astrostatistical problem. We are exploring the use of a newly introduced enhanced F-test, proposed by de Diego 2014. The presented results show that out of our four observed targets, we were able to apply this statistical method to three of them. Evidence of microvariations is clear in the case of quasar J0802+2552 in all used filters (g',r' and i') during both observing nights, the microvariations are present in one of the nights of observations of J1258+5239 in one filter (i'), while for the J1316+4452, there is evidence for microvariability within our detection levels during one night and two filters (r' and i'). We demonstrate the feasibility of the enhanced F-test to detect microvariability in obscured type 2 quasars. At the end of this paper, we discuss possible causes of microvariability. One of the options is the misclassification of the targets. A likely scenario for explanation of the phenomenon involves optically thin gaps in a clumpy obscuring medium, in accordance with the present view of the circumnuclear region. There is a possible interesting connection between the merging state of the targets and detection of microvariability.
Highlights
Active Galactic Nuclei (AGN hereafter) can be explained by the standard model, introduced by Antonucci (1993)
An AGN is described as a central supermassive black hole, surrounded by an accretion disc of an optically thick plasma emitting great amounts of energy in UV and X-ray wavelengths, and by an optically thin region of free fall onto the central black hole, where c 2016 The Authors hard X-rays and gamma rays are emitted
On top of the accretion disc, there is a corona of energetic electrons, able to scatter the light via the inverse Compton effect
Summary
Active Galactic Nuclei (AGN hereafter) can be explained by the standard (unified) model, introduced by Antonucci (1993). Based on the unified model, the central engine of type 1 AGNs is directly observable These include Seyfert 1 galaxies and type 1 quasars (in the cases of low and high luminosities, respectively). As according to the causal arguments, we can assume that the microvariations are originating close to the central engine of the AGN, directly accessible in blazars and type 1 sources. Following this assumption, microvariability helps us gain insights about the innermost regions close to the central black hole. We are presenting the results from a campaign dedicated to searching microvariability in a sample of four type 2 quasars, using the enhanced F-test as proposed by de Diego (2014). The paper is organized as following: section 2 describes the sample and the data reduction, section 3 describes in the detail the enhanced F-test, section 4 contains discussion about the results obtained on every target and section 5 provides conclusions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
