A Hidden Cosmic Collision: Astronomers Uncover the Missing Merger Companion and Dark Matter Bridge in the Perseus Cluster

Figure 1: Dark matter in the Perseus Cluster. The distribution of dark matter (in blue) is overlayed on an image taken by Hyper Sprime-Cam on the Subaru Telescope. The newly detected subcluster located near the galaxy NGC 1264 lies about 1.4 million light-years to the west (right side of the image) of Perseus’s central galaxy, NGC 1275. A faint bridge connects the two structures. An original image without text can be found here (1 MB). (Credit: HyeongHan et al.)

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An international team of astronomers has solved one of the longstanding cosmic mysteries by uncovering direct evidence of a massive, long-lost object that collided with the Perseus cluster. Using high-resolution data from the Subaru Telescope, the researchers successfully traced the remnant of this ancient merger through the dark matter distribution.

Galaxy clusters, composed of thousands of galaxies bound together by gravity, are among the most massive structures in the Universe. They grow through energetic mergers — some of the most powerful events since the Big Bang.

Located about 240 million light-years from Earth, the Perseus cluster has a mass equivalent to 600 trillion Suns (called solar masses). For decades, astronomers believed it had long since settled into a stable, post-merger state. Its apparent lack of clear merger signatures earned it the reputation of being the "textbook example" of a relaxed cluster. However, advances in observational techniques have allowed researchers to peer deeper into its structure, uncovering subtle yet compelling evidence of past disruption. This raised a fundamental mystery: if there are signs of a collision, where is the object that collided with it?

To solve the mystery, the team analyzed archival data from Hyper Suprime-Cam on the Subaru Telescope. Gravitational lensing—a phenomenon where massive objects bend the light from background galaxies—served as a powerful tool to map the invisible dark matter. Through this technique, the researchers identified a massive clump of dark matter, weighing approximately 200 trillion solar masses, located about 1.4 million light-years west of the cluster core (Figure 1). Remarkably, this structure is connected to the core of the Perseus cluster by a faint but statistically significant "dark matter bridge," providing direct evidence of past gravitational interaction between them.

Numerical simulations conducted by the team suggest that this dark matter substructure collided with the Perseus cluster roughly five billion years ago. The remnants of that collision still shape the present-day structure of the cluster.

"This is the missing piece we’ve been looking for," says Dr. James Jee, corresponding author of the study. "All the odd shapes and swirling gas observed in the Perseus cluster now make sense within the context of a major merger."

"It took courage to challenge the prevailing consensus, but the simulation results from our collaborators and recent observations from the Euclid and XRISM space telescopes strongly support our findings," continues Dr. HyeongHan Kim, the study’s first author.

"This breakthrough was made possible by combining deep imaging data from the Subaru Telescope with advanced gravitational lensing techniques we developed —demonstrating the power of lensing to unveil the hidden dynamics of the Universe’s most massive structures," says Dr. Jee.

These results appeared as HyeongHan et al. "Direct Evidence of a Major Merger in the Perseus Cluster" in Nature Astronomy on April 16, 2025.

Source: Subaru Telescope

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Relevant Links

• Yonsei University April 21, 2025 Press Release
• Cosmic Dark Matter Web Detected in Coma Cluster (Subaru Telescope February 7, 2024)

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About the Subaru Telescope

The Subaru Telescope is a large optical-infrared telescope operated by the National Astronomical Observatory of Japan, National Institutes of Natural Sciences with the support of the MEXT Project to Promote Large Scientific Frontiers. We are honored and grateful for the opportunity of observing the Universe from Maunakea, which has cultural, historical, and natural significance in Hawai`i.

