<p>The Rhodes College press release <a href="https://news.rhodes.edu/stories/prof-david-rupke-and-team-astrophysicists-make-major-new-discovery-about-galaxy-evolution" rel="nofollow noreferrer">Prof. David Rupke and Team of Astrophysicists Make Major New Discovery About Galaxy Evolution</a> links to</p>
<ul>
<li>Astronomy Community/Nature.com: <a href="https://astronomycommunity.nature.com/posts/55431-the-making-of-makani?channel_id=1490-behind-the-paper" rel="nofollow noreferrer">The Making of Makani; The story of how we encountered an enormous galactic wind surrounding the Makani galaxy illuminates the scientific process of discovery and collaboration.</a></li>
<li>Vimeo: <a href="https://vimeo.com/369269470" rel="nofollow noreferrer">Makani 360-degree rotation of KCWI spectral cube</a></li>
</ul>
<p>and references the new Nature paper <a href="https://www.nature.com/articles/s41586-019-1686-1" rel="nofollow noreferrer">A 100-kiloparsec wind feeding the circumgalactic medium of a massive compact galaxy</a> (viewable in  <a href="https://arxiv.org/abs/1910.13507" rel="nofollow noreferrer">arXiv</a>)</p>
<p>and includes the video below, in which Prof. Rupke says near the end after about <code>03:43</code>:</p>
<blockquote>
<p>While I’m hopeful that it’s the tip of the iceberg, and that we will find many other galaxies in which we see these large winds extending into the circum-galactic medium, but of course we have to go out and look.</p>
<p><strong>These new instruments that are so sensitive that we can see these things have only been on telescopes for a few years.</strong></p>
<p>There’s more galaxies that we haven’t looked at than we have.</p>
</blockquote>
<p>The last sentence (taken by itself) is probably an understatement :-)</p>
<p><strong>Question:</strong> <em>What &quot;...new instruments</em> so sensitive that we can see these things have only been on telescopes for a few years&quot;? I'm guessing that &quot;instruments on telescopes&quot; means these are image sensors or imaging spectrometers on visible or IR telescopes on the ground, and not related to radio telescopes, but that's just a guess.</p>
<p><div class="youtube-embed"><div>
                <iframe width="640px" height="395px" src="https://www.youtube.com/embed/roiVjAra41o?start=223"></iframe>
            </div></div></p>
<p><a href="https://i.sstatic.net/tKLem.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/tKLem.jpg" alt="telescopes" /></a></p>
<hr />
<p><a href="https://i.sstatic.net/JuIh0.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/JuIh0.png" alt="Rupke et at. 2021, Figure 1 The giant galactic wind surrounding the massive, compact galaxy Makani, observed by emission from the [O II] line at λ=3726 A and 3729 A." /></a></p>
<blockquote>
<p>Figure 1 The giant galactic wind surrounding the massive, compact galaxy Makani, observed by emission from the [O II] line at λ=3726 A and 3729 A. The colour scale and white contours show observed-frame surface brightness, and the axes are labeled in kiloparsecs from the galaxy nucleus. Contours are 2–16% of peak flux, spaced by factors of 2. A rest-frame V-band image of the galaxy (Hubble Space Telescope/WFC3 F814W filter) is superimposed on the center of the [O II] image taken with KCWI at the Keck II telescope. The small circle at the centre illustrates the radius of the compact core (400 pc). North is up and east is to the left.</p>
</blockquote>

CC BY-SA 4.0
2021-05-23T08:41:11.387Z
The simple answer is probably “high spatial and spectral resolution integral field unit spectrographs on 8–10 m telescopes”, such as the KCWI (on Keck) they used for this study (another likely candidate would be MUSE on the Very Large Telescope).
Peter Erwin
CC BY-SA 4.0
2021-05-23T09:24:26.543Z
@PeterErwin I've been poking through the links, and the 2nd one (Astronomy Community) mentions "KCWI was designed specifically to be very sensitive to faint gas far from galaxies, using highly reflective image slicers (seen in the image at right)." Searching for "KCWI slicer" I found more of them here https://www2.keck.hawaii.edu/inst/kcwi/ Then I noticed that galaxy image has a hole in the middle right where it's supposed to be the brightest per the video, which reminds me further of "faint gas far from galaxies". Maybe it's the particularly clean image slicing that makes this possible?
uhoh
CC BY-SA 4.0
2021-05-23T10:52:06.307Z
I know that people are using MUSE for similar studies, so I don't think it's anything unique to the KCWI design. (Image slicing is one of the standard techniques for IFUs; MUSE uses it as well.)
Peter Erwin
CC BY-SA 4.0
2021-05-23T10:58:18.227Z
The "hole in the middle" of the galaxy image is not actually real. If you look at the paper, you'll see this description in the caption for Figure 1: "A rest-frame V -band image of the galaxy (Hubble Space Telescope/WFC3 F814W filter) is superimposed on the center of the [O II] image taken with KCWI at the Keck II telescope." This is clearly a negative image, so the "black" center of the galaxy is actually bright in V. Figure 3a shows the [O II] emission without the HST image, and you can see that the central region of the galaxy is actually very bright.
Peter Erwin
CC BY-SA 4.0
2021-05-23T11:00:29.050Z
(OK, I see that you quoted the Figure 1 caption in your question...)
Peter Erwin
CC BY-SA 4.0
2021-05-23T12:20:35.907Z
I'll note that earlier in the video, he specifically says, "Theres a really good instrument on there [Keck], that is a new instrument, that is one of the best of its kind in the world" and then goes on talk about applying for time to use it, and how they finally got good data for one galaxy. So he clearly means KCWI and things like it.
Peter Erwin
CC BY-SA 4.0
2021-05-23T13:08:50.267Z
@PeterErwin okay I think I will listen through it again now that I have a little bit better idea of what's going on, *thanks!*
uhoh
<observational-astronomy><galaxy><astrophysics><galactic-dynamics><circumgalactic-medium>
What new instruments "so sensitive that we can see (large circumgalactic winds) have only been on telescopes for a few years"?
uhoh
# What new instruments "so sensitive that we can see (large circumgalactic winds) have only been on telescopes for a few years"?

