Flares in the changing look AGN Mrk 590-I. The UV response to X-ray outbursts suggests a more complex reprocessing geometry than a standard disc
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Flares in the changing look AGN Mrk 590-I. The UV response to X-ray outbursts suggests a more complex reprocessing geometry than a standard disc. / Lawther, D.; Vestergaard, M.; Raimundo, S.; Koay, J. Y.; Peterson, B. M.; Fan, X.; Grupe, D.; Mathur, S.
In: Monthly Notices of the Royal Astronomical Society, Vol. 519, No. 3, 09.01.2023, p. 3903-3922.Research output: Contribution to journal › Journal article › Research › peer-review
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T1 - Flares in the changing look AGN Mrk 590-I. The UV response to X-ray outbursts suggests a more complex reprocessing geometry than a standard disc
AU - Lawther, D.
AU - Vestergaard, M.
AU - Raimundo, S.
AU - Koay, J. Y.
AU - Peterson, B. M.
AU - Fan, X.
AU - Grupe, D.
AU - Mathur, S.
PY - 2023/1/9
Y1 - 2023/1/9
N2 - Mrk 590 is a known changing-look active galactic nuclei (AGNs) which almost turned off in 2012, and then in 2017 partially re-ignited into a repeat flaring state, unusual for an AGN. Our Swift observations since 2013 allow us to characterize the accretion-generated emission and its reprocessing in the central engine of a changing-look AGN. The X-ray and UV variability amplitudes are higher than those typically observed in 'steady-state' AGN at similar moderate accretion rates; instead, the variability is similar to that of highly accreting AGN. The unusually strong X-ray to UV correlation suggests that the UV-emitting region is directly illuminated by X-ray outbursts. We find evidence that the X-rays are reprocessed by two UV components, with the dominant one at similar to 3 d and a faint additional reprocessor at near-zero lag. However, we exclude a significant contribution from diffuse broad line region continuum, known to contribute for bonafide AGN. A near-zero lag is expected for a standard 'lamp-post' disc reprocessing model with a driving continuum source near the black hole. That the overall UV response is dominated by the similar to 3-d lagged component suggests a complicated reprocessing geometry, with most of the UV continuum not produced in a compact disc, as also found in recent studies of NGC 5548 and NGC 4151. None the less, the observed flares display characteristic time-scales of similar to 100 rest-frame days, consistent with the expected thermal time-scale in an accretion disc.
AB - Mrk 590 is a known changing-look active galactic nuclei (AGNs) which almost turned off in 2012, and then in 2017 partially re-ignited into a repeat flaring state, unusual for an AGN. Our Swift observations since 2013 allow us to characterize the accretion-generated emission and its reprocessing in the central engine of a changing-look AGN. The X-ray and UV variability amplitudes are higher than those typically observed in 'steady-state' AGN at similar moderate accretion rates; instead, the variability is similar to that of highly accreting AGN. The unusually strong X-ray to UV correlation suggests that the UV-emitting region is directly illuminated by X-ray outbursts. We find evidence that the X-rays are reprocessed by two UV components, with the dominant one at similar to 3 d and a faint additional reprocessor at near-zero lag. However, we exclude a significant contribution from diffuse broad line region continuum, known to contribute for bonafide AGN. A near-zero lag is expected for a standard 'lamp-post' disc reprocessing model with a driving continuum source near the black hole. That the overall UV response is dominated by the similar to 3-d lagged component suggests a complicated reprocessing geometry, with most of the UV continuum not produced in a compact disc, as also found in recent studies of NGC 5548 and NGC 4151. None the less, the observed flares display characteristic time-scales of similar to 100 rest-frame days, consistent with the expected thermal time-scale in an accretion disc.
KW - galaxies: active
KW - galaxies: Seyfert
KW - ACTIVE GALACTIC NUCLEI
KW - RADIUS-LUMINOSITY RELATIONSHIP
KW - OPTICAL CONTINUUM EMISSION
KW - VARIABILITY TIME-SCALE
KW - DIGITAL SKY SURVEY
KW - ACCRETION DISK
KW - SPACE TELESCOPE
KW - LOOK AGN
KW - THERMAL REVERBERATION
KW - BLACK-HOLES
U2 - 10.1093/mnras/stac3515
DO - 10.1093/mnras/stac3515
M3 - Journal article
VL - 519
SP - 3903
EP - 3922
JO - Royal Astronomical Society. Monthly Notices
JF - Royal Astronomical Society. Monthly Notices
SN - 0035-8711
IS - 3
ER -
ID: 341015906