Nature 382, 426 - 428 (01 August 1996); doi:10.1038/382426a0

Detection of molecular gas in the quasar BR1202 – 0725 at redshift z = 4.69

K. Ohta^*†, T. Yamada^‡, K. Nakanishi^*, K. Kohno^§, M. Akiyama^* & R. Kawabe^§

^*Department of Astronomy, Kyoto University, Kyoto 606-01, Japan
^†Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, Hawaii 96822, USA
^‡Cosmic Radiation Laboratory, The Institute of Physical and Chemical Research (RIKEN), Hirosawa Wako, Saitama 351-01, Japan
^§Nobeyama Radio Observatory, National Astronomical Observatory, Minamimaki, Minamisaku, Nagano 384-13, Japan
Department of Astronomy, The University of Tokyo, Tokyo 113, Japan

ALTHOUGH great efforts^1–8 have been made to locate molecular gas—the material out of which stars form—in the early Universe, there have been only two firm detections at high redshift. Both are gravitationally lensed objects at redshift z 2.5 (refs 9–14). Here we report the detection of CO emission from the radio-quiet quasar BR1202 – 0725, which is at redshift z = 4.69. From the observed CO luminosity, we estimate that almost 10¹¹ solar masses of molecular hydrogen are associated with the quasar; this is comparable to the stellar mass of a present-day luminous galaxy. Our results suggest that BR1202 – 0725 is a massive galaxy, in which the gas is largely concentrated in the central region, and that it is currently undergoing a large burst of star formation.

References

1.	Brown, R. L. & Vanden Bout, P. A. Astrophys. J. 412, L21−L24 (1993).
2.	Ohta, K. et al. Publs. astr. Soc. Japan 46, L163−L166 (1994).
3.	Wiklind, T. & Combes, F. Astr. Astrophys. 288, L41−L44 (1994).
4.	Frayer, D. T., Brown, R. L. Vanden Bout, P. A. Astrophys. J. 433, L5−L8 (1994).
5.	Yamada, T. et al. Astrophys. J. 438, L5−L7 (1995).
6.	Ohta, K. et al. Publs. astr. Soc. Japan 47, 739−743 (1995).
7.	Yamada, T., Ohta, K., Tomita, A. & Takata, T. Astr. J. 110, 1564−1572 (1995).
8.	Evans, A. S. et al. Astrophys. J. 457, 658−670 (1996).
9.	Brown, R. L. & Vanden Bout, P. A. Astr. J. 102, 1956−1959 (1991).
10.	Kawabe, R., Sakamoto, K., Ishizuki, S. & Ishiguro, M. Astrophys. J. 397, L23−L26 (1992).
11.	Solomon, P. M., Downes, D. & Radford, S. J. E. Astrophys. J. 398, L29−L32 (1992).
12.	Tsuboi, M. & Nakai, N. Publs. astr. Soc. Japan 46, L179−L182 (1994).
13.	Barvainis, R., Tacconi, L., Antonucci, R., Alloin, D. & Coleman, P. Nature 371, 586−588 (1994).
14.	Barvainis, R. in CO: Twenty-five Years of Millimeter-wave Spectroscopy (Int. Astr. Un. Symp. No. 170, Kluwer, Dordrecht, in the press).
15.	Irwin, M., McMahon, R. G. & Hazard, C. in The Space Distribution of Quasars (ed. Crampton, D.) 117−126 (ASP Conf. Ser. 21, San Francisco, 1991).
16.	McMahon, R. G., Omont, A., Bergeron, J., Kreysa, E. & Haslam, C. G. T. Mon. Not. R. astr. Soc. 267, L9−L12 (1994).
17.	Isaak, K. G., McMahon, R. G., Hills, R. E. & Withington, S. Mon. Not. R. astr. Soc. 269, L28−L32 (1994).
18.	Storrie-Lombardi, L. J., McMahon, R. G., Irwin, M. J. & Hazard, C. Astrophys. J. Suppl. Ser. (in the press).
19.	Hu, E. M., McMahon, R. G. & Egami, E. Astrophys. J. 459, L53−L55 (1996).
20.	Petitjean, P., Peontal, E., Valls-Gabaud, D. & Chalot, S. Nature 380, 411−413 (1996).
21.	Solomon, P. M., Radford, S. J. E. & Downes, D. Nature 356, 318−319 (1992).
22.	Wright, E. L. et al. Astrophys. J. 381, 200−209 (1991).
23.	Brown, R. L. & Vanden Bout, P. A. Astrophys. J. 397, L19−L22 (1992).
24.	Broadhurst, T. & Lehár, J. Astrophys. J. 450, L41−L44 (1995).
25.	Arimoto, N., Sofue, Y. & Tsujimoto, T. Publs. astr. Soc. Japan 48, 275−284 (1996).
26.	Athanassoula, E., Bosma, A. & Papaionnou, S. Astr. Astrophys. 179, 23−40 (1987).
27.	Silk, J. Nature 301, 574−578 (1983).
28.	Kormendy, J. & Sanders, D. B. Astrophys. J. 390, L53−L56 (1992).