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Teaming Up To Observe the Perseus Cluster

An X-ray image of the Perseus cluster taken by Hitomi, the precursor mission to XRISM. Image credit: NASA/CXC/SAO/E.Bulbul, et al. Download Image

During the past week, NuSTAR observed the Perseus Cluster, the brightest galaxy cluster in the sky in the X-rays, in coordination with the JAXA-NASA-ESA mission XRISM. Perseus is a calibration source for the wide-field Xtend imager on XRISM, but it also provides extremely valuable science for the primary XRISM instrument, Resolve. Resolve is the first high-spectral-resolution X-ray imaging spectrometer to fly an extended mission, replacing the similar instrument lost on the Hitomi mission. The XRISM science team has studied earlier observations of Perseus to try to resolve Doppler motions of the super-heated intra-cluster medium (ICM) gas, groundbreaking studies that will help us understand how these enormous galaxy clusters formed and evolved. However, the supermassive black hole at the center of the Perseus cluster also emits copious X-rays, which need to be disentangled from the ICM X-ray signal to properly isolate and measure the cluster gas motions. Simultaneous observations by NuSTAR are in a higher energy band than XRISM where the data is dominated by X-rays from the black hole. This will allow the XRISM calibration team to account for the contribution from the black hole in the XRISM observations, and precisely measure not only the gas motion but also the abundances of key elements and the temperature structure of the ICM. Since this is a calibration target observed twice a year by XRISM, a very deep total exposure will be obtained, and the vital collaboration with NuSTAR will enable a transformative view into the astrophysics of galaxy clusters.

Authors: Eric D. Miller (XRISM In-Flight Calibration Lead, MIT Kavli Institute for Astrophysics and Space Research)

Source:  NASA's Nuclear Spectroscopic Telescope Array (NuSTAR)/News

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Black Holes Can Cook for Themselves, Chandra Study Shows

Perseus Cluster & the Centaurus Cluster

Credit: Perseus Cluster: X-ray: NASA/CXC/SAO/V. Olivares et al.; Optical/IR: DSS; H-alpha: CFHT/SITELLE; Centaurus Cluster: X-ray: NASA/CXC/SAO/V. Olivaresi et al.; Optical/IR: NASA/ESA/STScI; H-alpha: ESO/VLT/MUSE; Image Processing: NASA/CXC/SAO/N. Wolk

JPEG (85.8 kb) - Tiff (76.2 MB) - More Images

A Tour of Black Holes Can Cook for Themselves - More Videos

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Astronomers have taken a crucial step in showing that the most massive black holes in the universe can create their own meals. Data from NASA’s Chandra X-ray Observatory and the Very Large Telescope (VLT) provide new evidence that outbursts from black holes can help cool down gas to feed themselves.

This study was based on observations of seven clusters of galaxies. The centers of galaxy clusters contain the universe’s most massive galaxies, which harbor huge black holes with masses ranging from millions to tens of billions of times that of the Sun. Jets from these black holes are driven by the black holes feasting on gas.

These images show two of the galaxy clusters in the study, the Perseus Cluster and the Centaurus Cluster. Chandra data represented in blue reveals X-rays from filaments of hot gas, and data from the VLT, an optical telescope in Chile, shows cooler filaments in red.

The results support a model where outbursts from the black holes trigger hot gas to cool and form narrow filaments of warm gas. Turbulence in the gas also plays an important role in this triggering process.

According to this model, some of the warm gas in these filaments should then flow into the centers of the galaxies to feed the black holes, causing an outburst. The outburst causes more gas to cool and feed the black holes, leading to further outbursts.

This model predicts there will be a relationship between the brightness of filaments of hot and warm gas in the centers of galaxy clusters. More specifically, in regions where the hot gas is brighter, the warm gas should also be brighter. The team of astronomers has, for the first time, discovered such a relationship, giving critical support for the model.

This result also provides new understanding of these gas-filled filaments, which are important not just for feeding black holes but also for causing new stars to form. This advance was made possible by an innovative technique that isolates the hot filaments in the Chandra X-ray data from other structures, including large cavities in the hot gas created by the black hole’s jets.

The newly found relationship for these filaments shows remarkable similarity to the one found in the tails of jellyfish galaxies, which have had gas stripped away from them as they travel through surrounding gas, forming long tails. This similarity reveals an unexpected cosmic connection between the two objects and implies a similar process is occurring in these objects.

This work was led by Valeria Olivares from the University of Santiago de Chile, and was published Monday in Nature Astronomy and is available online. The study brought together international experts in optical and X-ray observations and simulations from the United States, Chile, Australia, Canada, and Italy. The work relied on the capabilities of the MUSE (Multi Unit Spectroscopic Explorer) instrument on the VLT, which generates 3D views of the universe.

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.

