The results are in a new paper published in The Astrophysical Journal titled “The ASTRID Simulation at z = 0: From Massive Black Holes to Large-scale Structure.<\/a>” The lead author is Yihao Zhou, a PhD student in Carnegie Mellon University’s (CMU) Department of Physics. <\/p>\n “We present the z = 0 results for the cosmological simulation ASTRID,” the authors write. “Hosting 2 \u00d7 55003 \u2248 0.33 trillion particles in a box of 370 Mpc per side, ASTRID is one of the largest cosmological hydrodynamic simulations evolved to z = 0.”<\/p>\n z is a measure of the redshift of light. As the Universe expands, light sources like galaxies move further from us, and the light is more strongly stretched or redshifted. In terms of z, the Big Bang has a z of infinity, since it’s a singularity. The highest redshift we can observe is z ~ 1090, which marks the Epoch of Recombination<\/a> and the appearance of the cosmic microwave backround (CMB). This is when light, or photons, could travel freely through the cosmos. Prior to that, the Universe was opaque. So when the authors say ASTRID ran to z = 0, that’s the present day. <\/p>\n “Large-scale cosmological simulations are continually pushing computational frontiers to understand galaxy formation in a cosmological context,” the authors write. They mention simulations like IllustrisTNG<\/a>, Eagle<\/a>, and MassiveBlack-II<\/a>. <\/p>\n ASTRID isn’t the largest of its type of simulations. MillenniumTNG’s<\/a> flagship simulation covers about 740 Mpc per side compared to ASTRID’s 370 Mpc per side. That’s about eight times more volume. But ASTRID is larger than other simulations like TNG300, and is also powerful in another way: It has a much higher particle count than others, giving it greater resolution. <\/p>\n ASTRID also contains a significant population of black holes. “ASTRID features a large population of massive black holes (MBHs), covering a wide mass range 4 \u00d7 104 \u223c 2 \u00d7 1011 M\u2299,” the authors write. <\/p>\n Now, ASTRID’s results are available to the research community. <\/p>\n \u201cThe most important information about our recent study is that we\u2019ve evolved the ASTRID simulation to z = 0, and that this data is available,\u201d lead author Zhou said in a press release<\/a>. Zhou and his collaborators started their simulation at z = 99, beginning at the Universe’s Cosmic Dawn. <\/p>\n \u201cWe have this very large simulation and piece of the universe, which captures the growth of black holes from the time at which they were formed all the way to today, as well as the galaxies that form, also from a very early time,\u201d said study co-author Tiziana Di Matteo. Di Matteo is the ASTRID principal investigator, and professor of physics and director of CMU\u2019s McWilliams Center for Cosmology & Astrophysics.<\/p>\n So how will this large, high-resolution simulation address our questions about the Universe, especially the early Universe as revealed by the JWST, with its surprisingly massive black holes?<\/p>\n \u201cWe can look into the questions posed by JWST data using this very large volume of ASTRID simulations, with quite amazing resolution and physical realism, that allows us to make predictions and understand some of the current puzzles that are coming through,\u201d Di Matteo said.<\/p>\n \u201cWe care about black hole mergers because even if we don’t see the light or the accretion, we now have detectors that can see an event such as black hole mergers,\u201d Di Matteo explained. \u201cThe Laser Interferometer Space Antenna (LISA), which will be launched in 2035, will find most of the massive black hole mergers in the early Universe.\u201d<\/p>\n Every cosmological simulation has strengths and weaknesses. One of ASTRID’s strengths is dynamical friction models. The bring greater resolution to understanding how black holes slowly sink into galactic center, and when mergers occur. <\/p>\n \u201cOur simulations have realistic black hole merger orbits, and a better estimation of the black hole merger timescales,\u201d Di Matteo added.<\/p>\n This is where ASTRID dovetails nicely with gravitational waves<\/a> (GW). GW are like little ripples in spacetime, created when two massive objects like black holes merge. Einstein predicted GWs a century ago, but they were first observed only a decade ago. GW observations are important to understand the growth of black holes through mergers over cosmic time. <\/p>\n ASTRID can help in the study of GWs by showing the best places to look for them with future GW observatories like LISA<\/a>. <\/p>\n \u201cWith ASTRID, we make predictions for which environments would host gravitational wave sources that are most likely to be detected. In the future, people can use our predictions to discover gravitational sources,\u201d Zhou explained.<\/p>\n \u201cFor the first time, ASTRID allows us to capture this piece of the process where galaxies merge,\u201d Di Matteo said. ASTRID simulates black holes at the center of merging galaxies, which approach each other and spiral toward one another. \u201cEventually they merge, and they produce this gravitational wave signal that we can produce in the simulation, as if we are already, observing a gravitational wave signal.”<\/p>\n “ASTRID includes MBHs in a mass range spanning nearly 7 orders of magnitude, and records over 3 million MBH mergers, encompassing the GW sources targeted by LISA and PTA (Pulsar Timing Array) experiments,” the researchers write in their paper. <\/p>\n \u201cMassive black holes are the key to the structure of the universe, and I would say the most interesting part of our universe,\u201d Zhou said.<\/p>\n Astrophysicists are interested in black hole seeds, objects that grew into SMBH over time. The JWST’s Little Red Dots are candidate black hole seeds. <\/p>\n![\"This](\"https:\/\/www.newsbeep.com\/ca\/wp-content\/uploads\/2026\/09\/astrid-z05.png__1920x1920_subsampling-2_20260901_180754.jpg\"\/)
<\/a> This illustration shows ASTRID’s simulation at z=0.5. The background shows the cosmic web of size 250 Mpc\/h. The orange inset zooms into a massive cluster region, illustrating the gas density field colored by temperature. Red and yellow spikes mark massive black holes larger than 100 million solar masses. That threshold is important in cosmology. BH more massive than that are good tracers of large-scale structure. Yellow indicates BHs in high-accretion quasar mode, usually found in star-forming galaxies, while red indicates BHs in low-accretion jet mode, usually found in quiescent galaxies. The yellow and red insets show examples of the host galaxies. Credit: Zhou et al. 2026\/astrid.psc.edu<\/p>\n
![\"This](\"https:\/\/www.newsbeep.com\/ca\/wp-content\/uploads\/2026\/09\/250520439v3-2.jpg__1920x1920_q85_subsampling-2_20260901_184523.jpg\"\/)
<\/a> This figure shows a slice from ASTRID at z=5. It also shows false-colour Little Red Dots (LRD) from Astrid. The LRDs are another puzzling finding from the JWST, and may be the seeds of supermassive black holes. Image Credit: Zhou et al. 2026. ApJ<\/p>\n![\"ASTRID](\"https:\/\/www.newsbeep.com\/ca\/wp-content\/uploads\/2026\/09\/Astrid_Sum_20260901_192303.jpg\"\/)
<\/a> ASTRID zooms in from the large-scale structure of the Universe down to SMBH in galaxies and their mergers. It’s high-resolution lets it model processes in greater detail than other cosmological simulations. Image Credit: astrid.psc.edu<\/p>\n