On the dearth of ultra-faint extremely metal poor galaxies

Understand

Local extremely metal-poor (XMP) galaxies are of particular astrophysical interest since they allow us to look into physical processes characteristic of the early Universe, from the assembly of galaxy disks to the formation of stars in conditions of low metallicity.

• Given the luminosity-metallicity relationship, all galaxies fainter than Mr < -13 are expected to be XMPs.
• Therefore, XMPs should be common in galaxy surveys.
• However, they are not, because several observational biases hamper their detection.