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Thermal Sunyaev-Zel'dovich effect at the core of CL J1226.9+3332 revealed by NOEMA

M. Muñoz-Echeverría, J. -F. Macías-Pérez, R. Neri, E. Pointecouteau, R. Adam, P. Ade, H. Ajeddig, S. Amarantidis, P. André, H. Aussel, A. Beelen, A. Benoît, S. Berta, M. Béthermin, A. Bongiovanni, J. Bounmy, O. Bourrion, M. Calvo, A. Catalano, D. Chérouvrier, U. Chowdhury, M. De Petris, F. -X. Désert, S. Doyle, E. F. C. Driessen, G. Ejlali, A. Ferragamo, A. Gómez, J. Goupy, C. Hanser, S. Katsioli, F. Kéruzoré, C. Kramer, B. Ladjelate, G. Lagache, S. Leclercq, J. -F. Lestrade, S. C. Madden, A. Maury, F. Mayet, A. Monfardini, A. Moyer-Anin, I. Myserlis, A. Paliwal, L. Perotto, G. Pisano, N. Ponthieu, V. Revéret, A. J. Rigby, A. Ritacco, H. Roussel, F. Ruppin, M. Sánchez-Portal, S. Savorgnano, K. Schuster, A. Sievers, C. Tucker, R. Zylka, I. Bartalucci, J. -B. Melin, G. W. Pratt

Abstract

We present first detailed maps of the thermal Sunyaev-Zel'dovich (tSZ) effect on a $z = 0.89$ cluster with the NOrthern Extended Millimeter Array (NOEMA). The high sensitivity of these observations enabled the effective identification and removal of the millimetre-wave sources contaminating the tSZ signal, thus isolating the influence of the hot electron gas of the cluster on the cosmic microwave background radiation from other emissions. The tSZ observed with success by NOEMA was modelled together with previous single-dish observations (IRAM 30-metre, Green Bank Telescope, and Caltech Sub-millimeter Observatory) to obtain the first core-to-outskirts (from $\sim$ 15 to $\sim$ 1500 kpc) pressure profile reconstruction on such a high-redshift galaxy cluster. NOEMA observations with a high angular resolution have shown that the pressure profile is flat in the core of the cluster. These observations confirm the disturbed nature of CL J1226.9+3332 and map for the first time the distribution of its thermal gas at arcsecond scales in the environments of the central cluster galaxy. Our results showcase the excellent capabilities of NOEMA to complement and enhance the data provided by other millimetre-wave instruments in resolving the core of high-redshift clusters via tSZ emission.

Thermal Sunyaev-Zel'dovich effect at the core of CL J1226.9+3332 revealed by NOEMA

Abstract

We present first detailed maps of the thermal Sunyaev-Zel'dovich (tSZ) effect on a cluster with the NOrthern Extended Millimeter Array (NOEMA). The high sensitivity of these observations enabled the effective identification and removal of the millimetre-wave sources contaminating the tSZ signal, thus isolating the influence of the hot electron gas of the cluster on the cosmic microwave background radiation from other emissions. The tSZ observed with success by NOEMA was modelled together with previous single-dish observations (IRAM 30-metre, Green Bank Telescope, and Caltech Sub-millimeter Observatory) to obtain the first core-to-outskirts (from 15 to 1500 kpc) pressure profile reconstruction on such a high-redshift galaxy cluster. NOEMA observations with a high angular resolution have shown that the pressure profile is flat in the core of the cluster. These observations confirm the disturbed nature of CL J1226.9+3332 and map for the first time the distribution of its thermal gas at arcsecond scales in the environments of the central cluster galaxy. Our results showcase the excellent capabilities of NOEMA to complement and enhance the data provided by other millimetre-wave instruments in resolving the core of high-redshift clusters via tSZ emission.

