NAOJ: Explosive Birth of Stars Swells Cores of Disk Galaxies

[bystander]

Explosive Birth of Stars Swells Cores of Disk Galaxies
National Astronomical Observatory of Japan | ALMA | 2017 Sep 10

ALMA spots transforming disk galaxies

[img3="Observation images of a galaxy 11 billion light-years away. Submillimeter waves detected with ALMA are shown in left, indicating the location of dense dust and gas where stars are being formed. Optical and infrared light seen with the Hubble Space Telescope are shown in the middle and right, respectively. A large galactic disk is seen in infrared, while three young star clusters are seen in optical light.
Credit: ALMA (ESO/NAOJ/NRAO), NASA/ESA Hubble Space Telescope, Tadaki et al."]https://alma-telescope.jp/assets/upload ... 1-2017.jpg[/img3][hr][/hr]

Astronomers found that active star formation upswells galaxies, like yeast helps bread rise. Using three powerful telescopes on the ground and in orbit, they observed galaxies from 11 billion years ago and found explosive formation of stars in the cores of galaxies. This suggests that galaxies can change their own shape without interaction with other galaxies. ...

Aiming to understand galactic metamorphosis, the international team explored distant galaxies 11 billion light-years away. Because it takes time for the light from distant objects to reach us, by observing galaxies 11 billion light-years away, the team can see what the Universe looked like 11 billion years ago, 3 billion years after the Big Bang. This corresponds the peak epoch of galaxy formation; the foundations of most galaxies were formed in this epoch.

Receiving faint light which has travelled 11 billion years is tough work. The team harnessed the power of three telescopes to anatomize the ancient galaxies. First, they used NAOJ’s 8.2-m Subaru Telescope in Hawai`i and picked out 25 galaxies in this epoch. Then they targeted the galaxies for observations with NASA/ESA’s Hubble Space Telescope (HST) and the Atacama Large Millimeter/submillimeter Array (ALMA). The astronomers used HST to capture the light from stars which tells us the “current” (as of when the light was emitted, 11 billion years ago) shape of the galaxies, while ALMA observed submillimeter waves from cold clouds of gas and dust, where new stars are being formed. By combining the two, we know the shapes of the galaxies 11 billion years ago and how they are evolving. ...

Rotating Starburst Cores in Massive Galaxies at z = 2.5 - Ken-ichi Tadaki et al

• Astrophysical Journal Letters 841(2):L25 (2017 Jun 01) DOI: 10.3847/2041-8213/aa7338
  arXiv.org > astro-ph > arXiv:1703.10197 > 29 Mar 2017 (v1), 14 May 2017 (v2)

Bulge-Forming Galaxies with an Extended Rotating Disk at z~2 - Ken-ichi Tadaki et al

• Astrophysical Journal 834(2):135 (2017 Jun 01) DOI: 10.3847/1538-4357/834/2/135
  arXiv.org > astro-ph > arXiv:1608.05412 > 18 Aug 2016 (v1), 25 Oct 2016 (v2)

[Ann]

Fascinating. So it is possible that disk galaxies can turn into elliptical galaxies all by themselves by forming huge numbers of stars in their own cores.

Click to view full size image

M82. Inset: X-ray: NASA/CXC/Tsinghua Univ./H. Feng et al.; Full-field:
X-ray: NASA/CXC/JHU/D.Strickland; Optical:
NASA/ESA/STScI/AURA/The Hubble Heritage Team;
IR: NASA/JPL-Caltech/Univ. of AZ/C. Engelbracht

My impression has been that Ultra Luminous Infra Red Galaxies, ULIRGs, are early galaxies suffering runaway star formation in such a way that they destroy their own disk shape and use up their own gas reservoir and turn into elliptical galaxies almost right away. But the galaxies in this study aren't ULIRGs, and yet their star formation might turn them into ellipticals.

The galaxies in this study are 11 billion light-years away, and when I saw that number, I associated it with M82 at 11.4-12.4 million light-years away. And M82 might just be a little brother of its early-universe brethren, because M82 is forming so many stars in its core that its disk is getting somewhat distorted. But a photo of M82 by Mike Hankey (with a supernova) doesn't suggest that its core is upswelled, in spite of all the star formation going on there. M82 is called the Cigar Galaxy for a reason.

Ann

[MargaritaMc]

The NAOJ link didn't work for me, returning a "the site cannot be reached" notice. I googled and found this one
https://www.nao.ac.jp/en/news/science/2 ... -alma.html


And this one
https://phys.org/news/2017-09-explosive ... cores.html