ALMA’s Long Baseline Campaign has produced amazing observations, and gathered detailed information about the inhabitants of the near and distant Universe.
As the part of the campaign, observations made at the end of the 2014 targeted a distant galaxy called HATLAS J090311.6+003906, all known as SDP.81. The light from this galaxy is due to a cosmic effect known as gravitational lensing.
A large galaxy sitting between SDP.81 and ALMA is acting like a lens, warping the more distant galaxy’s light and creating a near perfect example of Einstein Ring.
At least seven groups of scientists have independently analyzed the ALMA data on SDP.81. The research papers have unprecedented information about the galaxy revealing details about its structure, contents, motions and other characteristics.
ALMA acts as an interferometer. The array’s antennas work in perfect synchrony to collect light as an enormous virtual telescope. As a result, these images of SDP.81 have a resolution up to 6 times higher than those taken from the infrared with the Hubble Space Telescope.
The astronomer’s models reveal fine, never seen structure within SDP.81, in the form of dusty clouds thought to be giant repositories of cold molecular gas, the birthplaces of stars and planets. These models were able to correct for the distortion produced by the magnifying gravitational lens.
ALMA observations are so sharp that researchers can see clumps of star formation in the galaxy down to a size of about 200 light years, equivalent to observing giant versions of the Orion Nebula producing thousands of times more new stars at the far side of the universe. This is the first time this phenomenon has been seen at such an enormous distance.
Rob Ivison, ESO’s Director for Science, and co-author of the study said, “The reconstructed ALMA image of the galaxy is spectacular, ALMA’s huge collecting area, the large separation of its antennas, and the stable atmosphere above the Atacama desert all lead to exquisite detail in both images and spectra. That means that we get very sensitive observations, as well as information about how the different parts of the galaxy are moving. We can study galaxies at the other end of the Universe as they merge and create huge numbers of stars. This is the kind of stuff that gets me up in the morning!”
Using the spectral information gathered by ALMA, astronomers measured how the distant galaxy rotates and its estimates mass. The data shows that gas in this galaxy is unstable, clumps of it are collapsing inwards, and will likely turn into new giant star forming regions in the future.
The modeling of lensing effect indicates the existence of a supermassive black hole at the center of the foreground galaxy lens. The central part of SDP.81 is too faint to be detected, leading to the conclusion that the foreground galaxy holds a supermassive black hole with more than 200-300 million times the mass of the sun.
