The Prevalence and Properties of Outflowing Galactic Winds at z = 1

Katherine A. Kornei (UCLA) UC Riverside Astronomy Talk January 27, 2012

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Crystal Martin (UCSB)

Alice Shapley (UCLA)

Alison Coil (UCSD)

Several important people.

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Galaxies are not closed boxes.

enrich the IGM in metals/dust

…quench star formation

…regulate black hole growth

Outflowsoutfl

ows?

IGM

AGN feedback?

cold streams?

AGN feedback?

outfl

ows?

4

Outflows are seen in local starbursts.

HST/ACS BVIHα (M. Westmoquette)

M82 (z=0.0008)

6”

5

Outflows can be inferred through line offsets.

MgI MgII

Given outflowing material between the observer and the galaxy:

Wei

ner e

t al.

2009

[OII] 3727 ÅNebular line – at zsys zsys

Velocity (km/sec)

DN/s

ec/p

ixel MgII 2796/2803

MgI 2852

Outflowing gas will be blueshifted with respect to nebular lines tracing star forming regions.

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Galaxies near and far show blueshifted absorption lines.

Rupk

e et

al.

2005

ULIRGz = 0.2

LBGsz = 3

Shap

ley

et a

l. 20

03

Interstellar Absorption

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A variety of absorption lines are used to probe outflows.

Na I D ≈ 5900 Å z z = 0.5 1.0 3.0

Fe II/Mg II ≈ 2600 Å H I + others ≈ 1200 Å

Reddy et al. 2008

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The necessary data set.

Spectroscopy of lines tracing outflowing gas

lines tracing the systemic redshift

+ Photometry for calculating stellar masses, etc.

+ Ancillary data for obtaining dust-corrected SFRs, morphologies, galaxy inclinations, etc.

The ideal data set.

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50,000 galaxies at z ≈ 1 in 3.5 deg2

DEIMOS on Keck II (90 nights: ‘02-’05)

DEEP2 survey (the origin of our sample).

Slitmasks with 120 targets

R = 5000 (70 km s-1)

Resolved [OII] doublets

≈ 1 hour integration

Color cuts in 3/4 fields for z > 0.75

DEEP

2 Te

am

z < 0.75z > 0.75

B-R

R-I

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Extended Groth Strip – no color cuts and lots of ancillary data.

http:

//ae

gis.

ucol

ick.

org/

F606W

HST imaging (F606W, F814W)

6”

Spitzer imaging (IRAC, MIPS)

GALEX imaging (FUV, NUV)

The ideal data set. Photometry, imaging

✓

The necessary data set. Lines tracing outflows & systemic z

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LRIS observations to cover lines tracing winds.

LRIS: 3400-6700 Å LRIS: 7200-9000 Å

DEIMOS: 6500-9100 Å

[OII] (zsys)CIV, FeII, MgII, MgI (zout)

212 objects; B < 24.5 1.19 < z < 1.35 = CIV 1549, MgI 2852 coverage

Rest Wavelength (angstroms)

Nor

mal

ized

Flux

Si II, C IV

Fe IIFe II

Mg II

Al II Mg I

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Many analyses are possible. LRIS spectroscopy

fit FeII absorption lines to determine zout

measure fine structure FeII* emission lines

define zsys ([OII], Balmer series)

characterize MgII emission

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72 LRIS objects are in the Extended Groth Strip.

EGS (72)

Other fields (140)

star-formation ratesdust attenuationsHST imaging

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More analyses are possible for EGS objects. LRIS spectroscopy

fit FeII absorption lines

measure fine structure FeII* emission lines

define zsys ([OII], Balmer series)

characterize MgII emission

HST imaging

morphologies

colors

galaxy areas

inclinations

SFRs, dust attenuations from GALEX

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Blue, star-forming galaxies at z = 1.

Korn

ei e

t al.,

in p

rep.

Korn

ei e

t al.,

in p

rep.

16

Defining systemic and outflow velocities.

zsyszout Define a systemic reference frame, ideally from the LRIS spectra. Fit multiple emission lines ([OII], OIII, Balmer) using template spectra.

tilted [OII] lines(small fraction of

sample)

resonance abs.

fine structureemission

2250, 2260 2344, 2374 2587 Å

FeII

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A physical model for fitting absorption lines.

