Smithsonian Astrophysical Observatory
Weekly Science Update | 2014 Mar 28
- Far behind this nearby cluster of galaxies (Abell 773, seen here in the optical) lies a distant hyper-luminous galaxy seen as it was only about 800 million years after the big bang. The cluster, acting as a giant gravitational lens, has enable astronomers to study in detail the workings of this young giant. (Credit: ALFOSC, the Nordic Optical Telescope)
About fifteen years ago astronomers, using improved submillimeter wavelength telescopes, discovered a new class of very distant galaxies: submillimeter galaxies (SMGs). These objects are among the most luminous, rapidly star-forming galaxies known, and can shine brighter than a trillion Suns (about one hundred times more luminous than the Milky Way), but they are undetected in the visible. Their ultraviolet and optical light is absorbed by dust in the galaxies which is warmed and then emits in the submillimeter. SMGs are typically so distant that their light has been traveling for over ten billion years, more than 70% of the lifetime of the universe. Their power source is thought to be star formation, with some having rates as high as one thousand stars per year (in the Milky Way, the rate is more like a few stars per year), although the cause of such dramatic bursts is not understood.
Atomic and molecular lines are particularly important diagnostics of star formation, black hole activity, and interstellar gas properties. Furthermore, the shapes of the emission lines provide direct insights into the dynamics of the system. The observed far-infrared and submillimeter spectra of SMGs is dominated by such emission lines because the gas in their molecular clouds, as well as the dust, is exposed to ultraviolet flux from nearby young stars that stimulates the gas to glow. ...
[C II] and 12CO(1–0) Emission Maps in HLSJ091828.6+514223:
A Strongly Lensed Interacting System at z = 5.24 - T. D. Rawle et al