Astrophys. J., 896, 146-146 (2020/June-3)
Time-delay measurement of Mg II broad-line response for the highly accreting quasar HE 0413-4031: implications for the Mg II-based radius-luminosity relation.
ZAJACEK M., CZERNY B., MARTINEZ-ALDAMA M.L., RALOWSKI M., OLEJAK A., PANDA S., HRYNIEWICZ K., SNIEGOWSKA M., NADDAF M.-H., PYCH W., PIETRZYNSKI G., SOBRINO FIGAREDO C., HAAS M., SREDZINSKA J., KRUPA M., KURCZ A., UDALSKI A., GORSKI M. and SARNA M.
Abstract (from CDS):
We present the monitoring of the active galactic nuclei continuum and Mg II broad-line emission for the quasar HE 0413-4031 (z = 1.38) based on the six-year monitoring by the South African Large Telescope (SALT). We manage to estimate a time-delay of 302.6–33.1+28.7 days in the rest frame of the source using seven different methods: interpolated cross-correlation function, discrete correlation function (DCF), z-transformed DCF, JAVELIN, two estimators of data regularity (Von Neumann, Bartels), and χ2 method. This time-delay is below the value expected from the standard radius-luminosity relation. However, based on the monochromatic luminosity of the source and the spectral energy distribution modeling, we interpret this departure as the shortening of the time-delay due to the higher accretion rate of the source, with the inferred Eddington ratio of ∼0.4. The Mg II line luminosity of HE 0413-4031 responds to the continuum variability as Lline∝Lcont^0.43±0.10^, which is consistent with the light-travel distance of the location of Mg II emission at Rout ∼ 1018 cm. Using the data of 10 other quasars, we confirm the radius-luminosity relation for the broad Mg II line, which was previously determined for the broad Hβ line for lower-redshift sources. In addition, we detect a general departure of higher-accreting quasars from this relation in analogy to the Hβ sample. After the accretion-rate correction of the light-travel distance, the Mg II-based radius-luminosity relation has a small scatter of only 0.10 dex.
© 2020. The American Astronomical Society. All rights reserved.
Accretion - Active galaxies - Quasars - Radio-loud quasars - Supermassive black holes - Spectroscopy
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