[HN Gopher] A Cosmic Miracle: A Remarkably Luminous Galaxy at z=...
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A Cosmic Miracle: A Remarkably Luminous Galaxy at z=14.44 Confirmed
with JWST
Author : yread
Score : 97 points
Date : 2026-02-11 08:43 UTC (14 hours ago)
(HTM) web link (astro.theoj.org)
(TXT) w3m dump (astro.theoj.org)
| nasretdinov wrote:
| Why did we make just an infrared telescope then? Why don't go
| into even lower frequencies, surely we would detect something too
| if we just look?
| XorNot wrote:
| Lower frequencies are microwaves and radio waves. We already
| have the square kilometer array.
| jacques_morin wrote:
| The lower the frequency, the larger the wavelength and thus the
| larger the cupola needed to detect it. That's why
| radiotelescopes are on earth, they are HUGE.
| amluto wrote:
| Radio telescope _dishes_ are huge so that they can receive
| (or even transmit in the case of Arecibo, which is gone now)
| a narrow beam. At long wavelengths you need something huge to
| get a narrow beam.
|
| But you can also use multiple, much smaller antennas to
| synthesize a narrow beam, and those little antennas are often
| dishes but can also be very simple and rather small antennas.
| adgjlsfhk1 wrote:
| interferometry is good for seeing small objects, but not
| faint objects. for faint objects there's nothing that works
| better than a giant dish
| metalman wrote:
| "just an infrared telescope"
|
| how about you go make yourself conversant with "just" the
| technical requirements of the main cryogenic pump onboard,
| leaving out the rest of the thermal management systems for
| whatever remains of your life, which will have to be long in
| order to fail honorably.
| nasretdinov wrote:
| Sorry, I didn't mean it's easy to build, far from it :). I
| meant "just infrared" in terms of frequency -- why not go
| further? Is there a gap between the current infrared and
| radio on Earth?
| jacquesm wrote:
| Wavelength for electromagnetic waves = c/frequency.
|
| So to 'catch' a certain frequency with a receiver the size
| of the receiver gets proportionally larger as the frequency
| drops. Focusing light can be done with relatively small
| gear. Focusing radio waves, especially when the source is
| distant requires a massive structure and to keep that
| structure sufficiently cool and structurally rigid is a
| major challenge. It is already a challenge for the JWST at
| the current wavelengths, increasing the wavelength while
| maintaining the sensitivity would create some fairly
| massive complications.
|
| In the end this is a matter of funding, and JWST already
| nearly got axed multiple times due to its expense.
| metalman wrote:
| I am poking fun (at your expense) at the notion that
| because the light is already there, adding other sensors
| would be feasable. Once you grasp the requirements of
| building an infrared telescope, you will be going, oh!,
| damn, wow! It's actualy not that deep a dive to get a feel
| for just how special the JWST is from an engineering
| perspective, and then a look into just how difficult it
| will be to get visible light from those distances, which
| may require a interferometric telescope with multiple huge
| sub units flying in formation at distances, known to a
| fraction of the target wave length , but perhaps several
| hundred thousand km, apart. doable, but :), just
| jacquesm wrote:
| The temperature gradient across that thing is
| mindblowing.
| Sharlin wrote:
| Because near/mid infrared has many uses other than high-z
| objects, and it's been something of a relative blind spot to us
| until now, although before Webb we did have Spitzer.
|
| For far IR/submillimeter observations we had Herschel in space,
| SOFIA in the stratosphere (flying on a 747), and several large
| terrestrial telescopes at very high altitudes can also observe
| at FIR/submm wavelengths. But sure, there are likely many
| astronomers who would love nothing more than a new spaceborne
| FIR telescope, given that it's been more than a decade since
| Herschel's end of mission, and SOFIA was also retired in 2022.
|
| For microwave we've had several space telescopes (COBE, then
| WMAP, then Planck), mainly designed to map the cosmic microwave
| background. That's the farthest and reddest that you can see in
| any EM band, 300,000 years after the big bang.
|
| Past microwave, that's the domain of radio astronomy, with
| entirely different technology needed. We have huge radio
| telescope arrays on the ground - the atmosphere is fairly
| transparent to radio so there's no pressing reason to launch
| radio telescopes to space, and their size would make it
| completely infeasible anyway, at least until some novel low-
| mass, self-unfolding antenna technology.
| alex43578 wrote:
| This may be a silly question, but would you be able to create
| an interferometer style telescope array in space via a
| platform like starlink, ie small, inexpensive sats? Would
| that reduce/eliminate the need to launch large singular
| antennas?
| abbeyj wrote:
| That would probably be difficult at optical wavelengths. At
| radio wavelengths you might have a better shot, but we can
| build radio interferometric telescopes on Earth and since
| the atmosphere is relatively transparent at radio
| frequencies, you probably aren't going to get any advantage
| by trying to build one in Earth orbit.
|
| Though not the same thing, you may be interested in https:/
| /en.wikipedia.org/wiki/Laser_Interferometer_Space_Ant...