A single component fit with 4 free parameters.

covering fraction

op. depth at line center

line center

Doppler parameter

Primary quantity of interest is λ0, from which we estimate an outflow velocity.

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Blueshifted FeII absorption features are not ubiquitous in the sample.

Korn

ei e

t al.,

in p

rep.

12100420 z = 1.20

Mar

tin e

t al.,

in p

rep.

Inflow?

Other outflow diagnostics: MgII, FeII*

Velocities from FeII

Outflows Inflows

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The strength of outflows is correlated with various galaxy properties.

Mar

tin 2

005

outfl

ow v

eloc

ity (k

m/s

)

SFR (M*/yr)

dwarf starbursts

ULIRGs

Outflow velocity increases with increasing star formation rate.

Chen et al. 2010

Na D

edge-on

face-on

Outflows not seen in edge-on systems.

face-on edge-on

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No trend between outflow velocity and star-formation rate.

Martin 2005 1000 Msun yr-10.1 Msun yr-1

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Are outflows correlated with star-formation rate surface densities?

Σ

SFR estimate area estimate

UV, 24 μm, emission lines, etc.

Half-light radius?Petrosian radius?

A = πR2F606W

6”

Clumpy objects at high z – need a better area estimate that traces luminous regions.

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A new technique for estimating galaxy areas.

Given “clumpy” galaxies:

Include only those pixels brighter than a certain surface brightness

threshold, thereby flagging clumps.

F606W

Petrosianarea

Clumparea

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Higher star-formation rate surface density objects show larger blueshifts.

No trend seen:

Rubin et al. 2010(used half-light radius)

Steidel et al. 2010(ground-based imaging)

Kornei et al., in prep.

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Composite spectra show same trends as individual objects.

Kornei et al., in prep.

High Low

Star-formation rate surface density composites::

High: dV = -31 ± 7 km s-1 Low: dV = 44 ± 15 km s-1

High: dV = -300 km s-1

Mg II shows more kinematic variation than Fe II

MgII

SN IIFeII FeII

MgII in supernova ejecta; FeII merely entrained?

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The geometry of outflowing winds at z = 1.

Chen et al. 2010

Na D

edge-on

face-on

face-on edge-on

Estimate inclination from axis ratios from HST imaging:

i = cos-1(b/a)b

a

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Face-on galaxies show stronger blueshifts than edge-on systems.

More edge-on: dV = 28 ± 11 km s-1More face-on: dV = -19 ± 9 km s-1

Inclination composites::

Low High

face-on edge-on

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Mergers are not required to drive outflows.

Korn

ei e

t al.,

in p

rep.

Gini (G) – measure of how light is distributed in a galaxy

Law

et a

l. 20

07

high G low G

M20 – second order moment of a galaxy’s 20% brightest pixels

Lotz

et a

l. 20

08

high M20low M20

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Fine structure FeII* emission.

zsysv = 0

v = +100v = -100

2600 Å (resonance)

2626 Å (fine structure)

Leitherer et al. 2010

Kornei et al., in prep.

probing very different scales at z = 1 and z = 0

Does this emission come from star forming regions or from outflows?

F606W

8400 pc/” 16 pc/”

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FeII* emission is prevalent.

Kornei et al., in prep.

Stacks of FeII* emitters/non-emitters FeII* emitters FeII* non-emitters

The strongest FeII* emitters are bright and blue.

FeII* emission appears to be ubiquitous

FeII, FeII*

MgII

stronger FeII* = stronger MgII emission

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Complexities of the MgII feature at ≈ 2800 Å.

Composite spectrum Individual spectra show MgII emission

AGN? (Weiner et al. 2009)

Scattered wind? (Rubin et al. 2010)

MgII

MgII and FeII absorption are kinematically distinct.

Mar

tin e

t al.,

in p

rep.

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Measuring an outflow velocity from MgII

2796 Å (resonance)

A resonantly trapped transition.

MgII

Vmax

where 90% of the continuum is met.

No correlation:SFR and Vmax

Significant correlation:SFRSD and Vmax

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Summary.

Reddy et al. 2008

Petrosianarea

Clumparea

LRIS: 3400-6700 Å LRIS: 7200-9000 Å

DEIMOS: 6500-9100 Å

CIV, FeII, MgII, MgI (zout)[OII] (zsys)

Outflow velocity most strongly correlated with the concentration of star formation.

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