stellar feedback and galaxy evolution

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Q. Daniel Wang University of Massachusetts Stellar Feedback and Galaxy Evolution IRAC 8 micro K-band ACIS diffuse 0.5-2 keV

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Stellar Feedback and Galaxy Evolution. Q. Daniel Wang University of Massachusetts. IRAC 8 micro K-band ACIS diffuse 0.5-2 keV. Galaxy formation and evolution context. Toft et al. (2002); Muller & Bullock (2004). The missing baryon problem. - PowerPoint PPT Presentation

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Page 1: Stellar Feedback  and Galaxy Evolution

Q. Daniel Wang

University of Massachusetts

Stellar Feedback and Galaxy Evolution

IRAC 8 microK-bandACIS diffuse 0.5-2 keV

Page 2: Stellar Feedback  and Galaxy Evolution

Galaxy formation and evolution context

Toft et al. (2002); Muller & Bullock (2004)

Page 3: Stellar Feedback  and Galaxy Evolution

The missing baryon problem

• Observed baryon mass in stars and the ISM accounts for 1/3-1/2 of what is expected from the gravitational mass of a galaxy.

• Where is the remaining baryon matter:– In a hot gaseous galactic halo?– Or having been pushed away?

• Both are related to the galactic energy feedback!

Page 4: Stellar Feedback  and Galaxy Evolution

Forms of the galactic feedback

• AGNs (jets)• Nuclear starbursts or superwinds• Gradual energy inputs

– Galactic disks: massive star formation– Galactic bulges: Type Ia SNe.

Page 5: Stellar Feedback  and Galaxy Evolution

Karovska et al. 2002

AGN feedback• Centaurus A:

– D=3.5 Mpc– Nearest radio-bright AGN– Lx(AGN) ~ 1042 erg/s– Lx(diffuse) ~ 5x1038

erg/s

• The total mechanical energy output is not clear.

• Most nearby galaxies do not contain AGNs!

Page 6: Stellar Feedback  and Galaxy Evolution

Starburst feedback

Starbursts typically occur in low-mass gas-rich galaxies in the present Universe.

optical0.5-2 keV2-8 keV

Page 7: Stellar Feedback  and Galaxy Evolution

Feedback in normal galaxies: our Galaxy

X-ray binaryROSAT ¾-keV Diffuse Background Map: ~50% of the background is thermal and local (z < 0.01)The rest is mostly from faint AGNs (McCammon et al. 2002)

Page 8: Stellar Feedback  and Galaxy Evolution

X-ray absorption line spectroscopy

X-ray binaryROSAT all-sky

survey in the ¾-keV band

X-ray binaryAGN Wang et al. 05, Yao & Wang

05/06, Yao et al. 06/07

Page 9: Stellar Feedback  and Galaxy Evolution

LMXB X1820-303

Fe XVII K

In the GC NGC 6624– l, b = 2o.8, -8o

– Distance = 7.6 kpc tracing the global ISM

– 1 kpc away from the Galactic plane NHI

• Two radio pulsars in the GC: DM Ne

• Chandra observations:– 15 ks LETG (Futamoto et

al. 2004)– 21 ks HETG

Yao & Wang 2006, Yao et al. 2006

LETG+HETG spectrum

Page 10: Stellar Feedback  and Galaxy Evolution

X-ray absorption line spectroscopy along the X1820-303 sightline:

Results• Hot gas accounts for ~ 6% of the total O column

density

• Mean temperature T = 106.34 K

• O abundance: – 0.3 (0.2-0.6) solar in neutral atomic gas

– 2.0 (0.8-3.6) solar in ionized gas

• Hot Ne/O =1.4(0.9-2.1) solar (90% confidence)

• Hot Fe/Ne = 0.9(0.4-2.0) solar

• Velocity dispersion 255 (165–369) km/s

Page 11: Stellar Feedback  and Galaxy Evolution

Mrk 421 (Yao & Wang 2006)

OVI 1032 A

•Joint-fit with the absorption lines with the OVII and OVIII line emission (McCammon et al. 2002)

•Model: n=n0e-z/hn; T=T0e-z/hT

n=n0(T/T0), =hT/hn, L=hn/sin

b

Page 12: Stellar Feedback  and Galaxy Evolution

Galactic global hot gas properties

• Non-isothermal: – mean T ~ 106.3 K toward the inner region– ~ 106.1 K at solar neighborhood

• Velocity dispersion from ~200 km/s to 80 km/s• Consistent with solar abundance ratios• A thick Galactic disk with a scale height 1-2 kpc, ~ the values of OVI absorbers and free electrons • Enhanced hot gas around the Galactic bulge• No evidence for a large-scale (r ~ 102 kpc) X-ray-

emitting/absorbing halo with an upper limit of NH~1 x1019 cm-2

• But a large-scale hot halo is required to explain HVCs: confinement and OVI line absorption!