Quick Look: Black Holes Can Cook for Themselves, Chandra Study Shows

Source: NASA's Chandra X-Ray Observatory

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Visual Description:

This release features composite images shown side-by-side of two different galaxy clusters, each with a central black hole surrounded by patches and filaments of gas. The galaxy clusters, known as Perseus and Centaurus, are two of seven galaxy clusters observed as part of an international study led by the University of Santiago de Chile.

In each image, a patch of purple with neon pink veins floats in the blackness of space, surrounded by flecks of light. At the center of each patch is a glowing, bright white dot. The bright white dots are black holes. The purple patches represent hot X-ray gas, and the neon pink veins represent filaments of warm gas. According to the model published in the study, jets from the black holes impact the hot X-ray gas. This gas cools into warm filaments, with some warm gas flowing back into the black hole. The return flow of warm gas causes jets to again cool the hot gas, triggering the cycle once again.

While the images of the two galaxy clusters are broadly similar, there are significant visual differences. In the image of the Perseus Cluster on the left, the surrounding flecks of light are larger and brighter, making the individual galaxies they represent easier to discern. Here, the purple gas has a blue tint, and the hot pink filaments appear solid, as if rendered with quivering strokes of a paintbrush. In the image of the Centaurus Cluster on the right, the purple gas appears softer, with a more diffuse quality. The filaments are rendered in more detail, with feathery edges, and gradation in color ranging from pale pink to neon red.

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Fast Facts for Perseus Cluster:

Credit: X-ray: NASA/CXC/SAO/V. Olivares et al.; Optical/IR: DSS; H-alpha: CFHT/SITELLE; Image Processing: NASA/CXC/SAO/N. Wolk
Scale: Image is about 6.4 arcmin (450,000 light-years) across.
Category: Groups and Clusters of Galaxies
Coordinates (J2000): RA 3h 19m 47.71 | Dec +41° 31´ 15.8"
Constellation: Perseus
Observation Dates: 29 observations between Sep 20, 1999 and Nov 7, 2016
Observation Time: 416 hours 45 minutes (17 days 8 hours 45 minutes)

Obs. ID: 428, 502, 503, 3209, 3404, 1513, 4289, 4946, 4947, 3939-4953, 6139, 6145, 6146, 11713-11716, 12025, 12033, 12036, 12037, 19568, 19913-19915

Instrument: ACIS
References: Olivares, V. et al. 2025, Nature Astronomy; arXiv:2501.01902
Color Code: X-ray: blue; Optical: red, green, blue; H-alpha: red
Distance Estimate: About 240 million light-years from Earth

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Fast Facts for Centaurus Cluster:

Credit: X-ray: NASA/CXC/SAO/V. Olivaresi et al.; Optical/IR: NASA/ESA/STScI; H-alpha: ESO/VLT/MUSE; Image Processing: NASA/CXC/SAO/N. Wolk
Scale: Image is about 1.4 arcmin (57,000 light-years) across.
Category: Groups and Clusters of Galaxies
Coordinates (J2000): RA 12h 48m 49.2s | Dec -41° 18´ 43.8"
Constellation: Centaurus
Observation Dates: 16 observations from May 22, 2000 to Jun 05, 2014
Observation Time: 240 hours 1 minute (10 days 1 minutes)
Obs. ID: 504 ,505 ,1560 ,4190, 4191, 4954, 4955 ,5310, 16223-16225 ,16534 ,16607-16610
Instrument: ACIS
References: Olivares, V. et al. 2025, Nature Astronomy; arXiv:2501.01902
Color Code: X-ray: blue; Optical/IR: red, green, blue; H-alpha: red
Distance Estimate: About 145 million light-years from Earth

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Gemini North Captures Galactic Archipelago Entangled In a Web Of Dark Matter

PR Image noirlab2426a
NGC 1270: A Galactic Archipelago

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Videos


PR Video noirlab2426a
Cosmoview Episode 88: Gemini North Captures Galactic Archipelago Entangled In a Web Of Dark Matter


PR Video noirlab2426b
Pan on NGC 1270


PR Video noirlab2426c
Zooming into NGC 1270


PR Video noirlab2426d
Cosmoview Episodio 88: Un archipiélago galáctico en un mar de materia oscura

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One century after astronomers proved the existence of galaxies beyond the Milky Way, enormous galaxy clusters are offering clues to today’s cosmic questions

10 years ago Edwin Hubble discovered decisive evidence that other galaxies existed far beyond the Milky Way. This image, captured by the Gemini North telescope, one half of the International Gemini Observatory, features a portion of the enormous Perseus Cluster, showcasing its ‘island Universes’ in awe-inspiring detail. Observations of these objects continue to shed light not only on their individual characteristics, but also on cosmic mysteries such as dark matter.

