The Cosmic Horseshoe gravitational lens.
Credit: NASA/ESA (CC BY 4.0)
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'Most massive black hole ever discovered' is detected | The Royal Astronomical Society
The authors of
Genesis got so much so badly wrong that it’s difficult to find anything they got right — but the hardest place to find even a sliver of accuracy is their description of the universe. With their naïve attempt to explain the existence of different kinds of animals, they at least recognised that there were different species. Their notion of magical creation out of nothing, without ancestry, was of course laughably wrong, but at least they knew there
were distinct organisms requiring explanation.
By contrast, in their picture of the cosmos — centred on a small, flat world with a solid dome (the “firmament”) over it—about the only things they got right were the existence of Earth, the Sun and Moon, and “the stars”. Everything else was subsumed into that one word: “stars”, a bucket that included the visible planets, distant suns, and entire galaxies, all imagined as lights fixed to the dome, with the Sun and Moon set within it.
In short, almost everything in that description is wrong—not just what things are, but where they are. They spoke about light, but knew nothing of its nature. That they noticed that light comes from luminous bodies is probably the only thing they got right.
Black Holes: Nature’s Most Extreme Objects.
A black hole is a region of spacetime where gravity is so intense that nothing—not even light—can escape. They form when a massive star collapses under its own gravity or through the merger of smaller black holes.
Event Horizon
The vent horizon is the “point of no return” surrounding a black hole. Once anything crosses it, escape is impossible. From outside, the event horizon appears as a dark sphere; it’s not a physical surface but a boundary defined by relativity.
Singularity
At the very centre, according to general relativity, lies a singularity — a point where density and spacetime curvature become infinite, and the known laws of physics break down. In reality, quantum effects are expected to smooth out this infinity, but a complete theory of quantum gravity is needed to describe it properly.
Relativity vs Quantum Physics
Black holes are unique because they combine two regimes of physics:
- Einstein’s general relativity describes how they warp spacetime.
- Quantum mechanics governs the behaviour of particles and energy at extremely small scales.
The crossover between these domains lies deep inside the black hole, in a region near the singularity sometimes called the quantum gravity zone, where spacetime curvature reaches the Planck scale and neither theory works alone. This is not the event horizon, as is sometimes said; the event horizon is still very much part of the Relativity domain.
The Firewall Hypothesis
Stephen Hawking and others noted a paradox: quantum theory predicts that information cannot be destroyed, yet anything crossing an event horizon seems lost forever. One proposed resolution is the firewall hypothesis: instead of passing smoothly through, anything hitting the horizon would be incinerated by a burst of high-energy radiation. This “firewall” would break relativity’s expectation that crossing the horizon is uneventful (for a large black hole) but would preserve quantum theory’s rules.
Open Questions
- Does the singularity really exist, or is it replaced by something else in a quantum theory of gravity?
- Do firewalls exist, or is there a different resolution to the black hole information paradox?
- Can Hawking radiation—tiny energy leaks predicted by quantum field theory—eventually cause black holes to evaporate completely?
Black holes remain one of physics’ most powerful testing grounds, where the deepest laws of nature are pushed to their limits.
And of course, they could have known nothing about black holes, or about the relationship between mass and gravity that explains them and governs the motions of the “stars”.
A point I’ve made here before — worth making again — is that we can be certain the Bible was not written by a creator god by seeing how much of it is flatly wrong. Much of it can’t even be rescued as meaningful metaphor or allegory—the standard apologetic for obvious falsehoods. It is simply, unarguably, and unambiguously wrong on multiple levels.
If a creator god had written it as a vital message to humankind, why did it not include anything unknown at the time in unmistakable terms, as proof of divine authorship and omniscience? Why, for example, did it not tell us about atoms, germs, or galaxies; that Earth is an oblate spheroid orbiting the Sun along with other planets; or explain the relationship between mass and gravity and why black holes exist?
Why not? Because the authors of the Bible were ignorant of these things. They were not creator gods, but ancient Near Eastern writers doing their best to invent plausible narratives within their cultural preconceptions — of a spirit-filled world that ran on magic — when everything they knew lay within a few days’ walk of home in the hills of Canaan.
So, compare their description of the universe as they imagined it with what science now shows us: in this case, an ultramassive black hole revealed by how its gravity bends light from a background galaxy into an “Einstein ring”, a phenomenon predicted by Einstein’s general theory of relativity.