| privong wrote:
| There is a mission concept for a far-infrared
| interferometer: https://asd.gsfc.nasa.gov/spice/
|
| One would need to go to space for that of course.
| reedf1 wrote:
| It's safe to say that if we are sticking a 6-ton 20ft mirror
| into space that the scientists probably have a reason for it...
| watersb wrote:
| Excellent question!
|
| The longest wavelengths of light are generally classified as
| "radio".
|
| So radio telescopes have been tasked to explore the very early
| universe.
|
| https://en.wikipedia.org/wiki/Reionization
|
| If I understand it correctly, the "Period of Reionization" is
| first light we can see from processes like stars and galaxies.
|
| There was ionized plasma at the beginning but the universe was
| like a really thick fog everywhere, and that first light was
| scattered around and you can't really see stars. As the
| universe expanded, that fog cooled down, and you could see, but
| cold matter doesn't emit much light, so there wasn't much to
| see. It took a while for gas clouds to collapse into the first
| stars, heating up the gas to ionized plasma once again, so it's
| re-ionized matter.
|
| The Low Frequency Array, LOFAR, has been used to study this
| "Cosmic Dawn".
|
| The Square Kilometer Array was designed to explore this era.
|
| But! Not a radio telescope JWST has revealed unexpected, huge
| globs that seem to be galaxy-sized gas clouds collapsing into
| (maybe) black hole cores; the thermal emission from the
| collapse isn't nuclear fusion, so I don't know if those are
| "stars". But it's very early light.
|
| Honestly, every time a new class of telescope is built, it
| discovers fundamentally new phenomena.
|
| https://duckduckgo.com/?q=LOFAR+square+kilometer+array+reion...
|
| https://news.ycombinator.com/item?id=44739618
|
| https://news.ycombinator.com/item?id=46938217
|
| I searched "Reionization" and "Cosmic Dawn" plus some favorite
| telescopes via web and here using the Hacker News search
| (Agolia).
|
| (Certainly you know the difference between radio and infrared,
| but I had to look into how those choices of telescope have
| observed different aspects of Reionization Era, got nerd-
| sniped, and just had to write it down in a couple of
| sentences.)
| adgjlsfhk1 wrote:
| because infrared is the hardest to observe from the ground. Hot
| objects glow, and the sky is at the temperature where it glows
| infrared.
| 317070 wrote:
| I love the finding, but I really like the first sentence on their
| abstract: "JWST has revealed a stunning population of bright
| galaxies at surprisingly early epochs, z>10, where few such
| sources were expected."
|
| Unless stunning has a technical meaning I'm unaware of, I like
| this approach of starting a technical paper with something less
| dry.
| belter wrote:
| In scientific writing stunning can also be used in a neutral
| sense to mean far outside the baseline. It does not necessarily
| carry an aesthetic meaning like stunningly beautiful... :-)
| dguest wrote:
| arXiv link: https://arxiv.org/abs/2505.11263v2
|
| Note: I like arXiv links anyway, but in this case something about
| the page was killing my browser, had to reload a few times.
| eitau_1 wrote:
| Does anyone know if JWST has seen stuff far enough for this
| effect to kick in?
|
| [Angular Diameter Turnaround](https://xkcd.com/2622/)
| jdiff wrote:
| Yes, JWST can see as far back as 300 million years after the
| big bang.
| ben_w wrote:
| Yes, as per Wikipedia that happens much closer to us, at
| redshift 1.5:
| https://en.wikipedia.org/wiki/Angular_diameter_distance
|
| (Note: the reason to measure in red shift rather than light
| years is that when this comes up it suddenly gets very
| important to be very careful about what exactly you even mean
| by "how far away is that thing?")
| jahnu wrote:
| Incredible!
|
| So if I understand this correctly, the galaxy above in the
| paper is at Z=14.4 and that means it appears in the sky about
| as big as if it were a very small Z or roughly 350
| megaparsecs away?
| metalliqaz wrote:
| I think about that one a lot. It goes all the way back to the
| CMB, which is so "big" that it is literally everywhere you look
| and the shapes we see were apparently at the quantum scale.
| abainbridge wrote:
| We're seeing this galaxy as it was 280 million years after the
| Big Bang. But the universe didn't become transparent to photons
| until 100 million years after that
| (https://en.wikipedia.org/wiki/Recombination_(cosmology)). So
| that's impossible. Who's wrong, Recombination theory or this
| paper?
|
| Or have I missed something?
| ben_w wrote:
| I think you've mistaken thousands of years for millions.
|
| As per your own link: Solving for z_rec gives
| value around 1100, which converts to a cosmic time value around
| 400,000 years
| abainbridge wrote:
| Doh. Thanks.
| magicalhippo wrote:
| If it makes you feel any better I had the same exact
| reaction as you and almost posted the same thing, but
| managed to catch my error just in time.
| rwmj wrote:
| That's the most authors I've seen on any paper. I counted 46
| across 36 separate institutions.
| jeffbee wrote:
| Turns out launching a gigantic camera into orbit and developing
| a photograph of the beginning of the universe takes teamwork.
