Thesis Topic: Studies of the Intracluster Medium through the Sunyaev-Zel’dovich (SZ) effect

Thesis Supervisor:

 Tony Mroczkowski (ESO)

Depending on the exact project and student's interests, potential co-supervisors include, but are not limited to:

Paola Andreani (ESO)

Eugene Churazov (MPA)

Gergö Popping(ESO)


Galaxy clusters are large, nearly representative volumes of the universe, having baryon to dark matter mass ratios that approach the universal baryon fraction. The baryonic component is predominantly in the hot intracluster medium (ICM), which has traditionally been studied through X-ray observations. However, the millimeter band provides an alternative window on the ICM through the Sunyaev-Zel'dovich Effect (SZE), which is due to inverse Compton scattering of photons from the Cosmic Microwave Background (CMB) by hot ICM electrons. The SZE has two main forms, both redshift independent in surface brightness, making it a powerful complement to X-ray observations, particularly at high redshift. The form is the thermal SZE, which scales as the line of sight integrated pressure, and the secondary is the kinetic SZE, which scales as the product of peculiar velocity and electron opacity through the ICM. These two effect are separable at bands imaged by the Atacama Large Millimeter/Submillimeter Array (ALMA), but large scale information beyond the spatial scales accessible to the interferometer must be obtained by complementary single dish experiments.

Using in-hand data from the Atacama Cosmology Telescope (ACT), ALMA, MUSTANG-2 on the 100-meter Green Bank Telescope, NIKA2 on the 30-meter IRAM telescope, and potentially public data from Planck, SPT, and Bolocam, the student will work with advanced tools (see Di Mascolo et al. references) to combine the SZ data to improve our understanding of ICM physics and cluster/protocluster evolution.  The student can potentially also work on tools to combine the data with X-ray observations from Chandra, XMM-Newton, and others.  The student may also work on cosmology and astrophysics forecasts for advanced mm/submm instrumentation and platforms, such as AtLAST (, CMB-HD (, and upgrades to ALMA.


  • Mroczkowski et al., Astrophysics with the Spatially and Spectrally Resolved Sunyaev-Zeldovich Effects. A Millimetre/Submillimetre Probe of the Warm and Hot Universe, Space Science Reviews, Volume 215, Issue 1, article id. 17, 60 pp. (2019SSRv..215...17M)
  • Di Mascolo et al., An ALMA+ACA measurement of the shock in the Bullet Cluster, Astronomy & Astrophysics, Volume 628, id.A100, 9 pp., (2019A&A...628A.100D )
  • Di Mascolo et al., The Massive and Distant Clusters of WISE Survey. SZ effect of Verification with the Atacama Compact Array - Localization and Cluster Analysis, Astronomy & Astrophysics, Volume 638, id.A70, 17 pp., (2020A&A...638A..70D)
  • Di Mascolo et al., A joint ALMA-Bolocam-Planck SZ study of the pressure distribution in RX J1347.5-1145, Monthly Notices of the Royal Astronomical Society, Volume 487, Issue 3, p.4037-4056, (2019MNRAS.487.4037D)