The description comes from the
Royal Astronomical Society news release and the open-access paper in
Monthly Notices of the Royal Astronomical Society.
First, let's see how the Bible's author described the entire universe as they saw it without the benefit of scientific instruments or theoretical physics:
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And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters. And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so. And God called the firmament Heaven. And the evening and the morning were the second day. And God said, Let the waters under the heaven be gathered together unto one place, and let the dry land appear: and it was so. And God called the dry land Earth; and the gathering together of the waters called he Seas: and God saw that it was good. (Genesis 1.6-10)
And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also. And God set them in the firmament of the heaven to give light upon the earth, And to rule over the day and over the night, and to divide the light from the darkness: and God saw that it was good.(Genesis 1.16-18)
Now compare that to this image of a tiny fragment of it that astronomers at the Royal Astronomical Society have just released. It shows the gravity lensing effect and the resulting Einstein ring. Ber in mind that this is a tiny fragment of the universe that would be entirely hidden by a grain of rice held between the thumb and forefinger of your outstretched arm. There is absolutely nothing to compare it with in the Bible, obviously.
'Most massive black hole ever discovered' is detected
Astronomers have discovered potentially the most massive black hole ever detected.
The cosmic behemoth is close to the theoretical upper limit of what is possible in the universe and is 10,000 times heavier than the black hole at the centre of our own Milky Way galaxy.
The Cosmic Horseshoe gravitational lens.
The newly discovered ultramassive blackhole lies at the centre of the orange galaxy. Far behind it is a blue galaxy that is being warped into the horseshoe shaped ring by distortions in spacetime created by the immense mass of the foreground orange galaxy.
Credit: NASA/ESA (CC BY 4.0)
Such is the enormousness of the ultramassive black hole’s size, it equates to 36 billion solar masses, according to a new paper published today in Monthly Notices of the Royal Astronomical Society.
It is thought that every galaxy in the universe has a supermassive black hole at its centre and that bigger galaxies host bigger ones, known as ultramassive black holes.
This is amongst the top 10 most massive black holes ever discovered, and quite possibly the most massive. Most of the other black hole mass measurements are indirect and have quite large uncertainties, so we really don't know for sure which is biggest. However, we’ve got much more certainty about the mass of this black hole thanks to our new method.
Professor Thomas Collett, co-author
Institute of Cosmology and Gravitation
University of Portsmouth,
Portsmouth, UK.
Researchers detected the Cosmic Horseshoe black hole using a combination of gravitational lensing and stellar kinematics (the study of the motion of stars within galaxies and the speed and way they move around black holes).
The latter is seen as the gold standard for measuring black hole masses, but doesn't really work outside of the very nearby universe because galaxies appear too small on the sky to resolve the region where a supermassive or ultramassive black hole lies.
[Adding in gravitational lensing helped the team] push much further out into the universe. We detected the effect of the black hole in two ways – it is altering the path that light takes as it travels past the black hole and it is causing the stars in the inner regions of its host galaxy to move extremely quickly (almost 400 km/s). By combining these two measurements we can be completely confident that the black hole is real.
Professor Thomas Collett.
This discovery was made for a 'dormant' black hole – one that isn’t actively accreting material at the time of observation. Its detection relied purely on its immense gravitational pull and the effect it has on its surroundings. What is particularly exciting is that this method allows us to detect and measure the mass of these hidden ultramassive black holes across the universe, even when they are completely silent.
Carlos Melo-Carneiro, lead author.
Instituto de Física
Universidade Federal do Rio Grande do Sul,
Porto Alegre, Brazil.
Another image of the Cosmic Horseshoe, but with the pair of images of a second background source highlighted.The faint central image forms close to the black hole, which is what made the new discovery possible.
NASA/ESA/Tian Li (University of Portsmouth) (CC BY 4.0).
Typically, for such remote systems, black hole mass measurements are only possible when the black hole is active. But those accretion-based estimates often come with significant uncertainties. Our approach, combining strong lensing with stellar dynamics, offers a more direct and robust measurement, even for these distant systems.
Carlos Melo-Carneiro.
The discovery is significant because it will help astronomers understand the connection between supermassive black holes and their host galaxies.
We think the size of both is intimately linked, because when galaxies grow they can funnel matter down onto the central black hole. Some of this matter grows the black hole but lots of it shines away in an incredibly bright source called a quasar. These quasars dump huge amounts of energy into their host galaxies, which stops gas clouds condensing into new stars.
