The unexpectedly large dust and gas content of quiescent galaxies at z>1.4

Understand

Early type galaxies (ETG) contain most of the stars present in the local Universe and, above a stellar mass of ~5e10 Msun, vastly outnumber spiral galaxies like the Milky Way.

• These massive spheroidal galaxies have, in the present day, very little gas or dust, and their stellar populations have been evolving passively for over 10 billion years.
• The physical mechanisms that led to the termination of star formation in these galaxies and depletion of their interstellar medium remain largely conjectural.
• In particular, there are currently no direct measurements of the amount of residual gas that might be still present in newly quiescent spheroids at high redshift.