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Extragalactic Sources

In the spectral range covered by PLANCK we can identify three regions characterized by the predominance of drastically different classes of extragalactic sources:

1.
In the low frequency channels ($\nu=$ 30 to 90 GHz), we expect to detect mainly radio-loud, flat-spectrum radiogalaxies and QSOs, blazars, and possibly some inverted-spectrum radiosources.
2.
In the millimetre channels (90 to 300 GHz), the predominant extragalactic sources will be rich clusters of galaxies detected via the SZ effect.

3.
In the sub-millimetre channels (300 to 900 GHz), we expect to detect many thousands of infra-red luminous galaxies (both normal and starbursting) and (mostly radio-quiet) AGNs, and a few high-redshift galaxies and QSOs.

For recent detailed analyses of the extragalactic sources at Planck frequencies see e.g., De Zotti et al. 1998, De Zotti & Toffolatti 1998, De Zotti et al. 1999.

In addition, studies of the anisotropies of the diffuse background at these wavelengths will constrain galaxy counts to faint flux levels and, consequently lead to strong constraints on models of galaxy evolution.


 
$\nu_{eff}$ $\lambda_{eff}$ Beam $\sigma_{noise}$ $\sigma_{conf}^1$ $\sigma_{CMB}^2$ No. sources3
(GHz) (mm) (arcmin) (mJy) (mJy) (mJy) (8 steradians)
31 10 30 40 50 60 350 - 2500
53 6 18 40 50 57 250 - 2000
90 3 12 80 50 90 130 - 1000
125 2.4 10 210 40 81 50 - 300
150 2 10 24 6 114 -
217 1.4 7.5 15 5 66 400 - 2000
353 0.85 4.5 20 16 15 3000 - 15000
545 0.55 4.5 32 40 3 7000 - 50000
857 0.35 4.5 190 100 - 5000 - 20000

1 Standard deviation of the pixel brightness fluctuations due to galaxies, after removal of the brightest pixels, i.e. those with signal $D \gt 5 \sigma_{conf}$.
2 Sky variance induced by CMB anisotropies corresponding to $\Delta T/T=10^{-5}$.
3 Expected number of sources with flux $S\gt 4\sigma$ in 70% of the sky. The lower value is without evolution, the upper one for the RG and PLE models.

Table 1.1: Instrumental and confusion noise estimates for PLANCK and number of extragalactic sources anticipated without evolution (NE), and in a particular evolutionary model (radiogalaxies and galaxies respectively evolve according to the RG and PLE models).


 


[last update: 1 August 1999 by P. Fosalba]