A Caltech Library Service

Rapidly star-forming galaxies adjacent to quasars at redshifts exceeding 6

Decarli, R. and Walter, F. and Venemans, B. P. and Bañados, E. and Bertoldi, F. and Carilli, C. L. and Fan, X. and Farina, E. P. and Mazzucchelli, C. and Riechers, D. and Rix, H.-W. and Strauss, M. A. and Wang, R. and Yang, Y. (2017) Rapidly star-forming galaxies adjacent to quasars at redshifts exceeding 6. Nature, 545 (7655). pp. 457-461. ISSN 0028-0836. PMCID PMC5447817.

[img] PDF - Accepted Version
See Usage Policy.

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


The existence of massive (10^(11) solar masses) elliptical galaxies by redshift z ≈ 4 (refs 1, 2, 3; when the Universe was 1.5 billion years old) necessitates the presence of galaxies with star-formation rates exceeding 100 solar masses per year at z > 6 (corresponding to an age of the Universe of less than 1 billion years). Surveys have discovered hundreds of galaxies at these early cosmic epochs, but their star-formation rates are more than an order of magnitude lower. The only known galaxies with very high star-formation rates at z > 6 are, with one exception, the host galaxies of quasars, but these galaxies also host accreting supermassive (more than 10^9 solar masses) black holes, which probably affect the properties of the galaxies. Here we report observations of an emission line of singly ionized carbon ([C II] at a wavelength of 158 micrometres) in four galaxies at z > 6 that are companions of quasars, with velocity offsets of less than 600 kilometres per second and linear offsets of less than 100 kiloparsecs. The discovery of these four galaxies was serendipitous; they are close to their companion quasars and appear bright in the far-infrared. On the basis of the [C II] measurements, we estimate star-formation rates in the companions of more than 100 solar masses per year. These sources are similar to the host galaxies of the quasars in [C II] brightness, linewidth and implied dynamical mass, but do not show evidence for accreting supermassive black holes. Similar systems have previously been found at lower redshift. We find such close companions in four out of the twenty-five z > 6 quasars surveyed, a fraction that needs to be accounted for in simulations. If they are representative of the bright end of the [C II] luminosity function, then they can account for the population of massive elliptical galaxies at z ≈ 4 in terms of the density of cosmic space.

Item Type:Article
Related URLs:
URLURL TypeDescription ReadCube access CentralArticle Paper
Decarli, R.0000-0002-2662-8803
Walter, F.0000-0003-4793-7880
Venemans, B. P.0000-0001-9024-8322
Bañados, E.0000-0002-2931-7824
Bertoldi, F.0000-0002-1707-1775
Carilli, C. L.0000-0001-6647-3861
Fan, X.0000-0003-3310-0131
Farina, E. P.0000-0002-6822-2254
Mazzucchelli, C.0000-0002-5941-5214
Riechers, D.0000-0001-9585-1462
Rix, H.-W.0000-0003-4996-9069
Strauss, M. A.0000-0002-0106-7755
Wang, R.0000-0003-4956-5742
Yang, Y.0000-0003-3078-2763
Additional Information:© 2017 Macmillan Publishers Limited. Received 23 January 2017. Accepted 21 March 2017. Published online 24 May 2017. We thank J. Hennawi, Y. Shen, A. Myers and L. Guzzo for comments on the QSO clustering. Support for R.D. was provided by the DFG priority programme 1573 “The physics of the interstellar medium.” F.W., B.V. and E.P.F. acknowledge support through ERC grant COSMIC-DAWN. R.W. acknowledges support from the National Science Foundation of China (NSFC; grant numbers 11473004 and 11533001) and the National Key Program for Science and Technology Research and Development (grant 2016YFA0400703). ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (South Korea), in cooperation with Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. E.B. is a Carnegie-Princeton Fellow. Author Contributions: R.D. led the writing and analysis. F.W. was principle investigator of the ALMA programme that led to this discovery. F.W. and B.P.V. played a central part in the project design and implementation. E.P.F. provided the clustering analysis. E.B., B.P.V., E.P.F., C.M., F.W. and H.W.R. contributed to the identification of Pan-STARRS1 quasars. X.F. provided the Hubble observations of J0842+1218. All authors contributed to writing the proposal, and reviewed, discussed and commented on the manuscript. Data Availability. The datasets generated and analysed during this study are available from the corresponding author on reasonable request. The ALMA observations presented here are part of the project 2015.1.01115.S ( The authors declare no competing financial interests. Reviewer Information: Nature thanks D. Frayer and the other anonymous reviewer(s) for their contribution to the peer review of this work.
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)1573
European Research Council (ERC)COSMIC-DAWN
National Natural Science Foundation of China11473004
National Natural Science Foundation of China11533001
National Key Basic Research Program of China2016YFA0400703
Carnegie-Princeton FellowshipUNSPECIFIED
Issue or Number:7655
PubMed Central ID:PMC5447817
Record Number:CaltechAUTHORS:20170530-122922468
Persistent URL:
Official Citation:Decarli, R., Walter, F., Venemans, B. et al. Rapidly star-forming galaxies adjacent to quasars at redshifts exceeding 6. Nature 545, 457–461 (2017).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77830
Deposited By: George Porter
Deposited On:30 May 2017 20:08
Last Modified:21 Apr 2020 17:52

Repository Staff Only: item control page