<p>Answering the who is part of the question.</p>

<p><a href="https://en.wikipedia.org/wiki/Carl_Keenan_Seyfert" rel="nofollow noreferrer">Carl Seyfert</a> (1911-1960) was a US astronomer. </p>

<blockquote>
  <p>He is best known for his 1943 research paper on high-excitation line emission from the centers of some spiral galaxies, which are named Seyfert galaxies after him. <a href="https://en.wikipedia.org/wiki/Seyfert%27s_Sextet" rel="nofollow noreferrer">Seyfert's Sextet</a>, a group of galaxies, is also named after him. </p>
</blockquote>

CC BY-SA 4.0
2019-10-08T16:24:28.397Z
Thanks for the additional information!
uhoh
CC BY-SA 4.0
2019-10-08T15:55:10.713Z
2019-10-08T15:55:10.713Z
Fred
<p>As has now been corrected, BBC has misunderstood term "Seyfert flare", instead calling it a "<em>Sifter</em> flare".</p>

<hr>

<p>A "Seyfert flare", is not really a common term, but the authors refer to an energetic outburst from the type of active galaxies called <a href="https://en.wikipedia.org/wiki/Seyfert_galaxy" rel="nofollow noreferrer">Seyfert galaxies</a> (after <a href="https://en.wikipedia.org/wiki/Carl_Keenan_Seyfert" rel="nofollow noreferrer">Carl Seyfert</a>).</p>

<p>Like a quasar, a Seyfert galaxy is powered by gas accretion onto a central, supermassive black hole, although they're less luminous by roughly two orders of magnitude.</p>

<p>In this case, there is evidence for a highly energetic (<span class="math-container">$10^{56\text{-}57}\,\mathrm{erg}$</span>) explosion occurring only a few million years ago, resulting a an ionizing, bipolar cone extending outward from the Milky Way's central black hole, Sgr A*.</p>

<p>This powerful flare resulted in huge, 10 kpc-scale, X-ray/gamma-ray-emitting bubbles. The line ratios of <span class="math-container">$\mathrm{C\,IV}/\mathrm{C\,II}$</span> and <span class="math-container">$\mathrm{Si\,IV}/\mathrm{Si\,II}$</span> points toward ionizing radiation energies of at least 50 eV.</p>

<p>The orientation of these cones is seen in this figure from the paper, which will be on the arXiv tomorrow. The first-author, Joss Bland-Hawthorn, explains in a video <a href="https://www.youtube.com/watch?time_continue=2&amp;v=Y16XMNZbbIM" rel="nofollow noreferrer">here</a>.</p>

<p><a href="https://i.sstatic.net/jItlK.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/jItlK.jpg" alt="enter image description here"></a></p>

