The HI gas content of galaxies around Abell 370, a galaxy cluster at z = 0.37

Understand

We used observations from the Giant Metrewave Radio Telescope to measure the atomic hydrogen gas content of 324 galaxies around the galaxy cluster Abell 370 at a redshift of z = 0.37 (a look-back time of ~4 billion years).

• The HI 21-cm emission from these galaxies was measured by coadding their signals using precise optical redshifts obtained with the Anglo-Australian Telescope.
• The average HI mass measured for all 324 galaxies is (6.6 +- 3.5)x10^9 solar masses, while the average HI mass measured for the 105 optically blue galaxies is (19.0 +- 6.5)x10^9 solar masses.
• The significant quantities of gas found around Abell 370, suggest that there has been substantial evolution in the gas content of galaxy clusters since redshift z = 0.37.