The Sunburst Arc
Sunburst Arc 1
Sunburst Arc 2
Sunburst Arc 3
Area surrounding the Sunburst Arc (ground-based image)
Videos
Pan of the Sunburst Arc
Animation of gravitational lensing (artist’s impression)
Astronomers using the NASA/ESA Hubble
Space Telescope have observed a galaxy in the distant regions of the
Universe which appears duplicated at least 12 times on the night sky.
This unique sight, created by strong gravitational lensing, helps
astronomers get a better understanding of the cosmic era known as the
epoch of reionisation.
This new image from the NASA/ESA Hubble Space Telescope shows an astronomical object whose image is multiplied by the effect of strong gravitational lensing.
The galaxy, nicknamed the Sunburst Arc, is almost 11 billion
light-years away from Earth and has been lensed into multiple images by a
massive cluster of galaxies 4.6 billion light-years away [1].
The mass of the galaxy cluster is large enough to bend and
magnify the light from the more distant galaxy behind it. This process
leads not only to a deformation of the light from the object, but also
to a multiplication of the image of the lensed galaxy.
In the case of the Sunburst Arc the lensing effect led to
at least 12 images of the galaxy, distributed over four major arcs.
Three of these arcs are visible in the top right of the image, while one
counterarc is visible in the lower left — partially obscured by a
bright foreground star within the Milky Way.
Hubble uses these cosmic magnifying glasses to study
objects otherwise too faint and too small for even its extraordinarily
sensitive instruments. The Sunburst Arc is no exception, despite being
one of the brightest gravitationally lensed galaxies known.
The lens makes various images of the Sunburst Arc between
10 and 30 times brighter. This allows Hubble to view structures as small
as 520 light-years across — a rare detailed observation for an object
that distant. This compares reasonably well with star forming regions in
galaxies in the local Universe, allowing astronomers to study the
galaxy and its environment in great detail.
Hubble’s observations showed that the Sunburst Arc is an
analogue of galaxies which existed at a much earlier time in the history
of the Universe: a period known as the epoch of reionisation — an era which began only 150 million years after the Big Bang [2].
The epoch of reionisation was a key era in the early
Universe, one which ended the “dark ages”, the epoch before the first
stars were created when the Universe was dark and filled with neutral
hydrogen [3].
Once the first stars formed, they started to radiate light, producing
the high-energy photons required to ionise the neutral hydrogen [4].
This converted the intergalactic matter
into the mostly ionised form in which it exists today. However, to
ionise intergalactic hydrogen, high-energy radiation from these early
stars would have had to escape their host galaxies without first being
absorbed by interstellar matter. So far only a small number of galaxies
have been found to “leak” high-energy photons into deep space. How this
light escaped from the early galaxies remains a mystery.
The analysis of the Sunburst Arc helps astronomers to add
another piece to the puzzle — it seems that at least some photons can
leave the galaxy through narrow channels in a gas rich neutral medium.
This is the first observation of a long-theorised process [5].
While this process is unlikely to be the main mechanism that led the
Universe to become reionised, it may very well have provided a decisive
push.
Source: ESA/Hubble/News
Notes
[1] The official designation of the Sunburst Arc galaxy is PSZ1 G311.65-18.48.
[5] The paper outlining these observations will appear in Science on 8 November 2019.
More Information
The international team of astronomers in this study consists of T. Emil Rivera-Thorsen (University of Oslo, Norway), Håkon Dahle (University of Oslo, Norway), John Chisholm (Université de Genève, Switzerland; University of California Santa Cruz, USA), Michael K. Florian (NASA Goddard Space Flight Center, USA), Max Gronke (University of California Santa Barbara, USA), Michael D. Gladders (University of Chicago, USA), Jane R. Rigby (NASA Goddard Space Flight Center, USA), Guillaume Mahler (University of Michigan, USA), Keren Sharon (University of Michigan, USA), Matthew Bayliss (MIT-Kavli Center for Astrophysics and Space Research, USA) and included data from Hubble programs 15418 and 15101.
Image credit: ESA, NASA, E. Rivera-Thorsen et al.
Links
Contacts:
Emil Rivera-Thorsen
Department of Astronomy, Stockholm University
Stockholm, Sweden
Tel: +46 737 703 603
Email: trive@astro.su.se
Håkon Dahle
Institute of Theoretical Astrophysics
Oslo, Norway
Tel: +47 93266331
Email: hakon.dahle@astro.uio.no
Bethany Downer
ESA/Hubble, Public Information Officer
Garching, Germany
Email: bethany.downer@partner.eso.org
[1] The official designation of the Sunburst Arc galaxy is PSZ1 G311.65-18.48.
[2] The further we look into
space, the further back we look in time. This allows astronomers to
study different epochs of the Universe, by studying objects at different
distances.
[3] Ionisation
is the process of gaining or losing electrons to leave electrically
charged particles. The era is known as reionisation because, after the
Big Bang, matter formed first into protons and electrons. Then, during
the era of recombination — about 380 000 years after the Big Bang — neutral hydrogen formed from these particles for the first time.
[4] While an ionised
hydrogen atom consists of only the core of the atom (one proton) a
neutral hydrogen atom contains a nucleus of one proton which is orbited
by one electron.
[5] The paper outlining these observations will appear in Science on 8 November 2019.
More Information
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
The international team of astronomers in this study consists of T. Emil Rivera-Thorsen (University of Oslo, Norway), Håkon Dahle (University of Oslo, Norway), John Chisholm (Université de Genève, Switzerland; University of California Santa Cruz, USA), Michael K. Florian (NASA Goddard Space Flight Center, USA), Max Gronke (University of California Santa Barbara, USA), Michael D. Gladders (University of Chicago, USA), Jane R. Rigby (NASA Goddard Space Flight Center, USA), Guillaume Mahler (University of Michigan, USA), Keren Sharon (University of Michigan, USA), Matthew Bayliss (MIT-Kavli Center for Astrophysics and Space Research, USA) and included data from Hubble programs 15418 and 15101.
Image credit: ESA, NASA, E. Rivera-Thorsen et al.
Links
Contacts:
Emil Rivera-Thorsen
Department of Astronomy, Stockholm University
Stockholm, Sweden
Tel: +46 737 703 603
Email: trive@astro.su.se
Håkon Dahle
Institute of Theoretical Astrophysics
Oslo, Norway
Tel: +47 93266331
Email: hakon.dahle@astro.uio.no
Bethany Downer
ESA/Hubble, Public Information Officer
Garching, Germany
Email: bethany.downer@partner.eso.org
