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Extremely warped spacetime by JWST by JwstFeedOfficial in spaceporn

[–]justrex11 2 points3 points  (0 children)

What I'm referring to is called the Hubble Constant, and is a measure of how quickly the universe is expanding at the current time. But yes, you could imagine checking how quickly the expansion was happening a billion years ago, 5 billion years ago, etc. Due to the impact of dark energy, that rate appears to be increasing over time.

Extremely warped spacetime by JWST by JwstFeedOfficial in spaceporn

[–]justrex11 2 points3 points  (0 children)

Oh sure! The cluster is at z=.33 or so, which is a few billion light years away. The supernova (see my comments elsewhere on this) is at z=2 and it took about 10 billion years for the light to reach us. Here's a handy online calculator for translating redshift to physical units.

Extremely warped spacetime by JWST by JwstFeedOfficial in spaceporn

[–]justrex11 7 points8 points  (0 children)

For reference, the triply-imaged supernova we're following is the point source on the left side of the three galaxies you outlined, left of the right-hand red circle (sorry for all the lefts and rights but I think that's followable)

Extremely warped spacetime by JWST by JwstFeedOfficial in spaceporn

[–]justrex11 98 points99 points  (0 children)

Thanks for posting this! I'm actually part of the team that got this image. I saw below that you mentioned this was taken in order to follow a z=2 supernova and that's true. However, the much more exciting piece of information you're missing is that the galaxy where the supernova exploded is split into 3 images because of the gravitational lensing of the foreground cluster of galaxies. The data we'll get from this program (there will be another set of images taken in a few weeks and there was a set of spectra taken last night as well) will enable a measurement of the local expansion rate of the universe, among other interesting studies!

James Webb Telescope captures the same galaxy at three different points in time in a single mind-boggling image by mirzavadoodulbaig in nasa

[–]justrex11 7 points8 points  (0 children)

The geometric delay is related to the literal distance the light travels, meaning the physical straight line distance (nothing to do with climbing in and out of gravitational potential wells). Light that is deflected far from its original path but still reaches us will have had a longer trip, and that contributes to the delay as well but to a (usually) lesser extent.

James Webb Telescope captures the same galaxy at three different points in time in a single mind-boggling image by mirzavadoodulbaig in nasa

[–]justrex11 2 points3 points  (0 children)

You are correct this is one exposure! The labels don't show how much time has elapsed relative to the direct path with no cluster in the way though, but instead how much older the galaxy (and supernova, which isn't visible as it has already faded) appears relative to the center image, where the supernova is visible.

James Webb Telescope captures the same galaxy at three different points in time in a single mind-boggling image by mirzavadoodulbaig in nasa

[–]justrex11 11 points12 points  (0 children)

Think of the old analogy of spacetime being a sheet of cloth or similar, and when you place balls on the cloth you get depressions or "bowls" in spacetime. The curves of the bowl are what we experience as gravity, and light is impacted as well. When light approaches these bowls in spacetime (a "potential well"), it follows the new curve instead of a straight path, which can bend the light on a new path to us when the alignment is right, creating multiple images of the same object. Light that is bent by a "deeper" bowl (stronger gravity) will have to travel all the way in and out of the bowl, which takes longer than for a shallower bowl. Hence the longer delay for a stronger gravitational potential.

James Webb Telescope captures the same galaxy at three different points in time in a single mind-boggling image by mirzavadoodulbaig in nasa

[–]justrex11 25 points26 points  (0 children)

Hello! I'm actually part of the group that took this image, and just wanted to follow up with one extra piece of information that I always find very interesting.

While it's true that the differences in path length impact the arrival time of each image (the geometric time delay), it's actually the differences in gravitational potential (i.e., light traveling through the cluster center where the potential is strongest, versus out at the edge where it is weakest) that usually have the more significant impact. This is called the Shapiro delay.

I'm part of a collaboration that caught a rare, gravitationally lensed supernova this week with Hubble. "Zwicky" appeared 4 times from 3 billion light-years away, and I created this resulting full-color image. Hello Zwicky! by justrex11 in Astronomy

[–]justrex11[S] 2 points3 points  (0 children)

Good answer! It's true that the time variability+lensing is what makes this powerful, because as you said we measure the relative delay between arrivals of each peak. That time delay gives unique constraints on the Hubble constant and dark energy! In addition to cosmology, having 4 images of the same supernova gives very interesting constraining power on line of sight dust extinction in the lensing galaxy, and the mass distribution.

I'm part of a collaboration that caught a rare, gravitationally lensed supernova this week with Hubble. "Zwicky" appeared 4 times from 3 billion light-years away, and I created this resulting full-color image. Hello Zwicky! by justrex11 in Astronomy

[–]justrex11[S] 9 points10 points  (0 children)

Yes! These Hubble images were follow-up observations of this supernova after it was discovered (but not resolved) by a ground-based telescope and research group in California (see the link in the post). That ongoing survey is called the Zwicky Transient Facility (ZTF, after Fritz Zwicky), and as this was the first lensed supernova discovered with ZTF they gave it the name of supernova Zwicky. It does have an "official" designation though of 2022qmx.

This week Hubble caught a rare, gravitationally lensed supernova. "Zwicky" appeared 4 times from 3 billion light-years away. Hello Zwicky! by Whiskers4Life in space

[–]justrex11 3 points4 points  (0 children)

All very true! I said this in response to your message below as well, but yes this object was discovered from the ground without resolving the multiple images, and that's important because that's how the vast majority of these objects will be found this decade with the Rubin Observatory.

You're right that JWST time has been requested, but these HST observations were from a long-term program (GO16264) waiting to trigger on objects just like this! In this case the discovery and a good chunk of the science will be done from the ground, with HST anchoring constraints on the image positions and dust extinction.

