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Early Galaxies - A Look at CfA Discoveries from Recent Journals

4 Jan 2020, 13:35 UTC
Early Galaxies - A Look at CfA Discoveries from Recent Journals
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Galaxies that are very luminous in the infrared are generally active in making new stars whose ultraviolet radiation heats the dust. The energy, re-radiated by the dust at infrared wavelengths, is characterized by having a broad spectral shape with a distinct emission peak.As the universe expands, and as the observed spectra of galaxies shift to the red, light at the wavelength of this peak moves into the submillimeter band leaving the levels of observed infrared flux deficient. Star-forming galaxies in the very distant universe are thus fainter in the infrared than in the submillimeter.Thousands of galaxies have been discovered dating from epochs only a few billion years after the big bang. Most of them are small, low-mass galaxies that are faint and relatively difficult to study. Although more luminous, massive star-forming galaxies should also be present, these large objects are difficult to assemble at early cosmic times and there are not as many of them. One type of such luminous early galaxy is called a dusty-star-forming galaxy. They contain so much obscuring dust that they are invisible at optical wavelengths, and (based on their luminosities) have star-formation rates exceeding a thousand solar-masses per year; for comparison, the Milky Way produces ...

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