<blockquote>
<p>The referred by me article was of 2020. Now is the end of 2021... Were any HCSSs - (supermassive black holes with a tight bunch of gravitationally bound stars) have been detected since then by now?</p>
</blockquote>
<p>No, not yet.</p>
<blockquote>
<p>What projects are currently actively searching for HCSSs?</p>
</blockquote>
<p>This recent study, <a href="https://ui.adsabs.harvard.edu/abs/2021ApJ...917...17G/abstract" rel="nofollow noreferrer">A Search for Wandering Black Holes in the Milky Way with Gaia and DECaLS</a>, for such systems near the Milky Way used data from Gaia and DECaLs. They expected to see &quot;~100 wandering intermediate-mass black holes if every infalling satellite hosts a black hole,&quot; but no such black holes were found in their search.</p>
<p>For future outlook, this recent study, <a href="https://academic.oup.com/mnras/article/495/2/1771/5831081" rel="nofollow noreferrer">Hypercompact stellar clusters: morphological renditions and spectrophotometric models</a>, explores prospects for observing these systems with &quot;Pan-STARRS and in forthcoming Euclid images.&quot;</p>

CC BY-SA 4.0
2021-12-05T14:14:20.013Z
2021-12-05T14:14:20.013Z
Daddy Kropotkin
<p><a href="https://www.sciencealert.com/there-could-be-runaway-missing-link-black-holes-zooming-around-the-universe" rel="nofollow noreferrer">This article</a> from sciencealert states:</p>
<blockquote>
<p>Astronomers think these two galactic cores could merge into one larger
black hole, sending huge gravitational waves rippling out across
spacetime. But if there's any asymmetry in the galactic merger, the
newly forged black hole could be punted clean out of the galaxy and
sent zooming across the Universe by gravitational wave recoil, taking
a swarm of stars with it. Such runaway objects, theorised in the late
noughties, are called hypercompact stellar systems (HCSSs) - a
supermassive black hole with a tight bunch of gravitationally bound
stars, careening away into the cosmos.</p>
</blockquote>
<p>This article was written in 2020; now is the end of 2021.
Have any HCSSs (supermassive black holes with a tight bunch of gravitationally bound stars) been detected since then?</p>
<p>What projects are currently actively searching for HCSSs?</p>

CC BY-SA 4.0
2021-12-05T11:28:50.207Z
Did you read here? There has not yet been a confident identification of such a system https://en.wikipedia.org/wiki/Hypercompact_stellar_system#Search
Daddy Kropotkin
CC BY-SA 4.0
2021-12-05T13:02:49.897Z
@Daddy Kropotkin The referred by me article was of 2020. Now is the end of 2021... Has anything changed by now?
Alex
<black-hole><supermassive-black-hole>
Have any HCSSs (supermassive black holes with a tight bunch of gravitationally bound stars) ever been detected?
Alex
# Have any HCSSs (supermassive black holes with a tight bunch of gravitationally bound stars) ever been detected?

(Asked by: username_0 on 2021-12-03)

[This article](https://www.sciencealert.com/there-could-be-runaway-missing-link-black-holes-zooming-around-the-universe) from sciencealert states:

> Astronomers think these two galactic cores could merge into one larger
> black hole, sending huge gravitational waves rippling out across
> spacetime. But if there's any asymmetry in the galactic merger, the
> newly forged black hole could be punted clean out of the galaxy and
> sent zooming across the Universe by gravitational wave recoil, taking
> a swarm of stars with it. Such runaway objects, theorised in the late
> noughties, are called hypercompact stellar systems (HCSSs) - a
> supermassive black hole with a tight bunch of gravitationally bound
> stars, careening away into the cosmos.

This article was written in 2020; now is the end of 2021.
Have any HCSSs (supermassive black holes with a tight bunch of gravitationally bound stars) been detected since then?

What projects are currently actively searching for HCSSs?

**Tags:** black-hole, supermassive-black-hole

> **Comments:**
> **username_1**: Did you read here? There has not yet been a confident identification of such a system https://en.wikipedia.org/wiki/Hypercompact_stellar_system#Search  
> **username_0**: @username_1 The referred by me article was of 2020. Now is the end of 2021... Has anything changed by now?  

---

## 1 answers

### Answer by username_1 on 2021-12-05. Score: 4 | Accepted answer

> The referred by me article was of 2020. Now is the end of 2021... Were any HCSSs - (supermassive black holes with a tight bunch of gravitationally bound stars) have been detected since then by now?

No, not yet.

> What projects are currently actively searching for HCSSs?

This recent study, [A Search for Wandering Black Holes in the Milky Way with Gaia and DECaLS](https://ui.adsabs.harvard.edu/abs/2021ApJ...917...17G/abstract), for such systems near the Milky Way used data from Gaia and DECaLs. They expected to see "~100 wandering intermediate-mass black holes if every infalling satellite hosts a black hole," but no such black holes were found in their search.

For future outlook, this recent study, [Hypercompact stellar clusters: morphological renditions and spectrophotometric models](https://academic.oup.com/mnras/article/495/2/1771/5831081), explores prospects for observing these systems with "Pan-STARRS and in forthcoming Euclid images."


---

