Issue |
A&A
Volume 405, Number 3, July III 2003
|
|
---|---|---|
Page(s) | 803 - 812 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20030588 | |
Published online | 30 June 2003 |
Narrow band survey for intragroup light in the Leo HI cloud *
Constraints on the galaxy background contamination in imaging surveys for intracluster planetary nebulae
1
Astronomisches Institut, Universitaet Basel, Venusstrasse 7, 4102 Binningen, Switzerland
2
Instituto de Astrofísica de Canarias, 38205 La Laguna, Spain
3
INAF, Osservatorio Astronomico di Torino, Via Osservatorio 20, 10025 Pino Torinese
4
INAF, Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Naples
5
RSAA, Mt. Stromlo and Siding Spr. Obs., Private Bag, Woden PO, Canberra, ACT 2606, Australia
6
Kapteyn Institute, Postbus 800, Groningen 9700 AV, The Netherlands
Corresponding author: N. Castro-Rodríguez, ncastro@astro.unibas.ch
Received:
3
February
2003
Accepted:
31
March
2003
We have observed emission line objects located in a 0.26 deg2 field in the M 96 (Leo) group, coincident with the
intergalactic HI cloud. The emission line objects were selected
using the same procedure as used for the search for intracluster
planetary nebulae in the Virgo cluster. 29 emission line objects
were identified, with [OIII] filter magnitudes brighter than
. Their m5007 luminosity function has a bright
cut-off
1.2 mag fainter than for the luminosity
function of the planetary nebulae (PN) associated with the
elliptical galaxies in the M 96 group. Therefore the vast
majority of these emission line objects are compatible with not
being intragroup planetary nebulae at the Leo group distance of 10 Mpc. Spectroscopic follow-up of two emission line objects in this
Leo field showed that indeed these do not have the [OIII]
Å doublet expected for a real PN. The
brighter source is identified as an AGN at redshift
, because of a second emission in the near infrared,
identified as FeII (
Å).
From these data we derive three main results: (i) from the absence
of PN we can determine a more stringent upper limit to the surface
brightness in any old stellar population associated with the Leo HI
cloud at the surveyed position,
. (ii) This translates to an upper limit of
for the fraction of luminosity in a diffuse intragroup component in
the densest
area of the Leo group, relative
to the light in galaxies. (iii) Using this Leo field as a blank
field, we derive an average fraction of 13.6% background emission
line objects that enter in surveys of Virgo intracluster PN. This
is in agreement with an earlier estimate (15%) obtained from the Ly
break galaxy population at
. The small fraction confirms
the validity of the selection criteria for intracluster PN
candidates in Virgo.
Key words: planetary nebulae: general / galaxies: clusters: individual: M 96 / galaxies: intergalactic medium / galaxies: ISM
© ESO, 2003
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