Abstract. The James Webb Space Telescope (JWST) is a large (6.6 m), cold (<50 K), infrared (IR)-optimized space observatory that will be launched early in the next decade into orbit around the second Earth-Sun Lagrange point. The observatory will have four instruments: a near-IR camera, a near-IR multiobject spectrograph, and a tunable filter imager will cover the wavelength range, 0.6 < λ < 5.0 μm, while the mid-IR instrument will do both imaging and spectroscopy from 5.0 < λ < 29 μm.The JWST science goals are divided into four themes. The key objective of The End of the Dark Ages: First Light and Reionization theme is to identify the first luminous sources to form and to determine the ionization history of the early universe. The key objective of The Assembly of Galaxies theme is to determine how galaxies and the dark matter, gas, stars, metals, morphological structures, Space Science Reviews (2006) and active nuclei within them evolved from the epoch of reionization to the present day. The key objective of The Birth of Stars and Protoplanetary Systems theme is to unravel the birth and early evolution of stars, from infall on to dust-enshrouded protostars to the genesis of planetary systems. The key objective of the Planetary Systems and the Origins of Life theme is to determine the physical and chemical properties of planetary systems including our own, and investigate the potential for the origins of life in those systems. Within these themes and objectives, we have derived representative astronomical observations. To enable these observations, JWST consists of a telescope, an instrument package, a spacecraft, and a sunshield. The telescope consists of 18 beryllium segments, some of which are deployed. The segments will be brought into optical alignment on-orbit through a process of periodic wavefront sensing and control. The instrument package contains the four science instruments and a fine guidance sensor. The spacecraft provides pointing, orbit maintenance, and communications. The sunshield provides passive thermal control. The JWST operations plan is based on that used for previous space observatories, and the majority of JWST observing time will be allocated to the international astronomical community through annual peer-reviewed proposal opportunities.

We report on a complete sample of 7 luminous early-type galaxies in the Hubble Ultra Deep Field (UDF) with spectroscopic redshifts between 1.39 and 2.47 and to K AB < 23. Using the BzK selection criterion we have pre-selected a set of objects over the UDF which fulfill the photometric conditions for being passively evolving galaxies at z > 1.4. Low-resolution spectra of these objects have been extracted from the HST+ACS grism data taken over the UDF by the GRAPES project. Redshift for the 7 galaxies have been identified based on the UV feature at rest frame 2640 < λ < 2850 Å. This feature is mainly due to a combination of FeII, MgI and MgII absorptions which are characteristic of stellar populations dominated by stars older than ∼ 0.5 Gyr. The redshift identification and the passively evolving nature of these galaxies is further supported by the photometric redshifts and by the overall spectral energy distribution (SED), with the ultradeep HST+ACS/NICMOS imaging revealing compact morphologies typical of elliptical/early-type galaxies. From the SED we derive stellar masses of > ∼ 10 11 M ⊙ and ages of ∼ 1 Gyr. Their space density at < z >= 1.7 appears to be roughly a factor of 2-3 smaller than that of their local counterparts, further supporting the notion that such massive and old galaxies are already ubiquitous at early cosmic times. Much smaller effective radii are derived for some of the objects compared to local massive ellipticals, which may be due to morphological K corrections, evolution, or the presence of a central point-like source. Nuclear activity is indeed present in a subset of the galaxies, as revealed by them being hard X-ray sources, hinting to AGN activity having played a role in discontinuing star formation.

This paper presents the Hubble Ultra Deep Field (HUDF), a one million second exposure of an 11 square minute-of-arc region in the southern sky with the Hubble Space Telescope. The exposure time was divided among four filters, F435W (B435), F606W (V606), F775W (i775), and F850LP (z850), to give approximately uniform limiting magnitudes mAB~29 for point sources. The image contains at least 10,000 objects presented here as a catalog. Few if any galaxies at redshifts greater than ~4 resemble present day spiral or elliptical galaxies. Using the Lyman break dropout method, we find 504 B-dropouts, 204 V-dropouts, and 54 i-dropouts. Using these samples that are at different redshifts but derived from the same data, we find no evidence for a change in the characteristic luminosity of galaxies but some evidence for a decrease in their number densities between redshifts of 4 and 7. The ultraviolet luminosity density of these samples is dominated by galaxies fainter than the characteristic luminosity, and the HUDF reveals considerably more luminosity than shallower surveys. The apparent ultraviolet luminosity density of galaxies appears to decrease from redshifts of a few to redshifts greater than 6. The highest redshift samples show that star formation was already vigorous at the earliest epochs that galaxies have been observed, less than one billion years after the Big Bang.Comment: 44 pages, 18 figures, to appear in the Astronomical Journal October 200

