NASA's Great Observatories are teaming up to look deeper into the universe than ever before. With a boost from natural "zoom lenses" found in space, they should be able to uncover galaxies that are as much as 100 times fainter than what the Hubble, Spitzer, and Chandra space telescopes can typically see. This ambitious collaborative program is called The Frontier Fields. Astronomers will spend the next three years peering at six massive clusters of galaxies. Researchers are interested not only as to what's inside the clusters, but also what's behind them. The gravitational fields of the clusters brighten and magnify distant background galaxies that are so faint they would otherwise be unobservable.
A team of astronomers has discovered a galaxy that sets the current distance record for galaxies whose distance has been definitively measured by spectroscopic redshift. The galaxy is seen as it was at a time just 700 million years after the Big Bang, when the universe was only about 5 percent of its current age of 13.8 billion years. This galaxy and dozens of others were selected for follow-up observations from the approximately 100,000 galaxies discovered in the Hubble Space Telescope CANDELS survey (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey). The team used the Keck I Telescope in Hawaii to measure the redshift of the CANDELS galaxy, designated z8_GND_5296, at 7.51. This is the highest galaxy redshift ever confirmed. The spectral redshift of galaxies is caused by the expansion of space from the Big Bang.
A galaxy rapidly forming stars 700 million years after the Big Bang at redshift 7.51
Nature 502, 7472 (2013). doi:10.1038/nature12657
Authors: S. L. Finkelstein, C. Papovich, M. Dickinson, M. Song, V. Tilvi, A. M. Koekemoer, K. D. Finkelstein, B. Mobasher, H. C. Ferguson, M. Giavalisco, N. Reddy, M. L. N. Ashby, A. Dekel, G. G. Fazio, A. Fontana, N. A. Grogin, J.-S. Huang, D. Kocevski, M. Rafelski, B. J. Weiner & S. P. Willner
Of several dozen galaxies observed spectroscopically that are candidates for having a redshift (z) in excess of seven, only five have had their redshifts confirmed via Lyman α emission, at z = 7.008, 7.045, 7.109, 7.213 and 7.215 (refs 1, 2, 3, 4). The small fraction of confirmed galaxies may indicate that the neutral fraction in the intergalactic medium rises quickly at z > 6.5, given that Lyman α is resonantly scattered by neutral gas. The small samples and limited depth of previous observations, however, makes these conclusions tentative. Here we report a deep near-infrared spectroscopic survey of 43 photometrically-selected galaxies with z > 6.5. We detect a near-infrared emission line from only a single galaxy, confirming that some process is making Lyman α difficult to detect. The detected emission line at a wavelength of 1.0343 micrometres is likely to be Lyman α emission, placing this galaxy at a redshift z = 7.51, an epoch 700 million years after the Big Bang. This galaxy’s colours are consistent with significant metal content, implying that galaxies become enriched rapidly. We calculate a surprisingly high star-formation rate of about 330 solar masses per year, which is more than a factor of 100 greater than that seen in the Milky Way. Such a galaxy is unexpected in a survey of our size, suggesting that the early Universe may harbour a larger number of intense sites of star formation than expected.
Radio astronomy: Finger on the pulsar
Nature 502, 7472 (2013). doi:10.1038/502439a
Author: Bernie Fanaroff
Bernie Fanaroff probes a study on how radio telescopes have opened up our understanding of the Universe.
Astrophysics: Recipe for regularity
Nature 502, 7472 (2013). doi:10.1038/502453a
Authors: Ellen Zweibel
A detailed astrophysical model has been laid out that not only reproduces the far-infrared–radio correlation for galaxies that are actively forming stars, but also predicts how the correlation is modified at high redshift.
Astronomy: New distance record for galaxies
Nature 502, 7472 (2013). doi:10.1038/502459a
Authors: Dominik A. Riechers
Spectroscopic measurements of 43 candidates for distant galaxies have confirmed one to be the most remote galaxy securely identified to date — and it forms stars more than 100 times faster than the Milky Way. See Letter p.524
Final word is near on dark-matter signal
Nature 502, 7472 (2013). http://www.nature.com/doifinder/10.1038/502421a
Author: Eugenie Samuel Reich
An influential US experiment prepares to release its first results.