Paper Structure

This paper contains 13 sections, 5 equations, 12 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Target and observations
  3. Data analysis
  4. Continuum: Combination of $uv$ tables
  5. tSZ with NOEMA
  6. Visibility profiles
  7. Continuum map
  8. Pressure profile of CL J1226.9+3332
  9. Fit of a pressure model to NOEMA visibilities
  10. Resolved pressure profile of CL J1226.9+3332
  11. Summary and conclusions
  12. Spectral analysis
  13. End-to-end simulation

Figures (12)

  • Figure 1: Top: Continuum NOEMA dirty map of CL J1226.9+3332 from the combination of point-source-contaminated LSB and USB data, merged without weighting for the tSZ effect spectral shape. The grey crosses indicate the positions of the three point sources identified from NOEMA data (Table \ref{['tab:firstfit']}). Bottom: Point-source-subtracted continuum NOEMA map of CL J1226.9+3332 cleaned with CLARK1980AA....89..377C and natural weighting. The data from different sidebands were combined as described in Sect. \ref{['sec:continuum']}. The map is not corrected for primary beam attenuation. The white contours indicate $\pm 2\sigma = \pm 11.2 \; \mu$Jy beam$^{-1}$ levels spaced by $2\sigma$. The size and orientation of the synthesized beam of NOEMA (4.6$^{\prime\prime}\,\times\,$3.8$^{\prime\prime}$ at PA $=54^\circ$) are indicated in the lower left corners.
  • Figure 2: Spectral distortion of the CMB by the tSZ effect. The relativistic corrections assume 10 keV. We consider a Compton parameter of $y = 10^{-4}$. The black markers indicate the tSZ spectrum evaluated at the four central frequencies ($\nu_B = 72.320, 76.192, 87.808, 91.680$ GHz) and the mean frequency of the four basebands ($\nu_{82}=82$ GHz). The dashed line shows the power-law approximation we used to scale the visibilities.
  • Figure 3: Real (top) and imaginary (bottom) visibility components as a function of binned $uv$ distances. The blue markers show the profile for the NOEMA data after subtraction of the point sources contribution from the visibilities. The error bars indicate $1\sigma$ uncertainties propagated from the error bar associated with each visibility. The solid black lines indicate the visibility profiles corresponding to the best-fitting model to the NOEMA data. The dashed black lines show the 16th to 84th percentiles of the fitted model.
  • Figure 4: Point-source-subtracted and cleaned continuum NOEMA map of CL J1226.9+3332 compared to NIKA2 and MUSTANG observations. Left: NIKA2 150 GHz 2023AA...671A..28M contours (black) starting from $2\sigma$ and spaced by $2\sigma$. The $18^{\prime\prime}$ beam is indicated in the lower left corner. Centre: MUSTANG 90 GHz 2018AA...612A..39R contours (red) starting from $2\sigma$ and spaced by $2\sigma$ with the beam ($9^{\prime\prime}$) in the lower left corner. Right: $2\sigma$ levels in the NOEMA map (white). The size and orientation of NOEMA's synthesized beam (4.6$^{\prime\prime}\,\times\,$3.8$^{\prime\prime}$ at PA $=54^\circ$) are indicated in the lower left corner. The red cross indicates the centre of the map as defined from the tSZ peak according to NOEMA data (Table \ref{['tab:firstfit']}). The grey crosses in left and central panels show the positions of the three sources we subtracted from the NOEMA data, but not from NIKA2 and MUSTANG to calculate contours.
  • Figure 5: Posterior probability distributions (1D and 2D) of the free parameters in the model fitted to the NOEMA visibilities. The pressure bins ($P_0, P_1, P_2,$ and $P_3$) are defined at 15, 60, 150, and 270 kpc and given here in keV/cm$^3$ units. The residual point source fluxes (Res. PS9, Res. $\text{PS260-S}$, and Res. $\text{PS260-N}$) are in $10^{-5}$ Jy units, $\Delta$RA$_{\mathrm{J2000}}$ and $\Delta$Dec$_{\mathrm{J2000}}$ offsets are shown in arcseconds, and the calibration factor (Calib) is in Jy/sr.
  • ...and 7 more figures