CC BY-SA 4.0
2019-10-07T07:28:04.923Z
This makes a lot more sense, thanks! They do get quotes wrong occasionally, cf. [What are “large hadrons”? Are there also “small hadrons”?](https://physics.stackexchange.com/q/454554/83380)
uhoh
CC BY-SA 4.0
2019-10-07T10:58:48.280Z
@uhoh Ha ha embarrassing :D
pela
CC BY-SA 4.0
2019-10-07T13:00:52.820Z
As noted on the OP the article has been updated with the correct term, don't think that affects the answer much however! :)
bertieb
CC BY-SA 4.0
2019-10-08T12:28:04.953Z
Any thoughts on [Should I change the title of my question to make the results more searchable?](https://astronomy.meta.stackexchange.com/q/539/7982)
uhoh
CC BY-SA 4.0
2019-10-08T13:32:48.857Z
@uhoh I don't have a strong opinion, but I agree that it would make sense to update the question. If you do, I can update the answer as well.
pela
CC BY-SA 4.0
2019-10-08T16:29:46.483Z
I've updated the question. Feel free to edit it further if you see room for improvement.
uhoh
CC BY-SA 4.0
2019-10-08T16:40:12.740Z
Wow! That's a *lot* of energy, like 10,000 big supernovae (radiant energy + KE of ejecta), if I've done the calculation correctly.
PM 2Ring
CC BY-SA 4.0
2019-10-08T18:40:58.643Z
@PM2Ring yes, or even more. But over a longer timescale, so it might not be fair to compare.
pela
CC BY-SA 4.0
2019-10-07T07:14:12.007Z
2019-10-08T18:39:45.187Z
2019-10-08T18:39:45.187Z
pela
<p>The BBC's <a href="https://www.bbc.com/news/science-environment-49955468" rel="noreferrer">Milky Way's centre exploded 3.5 million years ago</a> says:</p>
<blockquote>
<p>A cataclysmic energy flare ripped through our galaxy, the Milky Way, about 3.5 million years ago, a team of astronomers say.</p>
<p>They say the so-called Sifter flare started near the super massive black hole in the centre of the galaxy.</p>
<p>The impact was felt 200,000 light-years away.</p>
<p>[...]The flare created two enormous &quot;ionisation cones&quot; that sliced through the Milky Way.</p>
</blockquote>
<p>It mentions &quot;The team - led by Professor Joss Bland-Hawthorn from Australia&quot; and &quot;co-author Magma Guglielmo from the University of Sydney&quot; and says &quot;The findings will be published in the Astrophysical Journal.&quot;</p>
<p>Right now I'm just asking the following:</p>
<p><strong>Question:</strong> Who is Sifter, and what is &quot;the so-called Sifter flare&quot;?</p>
<hr />
<p><strong>update:</strong> <a href="https://astronomy.stackexchange.com/questions/33606/who-is-sifter-and-what-is-the-so-called-sifter-flare?noredirect=1#comment63743_33606">@bertieb's comment</a> notes that the BBC has corrected the passage. The new sentence says:</p>
<blockquote>
<p>The so-called <strong>Seyfert flare</strong> started near the supermassive black hole in the centre of the galaxy, they add.</p>
</blockquote>
<p>When first published, the article called it a &quot;so-called <strong>Sifter flare</strong>&quot; and that's what originally inspired this question.</p>

CC BY-SA 4.0
2019-10-07T13:00:05.770Z
For what it's worth, the BBC article has been updated as of this comment :)
bertieb
CC BY-SA 4.0
2019-10-07T15:01:45.823Z
[Another news item](https://www.msn.com/en-au/news/techandscience/like-a-lighthouse-beam-supermassive-black-hole-at-centre-of-milky-way-exploded-as-humans-ancestors-walked-on-earth-scientists-find/ar-AAIocuW?li=AAgfYrC&ocid=mailsignout) about the same event. [Carl Seyfert](https://en.wikipedia.org/wiki/Carl_Keenan_Seyfert) (1911-1960) was a US astronomer ..."is best known for his 1943 research paper on high-excitation line emission from the centers of some spiral galaxies, which are named Seyfert galaxies after him".
Fred
CC BY-SA 4.0
2019-10-07T15:04:06.780Z
A bit more info on [Active galactic nucleus](https://en.wikipedia.org/wiki/Active_galactic_nucleus)
Fred
CC BY-SA 4.0
2019-10-08T03:07:42.213Z
@bertieb thanks for that! I've updated the question accordingly.
uhoh
<milky-way><active-galaxy>
Who is Seyfert, and what is "the so-called Seyfert flare"?
uhoh
# Who is Seyfert, and what is "the so-called Seyfert flare"?

(Asked by: username_0 on 2019-10-07)

The BBC's [Milky Way's centre exploded 3.5 million years ago](https://www.bbc.com/news/science-environment-49955468) says:

> A cataclysmic energy flare ripped through our galaxy, the Milky Way, about 3.5 million years ago, a team of astronomers say.
>
> They say the so-called Sifter flare started near the super massive black hole in the centre of the galaxy.
>
> The impact was felt 200,000 light-years away.
>
> [...]The flare created two enormous "ionisation cones" that sliced through the Milky Way.

It mentions "The team - led by Professor Joss Bland-Hawthorn from Australia" and "co-author Magma Guglielmo from the University of Sydney" and says "The findings will be published in the Astrophysical Journal."

Right now I'm just asking the following:

**Question:** Who is Sifter, and what is "the so-called Sifter flare"?

---

**update:** [@bertieb's comment](https://astronomy.stackexchange.com/questions/33606/who-is-sifter-and-what-is-the-so-called-sifter-flare?noredirect=1#comment63743_33606) notes that the BBC has corrected the passage. The new sentence says:

> The so-called **Seyfert flare** started near the supermassive black hole in the centre of the galaxy, they add.

