University of Hertfordshire Research Archive

        JavaScript is disabled for your browser. Some features of this site may not work without it.

        Browse

        All of UHRABy Issue DateAuthorsTitlesThis CollectionBy Issue DateAuthorsTitles

        Arkivum Files

        My Downloads
        View Item 
        • UHRA Home
        • University of Hertfordshire
        • Research publications
        • View Item
        • UHRA Home
        • University of Hertfordshire
        • Research publications
        • View Item

        Constraints on the nuclear emission of the Circinus galaxy : optical and near-IR spectropolarimetry

        Author
        Alexander, D.M.
        Heisler, C.A.
        Young, S.
        Lumsden, C.L.
        Hough, J.
        Bailey, J.
        Attention
        2299/3174
        Abstract
        We present optical and, for the first time, K-band spectropolarimetry of the nuclear region of the Circinus galaxy. In the optical we confirm the previous discovery of polarized broad Hα. We have not detected polarized broad Brγ in the K band, however we can place a 3σ upper limit of 7 × 10−15 erg s−1 cm−2. This corresponds to an upper limit of 7.7 mag of visual extinction along the broad-line scattered route assuming electron scattering and the Case B approximation. Analysis of these observations shows that galactic processes dominate in the optical total and polarized flux whilst the nucleus dominates the K-band polarized flux. From a sample of Seyfert 1 galaxies we find a tight non-stellar R-band continuum to broad Hα correlation that allows us to constrain the nuclear continuum contribution at optical wavelengths. Based on these constraints we have modelled our observations as electron scatterers distributed in a 50° inclined cone of 45° opening half-angle, visually extincted by 5 mag through the Galaxy and Circinus galactic disc. At near-IR wavelengths the nuclear emission region becomes visible and dichroically polarized through the dusty torus; we find a visual extinction to this region of 35 mag gives the best results, consistent with that determined using other techniques.
        Publication date
        2000
        Published in
        Monthly Notices of the Royal Astronomical Society
        Published version
        https://doi.org/10.1046/j.1365-8711.2000.03285.x
        Other links
        http://hdl.handle.net/2299/3174
        Metadata
        Show full item record
        Keep in touch

        © 2019 University of Hertfordshire

        I want to...

        • Apply for a course
        • Download a Prospectus
        • Find a job at the University
        • Make a complaint
        • Contact the Press Office

        Go to...

        • Accommodation booking
        • Your student record
        • Bayfordbury
        • KASPAR
        • UH Arts

        The small print

        • Terms of use
        • Privacy and cookies
        • Criminal Finances Act 2017
        • Modern Slavery Act 2015
        • Sitemap

        Find/Contact us

        • T: +44 (0)1707 284000
        • E: ask@herts.ac.uk
        • Where to find us
        • Parking
        • hr
        • qaa
        • stonewall
        • AMBA
        • ECU Race Charter
        • disability confident
        • AthenaSwan