The far-infrared-submillimetre spectral energy distribution of high-redshift quasars

被引:70
作者
Priddey, RS
McMahon, RG
机构
[1] Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England
[2] Imperial Coll, Blackett Lab, Astrophys Grp, London SW7 2BZ, England
关键词
dust; extinction; quasars : general; galaxies : starburst; infrared : ISM submillimetre;
D O I
10.1046/j.1365-8711.2001.04548.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We combine photometric observations of high-redshift (z > 4) quasars, obtained at submillimetre to millimetre wavelengths, to obtain a mean far-infrared (rest-frame) spectral energy distribution (SED) of the thermal emission from dust, parametrized by a single temperature (T) and power-law emissivity index (beta). The best-fitting values are T = 41 +/- 5 K and beta = 1.95 +/- 0.3. Our method exploits the redshift spread of this set of quasars, which allows us to sample the SED at a larger number of rest wavelengths than is possible for a single object: the wavelength range extends down to similar to 60 mum, and therefore samples the turnover in the greybody curve for these temperatures. This parametrization is of use to any studies that extrapolate from a flux at a single wavelength, for example to infer dust masses and far-infrared luminosities. We interpret the cool, submillimetre component as arising from dust heated by star formation in the host galaxy of the quasar, although we do not exclude the presence of dust heated directly by the active galactic nucleus (AGN). Applying the mean SED to the data, we derive consistent star formation rates similar to 1000 M. yr(-1) and dust masses similar to 10(9) M., and investigate a simple scheme of AGN and host galaxy co-evolution to account for these quantities. The time-scale for formation of the host galaxy is 0.5-1 Gyr, and the luminous quasar phase occurs towards the end of this period, just before the reservoir of cold gas is depleted. Given the youth of the Universe at z = 4 (1.6 Gyr), the coexistence of a massive black hole and a luminous starburst at high redshifts is a powerful constraint on models of quasar host galaxy formation.
引用
收藏
页码:L17 / L22
页数:6
相关论文
共 34 条
[1]   Hubble Space Telescope images of a sample of 20 nearby luminous quasars [J].
Bahcall, JN ;
Kirhakos, S ;
Saxe, DH ;
Schneider, DP .
ASTROPHYSICAL JOURNAL, 1997, 479 (02) :642-&
[2]   Resolving the submillimeter background: The 850 micron galaxy counts [J].
Barger, AJ ;
Cowie, LL ;
Sanders, DB .
ASTROPHYSICAL JOURNAL, 1999, 518 (01) :L5-L8
[3]  
BENFORD DJ, 1999, APJ, V451, pL9
[4]   1.25-MM OBSERVATIONS OF LUMINOUS INFRARED GALAXIES [J].
CARICO, DP ;
KEENE, J ;
SOIFER, BT ;
NEUGEBAUER, G .
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC, 1992, 104 (681) :1086-1090
[5]   Rotating nuclear rings and extreme starbursts in ultraluminous galaxies [J].
Downes, D ;
Solomon, PM .
ASTROPHYSICAL JOURNAL, 1998, 507 (02) :615-654
[6]   The SCUBA Local Universe Galaxy Survey - I. First measurements of the submillimetre luminosity and dust mass functions [J].
Dunne, L ;
Eales, S ;
Edmunds, M ;
Ivison, R ;
Alexander, P ;
Clements, DL .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2000, 315 (01) :115-139
[7]   Maximum dust masses in galaxies [J].
Edmunds, MG ;
Eales, SA .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1998, 299 (02) :L29-L31
[8]   ATLAS OF QUASAR ENERGY-DISTRIBUTIONS [J].
ELVIS, M ;
WILKES, BJ ;
MCDOWELL, JC ;
GREEN, RF ;
BECHTOLD, J ;
WILLNER, SP ;
OEY, MS ;
POLOMSKI, E ;
CUTRI, R .
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1994, 95 (01) :1-68
[9]  
Guilloteau S, 1999, ASTRON ASTROPHYS, V349, P363
[10]  
Guilloteau S., 1997, ASTRON ASTROPHYS, V328, P1