Curtin University Homepage
  • Library
  • Help
    • Admin

    espace - Curtin’s institutional repository

    JavaScript is disabled for your browser. Some features of this site may not work without it.
    View Item 
    • espace Home
    • espace
    • Curtin Research Publications
    • View Item
    • espace Home
    • espace
    • Curtin Research Publications
    • View Item

    Hard and soft spectral states of ULXs

    Access Status
    Open access via publisher
    Authors
    Soria, Roberto
    Date
    2011
    Type
    Journal Article
    
    Metadata
    Show full item record
    Citation
    Soria, R. 2011. Hard and soft spectral states of ULXs. Astronomische Nachrichten. 332 (4): pp. 330-336.
    Source Title
    Astronomische Nachrichten
    DOI
    10.1002/asna.201011493
    ISSN
    1521-3994
    School
    Curtin Institute of Radio Astronomy
    URI
    http://hdl.handle.net/20.500.11937/39815
    Collection
    • Curtin Research Publications
    Abstract

    I discuss some differences between the observed spectral states of ultraluminous X-ray sources (ULXs) and the canonical scheme of spectral states defined in Galactic black holes. The standard interpretation of ULXs with a curved spectrum, or a moderately steep power-law with soft excess and high-energy downturn, is that they are an extension of the very high state, up to luminosities ≈1–3L Edd. Two competing models are Comptonization in a warm corona, and slim disk; I suggest bulk motion Comptonization in the radiatively-driven outflow as another possibility. The interpretation of ULXs with a hard power-law spectrum is more problematic. Some of them remain in that state over a large range of luminosities; others switch directly to a curved state without going through a canonical high/soft state. I suggest that those ULXs are in a high/hard state not seen in Galactic black holes; that state may overlap with the low/hard state at lower accretion rates, and extend all the way to Eddington accretion rates. If some black holes can reach Eddington accretion rates without switching to a standard-disk-dominated state, it is also possible that they never quench their steady jets.

    Related items

    Showing items related by title, author, creator and subject.

    • A weak compact jet in a soft state of Cygnus X-1
      Rushton, A.; Miller-Jones, James; Campana, R.; Evangelista, Y.; Paragi, Z.; Maccarone, T.; Pooley, G.; Tudose, V.; Fender, R.; Spencer, R.; Dhawan, V. (2012)
      We present evidence for the presence of a weak compact jet during a soft X-ray state of Cygnus X-1. Very-high-resolution radio observations were taken with the VLBA, EVN and MERLIN during a hard-to-soft spectral state ...
    • Black hole masses and accretion states in ULXs
      Soria, Roberto; Kuncic, Z. (2008)
      We summarize indirect empirical arguments used for estimating black hole (BH) masses in ultraluminous X-ray sources (ULXs). The interpretation of the X-ray data is still too model-dependent to provide tight constraints, ...
    • Rapid Accretion State Transitions following the Tidal Disruption Event AT2018fyk
      Wevers, T.; Pasham, D.R.; Van Velzen, S.; Miller-Jones, James ; Uttley, P.; Gendreau, K.C.; Remillard, R.; Arzoumanian, Z.; Löwenstein, M.; Chiti, A. (2021)
      Following a tidal disruption event (TDE), the accretion rate can evolve from quiescent to near-Eddington levels and back over timescales of months to years. This provides a unique opportunity to study the formation and ...
    Advanced search

    Browse

    Communities & CollectionsIssue DateAuthorTitleSubjectDocument TypeThis CollectionIssue DateAuthorTitleSubjectDocument Type

    My Account

    Admin

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Follow Curtin

    • 
    • 
    • 
    • 
    • 

    CRICOS Provider Code: 00301JABN: 99 143 842 569TEQSA: PRV12158

    Copyright | Disclaimer | Privacy statement | Accessibility

    Curtin would like to pay respect to the Aboriginal and Torres Strait Islander members of our community by acknowledging the traditional owners of the land on which the Perth campus is located, the Whadjuk people of the Nyungar Nation; and on our Kalgoorlie campus, the Wongutha people of the North-Eastern Goldfields.