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z 2 Astrophysics Science Division, Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 ' 'Space Telescope European Coordinating Facility, Karl 8ohwomonhdd8t . 2,D85748Qorc6ing, Germany 4 S,600 nf Earth and Space Exploration, Arizona State University, Tempe, /\Z0S2Q? 5 D«yxztn`mntof Astronomy, University of Virginia, Charlottesville, V132004-4325 a Space Telescope Science Institute, Baltimore, MD 21218 7 1nternational Centre for Radio Astronomy Research, The University of Western Australia, Crawley WA, 6009 » Observatories ofthe Carnegie Institute of Washington, Pasadena, CA 91101 'Department of Physics & Astronomy, University nfCalifornia, BjvoroiJo ' CA 92521 » Dvymfouoot of Astronomy, University of Washington, Seattle, WA 98I95-1580 m Dcyar meut of Astronomy, University of Massachusetts, Amherst, MA 01003 "School of Physics and Astronomy, Cardiff University, Cardiff CF243AA, United Kingdom "Research School of Astronomy & Astrophysics, The Australian National University, ACT 20ll,Australia o /&mmoietioo of Universities for D,maozoh in Astronomy, Washington, DC 20005 14 Inatitntv for Astronomy, University of Hawaii, Houvbdn, ED 00822 "Department cf Astronomy, New Mexico State University, Las Cruces, lHb888083 "European Southern Observatory, QarchingboiDX0ooheu.83740Germany "National Optical Astronomy Observatories, Tucson, AZ 85726-6732 "Department of Physics, University of Oxford, Oxford O}Cl32U, United Kingdom "NASA—Jet Propulsion Laboratory, y*ovdouo. CA 91109 oo Crrcn IhboloInter-American Observatory, La Serena, Chile 2z 0ASA—Ames Research Center, Moffett Field, CA 94035
-2— ABSTRACT We present grism spectra of emission—line galaxies (ELGs) from 0.6-1.6 microns from the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). These new infrared grism data augment previous optical Advanced Camera for Surveys G800L (0.6-0.95 micron) grism data in GOODS—South, extending the wavelength covereage well past the G800L red cutoff. The ERS grism field was observed at a depth of 2 orbits per grism, yielding spectra of hundreds of faint objects, a subset of which are presented here. ELGs are studied via the Ha, [O iii ], and [Oil] emission lines detected in the redshift ranges 0.2 10"M;) ELGs are generally lower than their lower mass counterparts, in agreement with recent studies by Zheng et al. (2007) and Damen et al. (2009). These data demonstrate the effieciency of the WFC3 grisms in detecting star—forming galaxies at 2-0.22.0. This work sets the stage for larger area and deeper studies of star—forming galaxies with WFC3 in the future, which will serve to greatly increase the sample and statistics and will probe even fainter and less massive sources. This research was supported in part by an appointment to the NASA Postdoctoral Program at Goddard Space Flight Center, administered by Oak Ridge Associated Universities through a contract with NASA (ANS). This paper is based on Early Release Science observations made by the WFC3 Scientific Oversight Committee. We are grateful to the Director of the Space Telescope Science Institute for awarding Director's Discretionary time for this program. Support for program #11359 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
-9—
WFC3—ERS Loyout in GOODS—S
—27.7—
—27.8
—27.9 rs
53.25
53.15
53.05 RA
Fig. I.— ERS IT Layout in GOODS—South. Grey area is ACS GOODS—South with the numbers for that dataset. Yellow areas are the five ACS PEARS grism fields; the black box IT is ACS HUDF. The WFC3 ERS 11 UVIS fields are outlined in blue, and WFC3 ERS IR IT fields are outlined in red. The green box is the WFC3 ERS IR grism field.
_10—
50 G800Li
7; '
ID 370 Z_-0.610 19.5
G 102 Ho
40
G 141
iC
30
[Sill] -
10 . 6000
ad
.
. 8000
10000 12000 14000 Wavelength (A)
ID 258 zV =0.998 m,,, .=24.3
G102
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G141
E 1.51.00.5-
H. (011)
OVA, 0.0 6000
2.5
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Wavelength (A)
G800L
16000
ID 454 z,,—=0.852 m,,,.=22.8
0102 [Oily]
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G141 H.
1.5 [011]
1.0
X 0.5 6000
8000
10000 12000 14000 16000 Wavelength (A)
Fig. 2.— Three example grism spectra for ELGs (Table 1 Objects 176308, 119213, 199380 from top to bottom) pre-selected from the ACS PEARS grism ELG study of Straughn et al. (2009). Compared to ACS G800L., the higher-resolution WFC3 grisms allow detection of the [S II] and [S III] lines, and also are able to resolve the [0 in ] AA4959A, 500 71A lines (middle panel), which are blended in the C800L data.
-11—
—6 5 4 3 2
0 8000
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12000 14000 Wavelength (A)
16000
10000
12000 14000 Wavelength (A)
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4 3
2-0 2
rk.
0 8000
3.0 ID 251 G 102
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T 2.0 E
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G141
1.5 'H.
1.0 0.5 0.0
s ,tom
9000 10000 11000 12000 13000 14000 Wavelength (A)
Fig. 3.— Three example grism spectra for ELGs with detected emission lines only in the IR grisms. The 12 ELGs with lines only in the IR have an average continuum magnitude of AB(F098M) =22.8 mag and an average redshift of 1.27.
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10 8 6 E z z 4 2 OL 0.0
0.5
1.0 Redshift
1.5
2.0
Fig. 4.— Grism redshift distribution of WFC3 ELGs. The Ha [0 111 ] and [0 11] emission lines are visible in the WFC grisms at redshifts 0.2
