Astronomers create a new microwave map of the Milky Way and beyond

An international team of scientists has succeeded in mapping the magnetic field of our galaxy, the Milky Way, using telescopes that observe the sky in the microwave range. The new research has been published in Monthly Notices of the Royal Astronomical Society.

The team used the QUIJOTE (QUI JOint Tenerife) Collaboration, located at the TED Observatory in Tenerife in the Canary Islands. This includes two telescopes 2.5 meters in diameter, which observe the sky in the microwave part of the electromagnetic spectrum.

Mapping began in 2012 and is led by the Astronomical Institute of the Canary Islands (IAC). Almost a decade later, The Collaboration Group introduced a series of 6 scientific articles, giving the most accurate description yet of the Milky Way’s emission polarization at microwave wavelengths. Polarization is a property of transverse waves like light waves Which determines the direction of wave oscillations and indicates the presence of a magnetic field.

The studies complement previous space missions dedicated to studying cosmic microwave background radiation (CMB), the fossil radiation left over from the Big Bang, which has given detailed insight into the early history of the universe.

In addition to mapping the magnetic structure of the Milky Way, QUIJOTE data has also proven useful in other scenarios. The new data is also a unique tool for studying anomalous microwave emission (AME), a type of emission first detected 25 years ago. AME is thought to result from the rotation of very small particles of dust in the interstellar medium, which tend to be directed by the presence of the galactic magnetic field.

The new findings allowed the team to gain information about the structure of the Milky Way’s magnetic field, as well as help understand the energetic processes that occurred near the birth of the universe. To measure the signals from that time, scientists first need to remove the veil of emissions associated with our galaxy. New maps provided by QUIJOTE do just that, allowing us to better understand these elusive signals from the wider universe.

The maps from QUIJOTE also made it possible to study the recently detected increase in microwave emissions from the center of our galaxy. The origin of this emission is currently unknown, but it could be related to the decay processes of dark matter particles. Using QUIJOTE, the team confirmed the presence of this excess radiation, and found some evidence that it could be polarizing.

Finally, the new maps from QUIJOTE have allowed a systematic study of more than 700 sources of radio and microwave emissions, both of galactic and extragalactic origin, which means the data is helping scientists decipher signals coming from outside our galaxy, including Cosmic microwave background radiation.

“These new maps give detailed descriptions in a new frequency band, from 10 to 40 GHz, complementing those from space missions such as Planck and WMAP,” comments José Alberto Rubiño, principal scientist at the QUIJOTE Collaboration. “We have characterized the synchrotron emission from our galaxy with unprecedented precision. This radiation is the result of an emission from charged particles moving at speeds close to the speed of light within the galaxy’s magnetic field. These maps, the result of nearly 9,000 hours of observation, are a unique tool for studying magnetism in the universe.”

“One of the most interesting findings we have found is that the polarized synchrotron emission from our galaxy is much more variable than previously thought,” says Elena de la Hoz, a researcher at the Instituto Fesica de Cantabria (IFCA). “Our results are a reference to help future experiments reliably detect CMB signaling,” she adds.

“Scientific evidence indicates that the universe went through a phase of rapid expansion, called inflation, a fraction of a second after the Big Bang. If this is true, we expect to find some observable results when we study the polarization of the cosmic microwave background. Measuring these predicted features is an order of magnitude.” difficult, because they are small in breadth, but also because they are less bright than the polarized emission from our galaxy.” Rubiño notes, “If we finally measure them, however, we will obtain indirect information about the physical conditions in the very early stages of our universe, when energy scales were Far higher than those we can access or study from Earth. This has enormous implications for our understanding of fundamental physics.”

“The maps from QUIJOTE also made it possible to study microwave emission from the center of our galaxy. Recently microwave An emission has been detected from this region, the origin of which is unknown, but whose origin could be related to the decay processes of dark matter particles. With QUIJOTE, we confirmed the existence of this excess of radiation, and found some evidence that it could be polarizing,” comments Federica Guidi, researcher at the Astrophysical Institute Paris (IAP, France).

The work appears in “QUIJOTE SCIENTIFIC RESULTS – IV. Survey of the northern sky in intensity and polarization at 10–20 GHz using the multifrequency instrument”, Rubiño-Martin et al. , published in Monthly Notices of the Royal Astronomical Society.