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HCN observations of dense star-forming gas in high-redshift galaxies
Gao, Yu; Carilli, Chris L.; Solomon, Philip M.; Bout, Paul A. Vanden
2007-05-10
Source PublicationASTROPHYSICAL JOURNAL
Volume660Issue:2Pages:L93-L96
AbstractWe present here the sensitive HCN ( 1 - 0) observations made with the VLA of two submillimeter galaxies and two QSOs at high redshift. HCN emission is the signature of dense molecular gas found in giant molecular cloud (GMC) cores, the actual sites of massive star formation. We have made the first detection of HCN in a submillimeter galaxy, SMM J16359 + 6612. The HCN emission is seen with a signal-to-noise ratio of 4 sigma and appears to be resolved as a double source of less than or similar to 2 '' separation. Our new HCN observations, combined with previous HCN detections and upper limits, show that the FIR/ HCN ratios in these high-redshift sources lie systematically above the FIR/ HCN correlation established for nearby galaxies by about a factor of 2. Even considering the scatter in the data and the presence of upper limits, this is an indication that the FIR/ HCN ratios for the early universe molecular emissionline galaxies (EMGs) deviate from the correlation that fits Galactic GMC cores, normal spirals, and luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs, respectively). This indicates that the star formation rate per solar mass of dense molecular gas is higher in the high-z objects than in local galaxies including normal spirals, LIRGs, and ULIRGs. The limited HCN detections at high redshift show that the HCN/CO ratios for the high-z objects are high and are comparable to those of the local ULIRGs rather than those of normal spirals. This indicates that EMGs have a high fraction of dense molecular gas compared to total molecular gas traced by CO emission.
KeywordGalaxies : Formation Galaxies : High-redshift Galaxies : Ism Galaxies : Starburst Infrared : Galaxies Ism : Molecules
Indexed BySCI
Language英语
WOS IDWOS:000246574400004
Citation statistics
Document Type期刊论文
Identifierhttp://ir.bao.ac.cn/handle/114a11/7885
Collection太阳物理研究部
Affiliation1.Chinese Acad Sci, Purple Mt Observ, Nanjing 210008, Peoples R China
2.CAS, Natl Astron Observ, Beijing, Peoples R China
3.Tianjin Normal Univ, Joint Inst Galaxies, Tianjin, Peoples R China
4.Tianjin Normal Univ, AGN, Tianjin, Peoples R China
5.Natl Radio Astron Observ, Socorro, NM 87801 USA
6.SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA
7.Natl Radio Astron Observ, Charlottesville, VA 22903 USA
Recommended Citation
GB/T 7714
Gao, Yu,Carilli, Chris L.,Solomon, Philip M.,et al. HCN observations of dense star-forming gas in high-redshift galaxies[J]. ASTROPHYSICAL JOURNAL,2007,660(2):L93-L96.
APA Gao, Yu,Carilli, Chris L.,Solomon, Philip M.,&Bout, Paul A. Vanden.(2007).HCN observations of dense star-forming gas in high-redshift galaxies.ASTROPHYSICAL JOURNAL,660(2),L93-L96.
MLA Gao, Yu,et al."HCN observations of dense star-forming gas in high-redshift galaxies".ASTROPHYSICAL JOURNAL 660.2(2007):L93-L96.
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