The Lifecycle of (radiative) feedback-regulated GMCs

Transcription

1 The Lifecycle of (radiative) feedback-regulated GMCs Desika Narayanan Bart J Bok Fellow University of Arizona (with Phil Hopkins, Mark Krumholz, Eve Ostriker) awesome galaxy picture by adam leroy awesome galaxy simulation by desika narayanan

2 SFR

3 SFE SFR slope dynamic range in

4 Simulations 1. 1 pc res. GADGET 2. T < 100 K cooling 3. -HI breakdown (KMT) 4. GMCs ID d with FOF Star Formation 5. ρsfr ~ℇ x ρ(n>1000)/tff 6. P = Psn + Pw + Prad 7. Prad ~ (1+ *ϰ)l/c Galaxy 8. Mhalo = 1.6e12 9. Mbar = 7.1e10

5 ρsfr ~ℇ x ρ(n>1000)/tff No Rad. Winds Standard Hopkins, Narayanan, Murray & Quataert (2013)

6 ρsfr ~ℇ x ρ(n>1000)/tff Hopkins Narayanan, Hopkins & Murray (in progress)

7 Dense Gas Distribution Constraints on Feedback Model Ratio of Dense gas to All Gas Total Gas Mass Hopkins, Narayanan, Murray & Quataert (2012) Desika Narayanan

8 data by many people; plot by Kennicutt & Evans (2012)

9 Narayanan, Hopkins & Murray in prep.

10 virial parameter on KS plot - standard model Narayanan, Hopkins & Murray in prep.

11 virial parameter on KS plot - no radiative feedback Narayanan, Hopkins & Murray in prep.

12 SFE SFR slope dynamic range in

13 Radiative Feedback Dominated ISM in Starbursts slope ~ 2 SFR Ostriker & Shetty 2011 Shetty & Ostriker 2012 Desika Narayanan

14 How do we get the X-axis?

15 Bolatto, Wolfire, Leroy ARA&A Assume GMC is viralized and use line width as mass measurement II. Assume a DTG ratio and get dust masses III. CR + H 2 --> γ-ray Xco = N/Ico= 2-4 x cm -2 /K-km s -1

16 Merger Value X ~ few x10 19 cm -2 /K km s -1 Disk Value X ~ 2x10 20 cm -2 /K km s -1 Narayanan (2011)

17 Daddi+ 2010; Genzel+ 2010

18 HI Lyman-Werner Band Photons HI HI Z Z HI Z HI Av ~ 1 Desika Narayanan Wolfire, Hollenbach & McKee (2010) Glover & Mac Low (2011) Goldsmith (2001) Krumholz, McKee & Leroy (2011) Narayanan, Krumholz, Ostriker & Hernquist (2011)

19 HI HI HI HI HI TURTLEBEACH; Narayanan et al. 2006,2008 Desika Narayanan

20 The Physics Controlling Xco 1: Gas Kinematics and Thermal Structure Xco = N/W ~ N /(T*σ) I ~Tb~Tk Tk σ velocity Desika Narayanan

21 Xco = N/W ~ N /(T*σ) N ~10 22 cm -2 T~ 10 K σ ~ 5 km/s } X ~ 2x10 20 cm -2 /K km s -1 Narayanan, Krumholz, Ostriker & Hernquist 2011,2012 Narayanan & Hopkins (2012) Shetty, Glover+ 2011,2012

22 Xco = N/W ~ N /(T*σ) N ~10 22 cm -2 T~ 10 K σ ~ 5 km/s } Virialized GMCs unaffected by galactic environment X ~ 2x10 20 cm -2 /K km s -1 N ~10 23 cm -2 T~ 50 K σ ~ 50 km/s } non-virialized GMCs strongly affected by galactic environment X ~ few x10 19 cm -2 /K km s -1 Narayanan, Krumholz, Ostriker & Hernquist 2011,2012 Narayanan & Hopkins (2012)

23 Surface Brightness (K-km/s) (units of Z ) merger Xco where W disk Xco This results in a relation between X X = W 0.32 Z 0.65 is measured in K-km Narayanan, Krumholz, Ostriker, Hernquist 2011,2012

24 Narayanan, Krumholz, Ostriker & Hernquist 2011,2012 This results in a relation between X X = W 0.32 Z 0.65 where W is measured in K-km Sandstrom et al. (2012)

25 Narayanan, Krumholz, Ostriker, Hernquist 2011,2012 Daddi et al Genzel et al Desika Narayanan

26 Narayanan, Krumholz, Ostriker, Hernquist 2012 N~ Desika Narayanan N~1.8 SFR ~ ( 100 M pc -2 ) SFR ~ 2 ( 100 M pc -2 ) (Ostriker & Shetty, 2011)

27 Ways Forward: Excitation Modeling Cooray, Casey & Narayanan 2013 Physics Reports

28 Ways Forward: Excitation Modeling (J= 6-5) line ratio vs. SFR Cooray, Casey & Narayanan 2013 Physics Reports Narayanan & Krumholz (in progress)

29 Ways Forward: Excitation Modeling Example SLED: Eyelash (Lensed SMG at z~2) Cooray, Casey & Narayanan 2013 Physics Reports Narayanan & Krumholz (in progress)

30 Summary 1. Dense gas tail of density PDF strongly dependent on feedback strength - sets the SFE of galaxies 2. GMCs dominated by radiative feedback have a natural life cycle that limits the ~ 1000 M pc-2 With a smoothly varying model for Xco, at face value, KS relation has index ~2 (modulo excitation effects)