Srt Takes A Picture Of Andromeda At 6.6 GHz (Astronomy)

The image obtained at this frequency, in addition to being unprecedented, has allowed us to define in detail the morphology of the galaxy and in particular to identify the regions where the new stars are born. The results of the study, the result of the collaboration between Sapienza and the National Institute of Astrophysics, were published in the journal Astronomy & Astrophysics

Andromeda is one of the most studied galaxies of all time and probably also the best known to the general public for its proximity and similarity to our own galaxy, the Milky Way. A knowledge of the nature of the physical processes that take place within it would allow us to better understand what is happening in our galaxy, as if we were looking at it from the outside. Paradoxically, the very thing that has so far hindered a thorough observation of Andromeda in microwaves is its very conformation. In fact, due to its proximity to the Milky Way, it has an angular dimension of several degrees in the sky, which puts it out of the reach of interferometers made up of small antenna arrays. In order to observe Andromeda at frequencies of 6.

Today, a scientific collaboration between Sapienza University of Rome and the National Institute of Astrophysics (Inaf) has made it possible to obtain a completely new image of the Andromeda galaxy with the Sardinia Radio Telescope , at 6.6 GHz, a frequency never probed before. Now. The telescope’s excellent angular resolution made it possible to define the morphology in detail and thus expand the knowledge available so far on this galaxy.

The results of the study, carried out with the participation of numerous international institutions and universities such as the University of British Columbia, the Instituto de Radioastronomia y Astrophysics – Unam in Mexico, the Instituto de Astrofisica de Canarias, the Infrared Processing Analysis Center – Ipac in California was published in Astronomy & Astrophysics magazine .

Andromeda at various wavelengths. Credits: Radio: Wsrt / R. Braun; Microwave: Srt / S.Fatigoni et al .; Infrared: Nasa / Spitzer / K. Gordon; Visible: Robert Gendler; Ultraviolet: Nasa / Galex; X-ray: Hex / Xmm / W. Pietsch

At 6.6 GHz, the galaxy’s emission is close to its minimum, complicating the possibility of obtaining such a sharp image. Despite this, thanks to 66 hours of observation with the Sardinia Radio Telescope and a consistent data processing work, the researchers were able to map the galaxy with high sensitivity.

“By combining this new image with those previously acquired,” says Elia Battistelli of the Physics Department of Sapienza and coordinator of the study, “we have made significant progress in clarifying the nature of Andromeda’s microwave emission, distinguishing the physical processes that occur different regions of the galaxy ».

“In particular, we were able to determine the fraction of emission due to thermal processes related to the early stages of the formation of new stars, and the fraction of radio signal attributable to non-thermal mechanisms due to cosmic rays spiraling in the magnetic field present in the interstellar medium. Add Federico Radiconi of the Physics Department of Sapienza and Sofia Fatigoni of the University of British Columbia.

With the data obtained, it was thus possible for the researchers to estimate the rate of star formation of Andromeda and produce a detailed map that highlighted the disk of the galaxy as the region of choice for the birth of new stars.

To obtain this unique image of Andromeda, the team developed and implemented ad hoc software that allowed, among other things, to test new algorithms for the identification of lower emission sources in the field of view around Andromeda, the largest never examined at a frequency of 6.6 GHz: in this way the researchers extracted from the map a catalog of about a hundred point sources, namely stars, galaxies and other objects, against the background of Andromeda.

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Provided by INAF

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