Astronomers using the 8-m Subaru Telescope have identified 1,824 new supernova candidates, including 58 Type Ia supernovae over 8 billion light-years away.
Supernovae discovered by Yasuda et al: there are three images for each supernova — for before it exploded (left), after it exploded (middle), and the supernova itself. Image credit: Yasuda et al, doi: 10.1093/pasj/psz050.
“The 870 mega-pixel Hyper-Suprime Cam instrument on the Subaru Telescope is the only instrument mounted on the prime focus among the large (8-10 m) telescopes,” said Professor Naoki Yasuda from the Kavli Institute for the Physics and Mathematics of the Universe at the University of Tokyo and colleagues.
“It is unique in its wide field of view, with 104 charge-coupled devices (CCDs).”
The astronomers used the Subaru Hyper-Suprime Cam to hunt for distant stellar explosions.
“Supernovae are rare events, and there are only a handful of telescopes in the world capable of capturing sharp images of distant stars,” they explained.
“By taking repeated images of the same area of night sky over a six month period, we could identify new supernovae by looking for stars that suddenly appeared brighter before gradually fading out.”
As a result, Professor Yasuda and co-authors identified 1,824 supernova candidates.
Of these, five candidates were classified as superluminous supernovae and 433 as Type Ia supernovae.
In particular, 58 Type Ia supernovae are located more than 8 billion light-years away from Earth.
“The Subaru Telescope and its Hyper Suprime-Cam have already helped researchers create a 3D map of dark matter, and observation of primordial black holes, but now this result proves that this instrument has a very high capability finding supernovae very, very far away from Earth,” Professor Yasuda said.
“I want to thank all of my collaborators for their time and effort, and look forward to analyzing our data to see what kind of picture of the Universe it holds.”
“The next step will be to use the data to calculate a more accurate expansion of the Universe, and to study how dark energy has changed over time.”
The team’s paper appears in the Publications of the Astronomical Society of Japan (arXiv.org preprint).
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Naoki Yasuda et al. The Hyper Suprime-Cam SSP transient survey in COSMOS: Overview. Publications of the Astronomical Society of Japan, published online May 30, 2019; doi: 10.1093/pasj/psz050
