Bibcode
Flores-Cacho, I.; Rubiño-Martín, J. A.; Luzzi, G.; Rebolo, R.; de Petris, M.; Yepes, G.; Lamagna, L.; de Gregori, S.; Battistelli, E. S.; Coratella, R.; Gottlöber, S.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 400, Issue 4, pp. 1868-1880.
Advertised on:
12
2009
Citations
10
Refereed citations
9
Description
We study the thermal (tSZ) and kinetic Sunyaev-Zel'dovich (kSZ) effect
associated with superclusters of galaxies using the MareNostrum (MNU)
universe smoothed particle hydrodynamics (SPH) simulation. In
particular, we consider superclusters with characteristics (total mass,
overdensity and number density of cluster members) similar to those of
the Corona Borealis Supercluster (CrB-SC). This paper has been motivated
by the detection at 33 GHz of a strong temperature decrement in the
cosmic microwave background towards the core of this supercluster
(Génova-Santos et al.). Multifrequency observations with Very
Small Array (VSA) and Millimetre & Infrared Testa Grigia Observatory
(MITO) suggest the existence of a tSZ effect component in the spectrum
of this cold spot, with a Comptonization parameter value of y =
7.8+4.4-5.3 × 10-6 (Battistelli
et al.), which would account for roughly 25 per cent of the total
observed decrement. From the SPH simulation, we identify nine
(50h-1Mpc)3 regions containing superclusters
similar to CrB-SC, obtain the associated SZ maps and calculate the
probability of finding such SZ signals arising from hot gas within the
supercluster. Our results show that the warm/hot intergalactic medium
(WHIM) lying in the intercluster regions within the supercluster
produces a tSZ effect much smaller than the observed value by MITO/VSA.
Neither can, summing the contribution of small clusters and galaxy
groups (M < 5 × 1013h-1Msolar)
in the region, explain the amplitude of the SZ signal. Our synthetic
maps show peak y-values significantly below the observations. Less than
0.3 per cent are compatible at the lower end of the 1σ level, even
when considering privileged orientations in which the filamentary
structures are aligned along the line of sight (LOS). When we take into
account the actual posterior distribution from the observations, the
probability that WHIM can cause a tSZ signal like the one observed in
the CrB-SC is <1 per cent, rising up to a 3.2 per cent when the
contribution of small clusters and galaxy groups is included. If the
simulations provide a suitable description of the gas physics, then we
must conclude that the tSZ component of the CrB spot most probably
arises from an unknown galaxy cluster along the LOS. On the other hand,
the simulations also show that the kSZ signal associated with the
supercluster cannot provide an explanation for the remaining 75 per cent
of the observed cold spot in CrB.
Related projects
Anisotropy of the Cosmic Microwave Background
The general goal of this project is to determine and characterize the spatial and spectral variations in the temperature and polarisation of the Cosmic Microwave Background in angular scales from several arcminutes to several degrees. The primordial matter density fluctuations which originated the structure in the matter distribution of the present
Rafael
Rebolo López