Detalles de publicación
PP 08011
Search for Blue Compact Dwarf Galaxies During Quiescence
(1) Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife, Spain
(2) Instituto Nacional de Astrofisica Optica y Electronica, AP 51,
72000 Puebla, Mexico
Blue Compact Dwarf (BCD) galaxies are metal poor systems going
through a major starburst that cannot last for long.
We have identified galaxies which may be BCDs during quiescence
(QBCD), i.e., before the characteristic starburst sets in or
when it has faded away. These QBCD galaxies are assumed to be like
the BCD host galaxies. The SDSS/DR6 database provides ~21500 QBCD
candidates. We also select from SDSS/DR6 a complete sample of BCD
galaxies to serve as reference. The properties of these two galaxy
sets have been computed and compared. The QBCD candidates are thirty
times more abundant than the BCDs, with their luminosity functions
being very similar except for the scaling factor, and the expected
luminosity dimming associated with the end of the starburst.
QBCDs are redder than BCDs, and they have larger HII region based
oxygen abundance. QBCDs also have lower surface brightness.
The BCD candidates turn out to be the QBCD candidates with the
largest specific star formation rate (actually, with the largest
H_alpha equivalent width). One out of each three dwarf galaxies in
the local universe may be a QBCD. The properties of the selected BCDs
and QBCDs are consistent with a single sequence in galactic evolution,
which the quiescent phase lasting thirty times longer than the
starburst phase. The resulting time-averaged star formation rate
is low enough to allow this cadence of BCD -- QBCD phases during
the Hubble time.
through a major starburst that cannot last for long.
We have identified galaxies which may be BCDs during quiescence
(QBCD), i.e., before the characteristic starburst sets in or
when it has faded away. These QBCD galaxies are assumed to be like
the BCD host galaxies. The SDSS/DR6 database provides ~21500 QBCD
candidates. We also select from SDSS/DR6 a complete sample of BCD
galaxies to serve as reference. The properties of these two galaxy
sets have been computed and compared. The QBCD candidates are thirty
times more abundant than the BCDs, with their luminosity functions
being very similar except for the scaling factor, and the expected
luminosity dimming associated with the end of the starburst.
QBCDs are redder than BCDs, and they have larger HII region based
oxygen abundance. QBCDs also have lower surface brightness.
The BCD candidates turn out to be the QBCD candidates with the
largest specific star formation rate (actually, with the largest
H_alpha equivalent width). One out of each three dwarf galaxies in
the local universe may be a QBCD. The properties of the selected BCDs
and QBCDs are consistent with a single sequence in galactic evolution,
which the quiescent phase lasting thirty times longer than the
starburst phase. The resulting time-averaged star formation rate
is low enough to allow this cadence of BCD -- QBCD phases during
the Hubble time.