Purple Mountain Obs' CAS CHINA

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2005 LiJiang International Starburst Workshop
The Dense Molecular Connection Between IR and RC
Emission In Galaxies Fan Liu Yu Gao (Purple
Mountain Obs. CAS CHINA)
Purple Mountain Obs. CAS CHINA
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2005 LiJiang International Starburst Workshop
The Sample is drawn from Gao Solomons HCN
survey (2004) which include 65 galaxies. HCN, IR
and CO luminosities are gained from Gao
Solomons paper(2004). The radio continuum (RC)
flux is mainly gained from NVSS.
Purple Mountain Obs. CAS CHINA
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2005 LiJiang International Starburst Workshop
Figure 1 shows a very tight correlation between
RC and HCN luminosity with a correlation
coefficient R 0.90. Compare with the
correlation between IR and HCN (R 0.94), the
difference is not that significant.
Figure 2 shows the correlation between ratio
RC/CO (SFE) and ratio HCN/CO (dense molecular gas
fraction). The correlation coefficient is 0.62.
Purple Mountain Obs. CAS CHINA
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2005 LiJiang International Starburst Workshop
Some correlations between the ratios of the 4
quantities, RC, IR, HCN and CO, e.g.
The same conclusion is also summarized by the
3-parameter fits Log RC(HCN IR) ??0.002log
HCN 1.05 log IR 5.59 Log IR(HCN RC)
0.43 log HCN 0.54 log RC 4.35 Log HCN( IR
RC) 0.002 log RC 0.90 log IR
1.89.
suggest that only RCIR and HCNIR have truly
physical relations.
Purple Mountain Obs. CAS CHINA
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2005 LiJiang International Starburst Workshop
The Combination of the two tight correlations,
IRRC correlation and IRHCN correlation, results
in the tight correlation between RC and HCN,
which confirms us the practicability of using RC
luminosity instead of IR luminosity as an
indicator of star formation rate (SFR). The far
better high resolution capability of radio
observatories than IR observatories allow us to
study SFR of more distant galaxies and detailed
SF region in nearby galaxies.
Purple Mountain Obs. CAS CHINA
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2005 LiJiang International Starburst Workshop
Thanks!
Purple Mountain Obs. CAS CHINA