J/ApJ/758/135 DEEP2 galaxies with UV spectra in the EGS (Kornei+, 2012)
The properties and prevalence of galactic outflows at z ∼ 1 in the Extended
Groth Strip.
Kornei K.A., Shapley A.E., Martin C.L., Coil A.L., Lotz J.M.,
Schiminovich D., Bundy K., Noeske K.G.
<Astrophys. J., 758, 135 (2012)>
=2012ApJ...758..135K 2012ApJ...758..135K
ADC_Keywords: Galaxies, optical ; Magnitudes, absolute ; Redshifts ; Surveys ;
Spectra, ultraviolet
Keywords: galaxies: evolution; galaxies: high-redshift; galaxies: structure;
intergalactic medium; ultraviolet: ISM
Abstract:
We investigate galactic-scale outflowing winds in 72 star-forming
galaxies at z∼1 in the Extended Groth Strip. Galaxies were selected
from the DEEP2 survey and follow-up LRIS spectroscopy was obtained
covering Si II, C IV, Fe II, Mg II, and Mg I lines in the rest-frame
ultraviolet. Using Galaxy Evolution Explorer (GALEX), Hubble Space
Telescope (HST), and Spitzer imaging available for the Extended Groth
Strip, we examine galaxies on a per-object basis in order to better
understand both the prevalence of galactic outflows at z∼1 and the
star-forming and structural properties of objects experiencing
outflows. Gas velocities, measured from the centroids of Fe II
interstellar absorption lines, are found to span the interval
[-217,+155]km/s. We find that ∼40% (10%) of the sample exhibits
blueshifted Fe II lines at the 1σ (3σ) level. We also
measure maximal outflow velocities using the profiles of the Fe II and
Mg II lines; we find that Mg II frequently traces higher velocity gas
than Fe II. Using quantitative morphological parameters derived from
the HST imaging, we find that mergers are not a prerequisite for
driving outflows. More face-on galaxies also show stronger winds than
highly inclined systems, consistent with the canonical picture of
winds emanating perpendicular to galactic disks. In light of clumpy
galaxy morphologies, we develop a new physically motivated technique
for estimating areas corresponding to star formation. We use these
area measurements in tandem with GALEX-derived star formation rates
(SFRs) to calculate SFR surface densities. At least 70% of the sample
exceeds an SFR surface density of 0.1M☉/yr/kpc2, the threshold
necessary for driving an outflow in local starbursts. At the same
time, the outflow detection fraction of only 40% in Fe II absorption
provides further evidence for an outflow geometry that is not
spherically symmetric. We see a ∼3σ trend between outflow
velocity and SFR surface density, but no significant trend between
outflow velocity and SFR. Higher resolution data are needed in order
to test the scaling relations between outflow velocity and both SFR
and SFR surface density predicted by theory.
Description:
The objects presented here were drawn from the DEEP2 survey conducted
from 2002-2005 using DEIMOS on Keck II, with wavelength coverage from
∼6500 to 9100Å and R∼5000 (Newman et al. 2013ApJS..208....5N 2013ApJS..208....5N).
We obtained complementary spectroscopic data for 212 objects using the
LRIS spectrograph on Keck I, collected in 2007 October, 2008 June,
2008 September, and 2009 June. These observations, covering all four
DEEP2 survey fields, are described in further detail in Martin et al.
(2012ApJ...760..127M 2012ApJ...760..127M). In this paper, we discuss 72 objects in the EGS
that are drawn from our larger sample of 212 spectroscopically
confirmed DEEP2 objects with LRIS follow-up.
The 72 EGS objects presented in this paper have extensive
multiwavelength coverage from the AEGIS data set. These data products
cover observations over nine decades in wavelength, including Chandra
X-ray, GALEX FUV and NUV imaging, HST ACS F606W (V) and F814W (I)
imaging, optical CFHT and MMT observations, Palomar/WIRC J and Ks
imaging, Spitzer IRAC and MIPS pointings, and Very Large Array (VLA)
radio observations. Reduced HST images (Cycle 13, Program 10134, PI:
Marc Davis) were drizzled from four exposures to produce final
8000x8000 pixel images with a sampling of 0.03"/pixel and a
point-spread function (PSF) FWHM of ∼0.1".
