The detection of star formation driven gaseous outflows using the H narrow band line imaging techniques is a viable method to trace the distribution of the warm ionized medium in external galaxies on a global scale. Many of the actively star-forming galaxies show similar, yet different, morphologies as the starburst galaxies.
We have presented the individual results for the H survey galaxies. From the 74 investigated edge-on spirals we have detected eDIG in 30 galaxies, that is 40.5%. We can therefore conclude, that the presence of eDIG in halos of galaxies is not a unique case for only a few galaxies, rather it is found to be ubiquitous in galaxies, which exceed a certain level of SFR per unit area, or even at a fainter threshold in combination with enhanced dust temperatures Rossa & Dettmar (2003). However, it can thus also be concluded that eDIG is not a common feature among all late-type spiral galaxies, as many of them do not show eDIG (at the level of the observed sensitivities). The presence of eDIG is depending on the SF activity on both local and global scales.
The morphology of eDIG shows a wide variety ranging from individual plumes, and filaments in galaxies with mediocre SF activity, to pervasive layers in the actively SF galaxies. A few of our eDIG detected targets bear a more or less intense layer of extended emission with typical extraplanar distances of 1.5-2 kpc. Individual filaments of some galaxies (e.g., NGC4388, NGC5775) even reach distances of up to ~ 6 kpc. In the case of NGC4700 a good correlation between extended H emission and radio continuum (radio halo) is found, which further strengthens the disk-halo interaction scenario.
Galaxy | DIG morph. a | vertical extent | radial extent | Notes |
| z|[kpc] | RSF[kpc] | |||
NGC24 | d, n | 0.68 | 3.09 | not perfectly inclined |
NGC100 | n | 0.63 | 5.82 | HII regions in the disk |
UGC260 | eh2, f, hf, pec | 2.00 | 7.14 | pec = tidal debris?, galaxy? |
ESO540-16 | d | 0.73 | 7.88 | strong asymmetry of planar DIG |
MCG-2-3-16 | a, n | 0.43 | 2.67 | disturbed disk |
NGC360 | d | 0.59 | 11.71 | |
NGC669 | n | 28.33 | ||
UGC1281 | n | 0.42 | 3.34 | HII regions not aligned |
NGC891 | ee, eh2, f, hb | 2.15 | 9.85 | eDIG asymmetry (north-south) |
UGC2082 | d, n | 0.44 | 4.68 | |
IC1862 | d, n | 47.17 | slightly warped disk | |
NGC1247 | d, pa | 36.10 | ||
ESO117-19 | d | 27.89 | ||
IC2058 | n | 0.48 | 7.66 | |
ESO362-11 | hf | 2.47 | 7.80 | |
ESO121-6 | hf | 1.42 | 7.88 | |
NGC2188 | ee, eh2, f, pl | 1.35 | 6.18 | |
ESO209-9 | hb, pa, pl | 1.57 | 12.60 | + galactic emission |
UGC4559 | n | 1.00 | 6.29 | disk em. restr. near nucleus |
NGC2654 | d, n | 1.18 | 7.18 | clustered HII regions |
NGC2683 | d, n | 0.87 | 2.63 | strong disk emission |
NGC3003 | d, n | 9.35 | galaxy not perfectly edge-on | |
NGC3221 | ee, hf | 3.82 | 35.27 | |
NGC3365 | d, n | 1.00 | 2.23 | strong local disk emission |
NGC3501 | n | 0.85 | 7.19 | disk HII regions not aligned |
NGC3600 | ee | 1.24 | 4.20 | nuclear outflow?, warped disk |
NGC3628 | ee, eh2, f | 3.13 | prominent nuclear outflow | |
NGC3877 | ee, f, pl | 1.38 | 12.00 | clustered DIG emission |
NGC3936 | n | 11.46 | ||
ESO379-6 | ee, pl | 2.08 | 25.23 | |
NGC4206 | d, pa | 1.22 | 8.02 | |
NGC4216 | d, n | 11.48 | strong H bulge emission | |
NGC4235 | ee, hf | 2.50 | 4.58 | dust obscur. near nucleus |
NGC4256 | d, n | 13.17 | planar DIG asymmetry | |
NGC4388 | f, hf, pa | 5.92 | 15.50 | prominent halo patch |
NGC4700 | hb, f, pa | 2.18 | 12.50 | one filament z 3kpc |
NGC4945 | f, hb, pl | 5.28 | 22.42 | outflow cone |
NGC5290 | ee, f, hb | 4.00 | 13.00 | nucl. outflow, starburst? |
NGC5297 | d, n | 16.00 | not perfectly edge-on | |
NGC5775 | hb, f, pl | 5.38 | 21.44 | prominent filaments |
ESO274-1 | ee, f | 0.75 | strong local eDIG | |
NGC5965 | d, n | 19.78 | ||
NGC6722 | n | 42.86 | warped disk | |
IC4837A | d | 13.57 | strong local DIG | |
ESO142-19 | n | prominent dust lane | ||
IC4872 | n | 0.71 | 3.33 | |
NGC6875A | ee?, pa | 2.75 | 12.00 | not perfectly edge-on |
MCG-1-53-12 | n | 1.40 | 10.80 | |
IC5052 | a, ee, hb, pl | 1.24 | 9.90 | DIG distr. asymmetrically |
IC5071 | d | 20.85 | clustered DIG emission | |
IC5096 | n | 1.00 | 19.61 | strong bulge emission |
NGC7064 | ee, hf, pl | 0.92 | 7.20 | disk bi-sected |
NGC7090 | a, ee, f, hf | 1.78 | 8.39 | strong local emission |
UGC11841 | n | gal. barely vis. in H | ||
NGC7184 | d, n | 20.44 | strong emission in annulus | |
IC5171 | d | 10.19 | strong planar DIG | |
IC5176 | ee, hf | 2.35 | 10.22 | |
NGC7339 | n | 0.36 | 2.32 | disk HII regions not aligned |
NGC7361 | d, n | 9.49 | strong disk emission | |
NGC7412A | a, n | 0.47 | 4.77 | bright disk HII regions |
UGC12281 | n | 1.36 | 20.00 | |
NGC7462 | f, hf, pl | 1.76 | 10.81 | slight asymmetry |
UGC12423 | n | gal. barely vis. in H | ||
NGC7640 | d, n | 7.11 | strong planar DIG | |
ESO240-11 | n | 29.93 | slight disk asymmetry | |
a a=arc(s), d=disk emission (only planar DIG), ee=extended emission (locally), eh2=extraplanar HII region(s), f=filament(s), hb=bright halo, hf=faint halo, n=no (e)DIG, pa=patch(es), pec=peculiar, pl=plume(s) |
Figure 21. Distribution of the observed 74 galaxies of the H survey on the celestial sphere in Aitoff projection. The center position is 0,0 in R.A., Dec. |
Acknowledgements. It is our sincere pleasure to express our thanks to Dr. Francisco Prada for carrying out some of the observations at Calar Alto in an emergency case. We owe special thanks to Dr. Michael Dahlem for providing us with the data on NGC 3936, kindly observed by Dr. Eva Grebel. We would also like to thank the anonymous referee for his/her helpful comments. The authors would like to thank Deutsches Zentrum für Luft - und Raumfahrt (DLR) for financial support of this research project through grant 50 OR 9707. Additional travel support for the Calar Alto observing runs is acknowledged from the DFG through various grants. This research has made extensive use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. The Southern H Sky Survey Atlas (SHASSA) is supported by the National Science Foundation.