AstroTalk Episode July 6, 2017

Hubble and Gravitational Lensing

3:17pm - 3:35pm

With help from the Hubble Space Telescope, scientists have viewed a distant cluster of galaxies, that has been microlensed, and then capture by the lens of HST. J143450.5+033843 lies 11 Billion light years away, and without the aid of gravitational lensing, and HST, it would not be visible. The light of the faint galaxy is being magnified by a cluster of foreground, or closer, galaxies, and without this magnification, HST would not be able to image it well. The strong gravity of the galaxy cluster acts as a magnifier, multiplying the light intensity coming from this far away galaxy. Presently, HST is only able to image the younger stars in this galaxy, but when the James Webb Telescope becomes operational, JSWT will be able to image the older stars in the galaxy. As for the HST, the images it would produce would seem unremarkable without the lensing effect. Astronomers would not be able to make out or spot the hundreds of galaxies, or the knots of galaxies, as astronomers are calling them. Knots of stars, forming in galaxies 200 -- 300 light years across are now visible. Without the lensing and the HST, the light would appear to be smooth; so the formation of the stars would not be visible.