Connecting Dense Gas Tracers of Star Formation in our Galaxy to High-z Star Formation
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nnecting Dense Gas Tracers of Star Formation nnecting Dense Gas Tracers of Star Formation in our Galaxy to High-z Star Formation in our Galaxy to High-z Star Formation Jingwen Wu (The Univ. of Texas at Austin) Collaborators: Neal Evans (Advisor, UTexas at Austin) Neal Evans (Advisor, UTexas at Austin) Yu Gao (PMO); Yu Gao (PMO); Phil Solomon, Tom Mooney (SUNY-SB); Phil Solomon, Tom Mooney (SUNY-SB); Paul Vanden Bout, Yancy Shirley (NRAO) Paul Vanden Bout, Yancy Shirley (NRAO)
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Connecting Dense Gas Tracers of Star Formation in our Galaxy to High-z Star Formation. Jingwen Wu ( The Univ. of Texas at Austin ). Collaborators: Neal Evans (Advisor, UTexas at Austin) Yu Gao (PMO); Phil Solomon, Tom Mooney (SUNY-SB); Paul Vanden Bout, Yancy Shirley (NRAO). - PowerPoint PPT Presentation
Transcript of Connecting Dense Gas Tracers of Star Formation in our Galaxy to High-z Star Formation
Connecting Dense Gas Tracers of Star Formation Connecting Dense Gas Tracers of Star Formation in our Galaxy to High-z Star Formationin our Galaxy to High-z Star Formation
Jingwen Wu(The Univ. of Texas at Austin)
Collaborators:Neal Evans (Advisor, UTexas at Austin)Neal Evans (Advisor, UTexas at Austin)
Yu Gao (PMO);Yu Gao (PMO);Phil Solomon, Tom Mooney (SUNY-SB);Phil Solomon, Tom Mooney (SUNY-SB);
Paul Vanden Bout, Yancy Shirley (NRAO)Paul Vanden Bout, Yancy Shirley (NRAO)
Molecules Seen to z>6Molecules Seen to z>6
Imol Tmoldv(K km /s)
+ + Local galaxiesLocal galaxies O O ULIRGSULIRGS High-z (EMGs)High-z (EMGs) Some have LARGE L(CO)Some have LARGE L(CO) L’L’molmol= 23.5 = 23.5 S*bS*b D DLL
22 I Imol mol (1+z) (1+z) -3-3
Can we make a Can we make a connection to well connection to well known local star known local star formation ?formation ?
z= 3 |
Solomon & Vanden Bout (2005, ARAA)Solomon & Vanden Bout (2005, ARAA)
Kennicutt (1998):
Composite star formation law Fit with CO, HI, Hα data on61 normal + 36 starbursts.
∑ SFR = A ∑gas1.40
Satr Formation in galaxies empirically follows “Schmidt Law” : SFR ~ A ρ N
Schmidt (1959) : N~2
But SFR/Mass (LBut SFR/Mass (LFIR FIR / L/ L‘‘COCO) ) Increases with SFRIncreases with SFR
SFR----LSFR----LFIRFIR L’co --- Luminosity of L’co --- Luminosity of
emission lineemission line Star Formation EfficiencyStar Formation Efficiency ---- ---- LLFIRFIR/L’co/L’co““Efficiency” increasing Efficiency” increasing or or CO fails to trace gas that is CO fails to trace gas that is
relevant to star formation ?relevant to star formation ?
Solomon & Vanden Bout (2005 ARAA)Solomon & Vanden Bout (2005 ARAA)
O O ULIRGSULIRGS High-z Early Universe Molecular Emission High-z Early Universe Molecular Emission Line galaxies (EMGs)Line galaxies (EMGs)+ + Local galaxiesLocal galaxiesL’L’molmol= 23.5 = 23.5 S*bS*b D DLL
22 I Imol mol (1+z) (1+z) -3-3
Gao & Solomon (2004a,b):
The correlation of The correlation of LIR-L'CO is non-linear, especially for high LIR:
CO can be misleading in starbursts LIR and L'HCN has a linear (N=1) and more tighter correlation than LIR-L'CO., for both normal spirals and starbursts including LIRGs and ULIRGs. The SFR/Mdense is consistent for both normal and starburst galaxies, over 3 orders of magnitude. A uniform star formation law (if proper dense gas tracer is used)? Will the correlation extend to lower/higher scales?
