NOIRLab - Results From Six Years of the Dark Energy Survey

It's the 365 days of Astronomy Podcast coming in three, two, one.

Hi, this is Rob Sparks of NSF New Arlab.

I'd like to welcome you to this episode of the 365 Days of Strangapodcast.

My guest today is you're on your own sign from NSF New Arlab.

Good morning. How are you doing this morning?

Very good. Thank you for having me.

Oh, you're so pleasure.

First, could you tell us about yourself and your role here at NSF New Arlab?

Right. So I am a assistant astronomer at New Arlab.

I joined the institution in 2022.

I mostly focused on very data, heavy research.

I think I belong to this relatively new generation of astronomers called survey scientists

that instead of going to telescopes to collect data just for myself.

What I mostly work on is a big project with a lot of scientists together

and we share the data we collect and we carry out different components of the work.

So that has been what I have been working on with the Dark Energy Survey,

the Dark Energy Spectroscopic Instrument,

and also recently the Barrow Rubin's Lexi Survey of Space and Time as well.

We've had podcast about all those in our series.

Look at our archives and find all those.

Today, we're going to spoke specifically on the Dark Energy Survey.

Before we get to the survey itself, could you give us the primer on what is Dark Energy?

So I think we really don't know what Dark Energy is at this moment,

but we do know some of its properties at this moment.

So I would like to start with saying that Dark Energy is very different from matter.

This is the kind of thing that we are more familiar with in the universe.

So matter basically refers to all of the things that everywhere has been more used to,

like the air we breathe, the food we eat, the human beings, the earth, the stars,

and all of the visible parts and not visible parts of galaxies as well.

So these are all made of matter.

And matter has an interesting property that, you know, as the universe expands,

the matter density will be dropping over time.

So, you know, as the universe expands, the distance between galaxies will get larger

and the densities of galaxies in the universe will drop a little bit.

But Dark Energy does not behave like that at all.

So for a long time that we think that Dark Energy is more like a constant,

which means that its energy content stays the same, even at the universe expands.

So that's why we label it as Dark Energy rather than something that's related to matter.

But of course, in more recently years, in the past, a couple of years,

where actually people have been finding that the density of Dark Energy seems to drop a little bit over time.

And that's mainly driven by the result from Desi.

But it is still not the same with matter.

We don't really know what Dark Energy is and, you know, what kind of things

would cause these kind of properties?

There have been many theories about it, for example,

where I was in graduate school, people are talking about vacuum energy as Dark Energy.

But for as far as I know, there has not been a well-accepted consensus on what Dark Energy might be.

We just know some of its properties.

Now it makes the universe expansion speed up, but maybe not at a constant rate as we just discovered recently.

So today we're going to talk about the Dark Energy Survey,

how it stayed Dark Energy and what instrument was used.

I could tell you about the Dark Energy Survey, the project that just released its six-year results,

and what about the camera that was used to conduct this survey?

Yeah, so the Dark Energy Survey is a big experiment that basically mapped a very large part of the sky

to use it for, you know, Dark Energy Studies and other kinds of astronomical studies as well.

It makes use of the Blanco telescope at cello-tolo in Chile that was built in the 1970s.

It's a very good and a very productive telescope, although it is not one of the largest telescopes in the world anymore.

It also uses the Dark Energy Camera, which was freshly built in the 2010s.

For this experiment of the Dark Energy Survey,

at the time it was built, the Dark Energy Camera for the Dark Energy Survey was the largest digital camera,

astronomy in the world, so it can map out a lot of the,

so it can take a lot of images of the sky very fast.

And that's how we carried out the Dark Energy Survey with, you know, a pretty good telescope

and with a very large camera that does a rapid scanning of the sky.

Was that okay? How should I try it?

Oh, that's great. Could you tell us a little about the Dark Energy Survey,

how it's conducted, what types of probes it used, that sort of thing?

So, the Dark Energy Survey mainly takes images of the sky,

and with all of those images, we could do a few different kinds of studies of dark energy, actually.

And the recently released papers from the Dark Energy Survey

was the combination of all of those probes, so it is a very exciting step from the experiment.

So, some of those probes are more about measuring the geometry of the universe,

how the university geometry has been changing over time, you know,

through things like the supernovae and the very acoustic oscillation

that Desi is actually particularly good at.

There is another kind of analysis that Dark Energy Survey is really good at,

is called structure growth to study dark energy.

And this is something that Dark Energy Survey has really been perfecting

over the past 10 years.

It basically says that, you know, when there's matter in the universe,

they should come together and grow over time because of the attractive gravitate between matter.

So, galaxies would come together to form, you know, larger groups of galaxies

or large clusters of galaxies.

But as the university expands, those kind of growth will be slowed a little bit

by the universe expansion by dark energy.

So, if we map out the matter growth over time in all of those images that Dark Energy Survey is taking,

then we can try to figure out the interactions between dark energy and gravity

and map out the Dark Energy's properties over time.

So, this is one of the things that I personally have been very excited about the Dark Energy Survey

and I think it has really contributed a lot for the field.

That's a great segue, so could you tell us about what are some of the major findings we've got

from the Dark Energy Survey and what do we learn about dark energy from it?

So, I think a major conclusion from the Dark Energy Survey at this moment is that the Dark Energy

as a universe constant actually works pretty well in explaining all of its observations so far.

And we've been getting quite a precise constraint on this

and it shows that dark energy as a constant basically just explains the data that we are saying.

And the result is also consistent with some of the other data analysis, for example,

from Desi, if you only consider this kind of constant energy there.

But I think Dark Energy Survey is still hoping to analyze the data to figure out about the evolving dark energy scenario

so that is something hopefully that will come out at some point in the future as well.

Okay, that's actually great, because that's a great bleed into the next question, our last question here.

So, how do the results of this Dark Energy Survey, how will they influence future research into dark energy?

I assume this data will continue to be used for many years in the dark energy research as well.

Well, the Dark Energy Survey right now still hasn't, you know,

they did the same analysis that have not released the result of the same analysis

with Desi's evolving dark energy model yet.

So, hopefully not in the too far future there will be more results coming out from the Dark Energy Survey

about more properties of dark energy going forward.

But I also want to mention that Dark Energy Survey at this moment has already contributed a lot to the legacy values of survey science in astronomy.

We perfected or at this moment have made really a lot of progresses in terms of studying dark energy with structured growth

and some of the future surveys like the legacy survey of space and time at a very Ruby Observatory

is going to continue to carry research in that direction with even bigger and better data sets.

We have also produced a lot of very good and high quality data that actually have been used for many other research in astronomy as well.

For example solar system discoveries, satellite galaxies, two milk ways.

So, and I think at this moment the community is recognizing the values of those very large and very good data sets.

And that there are a couple of upcoming missions planned delivering experiments with such strong legacy values in the future.

Yes, I can definitely test that because I've been doing this podcast for quite a while.

I think about half the things I've done with the dark energy survey here have been results that are not dark energy related.

Like I said, those solar system results are the other ones that come from these large data sets.

So, anyway, thank you very much and congratulations on finishing this dialysis of six years of the dark energy survey you're on run.

It has been fascinating journey through the data.

Thank you for having me.

Thank you, and this is Rob Sparks signing off this episode of 365 Days Drime Podcast.

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