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277 results on '"Windhorst, R. A."'

252. The Grism Spectroscopy of the Hubble Ultra Deep Fields

Author

Xu, C., Pirzkal, N., Malhotra, S., Rhoads, J., Anton Koekemoer, Ferguson, H., Moustakas, L., Panagia, N., Stiavelli, M., Walsh, J., Daddi, E., Kuemel, M., Cimatti, A., Vernet, J., Windhorst, R., Gardner, J., Gronwall, C., Haiman, Z., Pasquali, A., Tsvetanov, Z., and Yan, H.

255. Measuring galaxy morphology at $z〉1$. I - calibration of automated proxies

Author

Huertas-Company, M., Kaviraj, S., Mei, S., O Connell, R. W., Windhorst, R., Cohen, S. H., Hathi, P., Anton Koekemoer, Licitra, R., Raichoor, A., and Rutkowski, M. J.

Subjects
Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

[abridged] New near-infrared surveys, using the HST, offer an unprecedented opportunity to study rest-frame optical galaxy morphologies at z>1 and to calibrate automated morphological parameters that will play a key role in classifying future massive datasets like EUCLID or LSST. We study automated parameters (e.g. CAS, Gini, M20) of massive galaxies at 11: bulge-dominated systems have systematically higher concentration and Gini coefficients and are less asymmetric and rounder than disk-dominated galaxies. However, at z>1, galaxies are, on average, 50% more asymmetric and have Gini and M20 values that are 10% higher and 20% lower respectively. In bulge-dominated galaxies, morphological parameters derived from the rest-frame UV and optical wavelengths are well correlated; however late-type galaxies exhibit higher asymmetry and clumpiness when measured in the rest-frame UV. We find that broad morphological classes (e.g. bulge vs. disk dominated) can be distinguished using parameters with high (80%) purity and completeness of 80%. In a similar vein, irregular disks and mergers can also be distinguished from bulges and regular disks with a contamination lower than 20%. However, mergers cannot be differentiated from the irregular morphological class using these parameters, due to increasingly asymmetry of non-interacting late-type galaxies at z>1. Our automated procedure is applied to the CANDELS GOODS-S field and compared with the visual classification recently released on the same area getting similar results., Comment: submitted to MNRAS

257. VLA and ALMA Imaging of Intense, Galaxy-Wide Star Formation in z ~ 2 Galaxies

Author

Rujopakarn, W., Dunlop, J. S., Rieke, G. H., Ivison, R. J., Cibinel, A., Nyland, K., Preshanth Jagannathan, Silverman, J. D., Alexander, D. M., Biggs, A. D., Bhatnagar, S., Ballantyne, D. R., Dickinson, M., Elbaz, D., Geach, J. E., Hayward, C. C., Kirkpatrick, A., Mclure, R. J., Michalowski, M. J., Miller, N. A., Narayanan, D., Owen, F. N., Pannella, M., Papovich, C., Pope, A., Rau, U., Robertson, B. E., Scott, D., Swinbank, A. M., Werf, P., Kampen, E., and Windhorst, R. A.

258. Chronos: A NIR spectroscopic galaxy survey to probe the most fundamental stages of galaxy evolution

Author

Ferreras, I., Cropper, M., Sharples, R., Bland-Hawthorn, J., Bruzual, G., Charlot, S., Conselice, C. J., Driver, S., Dunlop, J., Hopkins, A. M., Kaviraj, S., Kitching, T., Barbera, F. La, Lahav, O., Pasquali, A., Serjeant, S., Silk, J., Windhorst, R., Ferreras, I., Cropper, M., Sharples, R., Bland-Hawthorn, J., Bruzual, G., Charlot, S., Conselice, C. J., Driver, S., Dunlop, J., Hopkins, A. M., Kaviraj, S., Kitching, T., Barbera, F. La, Lahav, O., Pasquali, A., Serjeant, S., Silk, J., and Windhorst, R.

