Scientists capture most-detailed radio image of Andromeda galaxy to date
Disk of galaxy identified as region where new stars are born

Date:
July 28, 2021
Source:
University of British Columbia
Summary:
Scientists have published a new, detailed radio image of the
Andromeda galaxy -- the Milky Way's sister galaxy -- which will
allow them to identify and study the regions of Andromeda where
new stars are born.



FULL STORY ========================================================================== Scientists have published a new, detailed radio image of the Andromeda
galaxy - - the Milky Way's sister galaxy -- which will allow them to
identify and study the regions of Andromeda where new stars are born.


==========================================================================
The study -- which is the first to create a radio image of Andromeda at
the microwave frequency of 6.6 GHz -- was led by University of British
Columbia physicist Sofia Fatigoni, with colleagues at Sapienza University
of Rome and the Italian National Institute of Astrophysics. It was
published online in Astronomy and Astrophysics.

"This image will allow us to study the structure of Andromeda and its
content in more detail than has ever been possible," said Fatigoni, a PhD student in the department of physics and astronomy at UBC. "Understanding
the nature of physical processes that take place inside Andromeda
allows us to understand what happens in our own galaxy more clearly --
as if we were looking at ourselves from the outside." Prior to this
study, no maps capturing such a large region of the sky around the
Andromeda Galaxy had ever been made in the microwave band frequencies
between one GHz to 22 GHz. In this range, the galaxy's emission is very
faint, making it hard to see its structure. However, it is only in this frequency range that particular features are visible, so having a map
at this particular frequency is crucial to understanding which physical processes are happening inside Andromeda.

In order to observe Andromeda at this frequency, the researchers required
a single-dish radio telescope with a large effective area. For the study,
the scientists turned to the Sardinia Radio Telescope, a 64-metre fully steerable telescope capable of operating at high radio frequencies.

It took 66 hours of observation with the Sardinia Radio Telescope and consistent data analysis for the researchers to map the galaxy with high sensitivity. They were then able to estimate the rate of star formation
within Andromeda, and produce a detailed map that highlighted the disk
of the galaxy as the region where new stars are born.

"By combining this new image with those previously acquired, we have
made significant steps forward in clarifying the nature of Andromeda's microwave emissions and allowing us to distinguish physical processes that occur in different regions of the galaxy," said Dr. Elia Battistelli,
a professor in the department of physics at Sapienza and coordinator of
the study.

"In particular, we were able to determine the fraction of emissions due
to thermal processes related to the early stations of new star formation,
and the fraction of radio signals attributable to non-thermal mechanisms
due to cosmic rays that spiral in the magnetic field present in the interstellar medium," Fatigoni said.

For the study, the team developed and implemented software that allowed -
- among other things -- to test new algorithms to identify never-before- examined lower emission sources in the field of view around Andromeda
at a frequency of 6.6 GHz. From the resulting map, researchers were
able to identify a catalog of about 100 point sources, including stars, galaxies and other objects in the background of Andromeda.

========================================================================== Story Source: Materials provided by University_of_British_Columbia. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. S. Fatigoni, F. Radiconi, E. S. Battistelli, M. Murgia, E. Carretti,
P.

Castangia, R. Concu, P. de Bernardis, J. Fritz, R. Genova-Santos, F.

Govoni, F. Guidi, L. Lamagna, S. Masi, A. Melis, R. Paladini, F. M.

Perez-Toledo, F. Piacentini, S. Poppi, R. Rebolo,
J. A. Rubino-Martin, G.

Surcis, A. Tarchi, V. Vacca. Study of the thermal and nonthermal
emission components in M 31: the Sardinia Radio Telescope view at
6.6 GHz.

Astronomy & Astrophysics, 2021; 651: A98 DOI:
10.1051/0004-6361/202040011 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/07/210728111338.htm

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