When first published, the article called it a "so-called **Sifter flare**" and that's what originally inspired this question.

**Tags:** milky-way, active-galaxy
> **Comments:**
> **username_1**: For what it's worth, the BBC article has been updated as of this comment :)  
> **username_2**: [Another news item](https://www.msn.com/en-au/news/techandscience/like-a-lighthouse-beam-supermassive-black-hole-at-centre-of-milky-way-exploded-as-humans-ancestors-walked-on-earth-scientists-find/ar-AAIocuW?li=AAgfYrC&ocid=mailsignout) about the same event. [Carl Seyfert](https://en.wikipedia.org/wiki/Carl_Keenan_Seyfert) (1911-1960) was a US astronomer ..."is best known for his 1943 research paper on high-excitation line emission from the centers of some spiral galaxies, which are named Seyfert galaxies after him".  
> **username_2**: A bit more info on [Active galactic nucleus](https://en.wikipedia.org/wiki/Active_galactic_nucleus)  
> **username_0**: @bertieb thanks for that! I've updated the question accordingly.  

---

## 2 answers

### Answer by username_3 on 2019-10-07. Score: 13 | Accepted answer

As has now been corrected, BBC has misunderstood term "Seyfert flare", instead calling it a "*Sifter* flare".

---

A "Seyfert flare", is not really a common term, but the authors refer to an energetic outburst from the type of active galaxies called [Seyfert galaxies](https://en.wikipedia.org/wiki/Seyfert_galaxy) (after [Carl Seyfert](https://en.wikipedia.org/wiki/Carl_Keenan_Seyfert)).

Like a quasar, a Seyfert galaxy is powered by gas accretion onto a central, supermassive black hole, although they're less luminous by roughly two orders of magnitude.

In this case, there is evidence for a highly energetic ($10^{56\text{-}57}\,\mathrm{erg}$) explosion occurring only a few million years ago, resulting a an ionizing, bipolar cone extending outward from the Milky Way's central black hole, Sgr A\*.

This powerful flare resulted in huge, 10 kpc-scale, X-ray/gamma-ray-emitting bubbles. The line ratios of $\mathrm{C\,IV}/\mathrm{C\,II}$ and $\mathrm{Si\,IV}/\mathrm{Si\,II}$ points toward ionizing radiation energies of at least 50 eV.

The orientation of these cones is seen in this figure from the paper, which will be on the arXiv tomorrow. The first-author, Joss Bland-Hawthorn, explains in a video [here](https://www.youtube.com/watch?time_continue=2&v=Y16XMNZbbIM).

[![enter image description here](https://i.sstatic.net/jItlK.jpg)](https://i.sstatic.net/jItlK.jpg)

> **Comments:**
> **username_0**: This makes a lot more sense, thanks! They do get quotes wrong occasionally, cf. [What are “large hadrons”? Are there also “small hadrons”?](https://physics.stackexchange.com/q/454554/83380)  
> **username_3**: @uhoh Ha ha embarrassing :D  
> **username_1**: As noted on the OP the article has been updated with the correct term, don't think that affects the answer much however! :)  
> **username_0**: Any thoughts on [Should I change the title of my question to make the results more searchable?](https://astronomy.meta.stackexchange.com/q/539/7982)  
> **username_3**: @uhoh I don't have a strong opinion, but I agree that it would make sense to update the question. If you do, I can update the answer as well.  
> **username_0**: I've updated the question. Feel free to edit it further if you see room for improvement.  
> **username_4**: Wow! That's a *lot* of energy, like 10,000 big supernovae (radiant energy + KE of ejecta), if I've done the calculation correctly.  
> **username_3**: @PM2Ring yes, or even more. But over a longer timescale, so it might not be fair to compare.  

---

### Answer by username_2 on 2019-10-08. Score: 1

Answering the who is part of the question.

[Carl Seyfert](https://en.wikipedia.org/wiki/Carl_Keenan_Seyfert) (1911-1960) was a US astronomer.

> He is best known for his 1943 research paper on high-excitation line emission from the centers of some spiral galaxies, which are named Seyfert galaxies after him. [Seyfert's Sextet](https://en.wikipedia.org/wiki/Seyfert%27s_Sextet), a group of galaxies, is also named after him.

> **Comments:**
> **username_0**: Thanks for the additional information!  

---

