“Such a system is indeed extraordinary,” said Dr. Thato Manamela. We are witnessing radio equivalent of a laser half way through the universe.
The “laser” under discussion is not a beam of lightsaber and nanodisc but a radio signal that is naturally enhanced, an astrophysical maser, of two galaxies colliding, and it comes their way. The source was named HATLAS J142935.3-002836 and is between 8 billion and 10 billion light-years distant; the microwaves that we hear today were emitted in the universe when it was approximately half its modern age.
Hydroxyl megamasers are created in one of the richest and most disordered places that are known: colliding galaxies. When the clouds surrounding them interlock with and squeeze through each other, the giant reservoirs of hydroxyl (OH) molecules are “pumped” to high-energy levels. When the aforementioned molecules relax, they give off microwaves; in the appropriate conditions the emission is coherent and self-amplifying. The concealed deceive is comparable to a designed laser, although the exaggerated radiation is not visible light; rather, it is a microwave radiation, thus astronomers refer to it as a maser. Here, the emission is clumped around 18 centimeters (approximately 1,665 megahertz), which is a long-wavelength regime radio telescopes are designed to observe.
The megamasers are sometimes called “cosmic beacons” due to their brightness which enables the galaxy crashes to be seen even in galaxies located at a very long distance and obscured by dust. The difference with this object is its intensity: the signal is bright enough to warrant the researchers in contending that it belongs to the next level in intensity, a “gigamaser,” not a standard megamaser. It is important since very bright masers give very clean spectral fingerprints, which allow astronomers to deduce what is happening in gas reservoirs to which mergers contributed, and would otherwise remain obscure.
The second evidence of cosmic engineering that is pointed out through the detection is the use of gravitational lensing. There is a giant foreground galaxy that is immediately in the near-perfect position in front of the merger, distorting space-time and boosting the background radio emission. The process of magnification can make a whisper audible enough to be measured, as a natural telescope would be overlaid upon human equipment. The maser record was made practicable in the new study with the combination of MeerKAT and strong gravitational lensing making the study feasible.
The story itself includes MeerKAT. The 64 dishes of the array are designed as sensitive at radio astronomy centimeter wavelengths, with half the battle being to be raw sensitive. The radio observations of to-day produce vast masses of data that need to be calibrated, purged and searched using special pipelines before a rare signal can be spotted. According to Prof. Roger Deane, this result is an eloquent demonstration of what MeerKAT is capable of achieving when combined with high-end computational infrastructure, purpose specific data processing pipelines and well-trained software support staff.
Gravitational lensing has made other so-called “beacons,” as well as a Hubble-assisted discovery referred to as the second-brightest quasar in the early universe, whereby the lensing of a distant black-hole enabled a core to be seen to be significantly brighter than it would have been otherwise. In radio, the geometry can bring rare masers in view, and turn unexpected coincidences into instruments of research into galaxy evolution under conditions as extreme as possible.
Having a single abnormally bright, lensed maser in hand, scientists are now aiming at additional lensed systems, in the hope of creating a far larger sample. This is but the start, Manamela. We do not want to discover one system, we want to discover hundreds and thousands.
