Sunyaev-Zeldovich decrements with no clusters?

Abstract

In this paper, we propose an alternative physical process which can produce detectable Sunyaev-Zeldovich decrements around quasars or quasar pairs in regions where no assembled, virialized clusters are detected in either the optical or X-ray waveband. Invoking quasar outflows, we argue that both thermal and kinematic decrements can be produced by the baryons swept up by the mechanical luminosity of quasars. In contrast to the case of decrements produced by the hot electrons confined within the cluster potential, the magnitude of these quasar outflow induced effects depends primarily on the luminosity of the QSO, and the physical scale of the outflow - which in turn depends on both the mean local density and the density gradient in the vicinity of the quasar. Quasar outflows produce: (i) a frequency-independent kinematic decrement △T/T ∼ 10-4; (ii) a frequency-dependent fluctuation in the intensity, △Jv/Jv ∼ a 20 per cent variation relative to △T/T, say, at 15 and 30 GHz; (iii) depending on the presence of any other local density inhomogeneities, potentially a temperature increment △T/T ∼ 10-4 on the opposite side of the QSO; (iv) a linear polarization signal over 20 arcsec at the ∼10-7 level; and therefore (v) patches of signal with △T/T ∼ 10-4 on degree scales. In principle, the effect ought to be observable for QSOs in cases with the appropriate opening angle and alignment of outflow to the line of sight, and preferentially for high mechanical luminosity, high-redshift, radio-quiet QSOs. These effects are of interest since they are potentially observable in the context of the next generation of cosmic microwave background experiments: MAP and Planck.