22 research outputs found
Hubble Space Telescope WFC3 Early Release Science: Emission-Line Galaxies from Infrared Grism Observations
We present grism spectra of emission-line galaxies (ELGs) from 0.6-1.6
microns from the Wide Field Camera 3 on the Hubble Space Telescope. These new
infrared grism data augment previous optical Advanced Camera for Surveys G800L
0.6-0.95 micron grism data in GOODS-South from the PEARS program, 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, [OIII], and [OII] emission lines detected in the redshift ranges 0.2<z<1.4,
1.2<z<2.2 and 2.0<z<3.3 respectively in the G102 (0.8-1.1 microns; R~210) and
G141 (1.1-1.6 microns; R~130) grisms. The higher spectral resolution afforded
by the WFC3 grisms also reveals emission lines not detectable with the G800L
grism (e.g., [SII] and [SIII] lines). From these relatively shallow
observations, line luminosities, star-formation rates, and grism spectroscopic
redshifts are determined for a total of 48 ELGs to m(AB)~25 mag. Seventeen
GOODS-South galaxies that previously only had photometric redshifts now have
new grism-spectroscopic redshifts, in some cases with large corrections to the
photometric redshifts (Delta(z)~0.3-0.5). Additionally, one galaxy had no
previously-measured redshift but now has a secure grism-spectroscopic redshift,
for a total of 18 new GOODS-South spectroscopic redshifts. The faintest source
in our sample has a magnitude m(AB)=26.9 mag. The ERS grism data also reflect
the expected trend of lower specific star formation rates for the highest mass
galaxies in the sample as a function of redshift, consistent with downsizing
and discovered previously from large surveys. These results demonstrate the
remarkable efficiency and capability of the WFC3 NIR grisms for measuring
galaxy properties to faint magnitudes and redshifts to z>2.Comment: Accepted for publication in AJ. Updated to include referee comments.
Updated sample using improved reduction contains 23 new galaxies (Table 1;
Figures 2 & 3
The Hubble Space Telescope Wide Field Camera 3 Early Release Science data: Panchromatic Faint Object Counts for 0.2-2 microns wavelength
We describe the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) Early
Release Science (ERS) observations in the Great Observatories Origins Deep
Survey (GOODS) South field. The new WFC3 ERS data provide calibrated, drizzled
mosaics in the UV filters F225W, F275W, and F336W, as well as in the near-IR
filters F098M (Ys), F125W (J), and F160W (H) with 1-2 HST orbits per filter.
Together with the existing HST Advanced Camera for Surveys (ACS) GOODS-South
mosaics in the BViz filters, these panchromatic 10-band ERS data cover 40-50
square arcmin at 0.2-1.7 {\mu}m in wavelength at 0.07-0.15" FWHM resolution and
0.090" Multidrizzled pixels to depths of AB\simeq 26.0-27.0 mag (5-{\sigma})
for point sources, and AB\simeq 25.5-26.5 mag for compact galaxies.
In this paper, we describe: a) the scientific rationale, and the data taking
plus reduction procedures of the panchromatic 10-band ERS mosaics; b) the
procedure of generating object catalogs across the 10 different ERS filters,
and the specific star-galaxy separation techniques used; and c) the reliability
and completeness of the object catalogs from the WFC3 ERS mosaics. The
excellent 0.07-0.15" FWHM resolution of HST/WFC3 and ACS makes star- galaxy
separation straightforward over a factor of 10 in wavelength to AB\simeq 25-26
mag from the UV to the near-IR, respectively.Comment: 51 pages, 71 figures Accepted to ApJS 2011.01.2
The Hubble Space Telescope wide field camera 3 early release science data: Panchromatic faint object counts for 0.2-2 μm wavelength
We describe the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) Early Release Science (ERS) observations in the Great Observatories Origins Deep Survey (GOODS) South field. The new WFC3 ERS data provide calibrated, drizzled mosaics in the UV filters F225W, F275W, and F336W, as well as in the near-IR filters F098M (Ys ), F125W (J), and F160W (H) with 1-2 HST orbits per filter. Together with the existing HST Advanced Camera for Surveys (ACS) GOODS-South mosaics in the BViz filters, these panchromatic 10-band ERS data cover 40-50arcmin2 at 0.2-1.7 μm in wavelength at 007-015 FWHM resolution and 0090 Multidrizzled pixels to depths of AB≃ 26.0-27.0mag (5σ) for point sources, and AB≃ 25.5-26.5mag for compact galaxies. In this paper, we describe (1) the scientific rationale, and the data taking plus reduction procedures of the panchromatic 10-band ERS mosaics, (2) the procedure of generating object catalogs across the 10 different ERS filters, and the specific star-galaxy separation techniques used, and (3) the reliability and completeness of the object catalogs from the WFC3 ERS mosaics. The excellent 007-015 FWHM resolution of HST/WFC3 and ACS makes star-galaxy separation straightforward over a factor of 10 in wavelength to AB≃ 25-26mag from the UV to the near-IR, respectively. Our main results are: (1) proper motion of faint ERS stars is detected over 6 years at 3.06 ± 0.66masyear-1 (4.6σ), consistent with Galactic structure models; (2) both the Galactic star counts and the galaxy counts show mild but significant trends of decreasing count slopes from the mid-UV to the near-IR over a factor of 10 in wavelength; (3) combining the 10-band ERS counts with the panchromatic Galaxy and Mass Assembly survey counts at the bright end (10mag ≲ AB≲ 20mag) and the Hubble Ultra Deep Field counts in the BVizYsJH filters at the faint end (24mag ≲ AB≲ 30mag) yields galaxy counts that are well measured over the entire flux range 10mag ≲ AB≲ 30mag for 0.2-2 μm in wavelength; (4) simple luminosity+density evolution models can fit the galaxy counts over this entire flux range. However, no single model can explain the counts over this entire flux range in all 10 filters simultaneously. More sophisticated models of galaxy assembly are needed to reproduce the overall constraints provided by the current panchromatic galaxy counts for 10mag ≲ AB≲ 30mag over a factor of 10 in wavelength
The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies,
expounded a compelling and poetic vision for the future of astronomy, calling
for an infrared-optimized space telescope with an aperture of at least .
With the support of their governments in the US, Europe, and Canada, 20,000
people realized that vision as the James Webb Space Telescope. A
generation of astronomers will celebrate their accomplishments for the life of
the mission, potentially as long as 20 years, and beyond. This report and the
scientific discoveries that follow are extended thank-you notes to the 20,000
team members. The telescope is working perfectly, with much better image
quality than expected. In this and accompanying papers, we give a brief
history, describe the observatory, outline its objectives and current observing
program, and discuss the inventions and people who made it possible. We cite
detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space
Telescope Overview, 29 pages, 4 figure
The Science Performance of JWST as Characterized in Commissioning
This paper characterizes the actual science performance of the James Webb
Space Telescope (JWST), as determined from the six month commissioning period.
We summarize the performance of the spacecraft, telescope, science instruments,
and ground system, with an emphasis on differences from pre-launch
expectations. Commissioning has made clear that JWST is fully capable of
achieving the discoveries for which it was built. Moreover, almost across the
board, the science performance of JWST is better than expected; in most cases,
JWST will go deeper faster than expected. The telescope and instrument suite
have demonstrated the sensitivity, stability, image quality, and spectral range
that are necessary to transform our understanding of the cosmos through
observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures;
https://iopscience.iop.org/article/10.1088/1538-3873/acb29