XY i

M82Blue: ChandraRed: SpitzerGreen & Orange: Hubble

Face-oni = 0

Edge-on

i = 90

Absorption-line probes of the prevalence and properties Absorption-line probes of the prevalence and properties of outflows in the present-day star-forming galaxies?of outflows in the present-day star-forming galaxies?

Chen, Y.-M.(UW-Madison/NJU), Tremonti, C., Heckman, T., Kauffmann, G., Chen, Y.-M.(UW-Madison/NJU), Tremonti, C., Heckman, T., Kauffmann, G., Weiner, B., Brinchmann, J., Wang, J.Weiner, B., Brinchmann, J., Wang, J.

Outline

• Background

• Sample

• Data analysis

• Results

Outflow velocity vs. SFROutflow velocity vs. SFR

Outflow velocity vs. SFROutflow velocity vs. SFR

Voff ~ SFR0.35

Martin 2005

Sample: SDSS DR7 star forming galaxies

• 0.05<z<0.18

• r-band fracDeV<0.8

• D4000<1.5

•

Main steps of data analysisMain steps of data analysis

stellarstellar

Disk-likeDisk-like （（ vv=0=0 ））

ISMISM outflowoutflow

Na D AbsorptionNa D Absorption

1. stack spectra 1. stack spectra (i, Av, SFR, SSFR, (i, Av, SFR, SSFR, MM** ...) ...)

2. 2. subtract stellar contribution (CB08)subtract stellar contribution (CB08)

3. fit ISM absorption with two components3. fit ISM absorption with two components

Stack spectrum and stellar continuumStack spectrum and stellar continuum

Mg I He I

Na I

Two-component fit of ISM Na DTwo-component fit of ISM Na D

• Line center shift: outflow velocity Voff

• Line strength (EW): covering factor Cf • Line width b

• Line ratio τ0

Two-component fit of ISM Na DTwo-component fit of ISM Na D

• Line center shift: outflow velocity Voff

• Line strength (EW): covering factor Cf • Line width b

• Line ratio τ0

Inclination effectInclination effect

face on edge on

Isolate the main driver of the observedcorrelation: Disk-like components

Isolate the main driver of the observedcorrelation: outflow components

Outflow velocity vs. SFROutflow velocity vs. SFR

Voff ~ SFR0.3

Summary

• outflow is perpendicular to the disk and has an opening angle of ～ 60 degree

• disk component is highly dependent on the dust extinction, and secondarily on SFR surface density

• outflow component depends on SFR surface density strongly and secondarily on Av

• we do not find the correlation between outflow velocity and SFR from our sample, more observations on the low SFR end are needed

Thanks!

From optical absorption lines (Rupke et al. 2005a,b,c)

dwarf galaxies from Schwartz & Martin 2004

= Starbursts = Seyfert 2s

Background

Outflow velocity vs. SFROutflow velocity vs. SFRBackground

Martin et al. 2009

Spectra from LRIS on Keck I

Using multi-components to fit each absorption line

Through the fitting in last slides, they find that components with different velocity have different covering factoroutflow is accelerating

From optical absorption lines—NaD(5890,5896A)

(Rupke et al. 2005a,b,c)

• Larger sample

• New method for Fitting NaD

-- line shift Velocity-- doublet ratio Optical depth-- line strength covering factor

Circular velocity Star formation rate

Ou

tflo

w v

eloc

ity

isothermal escape speed

From optical absorption lines (Rupke et al. 2005a,b,c)

Murray et al. 2004, Martin 2005

Spectra from LRIS on Keck I

Using multi-components with different velocity to fit each absorption line

Martin et al. 2009

Outflows are ubiquitous in galaxies in which the global SFR per unit area exceeds roughly 0.1 solar mass per year per kpc^2 (Heckman et al. 2002)

Are there any outflows in local normal star forming galaxies?

Two categories of the gas in a SF/SB galaxy wind

• Ambient interstellar medium

• Energetic fluid created by thermalization of the SB’s stellar eject

The hydrodynamical interaction between these two generates the multiphase starburst-driven galactic wind.

Observations of multiphase wind (cold, warm, hot gas & dust)

• X-ray

• Morphology and kinematics of interstellar emission lines (e.g. Ha…)

• Outflow kinematics in the interstellar absorption lines (e.g. MgII, NaD)

From optical absorption lines--NaD(5890,5896A)Low- ionization potential 5.1eV(Martin et al. 2005, 2006)

V = -96 km/s

V = -435 km/s

He I

Disk-like componentDisk-like component

Outflow componentOutflow component

From X-ray: Hot Gas Escapes From X-ray: Hot Gas Escapes from Dwarf Starburstsfrom Dwarf Starbursts

Martin 1999, Heckman et al 2000, Martin 2004

Rotation Speed Tremonti et al. 2004

Vc= 130 km/s