EDP Sciences
Free Access
Volume 406, Number 2, August I 2003
Page(s) 493 - 503
Section Galactic structure and dynamics
DOI https://doi.org/10.1051/0004-6361:20030615
Published online 17 November 2003

A&A 406, 493-503 (2003)
DOI: 10.1051/0004-6361:20030615

An H $\alpha$ survey aiming at the detection of extraplanar diffuse ionized gas in halos of edge-on spiral galaxies

I. How common are gaseous halos among non-starburst galaxies?
J. Rossa1, 2 and R.-J. Dettmar1

1  Astronomisches Institut, Ruhr-Universität Bochum, 44780 Bochum, Germany
    e-mail: dettmar@astro.ruhr-uni-bochum.de
2  Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA (Present address)

(Received 28 January 2003 / Accepted 15 April 2003 )

In a series of two papers we present results of a new H $\alpha$ imaging survey, aiming at the detection of extraplanar diffuse ionized gas in halos of late-type spiral galaxies. We have investigated a sample of 74 nearby edge-on spirals, covering the northern and southern hemisphere. In 30 galaxies we detected extraplanar diffuse emission at mean distances of $\vert z\vert\sim1{-}2$ kpc. Individual filaments can be traced out to $\vert z\vert\leq6$ kpc in a few cases. We find a good correlation between the FIR flux ratio ( S60/S100) and the SFR per unit area ( $L_{\rm FIR}/D^2_{25}$), based on the detections/non-detections. This is actually valid for starburst, normal and for quiescent galaxies. A minimal SFR per unit area for the lowest S60/S100 values, at which extended emission has been detected, was derived, which amounts to $\dot{E}_{\rm A25}^{\rm {thres}} =
(3.2\pm0.5)\times10^{40}\rm {\,erg\,s^{-1}\,kpc^{-2}}$ . There are galaxies where extraplanar emission was detected at smaller values of $L_{\rm FIR}/D^2_{25}$, however, only in combination with a significantly enhanced dust temperature. The results corroborate the general view that the gaseous halos are a direct consequence of SF activity in the underlying galactic disk.

Key words: galaxies: halos -- galaxies: spiral -- galaxies: starburst -- galaxies: ISM -- galaxies: structure

Offprint request: J. Rossa, jrossa@stsci.edu

SIMBAD Objects

© ESO 2003

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.