St Andrews Research Repository

St Andrews University Home
View Item 
  •   St Andrews Research Repository
  • University of St Andrews Research
  • University of St Andrews Research
  • University of St Andrews Research
  • View Item
  •   St Andrews Research Repository
  • University of St Andrews Research
  • University of St Andrews Research
  • University of St Andrews Research
  • View Item
  •   St Andrews Research Repository
  • University of St Andrews Research
  • University of St Andrews Research
  • University of St Andrews Research
  • View Item
  • Login
JavaScript is disabled for your browser. Some features of this site may not work without it.

Accretion disk reverberation with Hubble Space Telescope observations of NGC 4593 : evidence for diffuse continuum lags

Thumbnail
View/Open
Cackett_2018_AJ_Diffusecontinuumlags_VoR.pdf (2.130Mb)
Date
12/04/2018
Author
Cackett, Edward M.
Chiang, Chia-Ying
McHardy, Ian
Edelson, Rick
Goad, Michael R.
Horne, Keith
Korista, Kirk T.
Keywords
Galaxies: active
Galaxies: individual (NGC 4593)
Galaxies: nuclei
Galaxies: Seyfert
QB Astronomy
QC Physics
NDAS
Metadata
Show full item record
Altmetrics Handle Statistics
Altmetrics DOI Statistics
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 - 10,000 Å. 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 (AGN). 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 AGN. In all cases these large disk sizes, which are also implied by independent gravitational microlensing of higher-mass AGN, 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 Å 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 in comprehensively modeling and understanding AGN lag spectra.
Citation
Cackett , E M , Chiang , C-Y , McHardy , I , Edelson , R , Goad , M R , Horne , K & Korista , K T 2018 , ' Accretion disk reverberation with Hubble Space Telescope observations of NGC 4593 : evidence for diffuse continuum lags ' , Astrophysical Journal , vol. 857 , no. 1 , 53 . https://doi.org/10.3847/1538-4357/aab4f7
Publication
Astrophysical Journal
Status
Peer reviewed
DOI
https://doi.org/10.3847/1538-4357/aab4f7
ISSN
0004-637X
Type
Journal article
Rights
© 2018. The American Astronomical Society. All rights reserved. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at: https://doi.org/10.3847/1538-4357/aab4f7
Description
K.H. acknowledges support from STFC grant ST/M001296/1.
Collections
  • University of St Andrews Research
URI
http://hdl.handle.net/10023/13190

Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

Advanced Search

Browse

All of RepositoryCommunities & CollectionsBy Issue DateNamesTitlesSubjectsClassificationTypeFunderThis CollectionBy Issue DateNamesTitlesSubjectsClassificationTypeFunder

My Account

Login

Open Access

To find out how you can benefit from open access to research, see our library web pages and Open Access blog. For open access help contact: openaccess@st-andrews.ac.uk.

Accessibility

Read our Accessibility statement.

How to submit research papers

The full text of research papers can be submitted to the repository via Pure, the University's research information system. For help see our guide: How to deposit in Pure.

Electronic thesis deposit

Help with deposit.

Repository help

For repository help contact: Digital-Repository@st-andrews.ac.uk.

Give Feedback

Cookie policy

This site may use cookies. Please see Terms and Conditions.

Usage statistics

COUNTER-compliant statistics on downloads from the repository are available from the IRUS-UK Service. Contact us for information.

© University of St Andrews Library

University of St Andrews is a charity registered in Scotland, No SC013532.

  • Facebook
  • Twitter