| PhoenixFlame101 wrote:
| Relevant PhD comics: https://phdcomics.com/comics.php?f=1911
| JBorrow wrote:
| 46 authors isn't that many. Big projects necessitate many
| authors (e.g. https://arxiv.org/abs/1807.06209)
| mr_mitm wrote:
| In high energy physics it can easily be thousands of authors,
| like in the ATLAS collaboration.
| reactordev wrote:
| The big bang time relativity problem sometimes makes your brain
| hurt but this is amazing!
|
| I'm so fascinated by the fact that we can look back through time
| by looking at these distant objects. I wish I went into
| astrophysics instead of engineering...
| shipman05 wrote:
| Everyone I know who studied astrophysics ended up in Fintech
| doing data science anyway. "illusion of choice"
| reactordev wrote:
| I met a few in MarTech as well...
| SoleilAbsolu wrote:
| Well there is Brian May, guitarist from Queen, who finished
| his astrophysics PhD in 2007 but he is probably an outlier!
| rirze wrote:
| I went into astrophysics and came out very discouraged. The
| researchers actually pushing the envelope are 1% of academia
| and if you don't find a department with them, you are paddling
| in the open sea. There is an incredible amount of cruft in
| academia, not to mention how financially insecure that life is.
|
| Truly, only those who think about nothing but (astro)physics
| can bear it.
|
| I still love thinking about fundamental problems and upcoming
| research however. That will never be gone.
| reactordev wrote:
| I realize my choice was definitely financially driven but in
| a future where that's _easier_ with AI, I'd like to focus on
| things that make my brain tingle.
|
| I used to love engineering but with AI I feel like all the
| passion (learning things, making brain squeeze) is gone and
| I'm just managing another resource.
|
| Don't get me wrong, I like building things. I also like
| solving challenges and hard problems and I haven't done that
| in a few years now.
| metalliqaz wrote:
| what do the other 99% of researchers do?
| voxl wrote:
| Most research is boring incremental stuff, and very often
| you will find a dejected or disappointed individual that
| realizes this. The invention of relativity only made one
| scientist a household name. I guess everyone else that came
| before and after were doing nothing at all.
| reactordev wrote:
| I know a few more household names but he's right.
|
| There's a scene in Good Will Hunting where the two
| professors talk about Will [0] and Sean (Robin Williams)
| says it's "There's more to life than a fucking Fields
| medal". Both are correct but there's only a few names in
| history that will be remembered as "The Greats".
|
| [0] https://www.youtube.com/watch?v=AjXgJ1gneK8
| fusslo wrote:
| could someone ELI5 for this ignoramus?
|
| It sounds like JWST found a galaxy where one wasn't expected to
| be for the time in which it takes light to reach where JWST is?
|
| I assume it's important because we expected nothing and there was
| something?
|
| But I am just guessing, honestly
| yread wrote:
| It's a galaxy far far away and more importantly very very old.
| The image is 13.5 B years old, the photons were created just
| 280 million years after big bang. It's the oldest thing we have
| seen so far. And it looks mildly different than what we
| expected to see
| scotty79 wrote:
| In our current understanding of how universe formed galaxies
| accumulate gradually and it takes time. This one was quite
| large already, very shortly after the Big Bang, which is at
| odds with our understanding.
| mandevil wrote:
| The Cosmic Microwave Background Explorer was a satellite back
| in the 1990s that measured the Cosmic Microwave Background of
| the universe. This CMB is the afterimage of the Big Bang, about
| 400,000 years after the Big Bang when the universe suddenly
| became transparent to photons- the earliest images of the
| universe we can possibly capture in light.
|
| And it found that everything was the same no matter where you
| looked, to about 10 parts per million. So that is the level of
| variation in the density of the universe about a half-million
| years after the Big Bang, the differences are measured at the
| level of parts per million.
|
| And then back in the 1990s the Hubble Space Telesecope took
| pictures of the previously most luminous galaxy ever recorded,
| and it was really far back in time, within half a billion years
| of the Big Bang. And these luminous galaxies were something
| that we expected to mean that they were built around gigantic
| supermassive Black Holes. Which means that in a very short
| amount of time we must have gone from "everything is the same
| to parts per million" to "here is a gigantic accumulation of
| mass concentrated in this one spot so densely that all of our
| models of physics don't work any more."
|
| And so the Webb Space Telescope was built specifically to look
| for things in between what the Hubble had seen (in Visual
| Light) and what the COBE had seen (in Microwave), that is
| Infrared. It is designed to look for these supermassive
| galaxies that had Red Shifted (1) so far they had left the
| visual spectrum and gone into Infrared. Figuring out how all of
| these super luminous galaxies formed is the main question that
| the whole thing was designed around.
|
| 1: As things move away from us, the photons shift to the red
| end of the spectrum. According to Hubble's Law, things the
| faster something is moving away from us the earlier it is in
| time, and the further its photons are shifted to the right:
| this is why the Cosmic Microwave Background is in microwave,
| because it has been red shifted so far it has gone into the
| Microwave part of the spectrum.
| scotty79 wrote:
| Controversial idea. Black holes are older than the Big Bang.
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