Abstract

We propose a dedicated, ultra-deep spectroscopic survey in the near infrared (NIR), that will target a mass-limited sample of galaxies during two of the most fundamental epochs of cosmic evolution: the formation of the first galaxies (at z ≳ 6; comsmic dawn), and at the peak of galaxy formation activity (at redshift z∼ 1–3; cosmic noon). By way of NIR observations (λ= 0.8–2μ m), it is possible to study the UV Lyman-α region in the former, and the optical rest-frame in the latter, allowing us to extract fundamental observables such as gas and stellar kinematics, chemical abundances, and ages, providing a unique legacy database covering these two crucial stages of cosmic evolution. The need to work in the NIR at extremely low flux levels makes a ground-based approach unfeasible due to atmospheric emission and absorption. Only with the largest facilities of the future (e.g. ELT) will be possible to observe a reduced set of targets, comprising at most of order thousands of galaxies. Likewise, from space, the small field of view of JWST and its use as a general purpose facility will yield a rather small set of high quality NIR spectra of distant galaxies (in the thousands, at best). Our project (codename Chronos) aims to produce ∼ 1 million high quality spectra, with a high S/N in the continuum, where information about the underlying stellar populations is encoded. The main science drivers are: The connection between the star formation history and the mass assembly history.The role of AGN and supernova feedback in shaping the formation histories of galaxies, with a quantitative estimate of quenching timescales.The formation of the first galaxies.The source of reionization.Evolution of the metallicity-mass relation, including [α/Fe] and individual abundances.Precision cosmology through detailed studies of the “baryon physics” of galaxy formation, probing the power spectrum over scales k∼ 1 Mpc− 1

271. Chronos: A NIR spectroscopic galaxy survey to probe the most fundamental stages of galaxy evolution.

Author

Ferreras, I., Cropper, M., Sharples, R., Bland-Hawthorn, J., Bruzual, G., Charlot, S., Conselice, C. J., Driver, S., Dunlop, J., Hopkins, A. M., Kaviraj, S., Kitching, T., Barbera, F. La, Lahav, O., Pasquali, A., Serjeant, S., Silk, J., and Windhorst, R.

Subjects
*GALACTIC evolution, *GALAXIES, *PHYSICAL cosmology, *GALAXY formation, *STELLAR populations, *GALAXY spectra
Abstract

We propose a dedicated, ultra-deep spectroscopic survey in the near infrared (NIR), that will target a mass-limited sample of galaxies during two of the most fundamental epochs of cosmic evolution: the formation of the first galaxies (at z ≳ 6; cosmic dawn), and at the peak of galaxy formation activity (at redshift z ∼ 1–3; cosmic noon). By way of NIR observations (λ= 0.8–2μ m), it is possible to study the UV Lyman-α region in the former, and the optical rest-frame in the latter, allowing us to extract fundamental observables such as gas and stellar kinematics, chemical abundances, and ages, providing a unique legacy database covering these two crucial stages of cosmic evolution. The need to work in the NIR at extremely low flux levels makes a ground-based approach unfeasible due to atmospheric emission and absorption. Only with the largest facilities of the future (e.g. ELT) will be possible to observe a reduced set of targets, comprising at most of order thousands of galaxies. Likewise, from space, the small field of view of JWST and its use as a general purpose facility will yield a rather small set of high quality NIR spectra of distant galaxies (in the thousands, at best). Our project (codename Chronos) aims to produce ∼ 1 million high quality spectra, with a high S/N in the continuum, where information about the underlying stellar populations is encoded. The main science drivers are: The connection between the star formation history and the mass assembly history. The role of AGN and supernova feedback in shaping the formation histories of galaxies, with a quantitative estimate of quenching timescales. The formation of the first galaxies. The source of reionization. Evolution of the metallicity-mass relation, including [α/Fe] and individual abundances. Precision cosmology through detailed studies of the "baryon physics" of galaxy formation, probing the power spectrum over scales k ∼ 1 Mpc− 1. [ABSTRACT FROM AUTHOR]

Published
2021
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272. Deep Extragalactic VIsible Legacy Survey (DEVILS): Consistent multi-wavelength photometry for the DEVILS regions (COSMOS, XMMLSS & ECDFS)

Author

M. Siudek, B. Häußler, Abdolhosein Hashemizadeh, Mattia Vaccari, Martin Meyer, Peter Hurley, Benne W. Holwerda, C. Lidman, Aaron S. G. Robotham, Sabine Bellstedt, Caroline Foster, N. J. Adams, Natasha Maddox, Matías Bravo, Luke J. M. Davies, J. E. Thorne, Mario Radovich, S. Phillipps, Rogier A. Windhorst, Simon P. Driver, Rebecca A. A. Bowler, Luca Cortese, Matt J. Jarvis, Meiert W. Grootes, Maurizio Paolillo, Maciej Bilicki, A Davies, L. J. M., Thorne, J. E., Robotham, A. S. G., Bellstedt, S., Driver, S. P., Adams, N. J., Bilicki, M., Bowler, R. A. A., Bravo, M., Cortese, L., Foster, C., Grootes, M. W., Häußler, B., Hashemizadeh, A., Holwerda, B. W., Hurley, P., Jarvis, M. J., Lidman, C., Maddox, N., Meyer, M., Paolillo, M., Phillipps, S., Radovich, M., Siudek, M., Vaccari, M., and Windhorst, R. A.