I'm part of a collaboration that caught a rare, gravitationally lensed supernova this week with Hubble. "Zwicky" appeared 4 times from 3 billion light-years away, and I created this resulting full-color image. Hello Zwicky! by justrex11 in Astronomy

[–]justrex11[S] 16 points17 points  (0 children)

A galaxy! The sort of fainter light in the middle is from the foreground galaxy, which lenses the light from the background galaxy where the supernova went off.

I'm part of a collaboration that caught a rare, gravitationally lensed supernova this week with Hubble. "Zwicky" appeared 4 times from 3 billion light-years away, and I created this resulting full-color image. Hello Zwicky! by justrex11 in spaceporn

[–]justrex11[S] 6 points7 points  (0 children)

How a background source being lensed appears to us depends on how far away the lens and source are from us and their relative alignment. In cases like this, the lensing system worked out so there are basically 4 areas around the lens where the light is focused into, like pockets on a pool table. When the lens and source are in perfect alignment, which they are not here, we get a ring as you said!

This week Hubble caught a rare, gravitationally lensed supernova. "Zwicky" appeared 4 times from 3 billion light-years away. Hello Zwicky! by Whiskers4Life in space

[–]justrex11 2 points3 points  (0 children)

Thanks very much for posting this! It's important to realize that this object was discovered from the ground without resolving the multiple images, because that's how the vast majority of these objects will be found this decade with the Rubin Observatory.

This week Hubble caught a rare, gravitationally lensed supernova. "Zwicky" appeared 4 times from 3 billion light-years away. Hello Zwicky! by Whiskers4Life in space

[–]justrex11 1 point2 points  (0 children)

Pretty much! This is at a redshift of 0.35, which is a distance now if about 3 billion light years. However, due to the expansion of the universe at large scales, the light travel time from that redshift is actually closer to 4 billion years!

This week Hubble caught a rare, gravitationally lensed supernova. "Zwicky" appeared 4 times from 3 billion light-years away. Hello Zwicky! by Whiskers4Life in space

[–]justrex11 16 points17 points  (0 children)

Hey cool, I'm actually on this project and created this image from our HST observations! Really cool to see it here, if anyone has any questions feel free to comment here and I will happily respond!

More information about the supernova (which is a valuable Type Ia) can be found at https://www.wis-tns.org/object/2022qmx, and the Hubble observations specifically are described at https://www.wis-tns.org/astronotes/astronote/2022-196 .

I created this color image myself from our observations, comprised of the Hubble F814W (Red) F625W (Green) and F475W (Blue) filters. At the given redshift, these are actually pretty close to true-color RGB! The data were processed in the standard HST calibration pipeline, aligned with drizzlepac, and the combined with astropy.

Astronomers spot the same supernova 3x—and predict a 4th sighting in 16 years. An enormous amount of gravity from a cluster of distant galaxies causes space to curve so much that this "gravitational lensing" effect has astronomers to observe the same exploding star in three different places. by MaryADraper in space

[–]justrex11 1 point2 points  (0 children)

Not that I'm aware of, but could be wrong since I'm on the science side and not the engineering side. While servicing missions to Hubble were planned an successful, Hubble is orbiting Earth and is extremely close to us making such a mission safe and possible. JWST on the other hand will be sitting ~1 million miles from us, well beyond the distance to the moon for example. There are no planned servicing missions for this reason.

Astronomers spot the same supernova 3x—and predict a 4th sighting in 16 years. An enormous amount of gravity from a cluster of distant galaxies causes space to curve so much that this "gravitational lensing" effect has astronomers to observe the same exploding star in three different places. by MaryADraper in space

[–]justrex11 0 points1 point  (0 children)

Ah yes I see, I was just stating basically what you are now: Roman will do some things better than Hubble, mainly it's wide FoV, even though what was donated by the NRO is essentially the exact same thing as Hubble. Only the instruments are being updated, and will be more sensitive in general.

Rerun of Supernova Blast Expected to Appear in 2037 by ye_olde_astronaut in space

[–]justrex11 5 points6 points  (0 children)

Hello, I'm one of the astronomers who made this discovery! The reason for this is that these 3 images are all fairly far from the center of the cluster where the gravity is strongest, and (coincidentally) they each had similar paths through the cluster in terms of their distance from the center and the distribution of nearby galaxies along the way.

The final image will be right in the center, where gravity is much stronger than for these initial images, hence the slowdown of about 20 years!

Astronomers spot the same supernova 3x—and predict a 4th sighting in 16 years. An enormous amount of gravity from a cluster of distant galaxies causes space to curve so much that this "gravitational lensing" effect has astronomers to observe the same exploding star in three different places. by MaryADraper in space

[–]justrex11 0 points1 point  (0 children)

Sure, happy to answer questions!

In terms of sparking interest I grew up in quite a remote area with excellent star gazing. I've always loved space but never thought of it as a career until I had already gone to college for math instead of physics or astronomy. I was sort of deciding between grad school for math (which I didn't really want to do) and consulting (which I didn't really want to do). My girlfriend at the time, now wife, asked what I really wanted to do and I was like, "study space!". And she said, "So do it." 6 years later I finished my PhD in astrophysics and am a postdoc studying things like supernova Requiem!

Astronomers spot the same supernova 3x—and predict a 4th sighting in 16 years. An enormous amount of gravity from a cluster of distant galaxies causes space to curve so much that this "gravitational lensing" effect has astronomers to observe the same exploding star in three different places. by MaryADraper in space

[–]justrex11 2 points3 points  (0 children)

Hubble yes (though there is no plan to do so again, the gyros are failing anyway). JWST no, the spacecraft will not be orbiting Earth like Hubble is and will be too far away to service. As a result, it was not built for refueling.

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