SLIDE 1
The Jeans Conjecture and the IMF
Desika Narayanan Bart J Bok Fellow University of Arizona
(with Romeel Davé)
Monday, August 13, 12
Is the IMF at high-z Top-Heavy?
Indirect evidence from z~2 SFRs Davé 2008
Monday, August 13, 12
The Jeans Conjecture and the IMF Desika Narayanan Bart J Bok Fellow - - PowerPoint PPT Presentation
The Jeans Conjecture and the IMF Desika Narayanan Bart J Bok Fellow - - PowerPoint PPT Presentation
The Jeans Conjecture and the IMF Desika Narayanan Bart J Bok Fellow University of Arizona (with Romeel Dav) Monday, August 13, 12 Is the IMF at high- z Top-Heavy? Indirect evidence from z ~2 SFRs Dav 2008 Monday, August 13, 12 Is the IMF
SLIDE 2
SLIDE 3
Is the IMF at high-z Top-Heavy?
Indirect evidence from z~2 SFRs Davé 2008 Wilkins & Trentham (2008) Narayanan & Davé (2012)
Monday, August 13, 12
SLIDE 4
Is the IMF at high-z Top-Heavy?
Davé 2008 Wilkins & Trentham (2008) Narayanan & Davé (2012) van Dokkum 2008
Monday, August 13, 12
SLIDE 5
Is the IMF at high-z Top-Heavy?
Davé 2008 Wilkins & Trentham (2008) Narayanan & Davé (2012) van Dokkum 2008 Tacconi 2008
Monday, August 13, 12
SLIDE 6
Is the IMF at high-z Top-Heavy?
(then how are their descendents bottom-heavy?) Conroy & van Dokkum 2012 I n c r e a s i n g l y B
- t
t
- m
H e a v y
Monday, August 13, 12
SLIDE 7
Gadget: to get model discs and mergers at z=0,2 Springel et al. 2003-2005 T.J. Cox et al. 2005-2008 Jonsson et al. 2006, 2009 Jonsson & Primack 2010 Sunrise: to get dust temperatures
Monday, August 13, 12
SLIDE 8
Assumption: Mcrit ~ MJ
André et al. 2010
Monday, August 13, 12
SLIDE 9
Desika Narayanan
H2 H2 H2 H2 H2 H2 H2 H2 H2 H2 H2 H2 H2 H2 HI HI HI HI HI
CO CO CO CO CO CO CO CO CO CO CO CO CO CI/CII CI/CII CI/CII CI/CII CI/CII CI/CII CI/CII CI/CII CI/CII CI/CII CI/CII Av ~ 1
Krumholz, McKee & Leroy (2011) Narayanan et al. (2011b) scales with SFR becomes efficient at n~104 cm-3
MJ ~ T3/2 / n1/2
∑GMC > 100 M⦿pc-2
Monday, August 13, 12
SLIDE 10
scales with SFR becomes efficient at n~104 cm-3 Narayanan & Davé 2012
MJ ~ T3/2 / n1/2
Monday, August 13, 12
SLIDE 11
MJ ~ T3/2 / n1/2
Narayanan & Davé (in prep.) Kroupa
Mhalo SFR Mc M/L
Monday, August 13, 12
SLIDE 12
MJ ~ T3/2 / n1/2
Narayanan & Davé (in prep.) Kroupa n~104-105 cm-3 Tgas ~ Tdust
Mhalo SFR Mc M/L
Monday, August 13, 12
SLIDE 13
Desika Narayanan
z=0-2 SFR-M* relation Invariant IMF SFRs Model IMF SFRs Narayanan & Davé (2012)
Monday, August 13, 12
SLIDE 14
Desika Narayanan
Comparing Cosmic SFR Density Evolution against Stellar Mass buildup Narayanan & Davé (2012)
Monday, August 13, 12
SLIDE 15
MJ ~ T3/2 / n1/2
Narayanan & Davé (in prep.) Kroupa SFRs < SFRMW Tgas < 10 K
M/L Mc
n~104-105 cm-3 Tgas ~ Tdust
SFR Mhalo
Monday, August 13, 12
SLIDE 16
Narayanan & Davé (in prep.)
Monday, August 13, 12
SLIDE 17
Conclusions
Under the Jeans Assumption:
- 1. Dust-gas coupling can raise temperatures in high-z
galaxies enough to drive top-heavy/bottom-light IMFs
- 2. Decreased SFRs in gas where CRs dominate the
temperature can promote bottom-heavy IMFs at low-z: More massive galaxies have increasingly bottom-heavy IMFs at z~0 Do the Jeans properties of GMCs relate at all to the stellar IMF?
Monday, August 13, 12