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, Astronomy, FOS: Physical sciences, methods: observational, techniques: photometric, catalogues, surveys, galaxies: evolution, galaxies: general, Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Methods observational, Imaging data, Galaxy, Photometry (optics), Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Cosmos (category theory), 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The Deep Extragalactic VIsible Legacy Survey (DEVILS) is an ongoing high-completeness, deep spectroscopic survey of $\sim$60,000 galaxies to Y$, Comment: 33 pages, 22 figures, Accepted to MNRAS

Published
2021
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273. FIGS:spectral fitting constraints on the star formation history of massive galaxies since the cosmic noon

Author

Steven L. Finkelstein, Andrea Cimatti, Anna Pasquali, Sangeeta Malhotra, Göran Östlin, Nimish P. Hathi, John Pharo, Barry Rothberg, Rogier A. Windhorst, Robert W. O'Connell, Ignacio Ferreras, Anton M. Koekemoer, Norman A. Grogin, Bhavin Joshi, Lise Christensen, Russell E. Ryan, Nor Pirzkal, James E. Rhoads, Keunho Kim, Ferreras I., Pasquali A., Pirzkal N., Pharo J., Malhotra S., Rhoads J., Hathi N., Windhorst R., Cimatti A., Christensen L., Finkelstein S.L., Grogin N., Joshi B., Kim K., Koekemoer A., O'Connell R., Ostlin G., Rothberg B., and Ryan R.

Subjects
formation [galaxies], media_common.quotation_subject, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Noon, 01 natural sciences, Cosmology, Spitzer Space Telescope, galaxies: high-redshift, 0103 physical sciences, galaxies: formation, Astrophysics::Solar and Stellar Astrophysics, Spectral fitting, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, evolution [galaxies], media_common, Physics, COSMIC cancer database, 010308 nuclear & particles physics, Star formation, Astronomy, Astronomy and Astrophysics, stellar content [galaxies], Astrophysics - Astrophysics of Galaxies, Galaxy, Universe, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), galaxies: stellar content, Astrophysics::Earth and Planetary Astrophysics, galaxies: evolution, high-redshift [galaxies]
Abstract

We constrain the stellar population properties of a sample of 52 massive galaxies, with stellar mass log Ms>10.5, over the redshift range 0.5, Comment: 20 pages, 12+3 figures, 4+3 tables. MNRAS, in press

Published
2019

274. A Catalog of Emission-line Galaxies from the Faint Infrared Grism Survey: Studying Environmental Influence on Star Formation

Author

Caryl Gronwall, Steven L. Finkelstein, Anna Pasquali, Ignacio Ferreras, Amber Straughn, Vithal Tilvi, Anton M. Koekemoer, James E. Rhoads, John Pharo, Nimish P. Hathi, Andrea Cimatti, Lise Christensen, Russell E. Ryan, Rogier A. Windhorst, Robert W. O'Connell, Mark Smith, Pascale Hibon, Rebecca L. Larson, Sangeeta Malhotra, Santosh Harish, Norbert Pirzkal, Pharo J., Malhotra S., Rhoads J.E., Pirzkal N., Finkelstein S.L., Ryan R., Cimatti A., Christensen L., Hathi N., Koekemoer A., Harish S., Smith M., Straughn A., Windhorst R., Ferreras I., Gronwall C., Hibon P., Larson R., O'Connell R., Pasquali A., and Tilvi V.

Subjects
Physics, 010504 meteorology & atmospheric sciences, Stellar mass, Star formation, FOS: Physical sciences, Flux, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Emission line galaxies, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Galaxy, Space and Planetary Science, Galaxy evolution, Astrophysics of Galaxies (astro-ph.GA), Galaxy group, 0103 physical sciences, Galaxy formation and evolution, Galaxy environment, Emission spectrum, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Line (formation)
Abstract

