ENERGY-DEPENDENT TIME LAGS IN THE SEYFERT 1 GALAXY NGC 4593

Journal Article · Sat Aug 01 04:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/700/2/1042; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21313817

Sriram, K ^[1]; Agrawal, V K ^[2]

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1. Department of Astronomy, Osmania University, Hyderabad 500 07 (India)
2. Indian Space Research Organization, HQ., BEL Road, Bangalore 560 094 (India)

We investigate the energy-time lag dependence of the source NGC 4593 using XMM-Newton/EPIC pn data. We found that the time lag dependency is linear in nature with respect to the logarithm of different energy bands. We also investigate the frequency-dependent time lags and identify that at some frequency range (5 x 10{sup -5} Hz to 2 x 10{sup -4} Hz) the X-ray emission is highly coherent, mildly frequency dependent, and very strongly energy dependent. These observations can be explained in the framework of the thermal Comptonization process, and they indicate a truncated accretion disk very close to the black hole. We discuss the plausible spectral state to explain the phenomenon and conclude that the observed properties bear a close resemblance to the intermediate state or the steep power-law state, found in galactic black hole sources.

• OSTI ID: 21313817
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 700; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

99 GENERAL AND MISCELLANEOUS
ACCRETION DISKS
BLACK HOLES
ENERGY DEPENDENCE
FREQUENCY DEPENDENCE
GALAXIES
INTERMEDIATE STATE