MPIfR: Tune Your Radio: Galaxies Sing While Forming Stars

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MPIfR: Tune Your Radio: Galaxies Sing While Forming Stars

Post by bystander » Tue Feb 21, 2017 4:24 pm

Tune Your Radio: Galaxies Sing While Forming Stars
Max Planck Institute for Radio Astronomy | 2017 Feb 21

What radio emission tells us about star formation in distant spiral galaxies

A team of astronomers led by Fatemeh Tabatabaei from the Instituto de Astrofisica de Canarias (IAC), including scientists from two Max Planck institutes (MPIfR, Bonn and MPIA, Heidelberg), has measured the radio emission for a large sample of galaxies with the Effelsberg 100-m radio telescope at different wavelengths. These galaxies were selected from the KINGFISH sample previously observed in the infrared with the Herschel satellite. This allows for the first time a comparative study of a total of 52 spiral galaxies. A reliable method could be established to determine the star formation rate exclusively from radio data without including other spectral regimes.
[img3="The radio observations were based on the KINGFISH (“Key Insights on Nearby Galaxies: a Far-Infrared Survey with Herschel”) sample of galaxies. The compilation shows composite infrared images of these galaxies created from Spitzer and Herschel observations. © Maud Galametz"]http://www.mpifr-bonn.mpg.de/3674873/st ... 604861.jpg[/img3][hr][/hr]
Almost all the light we see in the universe comes from stars which form inside dense clouds of gas in the interstellar medium of galaxies. The rate at which they form (referred to as star formation rate) depends on the reserves of gas and its physical properties like density, temperature, and magnetic field strength. To understand how star formation works, measuring the star formation rate is a key task.

In order to derive the star formation rates, a variety of observations at different wavelengths had been undertaken until now, each with its advantages and disadvantages. The tracers used in the visible and the ultraviolet can be partly absorbed by interstellar dust. This led to the use of hybrid tracers, which combine two or more different wavelength ranges, among them the infrared, which can help to correct for the dust absorption. However, other emissions which are not related to the formation of massive stars can intervene and lead to confusion.

Now, an international research team made a detailed analysis of the spectral energy distribution of a subsample of the KINGFISH galaxies. The scientists determined for the first time the emitted radio energy which can be used as a tracer to calculate their star formation rates. ...

The Radio Spectral Energy Distribution and Star Formation Rate Calibration in Galaxies - F.S. Tabatabaei et al
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