We present a catalog of 208 $0.3 < z < 2.1$ Emission Line Galaxies (ELG) selected from 1D slitless spectroscopy obtained using Hubble's WFC3 G102 grism, as part of the Faint Infrared Grism Survey (FIGS). We identify ELG candidates by searching for significant peaks in all continuum-subtracted G102 spectra, and, where possible, confirm candidates by identifying consistent emission lines in other available spectra or with published spectroscopic redshifts. We provide derived emission line fluxes and errors, redshifts, and equivalent widths (EW) for H$\alpha$ $\lambda6563$, [OIII]$\lambda\lambda4959,5007$, and [OII]$\lambda\lambda3727$ emission lines, for emission line galaxies down to AB(F105W) $ > 28$ and $> 10^{-17}$ erg cm$^{-2}$ s$^{-1}$ line flux. We use the resulting line catalog to investigate a possible relationship between line emission and a galaxy's environment. We use 7th-nearest-neighbor distances to investigate the typical surroundings of ELGs compared to non-ELGs, and we find that [OIII] emitters are preferentially found at intermediate galaxy densities near galaxy groups. We characterize these ELGs in terms of the galaxy specific star formation rate (SSFR) versus stellar mass, and find no significant influence of environment on that relation. We calculate star formation rates (SFR), and find no dependence of SFR on local galaxy surface density for $0.3 < z < 0.8$ H$\alpha$ emitters and for $0.8, Comment: Accepted to ApJ. 36 pages, 14 figures

Published
2020

275. First results from Faint Infrared Grism Survey (FIGS): first simultaneous detection of Lyman-alpha emission and Lyman break from a galaxy at z=7.51

Author

James E. Rhoads, Barry Rothberg, G. Östlin, Huan Yang, John Pharo, Lise Christensen, Jeremy R. Walsh, Bhavin Joshi, Vithal Tilvi, Nimish P. Hathi, Rachael Livermore, Robert W. O'Connell, Nadia L. Zakamska, Anton M. Koekemoer, Norman A. Grogin, Amber N. Straughn, Rogier A. Windhorst, R. E. Ryan, Alessandro Cimatti, P. Hibon, Steve Finkelstein, Jonathan P. Gardner, Caryl Gronwall, Nor Pirzkal, Sangeeta Malhotra, University of Arizona, Space Telescope Science Institute (STSci), Green Infrastructure approach: linking environmental with social aspects in studying and managing urban forests, COST, European Cooperation in Science and Technology, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Département Hospitalo-Universitaire Fight Ageing and STress (DHU FAST ), Université Pierre et Marie Curie - Paris 6 (UPMC), CHU Pitié-Salpêtrière [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU), FOI, Linköping University (LIU), INAF - Osservatorio Astronomico di Bologna (OABO), Istituto Nazionale di Astrofisica (INAF), Oskar Klein Centre [Stockholm], Stockholm University, Department of Physics, Durham University, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Service de gériatrie à orientation cardiologique [CHU Pitié-Salpêtrière], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-CHU Pitié-Salpêtrière [AP-HP], Sorbonne Université (SU)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU), Service de Médecine Gériatrique [CHU Pitié-Salpêtrière], Sorbonne Université (SU)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP), Tilvi, V., Pirzkal, N., Malhotra, S., Finkelstein, S.L., Rhoads, J.E., Windhorst, R., Grogin, N.A., Koekemoer, A., Zakamska, N.L., Ryan, R., Christensen, L., Hathi, N., Pharo, J., Joshi, B., Yang, H., Gronwall, C., Cimatti, A., Walsh, J., O'Connell, R., Straughn, A., Ostlin, G., Rothberg, B., Livermore, R.C., Hibon, P., and Gardner, Jonathan P.

Subjects
Active galactic nucleus, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Spectral line, galaxies: high-redshift, 0103 physical sciences, Emission spectrum, 010303 astronomy & astrophysics, Reionization, Astrophysics::Galaxy Astrophysics, Line (formation), Physics, 010308 nuclear & particles physics, Astronomy and Astrophysics, Astronomy and Astrophysic, Astrophysics - Astrophysics of Galaxies, early universe, Redshift, Galaxy, Grism, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), dark ages, reionization, first star, intergalactic medium, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Galaxies at high redshifts provide a valuable tool to study cosmic dawn, and therefore it is crucial to reliably identify these galaxies. Here, we present an unambiguous and first simultaneous detection of both the Lyman-alpha emission and the Lyman break from a z = 7.512+/- 0.004 galaxy, observed in the Faint Infrared Grism Survey (FIGS). These spectra, taken with G102 grism on Hubble Space Telescope (HST), show a significant emission line detection (6 sigma) in multiple observational position angles (PA), with total integrated Ly{\alpha} line flux of 1.06+/- 0.12 e10-17erg s-1cm-2. The line flux is nearly a factor of four higher than the previous MOSFIRE spectroscopic observations of faint Ly{\alpha} emission at {\lambda} = 1.0347{\mu}m, yielding z = 7.5078+/- 0.0004. This is consistent with other recent observations implying that ground-based near-infrared spectroscopy underestimates total emission line fluxes, and if confirmed, can have strong implications for reionization studies that are based on ground-based Lyman-{\alpha} measurements. A 4-{\sigma} detection of the NV line in one PA also suggests a weak Active Galactic Nucleus (AGN), potentially making this source the highest-redshift AGN yet found. Thus, this observation from the Hubble Space Telescope clearly demonstrates the sensitivity of the FIGS survey, and the capability of grism spectroscopy to study the epoch of reionization., Comment: Published in ApJL; matches published version

