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

        The X-ray spectra of the luminous LMXBs in NGC 3379 : field and globular cluster sources

        View/Open
        904543.pdf (PDF, 511Kb)
        Author
        Brassington, Nicola
        Fabbiano, G.
        Blake, S.
        Zezas, A.
        Angelini, L.
        Davies, R. L.
        Gallagher, J.
        Kalogera, V.
        Kim, D. -W.
        King, A. R.
        Kundu, A.
        Trinchieri, G.
        Zepf, S.
        Attention
        2299/7269
        Abstract
        From a deep multi-epoch Chandra observation of the elliptical galaxy NGC 3379 we report the spectral properties of eight luminous LMXBs (L-X > 1.2 x 10(38) erg s(-1)). We also present a set of spectral simulations, produced to aid the interpretation of low-count single-component spectral modeling. These simulations demonstrate that it is possible to infer the spectral states of X-ray binaries from these simple models and thereby constrain the properties of the source. Of the eight LMXBs studied, three reside within globular clusters (GCs) and one is a confirmed field source. Due to the nature of the luminosity cut, all sources are either neutron star (NS) binaries emitting at or above the Eddington luminosity or black hole (BH) binaries. The spectra from these sources are well described by single-component models, with parameters consistent with Galactic LMXB observations, where hard-state sources have a range in photon index of 1.5-1.9 and thermally dominant (TD) sources have inner-disk temperatures between similar to 0.7 and 1.55 keV. The large variability observed in the brightest GC source (L-X > 4 x 10(38) erg s(-1)) suggests the presence of a BH binary. At its most luminous this source is observed in a TD state with kT(in) = 1.5 keV, consistent with a BH mass of similar to 4 M-circle dot. This observation provides further evidence that GCs are able to retain such massive binaries. We also observed a source transitioning from a bright state (L-X similar to 1 x 10(39) erg s(-1)), with prominent thermal and non-thermal components, to a less luminous hard state (L-X = 3.8 x 10(38) erg s(-1), Gamma = 1.85). In its high flux emission, this source exhibits a cool-disk component of similar to 0.14 keV, similar to spectra observed in some ultraluminous X-ray sources (ULXs). Such a similarity indicates a possible link between "normal" stellar-mass BHs in a high accretion state and ULXs.
        Publication date
        2010-12
        Published in
        The Astrophysical Journal
        Published version
        https://doi.org/10.1088/0004-637X/725/2/1805
        Other links
        http://hdl.handle.net/2299/7269
        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