(Asked by: username_0 on 2021-05-22)

The Rhodes College press release [Prof. David Rupke and Team of Astrophysicists Make Major New Discovery About Galaxy Evolution](https://news.rhodes.edu/stories/prof-david-rupke-and-team-astrophysicists-make-major-new-discovery-about-galaxy-evolution) links to

* Astronomy Community/Nature.com: [The Making of Makani; The story of how we encountered an enormous galactic wind surrounding the Makani galaxy illuminates the scientific process of discovery and collaboration.](https://astronomycommunity.nature.com/posts/55431-the-making-of-makani?channel_id=1490-behind-the-paper)
* Vimeo: [Makani 360-degree rotation of KCWI spectral cube](https://vimeo.com/369269470)

and references the new Nature paper [A 100-kiloparsec wind feeding the circumgalactic medium of a massive compact galaxy](https://www.nature.com/articles/s41586-019-1686-1) (viewable in [arXiv](https://arxiv.org/abs/1910.13507))

and includes the video below, in which Prof. Rupke says near the end after about `03:43`:

> While I’m hopeful that it’s the tip of the iceberg, and that we will find many other galaxies in which we see these large winds extending into the circum-galactic medium, but of course we have to go out and look.
>
> **These new instruments that are so sensitive that we can see these things have only been on telescopes for a few years.**
>
> There’s more galaxies that we haven’t looked at than we have.

The last sentence (taken by itself) is probably an understatement :-)

**Question:** *What "...new instruments* so sensitive that we can see these things have only been on telescopes for a few years"? I'm guessing that "instruments on telescopes" means these are image sensors or imaging spectrometers on visible or IR telescopes on the ground, and not related to radio telescopes, but that's just a guess.

[![telescopes](https://i.sstatic.net/tKLem.jpg)](https://i.sstatic.net/tKLem.jpg)

---

[![Rupke et at. 2021, Figure 1 The giant galactic wind surrounding the massive, compact galaxy Makani, observed by emission from the [O II] line at λ=3726 A and 3729 A.](https://i.sstatic.net/JuIh0.png)](https://i.sstatic.net/JuIh0.png)

> Figure 1 The giant galactic wind surrounding the massive, compact galaxy Makani, observed by emission from the [O II] line at λ=3726 A and 3729 A. The colour scale and white contours show observed-frame surface brightness, and the axes are labeled in kiloparsecs from the galaxy nucleus. Contours are 2–16% of peak flux, spaced by factors of 2. A rest-frame V-band image of the galaxy (Hubble Space Telescope/WFC3 F814W filter) is superimposed on the center of the [O II] image taken with KCWI at the Keck II telescope. The small circle at the centre illustrates the radius of the compact core (400 pc). North is up and east is to the left.

**Tags:** observational-astronomy, galaxy, astrophysics, galactic-dynamics, circumgalactic-medium

> **Comments:**
> **username_1**: The simple answer is probably “high spatial and spectral resolution integral field unit spectrographs on 8–10 m telescopes”, such as the KCWI (on Keck) they used for this study (another likely candidate would be MUSE on the Very Large Telescope).  
> **username_0**: @PeterErwin I've been poking through the links, and the 2nd one (Astronomy Community) mentions "KCWI was designed specifically to be very sensitive to faint gas far from galaxies, using highly reflective image slicers (seen in the image at right)." Searching for "KCWI slicer" I found more of them here https://www2.keck.hawaii.edu/inst/kcwi/ Then I noticed that galaxy image has a hole in the middle right where it's supposed to be the brightest per the video, which reminds me further of "faint gas far from galaxies". Maybe it's the particularly clean image slicing that makes this possible?  
> **username_1**: I know that people are using MUSE for similar studies, so I don't think it's anything unique to the KCWI design. (Image slicing is one of the standard techniques for IFUs; MUSE uses it as well.)  
> **username_1**: The "hole in the middle" of the galaxy image is not actually real. If you look at the paper, you'll see this description in the caption for Figure 1: "A rest-frame V -band image of the galaxy (Hubble Space Telescope/WFC3 F814W filter) is superimposed on the center of the [O II] image taken with KCWI at the Keck II telescope." This is clearly a negative image, so the "black" center of the galaxy is actually bright in V. Figure 3a shows the [O II] emission without the HST image, and you can see that the central region of the galaxy is actually very bright.  
> **username_1**: (OK, I see that you quoted the Figure 1 caption in your question...)  
> **username_1**: I'll note that earlier in the video, he specifically says, "Theres a really good instrument on there [Keck], that is a new instrument, that is one of the best of its kind in the world" and then goes on talk about applying for time to use it, and how they finally got good data for one galaxy. So he clearly means KCWI and things like it.  
> **username_0**: @PeterErwin okay I think I will listen through it again now that I have a little bit better idea of what's going on, *thanks!*  

---

## 0 answers

