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Testing Radio Continuum Emission As a Star Formation Tracer in Dwarf Galaxies
| Submitter: | Vasu Dipakkumar Pipwala |
| Description: | Star formation is a fundamental part of the gas cycle in galaxies. One way to trace star formation is to use radio continuum emission, which arises from electrons accelerated by supernovae in galactic magnetic field. These supernovae feeds back the gas in the interstellar medium (ISM) where neutral hydrogen (HI) is the dominant component and can be traced through 21cm emission line in galaxies. The radio continuum emission from galaxies is a powerful star formation tracer as it does not suffer from extinction by dust. However, its utility in dwarf galaxies is not well-tested. In order to investigate radio continuum as a star formation tracer in dwarf galaxies, we used data from the Apertif imaging surveys. We used a list of sources identified from their neutral hydrogen (HI) content that also had infrared emission from WISE. We cross-matched this to a catalog of radio continuum sources to build a catalog that contains information about HI content, radio flux and IR flux for the galaxies. After deriving the star formation rates (SFRs) from both the infrared and radio emission, we have compared them against each other. We found that SFRs derived from the radio continuum seems to correlate more efficiently with SFRs derived from the WISE W4 (23 µm) band, as opposed to W3 (12 µm) band. This is consistent with the W4 band measuring recent star formation on a longer timescale, similar to radio continuum, while W3 measures more active star formation. To investigate the flux calibration of Apertif data, we selected two sources with relatively high radio flux from our catalog. For these two source fields, we have re-processed the images through an improved calibration pipeline in-order to make new mosaic images and compared the measured fluxes of all sources in the field against the existing source catalog. The image above is the new mosaic of one of the fields, with the dwarf galaxy shown in the inset. |
| Copyright: | Vasu Dipakkumar Pipwala |
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