Are E+A galaxies dusty-starbursts?: VLA 20 cm radio continuum observation

Free access article

Issue		A&A Volume 427, Number 1, November III 2004


Page(s)		125 - 130
Section		Extragalactic astronomy
DOI		http://dx.doi.org/10.1051/0004-6361:20041250

A&A 427, 125-130 (2004)
DOI: 10.1051/0004-6361:20041250

Are E+A galaxies dusty-starbursts?: VLA 20 cm radio continuum observation

T. Goto

Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686, USA
e-mail: tomo@jhu.edu

(Received 6 May 2004 / Accepted 19 July 2004)

Abstract
E+A galaxies are characterized as a galaxy with strong Balmer absorption lines but without any [OII] or H $\alpha$ emission lines. The existence of strong Balmer absorption lines means that E+A galaxies have experienced a starburst within the last <1-1.5 Gyr. However, the lack of [OII] or H $\alpha$ emission lines indicates that E+A galaxies do not have any on-going star formation. Therefore, E+A galaxies are interpreted as a post-starburst galaxy. For more than 20 years, however, it has been a mystery

why E+A galaxies underwent a starburst then stopped abruptly.

One possible explanation to E+A galaxies is the dusty starburst scenario, where E+A galaxies have on-going star formation, but optical emission lines are invisible due to the heavy obscuration by dust. To test this dusty starburst scenario, we have observed 36 E+A galaxies carefully selected from the Sloan Digital Sky Survey Data Release 1 in 20 cm radio continuum using the VLA. Since the radio emission is not affected by the dust extinction, the star formation rate (SFR) in dusty galaxies can be revealed by the 20 cm continuum. All of our 36 target E+A galaxies are selected to have H $\delta$ equivalent width greater than 6 Å and no detection of [OII] or H $\alpha$ emission lines within 1 $\sigma$ . These selection criteria are much stronger than previous E+A selections in our attempt to select galaxies in the pure post-starburst phase without any remaining star formation. Except for the two galaxies with a nearby radio source, none of our 34 E+A galaxies are detected in 20 cm continuum to the limits reported in Table [see full textsee full textsee full textsee full textsee full text]. The obtained upper limits on the radio estimated SFR suggest that E+A galaxies do not possess strong starburst ( >100 $M_{\odot}$ yr ^-1) hidden by dust extinction for the whole sample while 15 ( z<0.08) E+As have lower SFR upper limits of ~15 $M_{\odot}$ yr ^-1.

Key words: galaxies: evolution -- galaxies: formation -- galaxies: starburst

SIMBAD Objects

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.