Star formation in disk galaxies driven by primordial H-2

被引:20
作者
Corbelli, E
Galli, D
Palla, F
机构
[1] Osservatorio Astrofisico di Arcetri, I-50125, Firenze
关键词
galaxies; evolution; starburst; molecular processes; instabilities;
D O I
10.1086/310865
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We show that gaseous HI disks of primordial composition irradiated by an external radiation field can develop a multiphase medium with temperatures between 10(2) and 10(4) K as a result of the formation of molecular hydrogen. For a given HI column density there is a critical value of the radiation held below which only the cold HI phase can exist. Because of a time-decreasing quasar background, the gas starts cooling slowly after recombination until the lowest stable temperature in the warm phase is reached at a critical redshift z = z(alpha). Below this redshift the formation of molecular hydrogen promotes a rapid transition toward the cold HI phase. We find that disks of protogalaxies with 10(20) less than or similar to N-HI less than or similar to 10(21) cm(-2) are gravitationally stable at T similar to 10(4) K and can start their star formation history only at z less than or similar to z(cr) similar to 2, after the gas in the central portion of the disk has cooled to temperatures T less than or similar to 200 K. Such a delayed starbust phase in galaxies of low gas surface density and low dynamical mass can disrupt the disks and cause them to fade away. These objects could contribute significantly to the faint blue galaxy population.
引用
收藏
页码:L53 / L56
页数:4
相关论文
共 43 条
[1]  
ABGRALL H, 1989, ASTRON ASTROPHYS SUP, V79, P313
[2]   The role of hydrogen molecules in the radiative cooling and fragmentation of cosmological sheets [J].
Anninos, P ;
Norman, ML .
ASTROPHYSICAL JOURNAL, 1996, 460 (02) :556-568
[3]   ON DWARF ELLIPTIC GALAXIES AND THE FAINT BLUE COUNTS [J].
BABUL, A ;
REES, MJ .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1992, 255 (02) :346-350
[4]   Faint blue galaxies and the epoch of dwarf galaxy formation [J].
Babul, A ;
Ferguson, HC .
ASTROPHYSICAL JOURNAL, 1996, 458 (01) :100-119
[5]  
BABUL A, 1993, EVOLUTION GALAXIES T, P80
[7]   A HYDRODYNAMIC APPROACH TO COSMOLOGY - METHODOLOGY [J].
CEN, R .
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1992, 78 (02) :341-364
[8]   THE ONSET OF THE COLD H-I PHASE IN DISKS OF PROTOGALAXIES [J].
CORBELLI, E ;
SALPETER, EE .
ASTROPHYSICAL JOURNAL, 1995, 450 (01) :32-40
[9]   H-I SPIN TEMPERATURES AND HEATING REQUIREMENTS IN OUTER REGIONS OF DISK GALAXIES [J].
CORBELLI, E ;
SALPETER, EE .
ASTROPHYSICAL JOURNAL, 1993, 419 (01) :94-103
[10]   The evolution of the distribution of star formation rates in galaxies [J].
Cowie, LL ;
Hu, EM ;
Songaila, A ;
Egami, E .
ASTROPHYSICAL JOURNAL, 1997, 481 (01) :L9-L13