University of Leicester
Browse
aa6340-06.pdf (953.97 kB)

High-resolution X-ray spectroscopy and imaging of the nuclear outflow of the starburst galaxy NGC 253

Download (953.97 kB)
journal contribution
posted on 2012-10-24, 09:06 authored by M. Bauer, W. Pietsch, G. Trinchieri, D. Breitschwerdt, M. Ehle, A. Read
Aims.Using XMM-Newton data, we have studied the nuclear outflow of the nearby starburst galaxy NGC 253 in X-rays with respect to its morphology and to spectral variations along the outflow. Methods.We analysed XMM-Newton RGS spectra, RGS brightness profiles in cross-dispersion direction, narrow-band RGS and EPIC images, and EPIC PN brightness profiles of the nuclear region and of the outflow from NGC 253. Results.We detect a diversity of emission lines along the outflow of NGC 253. This includes the He-like ions of Si, Mg, Ne, and O and their corresponding ions in the next higher ionisation state. Additionally transitions from $\ion{Fe}{xvii}$ and $\ion{Fe}{xviii}$ are prominent. The derived temperatures from line ratios along the outflow range from 0.21$\pm$0.01 to 0.79$\pm$0.06 keV, and the ratio of $\ion{Fe}{xvii}$ lines indicates a predominantly collisionally ionised plasma. Additionally, we see indications of either a recombining or an underionised plasma in the $\ion{Fe}{xvii}$ line ratio. Derived electron densities are 0.106$\pm$0.018 cm-3 for the nuclear region and 0.025$\pm$0.003 cm-3 for the outflow region closest to the centre. The RGS image in the $\ion{O}{viii}$ line energy clearly shows the morphology of an outflow extending out to ~750 pc along the southeast minor axis, while the northwest part of the outflow is not seen in $\ion{O}{viii}$ due to the heavy absorption by the galactic disc. This is the first time that the hot wind fluid has been detected directly. The limb brightening in Chandra and XMM-Newton EPIC observations is only seen in the energy range that contains the $\ion{Fe}{xvii}$ lines (550-750 eV). In all other energy ranges between 400 and 2000 eV, no clear evidence of limb brightening could be detected.

History

Citation

Astronomy & Astrophysics, 2007, 467 (3), pp. 979-989

Version

  • VoR (Version of Record)

Published in

Astronomy & Astrophysics

Publisher

EDP Sciences for European Southern Observatory (ESO)

issn

0004-6361

eissn

1432-0746

Copyright date

2007

Available date

2012-10-24

Publisher version

http://www.aanda.org/articles/aa/abs/2007/21/aa6340-06/aa6340-06.html

Language

en

Usage metrics

    University of Leicester Publications

    Categories

    No categories selected

    Keywords

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC