Sky & Telescope - May 2024 - 23

velous story of its own. Astronomers discovered GN-z11 in
2016 with the Hubble Space Telescope. For nearly seven years,
until the advent of JWST, GN-z11 held the record for the most
distant object known. In late 2022, it lost its place to another
galaxy named JADES-GS-z13-0 (S&T: Oct. 2023, p. 12).
But GN-z11 still had a story to tell. In 2023, astronomers
used JWST to study the galaxy's spectrum in detail. A spectrum
not only breaks apart the light seen from an astronomical
object into its constituent wavelengths, much like a
rainbow, but it also reveals how the material producing the
light is moving with respect to the observer. The spectrum of
GN-z11 showed that the gas in the innermost region of the
galaxy was moving at roughly 1,000 km/s (more than 2 million
mph) - the fingerprint of a massive, central black hole.
Using this information, the researchers estimated the mass
of this " small and vigorous black hole in the early universe, " as
they called it, was some 1.5 million solar masses. That makes
it one-third as massive as the black hole at the center of the
Milky Way today - a tiny object to be detected so far away.
In another plot twist, astronomers discovered that the
central black hole in GN-z11 is probably swallowing gas
furiously, turning itself into a floodlight. The rate at which a
black hole can accrete gas from its environment has a speed
limit, the so-called Eddington limit, whose namesake, Sir
Arthur Eddington, was a renowned 20th-century English
astronomer. Above the Eddington limit, the infalling gas's
own glow pushes material out and away from the black hole,
controlling how much the black hole can accrete.
In the high-redshift universe, with abundant gas to be
accreted, the Eddington limit is like the speed limit on a
highway: generally obeyed but not unbreakable. Most black
holes accrete around the speed limit. Some accrete somewhat
higher or lower than that. GN-z11, however, seems to
be accreting at about five times its Eddington limit. This rate
is remarkable: If, billions of years ago, GN-z11 continued
growing at this pace, it would reach the superlative mass of
1 billion solar masses by redshift 9.5, more than 13 billion
years ago. We are unaware of such extremely massive objects
at those redshifts; they must be scarce if they exist. SuperEddington
accretion might also be an episodic event, turning
on and off and keeping black hole growth in check.
The tiny supermassive black hole in GN-z11 became visible
to our telescopes because it's radiating away a vast amount
of energy. What we see in its spectrum also suggests that we
may be staring down at the accretion disk from above, hence
observing the black hole from its most luminous side.
GN-z11 is not the only remarkable black hole that JWST
has discovered in the very early universe. For example, the
crown for the farthest black hole known belonged previously to
CEERS 1019, a 10-million-solar-mass object shining at redshift
8.7, 13.1 billion years ago. Astronomers discovered this remarkable
source in the Cosmic Evolution Early Release Science
(CEERS) JWST survey. CEERS 1019 also accretes slightly above
the Eddington limit, indicating that violating the speed limit
could be common in this early population of compact objects.
When your eyes adjust to darkness,
you begin to discern a more numerous
population of dimmer stars. Astronomers
are having the same experience with the
early universe.
Countless Feeble Candles
GN-z11 and CEERS 1019 are relatively midsize when it comes
to supermassive black holes. Astronomers have found dozens
of giant quasars a little later in cosmic history, roughly 1 billion
years after the Big Bang. Before the advent of JWST, black
hole hunters' focus was on finding these extremely massive -
and bright - objects as far away as possible.
Yet the giant quasars discovered at very high redshift are
rare, extraordinary objects. Consider the distance between
the Milky Way and the Andromeda Galaxy, some 2.5 million
light-years. Multiply this distance by 1,000 and construct a
cube from this side. In the early universe, at redshift 6 (12.8
billion years ago), we estimate that there is just a single,
bright quasar in this immense volume. At redshift 10 (13.2
billion years ago), these objects are so rare that there may
only be one in the entire universe.
But there are other things in that great expanse besides
the majestic quasars. When you look up at the sky on a clear
and dark night, your eyes immediately see the brightest stars.
Then, when your eyes adjust to darkness, you begin to discern
a more numerous population of dimmer stars. Astronomers
are having the same experience with the early universe: They
are now discovering a population of smaller, fainter supermassive
black holes.
When analyzing the first deep images obtained by JWST,
different teams started to notice tiny red dots popping out
everywhere. These sources were distinctively crimson compared
to other sources in the field, because their emission at
longer, redder wavelengths was stronger. They also appeared
small in physical and angular size - so small, in fact, that
although the dots emitted as much light as a whole galaxy
does, that light came from a region that's between the size of
a large star cluster and the smallest dwarf galaxies.
After a careful spectral analysis, researchers discovered
that some of these peculiar sources were young galaxies hosting
black holes at their centers. Most were observed between
redshift 4 and 7, when the universe was between 770 million
and 1.6 billion years old. Astronomers discovered tens of
specimens of this large population and lovingly named them
" little red dots " or " hidden little monsters. "
Instead of billions of solar masses, these little monsters
commonly are black holes of 10 to 100 million solar masses.
If accreting at their Eddington rates, then these somewhat
smaller black holes generate a luminosity of about 100 billion
times that of our Sun; the most massive quasars we know of
blaze with a luminosity of almost 1,000 trillion times that of
our Sun.
The discovery of a population of fainter, less massive black
sk yand tele scope .o r g * MAY 2024 23
http://skyandtelescoper.org

Sky & Telescope - May 2024

Table of Contents for the Digital Edition of Sky & Telescope - May 2024

Contents
Sky & Telescope - May 2024 - Cover1
Sky & Telescope - May 2024 - Cover2
Sky & Telescope - May 2024 - 1
Sky & Telescope - May 2024 - Contents
Sky & Telescope - May 2024 - 3
Sky & Telescope - May 2024 - 4
Sky & Telescope - May 2024 - 5
Sky & Telescope - May 2024 - 6
Sky & Telescope - May 2024 - 7
Sky & Telescope - May 2024 - 8
Sky & Telescope - May 2024 - 9
Sky & Telescope - May 2024 - 10
Sky & Telescope - May 2024 - 11
Sky & Telescope - May 2024 - 12
Sky & Telescope - May 2024 - 13
Sky & Telescope - May 2024 - 14
Sky & Telescope - May 2024 - 15
Sky & Telescope - May 2024 - 16
Sky & Telescope - May 2024 - 17
Sky & Telescope - May 2024 - 18
Sky & Telescope - May 2024 - 19
Sky & Telescope - May 2024 - 20
Sky & Telescope - May 2024 - 21
Sky & Telescope - May 2024 - 22
Sky & Telescope - May 2024 - 23
Sky & Telescope - May 2024 - 24
Sky & Telescope - May 2024 - 25
Sky & Telescope - May 2024 - 26
Sky & Telescope - May 2024 - 27
Sky & Telescope - May 2024 - 28
Sky & Telescope - May 2024 - 29
Sky & Telescope - May 2024 - 30
Sky & Telescope - May 2024 - 31
Sky & Telescope - May 2024 - 32
Sky & Telescope - May 2024 - 33
Sky & Telescope - May 2024 - 34
Sky & Telescope - May 2024 - 35
Sky & Telescope - May 2024 - 36
Sky & Telescope - May 2024 - 37
Sky & Telescope - May 2024 - 38
Sky & Telescope - May 2024 - 39
Sky & Telescope - May 2024 - 40
Sky & Telescope - May 2024 - 41
Sky & Telescope - May 2024 - 42
Sky & Telescope - May 2024 - 43
Sky & Telescope - May 2024 - 44
Sky & Telescope - May 2024 - 45
Sky & Telescope - May 2024 - 46
Sky & Telescope - May 2024 - 47
Sky & Telescope - May 2024 - 48
Sky & Telescope - May 2024 - 49
Sky & Telescope - May 2024 - 50
Sky & Telescope - May 2024 - 51
Sky & Telescope - May 2024 - 52
Sky & Telescope - May 2024 - 53
Sky & Telescope - May 2024 - 54
Sky & Telescope - May 2024 - 55
Sky & Telescope - May 2024 - 56
Sky & Telescope - May 2024 - 57
Sky & Telescope - May 2024 - 58
Sky & Telescope - May 2024 - 59
Sky & Telescope - May 2024 - 60
Sky & Telescope - May 2024 - 61
Sky & Telescope - May 2024 - 62
Sky & Telescope - May 2024 - 63
Sky & Telescope - May 2024 - 64
Sky & Telescope - May 2024 - 65
Sky & Telescope - May 2024 - 66
Sky & Telescope - May 2024 - 67
Sky & Telescope - May 2024 - 68
Sky & Telescope - May 2024 - 69
Sky & Telescope - May 2024 - 70
Sky & Telescope - May 2024 - 71
Sky & Telescope - May 2024 - 72
Sky & Telescope - May 2024 - 73
Sky & Telescope - May 2024 - 74
Sky & Telescope - May 2024 - 75
Sky & Telescope - May 2024 - 76
Sky & Telescope - May 2024 - 77
Sky & Telescope - May 2024 - 78
Sky & Telescope - May 2024 - 79
Sky & Telescope - May 2024 - 80
Sky & Telescope - May 2024 - 81
Sky & Telescope - May 2024 - 82
Sky & Telescope - May 2024 - 83
Sky & Telescope - May 2024 - 84
Sky & Telescope - May 2024 - Cover3
Sky & Telescope - May 2024 - Cover4
https://www.nxtbook.com/nxtbooks/aas/st_202408
https://www.nxtbook.com/nxtbooks/aas/st_202407
https://www.nxtbook.com/nxtbooks/aas/st_202406
https://www.nxtbook.com/nxtbooks/aas/st_202405
https://www.nxtbook.com/nxtbooks/aas/st_202404_qr
https://www.nxtbook.com/nxtbooks/aas/st_202404
https://www.nxtbook.com/nxtbooks/aas/st_202403
https://www.nxtbook.com/nxtbooks/aas/st_202402
https://www.nxtbook.com/nxtbooks/aas/st_202401_aus
https://www.nxtbook.com/nxtbooks/aas/st_202401
https://www.nxtbook.com/nxtbooks/aas/st_202312_aus
https://www.nxtbook.com/nxtbooks/aas/st_202312
https://www.nxtbook.com/nxtbooks/aas/st_202311
https://www.nxtbook.com/nxtbooks/aas/st_202310
https://www.nxtbook.com/nxtbooks/aas/st_202309
https://www.nxtbook.com/nxtbooks/aas/st_202308
https://www.nxtbook.com/nxtbooks/aas/st_202307
https://www.nxtbook.com/nxtbooks/aas/st_202306
https://www.nxtbook.com/nxtbooks/aas/st_202305
https://www.nxtbook.com/nxtbooks/aas/st_202304
https://www.nxtbook.com/nxtbooks/aas/st_202304_qr
https://www.nxtbook.com/nxtbooks/aas/st_202303
https://www.nxtbook.com/nxtbooks/aas/st_202302
https://www.nxtbook.com/nxtbooks/aas/st_202301
https://www.nxtbook.com/nxtbooks/aas/st_202212
https://www.nxtbook.com/nxtbooks/aas/st_202211
https://www.nxtbook.com/nxtbooks/aas/st_202210
https://www.nxtbook.com/nxtbooks/aas/st_202209
https://www.nxtbook.com/nxtbooks/aas/st_202208
https://www.nxtbook.com/nxtbooks/aas/st_202207
https://www.nxtbook.com/nxtbooks/aas/st_202206
https://www.nxtbook.com/nxtbooks/aas/st_202205
https://www.nxtbook.com/nxtbooks/aas/st_202204
https://www.nxtbook.com/nxtbooks/aas/st_202203
https://www.nxtbook.com/nxtbooks/aas/st_202202
https://www.nxtbook.com/nxtbooks/aas/st_202201
https://www.nxtbook.com/nxtbooks/aas/st_202112
https://www.nxtbook.com/nxtbooks/aas/st_202111
https://www.nxtbook.com/nxtbooks/aas/st_202110
https://www.nxtbook.com/nxtbooks/aas/st_202109
https://www.nxtbook.com/nxtbooks/aas/st_202108
https://www.nxtbook.com/nxtbooks/aas/st_202107
https://www.nxtbook.com/nxtbooks/aas/st_202106
https://www.nxtbook.com/nxtbooks/aas/st_202105
https://www.nxtbook.com/nxtbooks/aas/st_202104
https://www.nxtbook.com/nxtbooks/aas/st_202103
https://www.nxtbook.com/nxtbooks/aas/st_202102
https://www.nxtbook.com/nxtbooks/aas/st_202101
https://www.nxtbook.com/nxtbooks/aas/skywatch_2021
https://www.nxtbook.com/nxtbooks/aas/st_202012
https://www.nxtbook.com/nxtbooks/aas/st_202011
https://www.nxtbook.com/nxtbooks/aas/st_202010
https://www.nxtbook.com/nxtbooks/aas/st_202009
https://www.nxtbook.com/nxtbooks/aas/st_202008
https://www.nxtbook.com/nxtbooks/aas/st_202007
https://www.nxtbook.com/nxtbooks/aas/st_202006
https://www.nxtbook.com/nxtbooks/aas/st_202005
https://www.nxtbook.com/nxtbooks/aas/st_202004
https://www.nxtbook.com/nxtbooks/aas/st_202003
https://www.nxtbook.com/nxtbooks/aas/st_202002
https://www.nxtbook.com/nxtbooks/aas/st_202001
https://www.nxtbook.com/nxtbooks/aas/st_201912
https://www.nxtbook.com/nxtbooks/aas/st_201911
https://www.nxtbook.com/nxtbooks/aas/st_201910
https://www.nxtbook.com/nxtbooks/aas/st_201909
https://www.nxtbook.com/nxtbooks/aas/st_201908
https://www.nxtbook.com/nxtbooks/aas/st_201907
https://www.nxtbook.com/nxtbooks/aas/st_201906
https://www.nxtbook.com/nxtbooks/aas/st_201905
https://www.nxtbook.com/nxtbooks/aas/st_201904
https://www.nxtbook.com/nxtbooks/aas/st_201903
https://www.nxtbook.com/nxtbooks/aas/st_201902
https://www.nxtbook.com/nxtbooks/aas/st_201901
https://www.nxtbook.com/nxtbooks/aas/st_201812
https://www.nxtbook.com/nxtbooks/aas/st_201811
https://www.nxtbook.com/nxtbooks/aas/st_201810
https://www.nxtbook.com/nxtbooks/aas/st_201809
https://www.nxtbook.com/nxtbooks/aas/st_201808
https://www.nxtbook.com/nxtbooks/aas/st_201807
https://www.nxtbook.com/nxtbooks/aas/st_201806
https://www.nxtbook.com/nxtbooks/aas/st_201805
https://www.nxtbook.com/nxtbooks/aas/st_201804
https://www.nxtbook.com/nxtbooks/aas/st_201803
https://www.nxtbook.com/nxtbooks/aas/st_201802
https://www.nxtbook.com/nxtbooks/aas/st_201801
https://www.nxtbook.com/nxtbooks/aas/st_201712
https://www.nxtbook.com/nxtbooks/aas/st_201711
https://www.nxtbook.com/nxtbooks/aas/st_201710
https://www.nxtbook.com/nxtbooks/aas/st_201709
https://www.nxtbook.com/nxtbooks/aas/st_201708
https://www.nxtbook.com/nxtbooks/aas/st_201707
https://www.nxtbook.com/nxtbooks/aas/st_201706
https://www.nxtbook.com/nxtbooks/aas/st_201705
https://www.nxtbook.com/nxtbooks/aas/st_201704
https://www.nxtbook.com/nxtbooks/aas/st_201703
https://www.nxtbook.com/nxtbooks/aas/st_201702
https://www.nxtbook.com/nxtbooks/aas/st_201701
https://www.nxtbook.com/nxtbooks/aas/st_201612
https://www.nxtbook.com/nxtbooks/aas/st_201611
https://www.nxtbook.com/nxtbooks/aas/st_201610
https://www.nxtbook.com/nxtbooks/aas/st_201609
https://www.nxtbook.com/nxtbooks/aas/st_201608
https://www.nxtbook.com/nxtbooks/aas/st_201607
https://www.nxtbook.com/nxtbooks/aas/st_201606
https://www.nxtbook.com/nxtbooks/aas/st_201605
https://www.nxtbook.com/nxtbooks/aas/st_201604
https://www.nxtbook.com/nxtbooks/aas/st_201603
https://www.nxtbook.com/nxtbooks/aas/st_201602
https://www.nxtbook.com/nxtbooks/aas/st_201601
https://www.nxtbook.com/nxtbooks/aas/st_201512
https://www.nxtbook.com/nxtbooks/aas/st_201511
https://www.nxtbook.com/nxtbooks/aas/st_201510
https://www.nxtbook.com/nxtbooks/aas/st_201509
https://www.nxtbook.com/nxtbooks/aas/st_201508