We mapped HCN 1-0 and 3-2 on Galactic dense cores, to compare with data from galaxies.
HCN 1-0 from FCRAO during 2004-2005
HCN 3-2 from CSO during 2003-2004
Study on massive Galactic dense cores is crucial to connect star formation from galactic to Galactic scales
Star formation in the Milky Way is dominated by massive star formation that occurs at GMC cores.
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HCN 1-0 galaxies Gao & Solomon 2004a
HCN 1-0 Galactic cores Observed at FCRAO
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HCN 3-2 Galactic cores Observed at CSO
HCN 3-2 galaxies Paglione et al. 1997 and our observations
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High z CO EMGs.Solomon & Vanden Bout 2005
CO 1-0 galaxies Gao & Solomon 2004a
CO 1-0 Galactic clouds Mooney & Solomon 1988
High z HCN 1-0 Carili et al. 2005
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HCN 1-0 Galactic cores HCN 1-0 galaxies CO 1-0 Galaxies Higz Z CO EMGs
Discussion:
What happens with CO ?
CO traces the overall mass of molecular clouds, not the dense cores. In the Galaxy, these dense cores occupy a negligible fraction of the mass of cloud (~a few percent). If the fraction of the dense gas in the overall mass of cloud Stays roughly constant, the Lir and L’co can stay linear. But for extreme starbursts, a much large fraction of molecular gas is in the form of dense gas, CO fails to trace the SFR in these galaxies.
Questions for the plot:Questions for the plot: Why the LWhy the LIRIR-L’-L’HCNHCN correlation is linear? correlation is linear? LLIRIR~ Luminosity~ Luminosity L’L’HCN HCN ~ Mass of dense gas~ Mass of dense gas L ~ ML ~ Mdensedense
11 ??? ???
Why there is a turn off for the slope of Why there is a turn off for the slope of correlation at lower luminosity?correlation at lower luminosity?
What causes the break? What causes the break?
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HCN 1-0 galaxies Gao & Solomon 2004a
HCN 1-0 Galactic cores Observed at FCRAO
log[
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Propose a Model of Basic UnitPropose a Model of Basic Unit
Each unit provides the same luminosityLarger structures are only different at how many such units they contain.
Luminosity depends strongly on mass available
Critical mass of dense gas
M > MM > Mcritcrit
M < MM < Mcritcrit
What is/ Why/ How is the What is/ Why/ How is the realistic of realistic of the basic unit the basic unit ??
LF of Galactic UC HII regionsLF of Galactic UC HII regionsCasassus et al. (2000)Casassus et al. (2000)
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HCN 1-0 Galactic cores HCN 1-0 galaxies
L = 10L = 1055 L Lsunsun ? ? Mdense ~ 300- 101033 Msun ? M*,max ~ n X 1010 Msun ? ……
If true, this basic unit can be the bridge to connect If true, this basic unit can be the bridge to connect star formation in our Galaxy to distant star formationstar formation in our Galaxy to distant star formation
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HCN 3-2 Galactic cores Observed at CSO
HCN 3-2 galaxies Paglione et al. 1997 and our observations
HCN 1-0 galaxies Gao & Solomon 2004a
High z HCN 1-0 Carili et al. 2005
HCN 1-0 Galactic cores Observed at FCRAO
High z CO EMGs.Solomon & Vanden Bout 2005
CO 1-0 galaxies Gao & Solomon 2004a
CO 1-0 Galactic clouds Mooney & Solomon 1988
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