Chia-Ying Chiang

TL;DR: The observation of multiple absorption lines from an extreme ultrafast gas flow in the X-ray spectrum of the active galactic nucleus IRAS 13224−3809, at 0.236 ± 0.006 times the speed of light, demonstrates a connection between accretion processes occurring on very different scales.

TL;DR: In this article, the spectrum of the narrow-line Seyfert 1 galaxy IRAS was observed with XMM-Newton for 500 ks with strong broad Fe − K and L emission features, interpreted as arising from reflection from the inner parts of an accretion disc around a rapidly spinning black hole.

TL;DR: In this paper, a detailed spectral analysis of the recent 1.5m XMM-Newton observing campaign on the narrow-line Seyfert 1 galaxy IRAS 13224−3809 is presented.

TL;DR: In this article, the authors report on the deep X-ray observation of the narrow-line Seyfert 1 galaxy Mrk 335 in the low-flux state obtained with Suzaku.

Abstract: The Seyfert 1 galaxy NGC 4593 was monitored spectroscopically with the Hubble Space Telescope as part of a reverberation mapping campaign that also included Swift, Kepler, and ground-based photometric monitoring. During 2016 July 12-August 6, we obtained 26 spectra across a nearly continuous wavelength range of ∼1150-10000 A. These were combined with Swift data to produce a UV/optical "lag spectrum," which shows the interband lag relative to the Swift UVW2 band as a function of wavelength. The broad shape of the lag spectrum appears to follow the τ ∝ λ 4/3 relation seen previously in photometric interband lag measurements of other active galactic nuclei (AGNs). This shape is consistent with the standard thin disk model, but the magnitude of the lags implies a disk that is a factor of ∼3 larger than predicted, again consistent with what has been previously seen in other AGNs. In all cases these large disk sizes, which are also implied by independent gravitational microlensing of higher-mass AGNs, cannot be simply reconciled with the standard model. However, the most striking feature in this higher-resolution lag spectrum is a clear excess around the 3646 A Balmer jump. This strongly suggests that diffuse emission from gas in the much larger broad-line region (BLR) must also contribute significantly to the interband lags. While the relative contributions of the disk and BLR cannot be uniquely determined in these initial measurements, it is clear that both will need to be considered to comprehensively model and understand AGN lag spectra.