排序方式： 共有487条查询结果，搜索用时 15 毫秒
31.
M. S. Westmoquette L. J. Smith J. S. Gallagher III K. M. Exter † 《Monthly notices of the Royal Astronomical Society》2007,381(3):913-931
We present a set of four Gemini-North Multi-Object Spectrograph/integral field unit (IFU) observations of the central disturbed regions of the dwarf irregular starburst galaxy NGC 1569, surrounding the well-known superstar clusters A and B. This continues on directly from a companion paper, in which we describe the data reduction and analysis techniques employed and present the analysis of one of the IFU pointings. By decomposing the emission-line profiles across the IFU fields, we map out the properties of each individual component identified and identify a number of relationships and correlations that allow us to investigate in detail the state of the ionized interstellar medium (ISM). Our observations support and expand on the main findings from the analysis of the first IFU position, where we conclude that a broad (≲400 km s−1 ) component underlying the bright nebular emission lines is produced in a turbulent mixing layer on the surface of cool gas knots, set up by the impact of the fast-flowing cluster winds. We discuss the kinematic, electron-density and excitation maps of each region in detail and compare our results to previous studies. Our analysis reveals a very complex environment with many overlapping and superimposed components, including dissolving gas knots, rapidly expanding shocked shells and embedded ionizing sources, but no evidence for organized bulk motions. We conclude that the four IFU positions presented here lie well within the starburst region where energy is injected, and, from the lack of substantial ordered gas flows, within the quasi-hydrostatic zone of the wind interior to the sonic point. The net outflow occurs at radii beyond 100–200 pc, but our data imply that mass-loading of the hot ISM is active even at the roots of the wind. 相似文献
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Jackie L. Cooper Geoffrey V. Bicknell Ralph S. Sutherland Joss Bland-Hawthorn 《Astrophysics and Space Science》2007,311(1-3):99-103
In order to better understand the formation of a starburst-driven wind, we have performed a series of three-dimensional hydrodynamical
simulations in an inhomogeneous interstellar medium. We present the results of these simulations, which provide new insights
into the formation of the optical filaments and the origin of the soft X-ray emission. 相似文献
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A. M. Mickaelian 《Astrophysics》2004,47(3):361-377
Results of spectral observations of 66 objects from the BIG (Byurakan IRAS Galaxies) sample made with the 1.93 m telescope at the Observatoire de Haute Provence (OHP, France) are presented. Emission lines are observed from 64 of the galaxies. The red shifts are determined, the radial velocities, distances, and absolute stellar magnitudes are calculated, the spectrum line parameters are determined, diagnostic diagrams are constructed, the objects are classified according to activity type, and their IR and far-IR luminosities are calculated. Of the 66 objects (corresponding to 61 IRAS sources), 6 are Sy2, 2 are LINERs, 8 are AGN (Sy2 or LINER), 10 are composite, 34 are HII, and 4 are Em of undetermined type. It is calculated that IRAS 07479+7832= BIG d141a is a ultraluminous IR galaxy (ULIG), and 21 are LIG. Spectra of several of the galaxies being studied are presented. 相似文献
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M. A. Worsley A. C. Fabian F. E. Bauer D. M. Alexander W. N. Brandt B. D. Lehmer 《Monthly notices of the Royal Astronomical Society》2006,368(4):1735-1741
The emission from individual X-ray sources in the Chandra Deep Fields and XMM – Newton Lockman Hole shows that almost half of the hard X-ray background above 6 keV is unresolved and implies the existence of a missing population of heavily obscured active galactic nuclei (AGN). We have stacked the 0.5–8 keV X-ray emission from optical sources in the Great Observatories Origins Deep Survey (GOODS; which covers the Chandra Deep Fields) to determine whether these galaxies, which are individually undetected in X-rays, are hosting the hypothesized missing AGN. In the 0.5–6 keV energy range, the stacked-source emission corresponds to the remaining 10–20 per cent of the total background – the fraction that has not been resolved by Chandra . The spectrum of the stacked emission is consistent with starburst activity or weak AGN emission. In the 6–8 keV band, we find that upper limits to the stacked X-ray intensity from the GOODS galaxies are consistent with the ∼40 per cent of the total background that remains unresolved, but further selection refinement is required to identify the X-ray sources and confirm their contribution. 相似文献
35.
Manuela Magliocchetti Steve J. Maddox Ed Hawkins John A. Peacock Joss Bland-Hawthorn Terry Bridges Russell Cannon Shaun Cole Matthew Colless Chris Collins Warrick Couch Gavin Dalton Roberto de Propris Simon P. Driver George Efstathiou Richard S. Ellis Carlos S. Frenk Karl Glazebrook Carole A. Jackson Bryn Jones Ofer Lahav Ian Lewis Stuart Lumsden Peder Norberg Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2004,350(4):1485-1494
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A. R. McDonald T. W. B. Muxlow A. Pedlar M. A. Garrett K. A. Wills S. T. Garrington P. J. Diamond P. N. Wilkinson 《Monthly notices of the Royal Astronomical Society》2001,322(1):100-106
Observations of the starburst galaxy, M82, have been made with a 20-station global very long-baseline interferometry (VLBI) array at λ 18 cm. Maps are presented of the brightest young supernova remnants (SNR) in M82 and the wide-field mapping techniques used in making images over a field of view of ∼1 arcmin with 3-milliarcsecond resolution are discussed. A limit has been placed on the power-law deceleration of the young supernova remnant (SNR) 43.31+592 with an index greater than 0.73±0.11 from observations with the European VLBI Network. Using the global array we have resolved compact knots of radio emission in the source which, with future global observations, will enable better constraints to be placed on the expansion parameters of this SNR.
The latest global observations have also provided high-resolution images of the most compact radio source in M82, 41.95+575. We determine an upper limit to the radial expansion rate along the major axis of 2000 km s−1 . However, the new images also show structure resembling that of collimated ejection which brings into question the previous explanation of the source as being a result of the confinement of a supernova by a high-density circumstellar medium.
It is apparent that we are now able to image the brightest supernova remnants in M82 with a linear scale which allows direct comparison with galactic SNR such as Cassiopeia A. 相似文献
The latest global observations have also provided high-resolution images of the most compact radio source in M82, 41.95+575. We determine an upper limit to the radial expansion rate along the major axis of 2000 km s
It is apparent that we are now able to image the brightest supernova remnants in M82 with a linear scale which allows direct comparison with galactic SNR such as Cassiopeia A. 相似文献