https://www.nxtbook.com/nxtbooks/aas/st_201507
https://www.nxtbook.com/nxtbooks/aas/st_201506
https://www.nxtbook.com/nxtbooks/aas/st_201505
https://www.nxtbook.com/nxtbooks/aas/st_201504
https://www.nxtbook.com/nxtbooks/aas/st_201503
https://www.nxtbook.com/nxtbooks/aas/st_201502
https://www.nxtbook.com/nxtbooks/aas/st_201501
https://www.nxtbook.com/nxtbooks/aas/st_201412
https://www.nxtbook.com/nxtbooks/aas/st_201411
https://www.nxtbook.com/nxtbooks/aas/st_201410
https://www.nxtbook.com/nxtbooks/aas/st_201409
https://www.nxtbook.com/nxtbooks/aas/st_201408
https://www.nxtbook.com/nxtbooks/aas/st_201407
https://www.nxtbook.com/nxtbooks/aas/st_201406
https://www.nxtbook.com/nxtbooks/aas/st_mars
https://www.nxtbook.com/nxtbooks/aas/st_201405
https://www.nxtbook.com/nxtbooks/aas/st_201404
https://www.nxtbook.com/nxtbooks/aas/st_201403
https://www.nxtbook.com/nxtbooks/aas/st_201402
https://www.nxtbook.com/nxtbooks/aas/st_201401
https://www.nxtbook.com/nxtbooks/aas/st_201312
https://www.nxtbook.com/nxtbooks/aas/st_201311
https://www.nxtbook.com/nxtbooks/aas/st_201310
https://www.nxtbook.com/nxtbooks/aas/st_201309
https://www.nxtbook.com/nxtbooks/aas/st_201308
https://www.nxtbook.com/nxtbooks/aas/st_201307
https://www.nxtbook.com/nxtbooks/aas/st_201306
https://www.nxtbook.com/nxtbooks/aas/st_201305
https://www.nxtbook.com/nxtbooks/aas/st_201304
https://www.nxtbook.com/nxtbooks/aas/st_201303
https://www.nxtbook.com/nxtbooks/aas/st_201302
https://www.nxtbook.com/nxtbooks/aas/st_201301
https://www.nxtbook.com/nxtbooks/aas/st_201212
https://www.nxtbook.com/nxtbooks/aas/st_201211
https://www.nxtbook.com/nxtbooks/aas/st_201210
https://www.nxtbook.com/nxtbooks/aas/st_201209
https://www.nxtbook.com/nxtbooks/aas/st_201208
https://www.nxtbook.com/nxtbooks/aas/st_201207
https://www.nxtbook.com/nxtbooks/aas/st_201206
https://www.nxtbook.com/nxtbooks/aas/st_201205
https://www.nxtbook.com/nxtbooks/aas/st_201204
https://www.nxtbook.com/nxtbooks/aas/st_201203
https://www.nxtbook.com/nxtbooks/aas/st_201202
https://www.nxtbook.com/nxtbooks/aas/st_201201
https://www.nxtbook.com/nxtbooks/aas/st_201112
https://www.nxtbook.com/nxtbooks/aas/st_201111
https://www.nxtbook.com/nxtbooks/aas/st_201110
https://www.nxtbook.com/nxtbooks/aas/st_201109
https://www.nxtbook.com/nxtbooks/aas/st_201108
https://www.nxtbook.com/nxtbooks/aas/st_201107
https://www.nxtbook.com/nxtbooks/aas/st_201106
https://www.nxtbook.com/nxtbooks/aas/st_201105
https://www.nxtbook.com/nxtbooks/aas/st_201104
https://www.nxtbook.com/nxtbooks/aas/st_201103
https://www.nxtbook.com/nxtbooks/aas/st_201102
https://www.nxtbook.com/nxtbooks/aas/st_201101
https://www.nxtbook.com/nxtbooks/aas/st_201012
https://www.nxtbook.com/nxtbooks/aas/st_201011
https://www.nxtbook.com/nxtbooks/aas/st_201010
https://www.nxtbook.com/nxtbooks/aas/st_201009
https://www.nxtbook.com/nxtbooks/aas/st_201008
https://www.nxtbook.com/nxtbooks/aas/st_201007
https://www.nxtbook.com/nxtbooks/aas/st_201006
https://www.nxtbook.com/nxtbooks/aas/st_201005
https://www.nxtbook.com/nxtbooks/aas/st_201004
https://www.nxtbook.com/nxtbooks/aas/st_201003
https://www.nxtbook.com/nxtbooks/aas/st_201002
https://www.nxtbook.com/nxtbooks/aas/st_201001
https://www.nxtbookmedia.com