First Direct Evidence for Keplerian Rotation in Quasar Inner Broad-line Regions

C. Fian, J. Jiménez-Vicente, E. Mediavilla, J. A. Muñoz, D. Chelouche, S. Kaspi, R. Forés-Toribio

Research output: Contribution to journalArticlepeer-review

Abstract

We introduce a novel method to derive rotation curves with light-day spatial resolution of the inner regions of lensed quasars. We aim to probe the kinematics of the inner part of the broad-line region by resolving the microlensing response—a proxy for the size of the emitting region—in the wings of the broad emission lines. Specifically, we assess the strength of the microlensing effects in the wings of the high-ionization lines Si iv and C iv across various velocity bins in five gravitationally lensed quasars: SDSS J1001+5027, SDSS J1004+4112, HE 1104−1805, SDSS J1206+4332, and SDSS J1339+1310. Using Bayesian methods to estimate the dimensions of the corresponding emission regions and adopting a Keplerian model as our baseline, we examine the consistency of the hypothesis of disklike rotation. Our results reveal a monotonic, smooth increase in microlensing magnification with velocity. The deduced velocity-size relationships inferred for the various quasars and emission lines closely conform to the Keplerian model of an inclined disk. This study provides the first direct evidence of Keplerian rotation in the innermost region of quasars across a range of radial distances spanning from ∼5 to 20 lt-days.

Original languageEnglish
Article numberL7
JournalAstrophysical Journal Letters
Volume972
Issue number1
DOIs
StatePublished - 1 Sep 2024

Bibliographical note

Publisher Copyright:
© 2024. The Author(s). Published by the American Astronomical Society.

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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