Credit: ALMA (ESO/NAOJ/NRAO)/T. Kitayama (Toho University, Japan)/ESA/Hubble & NASA
The events surrounding the Big Bang were so cataclysmic that they left an indelible imprint on the fabric of the cosmos. We can detect these scars today by observing the oldest light in the Universe. As it was created nearly 14 billion years ago, this light — which exists now as weak microwave radiation and is thus named the cosmic microwave background (CMB) — has now expanded to permeate the entire cosmos, filling it with detectable photons.
The CMB can be used to probe the cosmos via something known as the Sunyaev-Zel’dovich (SZ) effect,
which was first observed over 30 years ago. We detect the CMB here on
Earth when its constituent microwave photons travel to us through space.
On their journey to us, they can pass through galaxy clusters that contain high-energy electrons.
These electrons give the photons a tiny boost of energy. Detecting
these boosted photons through our telescopes is challenging but
important — they can help astronomers to understand some of the
fundamental properties of the Universe, such as the location and
distribution of dense galaxy clusters.
This image shows the first measurements of the thermal Sunyaev-Zel’dovich effect from the Atacama Large Millimeter/submillimeter Array
(ALMA) in Chile (in blue). Astronomers combined data from ALMA’s 7- and
12-metre antennas to produce the sharpest possible image. The target
was one of the most massive known galaxy clusters, RX J1347.5–1145,
the centre of which shows up here in the dark “hole” in the ALMA
observations. The energy distribution of the CMB photons shifts and
appears as a temperature decrease at the wavelength observed by ALMA,
hence a dark patch is observed in this image at the location of the
cluster.
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Source: ESO/Images/Potw
