Hubble Observes Multiply-Imaged, Gravitationally Lensed Supernova

The multiply-imaged supernova AT2016jka appeared in the distant giant galaxy MRG-M0138, gravitationally lensed by the foreground galaxy cluster MACS J0138.0-2155.

This Hubble image shows the galaxy cluster MACS J0138.0-2155, which is so massive that its gravity bent and magnified light streaming not only from an extremely distant background galaxy but also from a supernova event in this galaxy. The color image was made using observations from eight different filters spread across Hubble’s Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3). The color results from assigning different hues to each monochromatic image associated with an individual filter. Image credit: NASA / ESA / Hubble / A. Newman / M. Akhshik / K. Whitaker.

Galaxy clusters contain thousands of galaxies of all ages, shapes and sizes.

They have a mass of about one million billion times the mass of the Sun and form over billions of years as smaller groups of galaxies slowly come together.

Albert Einstein predicted in his theory of general relativity that massive objects will deform the fabric of space itself. When light passes one of these objects, such as a huge galaxy cluster, its path is changed slightly.

Called gravitational lensing, this effect is only visible in rare cases and only world’s best telescopes can observe the related phenomena.

Hubble’s sensitivity and high resolution allow it to see faint and distant gravitational lenses that cannot be detected with ground-based telescopes whose images are blurred by the atmosphere of our planet.

“When the light from a distant object passes very near to a foreground galaxy or cluster, gravitational lensing can cause it to appear as multiple images on the sky,” said Dr. Steven Rodney from the University of South Carolina and colleagues.

“If the source is variable, it can be used to constrain the cosmic expansion rate and dark energy models.”

“Achieving these cosmological goals requires many lensed transients with precise time delay measurements. Lensed supernovae are attractive for this purpose because they have relatively simple photometric behavior, with well-understood light curve shapes and colors — in contrast to the stochastic variation of quasars.”

Overview of the MACS J0138.0-2155 cluster field and the AT2016jka discovery; labels indicate the locations of the observed AT2016jka images (SN1-SN3), the expected future images (SN4-SN5), and the multiply-imaged host galaxy (H1-H4). Image credit: Rodney et al., arXiv: 2106.08935.

Using data collected by the NASA/ESA Hubble Space Telescope on July 18 and 19, 2016, the astronomers spotted four images of MRG-M0138, a massive red galaxy located 10 billion light-years away in the constellation of Cetus, lensed by the foreground galaxy cluster MACS J0138.0-2155.

Moreover, they found three lensed images of a supernova event, named AT2016jka, in the images of the background galaxy.

“It is likely a Type Ia supernova — the explosion of a low-mass stellar remnant, whose light curve can be used to measure cosmic distances,” the researchers said.

“In archival Hubble imaging, three lensed images of the supernova are detected with relative time delays of less than 200 days.”

“We predict a fourth image will appear close to the cluster core in the year 2037. Observation of the fourth image could provide a time delay precision of around 7 days, less than 1% of the extraordinary 20 year baseline.”

“The supernova classification and the predicted reappearance time could be improved with further lens modeling and a comprehensive analysis of systematic uncertainties.”

The team’s paper was published online on arXiv.org preprint server.

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Steven A. Rodney et al. 2021. A Gravitationally Lensed Supernova with an Observable Two-Decade Time Delay. arXiv: 2106.08935

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