We present Atacama Large Millimetre Array and Atacama Compact Array observations of the Sunyaev-Zel’dovich effect in the z = 2 galaxy cluster Cl J1449+0856, an X-ray-detected progenitor of typical massive clusters in the present day Universe. While in a cleaned but otherwise untouched 92 GHz map of this cluster little to no negative signal is visible, careful subtraction of known sub-millimetre emitters in the uv plane reveals a decrement at 5σ significance. The total signal is −190 ± 36 μJy, with a peak offset by 5″–9″ (∼50 kpc) from both the X-ray centroid and the still-forming brightest cluster galaxy. A comparison of the recovered uv-amplitude profile of the decrement with different pressure models allows us to derive total mass constraints consistent with the ∼6 × 1013M⊙ estimated from X-ray data. Moreover, we find no strong evidence for a deviation of the pressure profile with respect to local galaxy clusters, although a slight tension at small-to-intermediate spatial scales suggests a flattened central profile, opposite to that seen in a cool core and possibly an AGN-related effect. This analysis of the lowest mass single SZ detection so far illustrates the importance of interferometers when observing the SZ effect in high-redshift clusters, the cores of which cannot be considered quiescent, such that careful subtraction of galaxy emission is necessary.
- Galaxies: clusters: intracluster medium
- Galaxies: clusters: individual: Cl J1449+0856
Gobat, R., Daddi, E., Coogan, R. T., Le Brun, A. M. C., Bournaud, F., Melin, J. -B., Riechers, D. A., Sargent, M., Valentino, F., Hwang, H. S., Finoguenov, A., & Strazzullo, V. (2019). Sunyaev-Zel'dovich detection of the galaxy cluster Cl J1449+0856 at z=1.99: The pressure profile in uv space. Astronomy and Astrophysics, 629, [A104]. https://doi.org/10.1051/0004-6361/201935862