Published
2016
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276. GRAPES, Grism Spectroscopy of the Hubble Ultra Deep Field: Description and Data Reduction

Author

Massimo Stiavelli, Andrea Cimatti, Sangeeta Malhotra, Caryl Gronwall, N. Pirzkal, Joel Vernet, Emanuele Daddi, Zoltan Haiman, S. di Serego Alighieri, M. Kümmel, Zlatan Tsvetanov, Jeremy R. Walsh, Jonathan P. Gardner, Henry C. Ferguson, James E. Rhoads, Chun Xu, Anna Pasquali, Anton M. Koekemoer, Leonidas A. Moustakas, Rogier A. Windhorst, Haojing Yan, Nino Panagia, Pirzkal N., Xu C., Malhotra S., Rhoads J. E., Koekemoer A. M., Moustakas L. A., Walsh J. R., Windhorst R. A., Daddi E., Cimatti A., Ferguson H. C., Gardner Jonathan P., Gronwall C., Haiman Z., Kümmel M., Panagia N., Pasquali A., Stiavelli M., di Serego Alighieri S., Tsvetanov Z., Vernet J., and Yan H.

Subjects
Physics, Astrophysics (astro-ph), Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Hubble Ultra-Deep Field, Lambda, Galaxy, Redshift, Spectral line, Grism, Space and Planetary Science, Spectroscopy, Astrophysics::Galaxy Astrophysics, Data reduction
Abstract

We present deep unbiased spectroscopy of the Hubble Ultra Deep Field (UDF) carried out using the slitless grism spectroscopy mode of the Advance Camera for Surveys on the Hubble Space Telescope (HST). The GRIsm ACS Program for Extragalactic Science (GRAPES) achieves continuum detection as faint as $z_{AB}=27.2$ using 40 orbits ($9.2 \times 10^4$ seconds) on HST. The data were taken at four orientation angles to correct for the overlap of spectra. GRAPES data provide a unique, uninterrupted, low resolution (R=100) spectral coverage for $5500��< ��< 10500��$, and allow us to detect high redshift galaxies at $4 < z < 7$ whether they have $\lya$ lines or just show the Lyman Break, as well as find low luminosity AGNs in an unbiased fashion. This paper describes in detail the observations and the data reduction, and examines the quality of the extracted spectra. Subsequent papers will deal with the analysis of the data. The extracted and calibrated GRAPES spectra will be available from MAST at STScI., Accepted by ApJS

Published
2004

277. Passively evolving early-type galaxies at 1.4 ≲ z ≲ 2.5 in the Hubble Ultra Deep Field

Author

Alvio Renzini, Massimo Stiavelli, James E. Rhoads, Nino Panagia, Henry C. Ferguson, Anna Pasquali, Emanuele Daddi, Anton M. Koekemoer, S. di Serego Alighieri, N. Pirzkal, Rogier A. Windhorst, Chun Xu, Marcella Brusa, Leonidas A. Moustakas, Andrea Cimatti, Sangeeta Malhotra, Daddi E., Renzini A., Pirzkal N., Cimatti A., Malhotra S., Stiavelli M., Xu C., Pasquali A., Rhoads J. E., Brusa M., di Serego Alighieri S., Ferguson H. C., Koekemoer A. M., Moustakas L. A., Panagia N., and Windhorst R.

Subjects
Physics, COSMIC cancer database, Star formation, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Rest frame, Hubble Ultra-Deep Field, Galaxy, Redshift, Spectral line, Grism, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

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 K1.4. 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=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., Comment: 18 pages, 15 figures, ApJ in press

Published
2005

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