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Cited by 335

The DOI matches its Crossref record; 94 of the 94 references it cites were found in a registry or an index.

Multiwavelength Study of Massive Galaxies at z ∼ 2. II. Widespread Compton‐thick Active Galactic Nuclei and the Concurrent Growth of Black Holes and Bulges

Open access
Daddi, E., Alexander, D. M., Dickinson, M., Gilli, R., Renzini, A., Elbaz, D., Cimatti, A., Chary, R., Frayer, D., Bauer, F. E., Brandt, W. N., Giavalisco, M., Grogin, N. A., Huynh, M., Kurk, J., Mignoli, M., Morrison, G., Pope, A., Ravindranath, S.·2007·The Astrophysical Journal
DOI 10.1086/521820
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Abstract

Approximately 20%-30% of 1.4 ≲ z ≲ 2.5 galaxies with K Vega < 22 detected with Spitzer MIPS at 24 μm show excess mid-IR emission relative to that expected based on the rates of star formation measured from other multiwavelength data. These galaxies also display some near-IR excess in Spitzer IRAC data, with an SED peaking longward of 1.6 μm in the rest frame, indicating the presence of warm dust emission usually absent in star-forming galaxies. Stacking Chandra data for the mid-IR excess galaxies yields a significant hard X-ray detection at rest-frame energies >6.2 keV. The stacked X-ray spectrum rises steeply at >10 keV, suggesting that these sources host Compton-thick AGNs with column densities N H ≳ 10 24 cm -2 and an average, unobscured X-ray luminosity L 2-8 keV ≈ (1-4) × 10 43 ergs s -1 . Their sky density (~3200 deg -2 ) and space density (~2.6 × 10 -4 Mpc -3 ) are twice those of X-ray-detected AGNs at z ≈ 2, and much larger than those of previously known Compton-thick sources at similar redshifts. The mid-IR excess galaxies are part of the long sought after population of distant heavily obscured AGNs predicted by synthesis models of the X-ray background. The fraction of mid-IR excess objects increases with galaxy mass, reaching ~50%-60% for M ~ 10 11 M ☉ , an effect likely connected with downsizing in galaxy formation. The ratio of the inferred black hole growth rate from these Compton-thick sources to the global star formation rate at z = 2 is similar to the mass ratio of black holes to stars in local spheroids, implying concurrent growth of both within the precursors of today's massive galaxies.

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Metadata

Authors
Daddi, E., Alexander, D. M., Dickinson, M., Gilli, R., Renzini, A., Elbaz, D., Cimatti, A., Chary, R., Frayer, D., Bauer, F. E., Brandt, W. N., Giavalisco, M., Grogin, N. A., Huynh, M., Kurk, J., Mignoli, M., Morrison, G., Pope, A., & Ravindranath, S.
Venue
The Astrophysical Journal
Publisher
American Astronomical Society
Published
2007-11-20
Volume
670
Issue
1
Pages
173-189
ISSN
  • 0004-637X (ISSN-L)
  • 1538-4357
DOI
10.1086/521820
OpenAlex
W1972308849
Cited by
335
References
94
FWCI
27.38
Type
journal article
Language
en
Open access
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CoChat. (2026). Citation check: Multiwavelength Study of Massive Galaxies at z ∼ 2. II. Widespread Compton‐thick Active Galactic Nuclei and the Concurrent Growth of Black Holes and Bulges. https://app.cochat.ai/papers/10.1086/521820
The paper
Daddi, E., Alexander, D. M., Dickinson, M., Gilli, R., Renzini, A., Elbaz, D., Cimatti, A., Chary, R., Frayer, D., Bauer, F. E., Brandt, W. N., Giavalisco, M., Grogin, N. A., Huynh, M., Kurk, J., Mignoli, M., Morrison, G., Pope, A., & Ravindranath, S. (2007). Multiwavelength Study of Massive Galaxies at z ∼ 2. II. Widespread Compton‐thick Active Galactic Nuclei and the Concurrent Growth of Black Holes and Bulges. The Astrophysical Journal. https://doi.org/10.1086/521820

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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.