Professor Thomas Collett.
Our own galaxy, the Milky Way, hosts a 4 million solar mass black hole. Currently it's not growing fast enough to blast out energy as a quasar but we know it has done in the past, and it may will do again in the future.
The Andromeda Galaxy and our Milky Way are moving together and are expected to merge in about 4.5 billion years, which is the most likely time for our supermassive black hole to become a quasar once again, the researchers say.
An interesting feature of the Cosmic Horseshoe system is that the host galaxy is a so-called fossil group.
Fossil groups are the end state of the most massive gravitationally bound structures in the universe, arising when they have collapsed down to a single extremely massive galaxy, with no bright companions.
It is likely that all of the supermassive black holes that were originally in the companion galaxies have also now merged to form the ultramassive black hole that we have detected. So we're seeing the end state of galaxy formation and the end state of black hole formation.
Professor Thomas Collett.
The discovery of the Cosmic Horseshoe black hole was somewhat of a serendipitous discovery. It came about as the researchers were studying the galaxy’s dark matter distribution in an attempt to learn more about the mysterious hypothetical substance.
Now that they’ve realised their new method works for black holes, they hope to use data from the European Space Agency’s Euclid space telescope to detect more supermassive black holes and their hosts to help understand how black holes stop galaxies forming stars.
Publication:
Carlos R Melo-Carneiro, Thomas E Collett, Lindsay J Oldham, Wolfgang Enzi, Cristina Furlanetto, Ana L Chies-Santos, Tian Li, Unveiling a 36 billion solar mass black hole at the centre of the Cosmic Horseshoe gravitational lens, Monthly Notices of the Royal Astronomical Society, Volume 541, Issue 4, August 2025, Pages 2853–2871, https://doi.org/10.1093/mnras/staf1036
ABSTRACT
Supermassive black holes (SMBHs) are found at the centre of every massive galaxy, with their masses tightly connected to their host galaxies through a co-evolution over cosmic time. For massive ellipticals, the SMBH mass (\(\small M_\text{BH}\)) strongly correlates with the host central stellar velocity dispersion (\(\sigma_e\)), via the
relation. However, SMBH mass measurements have traditionally relied on central stellar dynamics in nearby galaxies (\(\small z \lt 0.1\)), limiting our ability to explore the SMBHs across cosmic time. In this work, we present a self-consistent analysis combining 2D stellar dynamics and lens modelling of the Cosmic Horseshoe gravitational lens system (\(z_l = 0.44\)), one of the most massive lens galaxies ever observed. Using MUSE integral-field spectroscopy and high-resolution Hubble Space Telescope imaging, we simultaneously model the radial arc – sensible to the inner mass structure – with host stellar kinematics to constrain the galaxy’s central mass distribution and SMBH mass. Bayesian model comparison yields a \(\small 5\sigma\) detection of an ultramassive black hole with \(\small \log _{10}(M_\text{BH}/{\rm M}_{\odot }) = 10.56^{+0.07}_{-0.08} \pm (0.12)^\text{sys}\), consistent across various systematic tests. Our findings place the Cosmic Horseshoe \(\small 1.5\sigma\) above the \(\small M_\text{BH}-\sigma_e\) relation, supporting an emerging trend observed in brightest cluster galaxies and other massive galaxies, which suggests a steeper \(\small M_\text{BH}-\sigma_e\) relationship at the highest masses, potentially driven by a different co-evolution of SMBHs and their host galaxies. Future surveys will uncover more radial arcs, enabling the detection of SMBHs over a broader redshift and mass range. These discoveries will further refine our understanding of the \(\small M_\text{BH}-\sigma_e\) relation and its evolution across cosmic time.
