CARMA observations of massivePlanck-discovered cluster candidates atz≳ 0.5 associated withWISEoverdensities: breaking the size–flux degeneracy

Abstract

We use a Bayesian software package to analyze CARMA-8 data towards 19 unconfirmed Planck SZ-cluster candidates from Rodríguez-Gonzálvez et al. (2015) that are associated with significant overdensities in WISE. We used two cluster parameterizations, one based on a (fixed shape) generalized-NFW pressure profile and another based on a β gas density profile (with varying shape parameters) to obtain parameter estimates for the nine CARMA-8 SZ-detected clusters. We find our sample is comprised of massive, Y 500 = 0.0010 ± 0.0015 arcmin 2 , relatively compact, θ 500 = 3.9 ± 2.0 ′ systems. Results from the β model show that our cluster candidates exhibit a heterogeneous set of brightness-temperature profiles. Comparison of Planck and CARMA-8 measurements showed good agreement in Y 500 and an absence of obvious biases. We estimated the total cluster mass M 500 as a function of z for one of the systems; at the preferred photometric redshift of 0.5, the derived mass, M 500 ≈ 0.8 ± 0.2 × 10 15 M ⊙ . Spectroscopic Keck/MOSFIRE data confirmed a galaxy member of one of our cluster candidates to be at z = 0.565. Applying a Planck prior in Y 500 to the CARMA-8 results reduces uncertainties for both parameters by a factor > 4, relative to the independent Planck or CARMA-8 measurements. We here demonstrate a powerful technique to find massive clusters at intermediate (z 0.5) redshifts using a cross-correlation between Planck and WISE data, with high-resolution follow-up with CARMA-8. We also use the combined capabilities of Planck and CARMA-8 to obtain a dramatic reduction by a factor of several, in parameter uncertainties.

Calibrating the Planck Cluster Mass Scale with Cluster Velocity Dispersions

“…The comparison of Planck and CARMA-8 measurements by Rodriguez-Gonzalvez et al (2017) shows that this tension is not due to any bias in the Planck flux measurements. Moreover, a recent analysis of the local X-ray cluster temperature function finds that the same mass bias value is needed to reconcile the X-ray cluster abundance with the CMB cosmology (Ilic et al 2015).…”

“…Higher angular resolution SZ observations show that the Planck determination of the SZ signal is robust (Rodriguez-Gonzalvez et al 2017;Sayers et al 2016). Planck calibrates the relation with mass proxies from XMM-Newton X-ray observations (Arnaud et al 2010); the proxies are in turn calibrated, assuming the hydrostatic equilibrium of the ICM (see the Appendix of Planck Collaboration et al 2014a).…”

Planck2015 results

“…Radio emission is known to be correlated with cluster positions, potentially "filling in" the SZ decrement, though recent estimates suggest that this effect is typically small in Planck data (Rodriguez-Gonzalvez et al 2015). Departures of the pressure distribution from spherical symmetry may also affect the completeness, though this effect is only likely to be significant for nearby and dynamically disturbed clusters, which are not small compared to the Planck beams.…”

Free-form modelling of galaxy clusters: a Bayesian and data-driven approach

“…Vikhlinin et al 2009, Ettori 2013, Mantz et al 2014and Olamaie et al 2015, the Sunyaev-Zel'dovich (SZ) effect (see e.g. Planck Collaboration et al 2013, Schammel et al 2013, Hasselfield et al 2013, Perrott et al 2015, Rumsey et al 2016, and Rodríguez-Gonzálvez et al 2017, and gravitational lensing (see e.g. Rozo et al 2010, Rozo et al 2014and Battaglia et al 2016.…”