This Special Issue of the Astrophysical Journal Letters is dedicated to presenting initial results from the Great Observatories Origins Deep Survey (GOODS) that are primarily, but not exclusively, based on multi-band imaging data obtained with the Hubble Space Telescope (HST) and the Advanced Camera for Surveys (ACS). The survey covers roughly 320 square arcminutes in the ACS F435W, F606W, F814W, and F850LP bands, divided into two well-studied fields. Existing deep observations from the Chandra X-ray Observatory (CXO) and groundbased facilities are supplemented with new, deep imaging in the optical and

We identify 73 z ∼ 7 and 59 z ∼ 8 candidate galaxies in the reionization epoch, and use this large 26-29.4 AB mag sample of galaxies to derive very deep luminosity functions to < −18 AB mag and the star formation rate density at z ∼ 7 and z ∼ 8 (just 800 Myr and 650 Myr after recombination, respectively). The galaxy sample is derived using a sophisticated Lyman-Break technique on the full two-year WFC3/IR and ACS data available over the HUDF09 (∼29.4 AB mag, 5σ), two nearby HUDF09 fields (∼29 AB mag, 5σ, 14 arcmin 2 ) and the wider area ERS (∼27.5 AB mag, 5σ, ∼40 arcmin 2 ). The application of strict optical non-detection criteria ensures the contamination fraction is kept low (just ∼7% in the HUDF). This very low value includes a full assessment of the contamination from lower redshift sources, photometric scatter, AGN, spurious sources, low mass stars, and transients (e.g., SNe). From careful modeling of the selection volumes for each of our search fields we derive luminosity functions for galaxies at z ∼ 7 and z ∼ 8 to < −18 AB mag. The faint-end slopes α at z ∼ 7 and z ∼ 8 are uncertain but very steep at α = −2.01 ± 0.21 and α = −1.91 ± 0.32, respectively. Such steep slopes contrast to the local α ∼ −1.4 and may even be steeper than that at z ∼ 4 where α = −1.73 ± 0.05. With such steep slopes (α −1.7) lower luminosity galaxies dominate the galaxy luminosity density during the epoch of reionization. The star formation rate densities derived from these new z ∼ 7 and z ∼ 8 luminosity functions are consistent with the trends found at later times (lower redshifts). We find reasonable consistency, with the SFR densities implied from reported stellar mass densities, being only ∼40% higher at z < 7. This suggests that (1) the stellar mass densities inferred from the Spitzer IRAC photometry are reasonably accurate and (2) that the IMF at very high redshift may not be very different from that at later times. HUDF09 observationsThe full two-year WFC3/IR observations from the HUDF09 program consist of 192 orbits of ultra-deep WFC3/IR data over the HUDF09 (111 orbits), HUDF09-

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We present a comprehensive analysis of z > 8 galaxies based on ultra-deep WFC3/IR data. We constrain the evolution of the UV luminosity function (LF) and luminosity densities from z ∼ 11 to z ∼ 8 by exploiting all the WFC3/IR data over the Hubble Ultra-Deep Field from the HUDF09 and the new HUDF12 program, in addition to the HUDF09 parallel field data, as well as wider area WFC3/IR imaging over GOODS-South. Galaxies are selected based on the Lyman Break Technique in three samples centered around z ∼ 9, z ∼ 10 and z ∼ 11, with seven z ∼ 9 galaxy candidates, and one each at z ∼ 10 and z ∼ 11. We confirm a new z ∼ 10 candidate (with z = 9.8 ± 0.6) that was not convincingly identified in our first z ∼ 10 sample. The deeper data over the HUDF confirms all our previous z 7.5 candidates as genuine high-redshift candidates, and extends our samples to higher redshift and fainter limits (H 160 ∼ 29.8 mag). We perform one of the first estimates of the z ∼ 9 UV LF and improve our previous constraints at z ∼ 10. Extrapolating the lower redshift UV LF evolution should have revealed 17 z ∼ 9 and 9 z ∼ 10 sources, i.e., a factor ∼ 3× and 9× larger than observed. The inferred star-formation rate density (SFRD) in galaxies above 0.7 M ⊙ yr −1 decreases by 0.6 ± 0.2 dex from z ∼ 8 to z ∼ 9, in good agreement with previous estimates. The low number of sources found at z > 8 is consistent with a very rapid build-up of galaxies across z ∼ 10 to z ∼ 8. From a combination of all current measurements, we find a best estimate of a factor 10× decrease in the SFRD from z ∼ 8 to z ∼ 10, following (1 + z) −11.4±3.1 . Our measurements thus confirm our previous finding of an accelerated evolution beyond z ∼ 8, and signify a rapid build-up of galaxies with M UV < −17.7 mag within only ∼ 200 Myr from z ∼ 10 to z ∼ 8, in the heart of cosmic reionization.