Star formation

A recipe for star formation is essential for understanding the origin of both our Sun and our Galaxy. While progress is being made in understanding star formation in the local Universe, it is neither observationally (nor theoretically) clear if the processes operate in the same manner in young galaxies in the early Universe.
 
[Credit: NASA/HST].

Submm surveys

One indication that star formation may be different in high-redshift galaxies is the very strong evolution seen in the numbers of the most strongly starbursting galaxies as we look back in time. The star formation rates in these systems can be up to 1000x that of our own Galaxy at the present day and suggest star formation is occuring in a much more vigorous mode.
 
The DustyGal programme builds upon results and data coming from wide-field submillimetre surveys undertaken with the SCUBA-2 instrument S2CLS) on the JCMT to select examples of vigorously star forming, but highly dust-obscured galaxies at high redshifts for further study.

Lensed submm
galaxies

For rare examples of strongly-lensed submm galaxies we can peer into their internal structure and observe how star formation is proceeding on sub-kiloparsec scales. This example is a 32x amplified submm galaxy which is forming 400 solar masses of new stars every year - over 100x faster rate than the Milky Way. [the lensing effect means we see two mirror-images of the galaxy, each containing four clumps]. New high-resolution interferometers (such as ALMA and eMERLIN) will allow unlensed galaxies (selected from well-defined surveys) to be studied at a comparable level of detail as part of the DustyGal.
 
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ALMA

The Atacama Large Millimeter Array is currently the only sub/millimetre interferometer with the combination of sensitivity and resolution necessary to map the distribution of dust and molecular and atomic gas within unlensed distant galaxies on sub-kpc scales. Such resolution is essential to investigate the physics of star formation within these systems and to both compare it to the star formation process in the local Universe and to test theoretical predictions for the modes of star formation in high-redshift galaxies.
 
[Credit: NRAO/ALMA].

eMERLIN

ALMA can trace the gas and dust in high-redshift starburst galaxies. But sub/millimetre observations provide an uncertain measure the rate of star formation. A more reliable tracer is the GHz frequency radio synchrotron emission from supernovae, reflecting the recent massive star formation. The eMERLIN interferometer can provide high-resolution radio maps of high-redshift starbursts to map their massive star formation on sub-kiloparsec scales.
 
Unfortunately eMERLIN in Northern England, cannot obtain high-fidelity maps of the well-studied equatorial survey fields visible to ALMA. But by incorporating radio dishes from the Goonhilly Earth Station in Cornwall, it will be possible to map these fields. Exploitation of this new facility is part of the DustyGal programme.
[Credit: eMERLIN/JBO].

eCOSMOS

One key element of DustyGal is to undertake a 1.4-GHz survey of the COSMOS field with the combined eMERLIN + Goonhilly radio interferometer, operated in a partnership by the Consortium of Universities for Goonhilly Astronomy (CUGA). This will yield 150 milli-arcsecond (~1 kiloparsec) resolution radio maps of luminous, high-redshift starbursts in this well-studied field, allowing DustyGal to map their extended star formation and disentangle it from nuclear starbursts and AGN activity.
 
[Credit: COSMOS].