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Long-term optical and X-ray variability of the Seyfert galaxy Markarian 79

Long-term optical and X-ray variability of the Seyfert galaxy Markarian 79
Long-term optical and X-ray variability of the Seyfert galaxy Markarian 79
We present the results of concurrent X-ray and optical monitoring of the Seyfert 1 galaxy Mrk 79 over a period of more than 5 yr. We find that on short to medium time-scales (days to a few tens of days) the 2–10 keV X-ray and optical u- and V-band fluxes are significantly correlated, with a delay between the bands consistent with 0 d. We show that most of these variations may be well reproduced by a model where the short-term optical variations originate from reprocessing of X-rays by an optically thick accretion disc. The optical light curves, however, also display long time-scale variations over thousands of days, which are not present in the X-ray light curve. These optical variations must originate from an independent variability mechanism and we show that they can be produced by variations in the (geometrically) thin disc accretion rate as well as by varying reprocessed fractions through changes in the location of the X-ray corona.
galaxies: active, galaxies: individual: Mrk 79, galaxies: Seyfert
0035-8711
427-437
Breedt, E.
f6429cea-d194-41bd-b05e-61de02cee62c
Arévalo, P.
16a262f1-5692-423c-83f4-a61364f9f958
McHardy, I.M.
4f215137-9cc4-4a08-982e-772a0b24c17e
Uttley, P.
db770bd7-d97e-43f5-99d4-a585bccd352a
Sergeev, S.G.
e60469ed-a4cb-46a3-a3ca-7a1a3ffe62c6
Minezaki, T.
502cb95e-1a04-4984-8c36-854b9921c147
Yoshii, Y.
18aec11a-889c-42c5-9b6e-860d7b176876
Gaskell, C.M.
e7e9fe22-27ce-4472-8a0a-7a11f4e9a2dc
Cackett, E.M.
2cd7b6af-a0e0-4265-94f6-092d68d1ba74
Horne, K.
53fcebf2-d0a1-453a-b141-6174ac5e4afe
Koshida, S.
65af12de-bc5e-4b10-8345-376a36e1885b
Breedt, E.
f6429cea-d194-41bd-b05e-61de02cee62c
Arévalo, P.
16a262f1-5692-423c-83f4-a61364f9f958
McHardy, I.M.
4f215137-9cc4-4a08-982e-772a0b24c17e
Uttley, P.
db770bd7-d97e-43f5-99d4-a585bccd352a
Sergeev, S.G.
e60469ed-a4cb-46a3-a3ca-7a1a3ffe62c6
Minezaki, T.
502cb95e-1a04-4984-8c36-854b9921c147
Yoshii, Y.
18aec11a-889c-42c5-9b6e-860d7b176876
Gaskell, C.M.
e7e9fe22-27ce-4472-8a0a-7a11f4e9a2dc
Cackett, E.M.
2cd7b6af-a0e0-4265-94f6-092d68d1ba74
Horne, K.
53fcebf2-d0a1-453a-b141-6174ac5e4afe
Koshida, S.
65af12de-bc5e-4b10-8345-376a36e1885b

Breedt, E., Arévalo, P., McHardy, I.M., Uttley, P., Sergeev, S.G., Minezaki, T., Yoshii, Y., Gaskell, C.M., Cackett, E.M., Horne, K. and Koshida, S. (2009) Long-term optical and X-ray variability of the Seyfert galaxy Markarian 79. Monthly Notices of the Royal Astronomical Society, 394 (1), 427-437. (doi:10.1111/j.1365-2966.2008.14302.x).

Record type: Article

Abstract

We present the results of concurrent X-ray and optical monitoring of the Seyfert 1 galaxy Mrk 79 over a period of more than 5 yr. We find that on short to medium time-scales (days to a few tens of days) the 2–10 keV X-ray and optical u- and V-band fluxes are significantly correlated, with a delay between the bands consistent with 0 d. We show that most of these variations may be well reproduced by a model where the short-term optical variations originate from reprocessing of X-rays by an optically thick accretion disc. The optical light curves, however, also display long time-scale variations over thousands of days, which are not present in the X-ray light curve. These optical variations must originate from an independent variability mechanism and we show that they can be produced by variations in the (geometrically) thin disc accretion rate as well as by varying reprocessed fractions through changes in the location of the X-ray corona.

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Published date: March 2009
Keywords: galaxies: active, galaxies: individual: Mrk 79, galaxies: Seyfert

Identifiers

Local EPrints ID: 144539
URI: https://eprints.soton.ac.uk/id/eprint/144539
ISSN: 0035-8711
PURE UUID: c5b45d2c-ead4-44bf-a9e3-f99e7bfec40e

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Date deposited: 24 May 2010 11:50
Last modified: 18 Jul 2017 23:08

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