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 85 72 Sample outflow parameters
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See also:
III/268 : DEEP2 Redshift Survey, Data Release 4 (Matthews+ 2013)
II/301 : The DEEP2-DR1 Photometric Catalog (Coil+ 2004)
J/ApJS/202/6 : XDEEP2 survey catalog (Goulding+, 2012)
J/A+A/526/A72 : Early-type galaxies in the EGS (Fernandez Lorenzo+, 2011)
J/ApJS/193/30 : UV-to-FIR analysis of sources in the EGS. II. (Barro+, 2011)
J/ApJS/193/13 : Spitzer/IRAC sources in the EGS I. SEDs (Barro+, 2011)
J/ApJ/728/38 : AEGIS: demographics of X-ray and optical AGN (Yan+, 2011)
J/ApJ/717/1181 : Spitzer power-law galaxies in EGS (Park+, 2010)
J/ApJS/180/102 : AEGIS-X: Chandra deep survey (Laird+, 2009)
J/ApJS/177/431 : Mid-IR sources in EGS (Barmby+, 2008)
J/ApJ/654/115 : DEEP2 Galaxy Redshift Survey: SDSS QSOs (Coil+, 2007)
J/MNRAS/377/806 : Tully-Fisher relation of DEEP2 galaxies (Chiu+, 2007)
J/AJ/132/2159 : IRAC counterparts of 6cm galaxies in EGS (Willner+, 2006)
J/AJ/128/163 : Galaxy morphological classification (Lotz+, 2004)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- ID [12008116/12100420] Source identification number
(<DEEP2-GRS NNNNNNNN> in Simbad)
10 A1 --- f_ID [i] Source with HST imaging (1)
12- 13 I2 h RAh Hour of right ascension (J2000)
15- 16 I2 min RAm Minute of right ascension (J2000)
18- 22 F5.2 s RAs Second of right ascension (J2000)
24 A1 --- DE- Sign of declination (J2000)
25- 26 I2 deg DEd Degree of declination (J2000)
28- 29 I2 arcmin DEm Arcminute of declination (J2000)
31- 35 F5.2 arcsec DEs Arcsecond of declination (J2000)
37- 43 F7.5 --- zsys [0.2/1.4] Systemic redshift (zsys) (2)
45- 50 F6.2 mag BMag [-22.2/-17.2] Absolute B-band magnitude
52- 55 F4.2 mag U-B [0.1/1.3] U-B color index
57- 60 F4.1 [Msun] M* [8.8/11.3] Log of stellar mass
62- 63 I2 Msun/yr SFR [0/97]? Dust-corrected UV star formation rate
estimated from GALEX observations
65- 67 F3.1 mag Auv [0/4.5] Dust attenuation estimated from UV colors
69- 71 I3 kpc2 Carea [0/427]? Galaxy "clump area" (Section 3.2)
73- 76 I4 kpc2 Parea [0/1391]? Galaxy Petrosian area (πR2P)
78- 81 I4 km/s V1 [-217/154]? Outflow velocity (3)
83- 85 I3 km/s e_V1 [13/185]? V1 uncertainty (3)
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Note (1):
i = Objects with HST imaging, although the S/N was too low to make robust
area measurements.
Note (2): For 63/72 objects (∼90%), it was possible to extract zsys from the
LRIS spectra. For the nine objects in the sample without [OII]
spectral coverage in the LRIS data, zsys was calculated from the
DEIMOS spectra using the same technique.
(See section 4.1 for further explanations).
Note (3): V1 outflow velocity measured from the simultaneous fit to five
resonance FeII absorption lines (Section 4.2).
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 09-Jul-2014