The first spectroscopic IR reverberation programme on Mrk 509

J. A.J. Mitchell, M. J. Ward, D. Kynoch, J. V.Hernández Santisteban, K. Horne, J. U. Pott, J. Esser, P. Mercatoris, C. Packham, G. J. Ferland, A. Lawrence, T. Fischer, A. J. Barth, C. Villforth, H. Winkler

Research output: Contribution to journalArticlepeer-review


Near IR spectroscopic reverberation of Active Galactic Nuclei (AGN) potentially allows the infrared (IR) broad line region (BLR) to be reverberated alongside the disc and dust continua, while the spectra can also reveal details of dust astro-chemistry. Here, we describe results of a short pilot study (17 near-IR spectra over a 183 d period) for Mrk 509. The spectra give a luminosity-weighted dust radius of Rd,lum = 186 ± 4 light-days for blackbody (large grain dust), consistent with previous (photometric) reverberation campaigns, whereas carbon and silicate dust give much larger radii. We develop a method of calibrating spectral data in objects where the narrow lines are extended beyond the slit width. We demonstrate this by showing our resultant photometric band light curves are consistent with previous results, with a hot dust lag at >40 d in the K band, clearly different from the accretion disc response at <20 d in the z band. We place this limit of 40 d by demonstrating clearly that the modest variability that we do detect in the H and K band does not reverberate on time-scales of less than 40 d. We also extract the Pa β line light curve, and find a lag which is consistent with the optical BLR H β line of ∼70-90 d. This is important as direct imaging of the near-IR BLR is now possible in a few objects, so we need to understand its relation to the better studied optical BLR.

Original languageEnglish
Pages (from-to)4824-4839
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Apr 1 2024

Bibliographical note

Publisher Copyright:
© 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.


  • galaxies: Seyfert
  • infrared: galaxies
  • quasars: emission lines
  • quasars: individual: Mrk 509

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'The first spectroscopic IR reverberation programme on Mrk 509'. Together they form a unique fingerprint.

Cite this