Student or educator? Sign up with your school email and get 6 months of Pro free.
CoChat
Sign Up
Cited by 866

The DOI matches its Crossref record; 50 of the 50 references it cites were found in a registry or an index.

Passively Evolving Early‐Type Galaxies at 1.4 ≲z≲ 2.5 in the Hubble Ultra Deep Field

Open access
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., Windhorst, R. A.·2005·The Astrophysical Journal
DOI 10.1086/430104
Open this paper in CoChat — free account

Abstract

We report on a complete sample of seven 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 preselected 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 Hubble Space Telescope ( HST ) ACS grism data taken over the UDF by the Grism ACS Program for Extragalactic Science (GRAPES) project. Redshifts for the seven 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 Fe II, Mg I, and Mg II 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 pointlike source. Nuclear activity is indeed present in a subset of the galaxies, as revealed by the fact that they are hard X-ray sources, which suggests that active galactic nucleus (AGN) activity may have played a role in discontinuing star formation.

Overview

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Integrity signals

Registry

Crossref · 10.1086/430104

Cites

50 of 50 references verified0 citation errors · 0 not checkable

Statistics

Verification

Claims the paper makes

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

The self-check needs the paper’s full text.

Citations

Cites

Show all 50 references

Cited by

See all 866

Metadata

Authors
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., & Windhorst, R. A.
Venue
The Astrophysical Journal
Publisher
American Astronomical Society
Published
2005-06-20
Volume
626
Issue
2
Pages
680-697
ISSN
  • 0004-637X (ISSN-L)
  • 1538-4357
DOI
10.1086/430104
OpenAlex
W2132651645
Cited by
866
References
50
FWCI
17.18
Type
journal article
Language
en
Open access
bronze

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review

How to cite

Cite CoChat for the checks on this page, and the paper for its own findings.

This page
CoChat. (2026). Citation check: Passively Evolving Early‐Type Galaxies at 1.4 ≲z≲ 2.5 in the Hubble Ultra Deep Field. https://app.cochat.ai/papers/10.1086/430104
The paper
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., & Windhorst, R. A. (2005). Passively Evolving Early‐Type Galaxies at 1.4 ≲z≲ 2.5 in the Hubble Ultra Deep Field. The Astrophysical Journal. https://doi.org/10.1086/430104

Data sources

Bibliographic data: Semantic Scholar, OpenAlex, Crossref.

Contains information from the Semantic Scholar Academic Graph Datasets, made available under the ODC Attribution License (ODC-BY 1.0).

Semantic Scholar’s data is described in: Kinney, R., et al. (2023). The Semantic Scholar Open Data Platform. arXiv:2301.10140.