1 INTRODUCTION
Most massive galaxies are believed to host a supermassive black hole (SMBH) at their centre. More importantly, host galaxies and their SMBHs exhibit clear scaling relations, pointing to a co-evolution between the galaxy and the SMBH (Kormendy & Ho 2013). The SMBH mass (\(\small M_{\text{BH}\)) has been shown to correlate with various galaxy properties, such as the bulge luminosity (e.g. Magorrian et al. 1998; Marconi & Hunt 2003; Gültekin et al. 2009), stellar bulge mass (e.g. Laor 2001; McLure & Dunlop 2002), dark matter (DM) halo mass (e.g. Marasco et al. 2021; Powell et al. 2022), number of host’s globular clusters (e.g. Burkert & Tremaine 2010; Harris, Poole & Harris 2014), and stellar velocity dispersion (e.g. Gebhardt et al. 2000; Beifiori et al. 2009.1). Notably, the \(\small M_\text{BH}-\sigma_e\) relation, which links SMBH mass to the effective stellar velocity dispersion of the host (\(\small \sigma_e\)), remains tight across various morphological types and SMBH masses (van den Bosch 2016). None the less, when SMBHs accrete mass from their neighbourhoods, they can act as active galactic nuclei (AGNs), injecting energy in the surrounding gas in a form of feedback. This feedback can be either positive, triggering star formation (Ishibashi & Fabian 2012; Silk 2013.1; Riffel et al. 2024), or negative quenching galaxy growth (e.g. Hopkins et al. 2006; Dubois et al. 2013.2; Costa-Souza et al. 2024.1).
It is expected that the most massive galaxies in the Universe, such as brightest cluster galaxies (BCGs), host the most massive SMBHs. Indeed, so-called ultramassive black holes (UMBHs; \(\small M_\text{BH} \ge 10^{10}M_\odot\)) have been found in such systems (e.g. Hlavacek-Larrondo et al. 2012.1). Most of these UMBHs have been measured through spatially resolved dynamical modelling of stars and/or gas. For instance, the UMBH in Holm 15A at \(\small z=0.055\) \(\small M_\text{BH} = (4.0 \pm 0.80) \times 10^{10}M_\odot\) (; Mehrgan et al. 2019) and the UMBH in NGC 4889 at \(\small z = 0.021\) (\(\small M_\text{BH} = (2.1 \pm 1.6) \times 10^{10}M_\odot\); McConnell et al. 2012.2) were both determined using stellar dynamical modelling. However, despite the success of this technique in yielding hundreds of SMBH mass measurements, the requirement for high-quality spatially resolved spectroscopy poses significant challenges for studies at increasing redshift (see e.g. Kormendy & Ho 2013, Suplemental Material S1).
None the less, the significance of these UMBHs lies in the fact that many of them deviate from the standard linear \(\small M_\text{BH} - \sigma_e\) relation (e.g. Kormendy & Ho 2013; den Bosch 2016). This suggests either a distinct evolutionary mechanism governing the growth of the largest galaxies and their SMBHs (McConnell et al. 2011), leading to a significantly steeper relation (Bogdán et al. 2018), or a potential decoupling between the SMBH and host galaxy co-evolution. Populating the high-mass end of the \(\small M_\text{BH} - \sigma_e\) relation, particularly through direct \(\small M_\text{BH}\) measurements, could help resolve this ongoing puzzle.
Recently, Nightingale et al. (2023), by modelling the gravitationally lensed radial image near the the Abell 1201 BCG (\(\small z=0.169\)), was able to measure the mass of its dormant SMBH as \(\small M_\text{BH} = (3.27 \pm 2.12) \times 10^{10}M_\odot\), therefore an UMBH. This provides a complementary approach to other high-z probes of SMBH mass, such as reverberation mapping (Blandford & McKee 1982; Bentz & Katz 2015) and AGN spectral fitting (Shen 2013.3). Unlike these methods, which require active accretion and depend on local Universe calibrations, the lensing technique offers a direct measurement independent of the SMBH’s accretion state.
In this paper, we analyse the Cosmic Horseshoe gravitational lens system (Belokurov et al. 2007), where the lens galaxy is one of the most massive strong gravitational lenses known to date. The lens galaxy is an early-type galaxy (ETG) at redshift \(\small z_i = 0.44\), possibly part of a fossil group (Ponman et al. 1994), and is notable for lensing one of its sources into a nearly complete Einstein ring (the Horseshoe). Additionally, a second multiply imaged source forms a radial arc near the centre of the lens galaxy.
Due to the radial image formed very close to the centre, the inner DM distribution of the Cosmic Horseshoe can be studied in detail, as done by Schuldt et al. (2019.1). By simultaneously modelling stellar kinematics from long-slit spectroscopy and the positions of the lensed sources, Schuldt et al. (2019.1) found that the DM halo is consistent with a Navarro–Frenk–White (NFW; Navarro, Frenk & White 1997) profile, with the DM fraction within the effective radius (\(\small R_e\)) estimated to be between 60 per cent and 70 per cent. Moreover, their models include a point mass at the galaxy’s centre, reaching values around \(\small \sim 10^{10} M_\odot\), which could represent an SMBH; however, they did not pursue further investigations into this possibility.