Page 13: Stellar Feedback  and Galaxy Evolution

Feedback from disk-wide star formation

Diffuse X-ray emission compared with HST/ACS images:

Red – HGreen – Optical R-bandBlue – 0.3-1.5 keV

• Lx(diffuse) ~ 4x1039 erg/s

• T1 ~ 106.3 K, T2 > 107.1 K• Scale height ~ 2 kpc +

more distant blubs.

Li et al. (2008)

NGC 5775

Page 14: Stellar Feedback  and Galaxy Evolution

M83

Soria & Wu (2002)

Page 15: Stellar Feedback  and Galaxy Evolution

Li et al. 2007

Page 16: Stellar Feedback  and Galaxy Evolution

Extraplanar hot gas seen in nearby galaxies

• At least two components of diffuse hot gas:– Disk – driven by massive star formation– Bulge – heated primarily by Type-Ia SNe

• Characteristic extent and temperature similar to the Galactic values

• No evidence for large-scale X-ray-emitting galactic halos

Page 17: Stellar Feedback  and Galaxy Evolution

Observations vs. simulations

• Little evidence for X-ray emission or absorption from IGM accretion.No “overcooling” problem?

• Missing stellar energy feedback, at least in early-type spirals. Where does the energy go?

Simulations by Toft et al. (2003)

Galaxy Vc

NGC 4565 250

NGC 2613 304

NGC 5746 307

NGC 2841 317

NGC 4594 370

Page 18: Stellar Feedback  and Galaxy Evolution
Page 19: Stellar Feedback  and Galaxy Evolution

1-D Simulations of galaxy formation with the stellar feedback

• Evolution of both dark and baryon matters (with the final mass 1012 Msun)

• Initial bulge formation (5x1010 Msun) starburst shock-heating and expanding of gas

• Later Type Ia SNe bulge wind/outflow, maintaining a low-density high-T halo, preventing a cooling flow

Tang & Wang 2007

Page 20: Stellar Feedback  and Galaxy Evolution

1-D Simulations of galaxy formation with the stellar

feedback• Both dark and baryon matters

evolve (with the final mass 1012 Msun)

• A blastwave is initiated by the SB (forming a 5x1010 Msun

bulge) and maintained by the Type Ia SN feedback.

• The IGM is heated beyond the virial radius

• The accretion can be stopped and the shocked hot gas expands

• The resultant low density allows the bulge wind.

• The wind can be shocked at a large radius.

z=1.4

z=0.5

z=0

Page 21: Stellar Feedback  and Galaxy Evolution

1-D Simulations of galaxy formation with the stellar

feedback• If the specific energy of the

feedback is reduced (e.g., because of mass-loading of the bulge wind), the wind has then evolved into a subsonic outflow.

• This outflow can be stable and long-lasting

• Consistent with observations of low Lx/LB galaxies (relative higher Lx, lower T, and more extended than those predicted by a supersonic wind.

z=1.4

z=0.5

z=0

Page 22: Stellar Feedback  and Galaxy Evolution

Evolution of Baryons around galaxies

• Galaxies such as the MW evolves in a hot bubble with a deficit of baryon matter

• This bubble explains the lack of large-scale X-ray halos.

• Bulge wind removes the present stellar feedback.

• Results are sensitive to the initial burst and to the bulge/halo mass ratio

Hot gas

Total baryon before the SB

Total baryon at present

Cosmological baryon fraction

Page 23: Stellar Feedback  and Galaxy Evolution

2-D simulations of galactic flows in M31

An ellipsoid bulge (q=0.6), a disk, and an NFW halo

SNu=0.06 SNu=0.12

Page 24: Stellar Feedback  and Galaxy Evolution

3-D simulations of a galactic bulge wind

• Energy not dissipated locally • Most of the energy is in the

bulk motion and in waves

• Parallel, adaptive mesh refinement FLASH code

• Finest refinement in one octant down to 6 pc

• Stellar mass injection and SNe, following stellar light

• SN rate ~ 4x10-4 /yr• Mass injection rate ~0.1

Msun/yr)

10x10x10 kpc3 box

density distribution

Page 25: Stellar Feedback  and Galaxy Evolution

Conclusions• Diffuse X-ray-emitting gas is strongly concentrated

toward galactic disks and bulges (< 20 kpc).• Heating is mostly due to SNe. But the bulk of their

energy is not detected in X-ray near galactic bulges/disks and is probably propagated into the halos.

• Feedback from a galactic bulge likely plays a key role in galaxy evolution: – Initial burst heating and expansion of gas beyond the

virial radius– Ongoing Type Ia SNe keeping the gas from forming a

cooling flow

• Low n and high T are characteristics of the gaseous halos

• Mass-loaded subsonic outflows account for diffuse X-ray emission from galactic bulges