37 research outputs found
Broad-line Region Characterization in Dozens of Active Galactic Nuclei Using Small-aperture Telescopes
No full textAbstract We present the results of a nearly decade-long photometric reverberation mapping (PRM) survey of the H α emission line in nearby (0.01 ≲ z ≲ 0.05) Seyfert galaxies using small (15–40 cm) telescopes. Broadband filters were used to trace the continuum emission, while narrowband filters tracked the H α -line signal. We introduce a new PRM formalism to determine the time delay between continuum and line emission using combinations of auto- and cross-correlation functions. We obtain robust delays for 33/80 objects, allowing us to estimate the broad-line region (BLR) size. Additionally, we measure multiepoch delays for six objects whose scatter per source is smaller than the scatter in the BLR size–luminosity relation. Our study enhances the existing H α size–luminosity relation by adding high-quality results for 31 objects, whose nuclear luminosities were estimated using the flux-variation gradient method, resulting in a scatter of 0.26 dex within our sample. The scatter reduces to 0.17 dex when the six lowest-luminosity sources are discarded, which is comparable to that found for the H β line. Single-epoch spectra enable us to estimate black hole masses using the H α line and derive mass accretion rates from the iron-blend feature adjacent to H β . A similar trend, as previously reported for the H β line, is implied whereby highly accreting objects tend to lie below the size–luminosity relation of the general population. Our work demonstrates the effectiveness of small telescopes in conducting high-fidelity PRM campaigns of prominent emission lines in bright active galactic nuclei.Deutsche Forschungsgemeinschaft 501100001659Deutsche Forschungsgemeinschaft 501100001659Deutsche Forschungsgemeinschaft 501100001659Israel Science Foundation 501100003977Israel Science Foundation 501100003977Deutsche Forschungsgemeinschaft 50110000165
On The Fine Tuning and Physical Origin of Line-Locked Absorption Systems in Active Galaxies
No full textLine locking (LL) of absorption line systems is a clear signature of the
dynamical importance of radiation pressure force in driving astrophysical
flows, with recent findings suggesting that it may be common in quasars
exhibiting multiple intrinsic narrow absorption-line (NAL) systems. In this
work we probe the phase space conducive to LL and follow the detailed
kinematics of those systems that may lock at the velocity separation of the CIV
doublet. We find that a small volume of the
phase-phase admits LL, suggesting a high-degree of fine-tuning between the
physical properties of locked systems. The stability of LL against quasar
luminosity variations is quantified with implications for the long-term
variability amplitude of quasars and the velocity-separation statistic between
multiple NAL systems. The high occurrence of LL by the CIV doublet implies that
the hidden extreme-UV emission from quasars is unlikely to be significantly
under-estimated by current models. Further, the ratio of the LL velocity to the
outflow velocity may serve as a powerful constraint on the composition of the
accelerating medium. We conclude that LL poses significant challenges to
current theories for the formation of non-intervening NAL systems, and
speculate that it may be a manifestation of expanding circumstellar shells
around asymptotic giant branch (AGB) stars in the quasar-host bulge.Comment: 22 pages, 13 figures, ApJ in pres