Using new integral-field spectroscopic data from the Multi Unit Spectroscopic Explorer (MUSE) and imaging from the Hubble Space Telescope (HST), we conducted a systematic modelling of the Cosmic Horseshoe system to reassess the evidence for an SMBH at the heart of the lens galaxy. We performed a self-consistent analysis of both strong gravitational lensing (SGL) and stellar dynamics, which demonstrated that the presence of an SMBH is necessary to fit both data sets simultaneously.
This paper is structured as follows: In Section 2, we present the HST imaging data and MUSE observations, along with the kinematic maps used for the dynamical modelling. Section 3 briefly summarizes the lensing and dynamical modelling techniques, including the multiple-lens-plane formalism, the approximations adopted in this work, and the mass profile parametrization. In Section 4, we present the results from our fiducial model and alternatives models, which we use to address the systematics on the SMBH mass. In Section 5 we discuss our results and present other astrophysical implications. Finally, we summarize and conclude in Section 6.
Unless otherwise, all parameter estimates are derived from the final sampling chain, with reported values representing the median of each parameter’s one-dimensional marginalized posterior distribution, with uncertainties corresponding to the \(\small 16^\text{th}\) and \(\small 84^\text{th}\) percentiles. Furthermore, throughout this paper, we adopt the cosmological parameters consistent with Planck Collaboration XIII (2016.1): \(\small \Omega _{\Lambda ,0} = 0.6911\), \(\small \Omega _{\text{m},0} = 0.3089\), \(\small \Omega _{\text{b},0} = 0.0486\), and \(\small H_0 = 67.74\) \(\small \text{km}\ \text{s}^{-1}\ \text{Mpc}^\text{-1}\).
Carlos R Melo-Carneiro, Thomas E Collett, Lindsay J Oldham, Wolfgang Enzi, Cristina Furlanetto, Ana L Chies-Santos, Tian Li, (2025)
Unveiling a 36 billion solar mass black hole at the centre of the Cosmic Horseshoe gravitational lens,
Monthly Notices of the Royal Astronomical Society, 541(4), 2853–2871, https://doi.org/10.1093/mnras/staf1036
Copyright: © 2025 The Royal Astronomical Society.
Published by Oxford University Press. Open access.
Reprinted under a
Creative Commons Attribution 4.0 International license (CC BY 4.0)
The discovery and analysis of black holes, and phenomena such as Einstein rings, would have been utterly incomprehensible to the authors of the Bible. These were people with no concept of galaxies, the vastness of the universe, or even that Earth is a sphere orbiting the Sun. Their worldview was of a flat Earth covered by a solid dome, with the Sun, Moon, and “stars” fixed to it. The very idea of light being bent by gravity, or of objects so massive that even light cannot escape, would have been as far beyond their imagination as quantum mechanics itself.
When we compare their primitive cosmology with what modern science reveals—billions of galaxies, relativistic spacetime, the quantum-scale behaviour of matter, and black holes bending light into perfect circles—the contrast could not be more stark. The biblical description is not merely simplified; it is wrong on almost every measurable level. It has Earth at the centre, the stars as small lights, and the sky as a hard surface holding back water. Science, by contrast, uncovers a cosmos governed by consistent natural laws, tested and confirmed through observation and mathematics.
This is compelling evidence that an omniscient creator god did not write the Bible. If it had done, it could have contained truths about the nature of the cosmos that were unknown at the time, expressed in terms clear enough to be recognisable today—atoms, germs, the vastness of space, or even the basic structure of the solar system. Instead, what we find are the assumptions of scientifically illiterate Bronze Age people, drawing on local myths and imagination. The difference between their errors and the precision of modern astrophysics is not a matter of interpretation—it is a matter of fact.
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DSS Finder Chart (30′ × 30′ field) — Highlights NGC 2835 with its approximate size and orientation.
Hydra Constellation Sky Chart — Shows the broader layout of Hydra, aiding visual positioning in the night sky.
Star‑chart zoomed‑in view — A close-up star chart marking the galaxy amid surrounding field stars.
Constellation Grid Overlay — Provides context with grid lines and star positions across Hydra.
