The Radial Profiles of Gas, Gas Metallicity and SFR in the SAMs for Molecular and Atomic Gas
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The Radial Profiles of Gas, Gas Metallicity and SFR in the SAMs for Molecular and Atomic Gas Fu Jian Max Planck Institute for Astrophysics, Garching 18/12/2012 1
description
The Radial Profiles of Gas, Gas Metallicity and SFR in the SAMs for Molecular and Atomic Gas. Fu Jian Max Planck Institute for Astrophysics, Garching 18/12/2012. Millennium and Millennium II Simulation. Millennium Simulation: Springel et al. 2005 - PowerPoint PPT Presentation
Transcript of The Radial Profiles of Gas, Gas Metallicity and SFR in the SAMs for Molecular and Atomic Gas
The Radial Profiles of Gas, Gas Metallicity and SFR in the SAMs for
Molecular and Atomic Gas
Fu JianMax Planck Institute for Astrophysics, Garching
18/12/2012
Millennium and Millennium II Simulation Millennium Simulation: Springel et al. 2005
Millennium II Simulation: Boylan-Kolchin et al. 2009
The mass resolution of MS-II is 125 larger than MS: use to study dwarf galaxies and small galaxies at high z
Millennium I (MS) Millennium II (MS-II)
Particle number 21603
Particle Mass 8.6×108M☉h-1 6.8×106 M☉h-1
Box size 500 h-1 Mpc 100 h-1 Mpc
Output snapshots 64 snapshotsBetween z=0 and 127
68 snapshotsBetween z=0 and 127
Minimum halo mass
1.7×1010M☉h-1 1.4×108M☉h-1
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Two phase interstellar gas in SAMs of galaxy formation
Galaxy formation models including only cold gas phase in ISM (e.g DLB07, Guo11, Bower et al. 2006)
Post-Processing models including molecular and atomic phase based on the outputs of models without two-phase gas (Obreschkow et al. 2009; Power et al. 2010) not self-consistent
Models including the atomic-molecular transition and star formation processes throughout the calculation (Cook et al. 2010; Fu et al. 2010; Lagos et al. 2011)
Trace the atomic and molecular gas radial profiles throughout the history
The SAMs of galaxy formation including molecular gas and neutral
gas
Multiple concentric ring for each disk The H2 formation recipes
H2 prescription 1: Krumholz et al. 2009; Mckee & Krumholz 2010
H2 prescription 2: Pressure related H2 fraction recipe
H2 proportional star formation law
Based on Munich L-Galaxies model by Guo et al. 2011 models with similar methods in Fu et al. 2010 (based on DLB07)
2H gas gas, Z/Hf
gas gas *2P r G r r f r r
2mol H HI 0/ /R M M P P
The star formation model
2SFR H/ constant
Leroy et al. 2008Schruba et al. 2011Genzel et al. 2010 for high z
gas crit
dyn
SFR in DLB07 & Guo11M M
t
2SFR H
The problem of gas consumption time scalewhen adopting H2 proportional star
formation law
Solution:Include the radial gas inflow→ Too much gas in outer disks flows inward to compensate too fast gas consumption in inner disk
•Too fast gas consumption in inner diskbecause of star formation and SN feedback
Improper gas surface density profiles compared to the observations
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Radial gas inflow and gas surface density profiles
Galaxy chemical evolution models with radial gas inflow: Lacey & Fall (1985) , Portinari & Chiosi (2000), Spitoni & Matteucci (2011), Schönrich & Binney (2009) etc.
Physical Mechanisms: The mixing of cooling gas with existant disk gas causes the change
of specific angular momentum of gas disk Suppress the increase of specific angular momentum of gas disk
caused by the difference of the gas consumption at different radius
Assumption: gas gas/ dtdL CL
inflow vv rgas gas gas cirL m r v
0 5 10 15 200
1
2
3
4
5
r [kpc]
v inflo
w [km
/s]
1 1 10.30 km s (kpc h )a constant value in the modelsv
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Radial gas inflow and gas surface density profiles
Bigiel et al. 2012
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DLB07 & Guo11: all metal from star formation mix with cold gas, supernova reheat cold gas and metal into halo hot gas too high gas metallicity in inner disk region
too shallow gas metallicity radial gradients compared to observations (e.g Moran et al. 2012)
Gas metallicity radial gradients and mixing of metal elements from star formation
0 5 10 15 20-0.2
0
0.2
0.4
0.6
r [kpc]
New model: metal from SN directly mix with halo hot gas; metal from AGB star mix with disk cold gas
flatter gas metallicity gradients
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Mass functions at z=0
7 8 9 10 11-6
-4
-2
0
7 8 9 10-6
-4
-2
0
Keres et al. 2003
8 9 10 11
-4
-2
0
Martin et al. 2010Zwaan et al. 2005
Li et al. 2009Baldry et al. 2008
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The trends of gas metallicity gradients Moran et al. 2012 :174 galaxies with M* >1010M ⊙ from GASS
survey: Galaxies with larger M* tends to have flatter metallicity gradients
Models give similar trends
0 2 4 6 8 10 128
8.2
8.4
8.6
8.8
9
10-1
100
0 2 4 6 8 10 128
8.2
8.4
8.6
8.8
9
10-1
100
0 5 10 15 208
8.2
8.4
8.6
8.8
9
10-1 1008
8.2
8.4
8.6
8.8
9
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The size of star formation rate surface density profiles Larger galaxies have larger size of (Leroy et al. 2008;
Moran et al. 2012)SFR
0 5 10 15
100
10-1
10-2
10-3
10-4
10-5
0 5 10 15 20
0 5 10 15
100
10-1
10-2
10-3
10-4
10-4
10-5
0 5 10 15 20
0 5 10 15 20
100
10-1
10-2
10-3
10-4
10-5
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The size of star formation rate surface density profiles
In the unit of r/rd, the size of and rd tend to be similar
lSFR ~ l*~lH2 (similar to results in Leroy et al. 2008)SFR
0 2 4 6 8
100
10-1
10-2
10-3
10-4
10-5
0 5 10 15 20
100
10-1
10-2
10-3
10-4
10-5
0 2 4 6
100
10-1
10-2
10-3
10-4
10-5
0 2 4 6 8
0 2 4 6
100
10-1
10-2
10-3
10-4
10-4
10-5
0 2 4 6 8
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The HI disk size and HI mass
2 HIHI HI HI 2
HI
constantMM rr
The inner disk has almost constant average HI surface density because of the transition between HI and H2
Broeils & Rhee 1997; Swaters et al. 2002
0.5 1 1.5 28.5
9
9.5
10
10.5
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H2 prescription 1
0.5 1 1.5 28.5
9
9.5
10
10.5
11H2 prescription 2
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Conclusions Radial gas inflow can solve the problem of too fast gas
consumption in inner disk and give proper gas surface density profiles when adopting H2 proportional star formation law.
The fraction of metal element directly mix with cold/hot gas components can affect the results of gas metallicity radial gradients.
Smaller galaxies tend to have larger gas metallicity gradients Larger galaxies tend to have larger size of star formation rate
surface density profiles, because all have similar tends.
The HI disk size and HI mass:
2SFR H *, ,l l l
2HI HIM r
Thank you!
