From Manu: “Hubble explores the origins of modern galaxies”


Manu Garcia, a friend from IAC.

The universe around us.
Astronomy, everything you wanted to know about our local universe and never dared to ask.

29/5/17

Astronomers are true forms of galaxies 11 billion years back in time.

1
Hubble sequence along the history of the Universe.

Astronomers have used observations from the Hubble survey to explore CANDELS sizes, shapes and colors of distant galaxies during the last 80% of the Universe’s history. In the universe galaxies today have a variety of different ways, and are classified through a system known as the Hubble sequence and it turns out that this sequence was already in place as soon as 11 billion years ago.

Sequence Hubble classified galaxies according to their morphology and star forming activity, arranging them in a cosmic zoo spiral, elliptical and irregular shapes with rotating arms, fuzzy halos and bright central protuberances. Two main types of galaxies are identified in this sequence: elliptical and spiral, with a third type, lenticular, settling somewhere between the two.

This accurately describes what we see in the region of space around us, but how to change the morphology of the galaxy as we look further back in time, when the universe was very young?

“This is a key question: when and in what time scale takes shape the Hubble Sequence?” BoMee Lee of the University of Massachusetts, USA, lead author of a new paper exploring the sequence says. “To do this we need to look at distant galaxies and compare their closest relatives, to see if it can also be described in the same way.”

Astronomers used Hubble to observe 11 billion years in time when the universe was very young, exploring the anatomy of distant galaxies.

Although it was known that the Hubble sequence was met about 8 billion years ago [1] ago, these new observations push 2,500 million years back in cosmic time, covering a whopping 80% of the past history of the universe. Previous studies had also come to this time of the cosmos to study low mass galaxies, but none had examined conclusively large, mature galaxies like the Milky Way. CANDELS new observations confirm that all galaxies so distant – both large and small – fit into the different classifications of the sequence.

“This is the only comprehensive study to date of the visual appearance of large, massive galaxies that existed at the time,” says Arjen van der Wel, co-author of the Max Planck Institute for Astronomy in Heidelberg, Germany. “The galaxies appear unusually mature, which is not predicted by models of galaxy formation such as that from the beginning in the history of the Universe”.

Galaxies in these earlier times seem to be divided between the blue star-forming galaxies with a complex structure including disks, lumps and bumps and desordenados- massive red galaxies that no longer form stars, as seen in the nearby Universe [2].

NASA/ESA Hubble Telescope

Or more such massive galaxies like the Milky Way are quite rare in the young Universe. This shortage has prevented previous studies could muster a large enough sample of mature galaxies to adequately describe its characteristics.

What was needed was a systematic set of observations, such as the Hubble CANDELS survey, which was large enough to allow astronomers to analyze a greater number of these galaxies consistently and detailed [3]. With the Wide Field Camera 3 (WFC3) Hubble, astronomers were able to observe in the infrared part of the spectrum to see how galaxies appeared in the frame visible [4] rest, which is easier to compare galaxies in our neighborhood.

“The huge dataset CANDELS was a great resource to use in order to consistently study the ancient galaxies in the early Universe,” concludes Lee. “And the resolution and sensitivity of Hubble’s WFC3 is unsurpassed in the infrared wave lengths necessary to carry out this estudio.La Hubble Sequence holding a lot of what we know about how galaxies form and evolve – It is a significant discovery. ”

Notes
[1] Previous studies have analyzed the proportions of the different types of galaxies in time (heic1002). Mixing spiral, elliptical, lenticular galaxies peculiar is different today, with many more peculiar in the distant universe we see around.

[2] In a recent article related, Alice Mortlock and his colleagues took a different but complementary to classify these distant galaxies by visual inspection approach. They found that the types of galaxies seen in the Hubble sequence are well defined in terms of color, structure and star formation rates at very large distances from us, but its morphology is still developing. While the morphology of a galaxy may be the final settling property, the fundamentals of the Hubble sequence are set much earlier.

[3] CANDELS, the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey is the largest project in the history of Hubble, with 902 orbits of observing time allocated. It is being carried out with two cameras aboard Hubble – WFC3 and ACS – and aims to explore the galaxy evolution in the early Universe and the first seeds of cosmic structure less than a billion years after the Big Bang.

NASA/ESA Hubble WFC3

NASA/ESA Hubble ACS

[4] Previous studies of this period of cosmic history were inconclusive because they were limited to visible light, showing only the ultraviolet emission from galaxies, which highlights the formation of stars. As this star formation dominated observations, galaxies appeared to be lumpy and disordered, without any resemblance to the galactic forms we see around us today. Pushing in the infrared part of the spectrum astronomers could observe how these distant galaxies appear in the visible part of the rest (now redshifted).

Notes
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

These results are described in an article entitled “CANDELS: The correlation between the morphology of galaxies and star formation activity as Z ~ 2”, to appear in The Astrophysical Journal.

[1] The international team of astronomers in this study consists of B. Lee (University of Massachusetts, USA), M. Giavalisco (University of Massachusetts, USA), CC Williams (University of Massachusetts, USA .S.), Y. Guo (United States), J. Lotz (Institute of Space Telescope Science, Baltimore, USA), A. van der Wel (Max Planck Institute for Astronomy, Heidelberg, Germany), HC Ferguson (Institute of Space Telescope Science, Baltimore, S. M Faber (University of California, USA), A. Koekemoer (Institute of Space Telescope Science, Baltimore, USA), N. Grogin (Institute Space Telescope, Baltimore, USA), D. Kocevski (University of Kentucky, CJ Conselice (University of Nottingham, UK), S. Wuyts (Max Planck Institute for Extraterrestrial Physics, Garching, Germany), Science A. Dekel (Hebrew University, Israel), J. Kartaltepe (NOAO-Tuscon, Arizona, EF Bell (University of Michigan, USA).

Image Credit: NASA, ESA

Here is the original NASA/ESA HUbble article from 15 August 2013

Links

Research Paper
Images of Hubble

See the full article here .

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