Among the many views of the Universe that modern telescopes offer, some of the most breathtaking are images like this. Dotted with countless galaxies — each one of incomprehensible size — they make apparent the tremendous scale and richness of the cosmos. Taking center stage here, beguiling in its seeming simplicity, the elliptical galaxy NGC 1270 radiates an ethereal glow into the surrounding darkness. And although it may seem like an island adrift in the deep ocean of space, this object is part of something much larger than itself.

NGC 1270 is just one member of the Perseus Cluster, a group of thousands of galaxies that lies around 240 million light-years from Earth in the constellation Perseus. This image, taken with the Gemini Multi-Object Spectrograph (GMOS) on the Gemini North telescope, one half of the International Gemini Observatory — supported in part by the U.S. National Science Foundation and operated by NSF NOIRLab — captures a dazzling collection of galaxies in the central region of this enormous cluster.

Looking at such a diverse array, shown here in spectacular clarity, it’s astonishing to think that when NGC 1270 was first discovered in 1863 it was not widely accepted that other galaxies even existed. Many of the objects that are now known to be galaxies were initially described as nebulae, owing to their cloudy, amorphous appearance. The idea that they are entities of a similar size to our own Milky Way, or ‘island Universes’ as Immanuel Kant called them, was speculated on by several astronomers throughout history, but was not proven. Instead, many thought they were smaller objects on the outskirts of the Milky Way, which many believed to comprise most or all of the Universe.

The nature of these mysterious objects and the size of the Universe were the subjects of astronomy’s famous Great Debate, held in 1920 between astronomers Heber Curtis and Harlow Shapley. The debate remained unsettled until 1924 when Edwin Hubble, using the Hooker Telescope at Mount Wilson Observatory, observed stars within some of the nebulae to calculate how far they were from Earth. The results were decisive; they were far beyond the Milky Way. Astronomers’ notion of the cosmos underwent a dramatic shift, now populated with innumerable strange, far-off galaxies as large and complex as our own.

As imaging techniques have improved, piercing ever more deeply into space, astronomers have been able to look closer and closer at these ‘island Universes’ to deduce what they might be like. For instance, researchers have observed powerful electromagnetic energy emanating from the heart of NGC 1270, suggesting that it harbors a frantically feeding supermassive black hole. This characteristic is seen in around 10% of galaxies and is detectable via the presence of an accretion disk — an intense vortex of matter swirling around and gradually being devoured by the central black hole.

It’s not only the individual galaxies that astronomers are interested in; hints at many ongoing mysteries lie in their relationship to and interactions with one another. For example, the fact that huge groups like the Perseus Cluster exist at all points to the presence of the enigmatic substance we call dark matter [1]. If there were no such invisible, gravitationally interactive material, then astronomers believe galaxies would be spread more or less evenly across space rather than collecting into densely populated clusters. Current theories suggest that an invisible web of dark matter draws galaxies together at the intersections between its colossal tendrils, where its gravitational pull is strongest.

Although dark matter is invoked to explain observed cosmic structures, the nature of the substance itself remains elusive. As we look at images like this one, and consider the strides made in our understanding over the past century, we can sense a tantalizing hint of just how much more might be discovered in the decades to come. Perhaps hidden in images like this are clues to the next big breakthrough. How much more will we know about our Universe in another century?

Source: NSF’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab)/News

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Notes

[1] The discovery of dark matter in galaxies is in-part attributed to American astronomer Vera C. Rubin, who used the rotation of galaxies to infer the presence of an invisible, yet gravitationally interactive, material holding them together. She is also the name inspiration for NSF–DOE Vera C. Rubin Observatory, currently under construction in Chile, which will begin operations in 2025.

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More information

NSF NOIRLab (U.S. National Science Foundation National Optical-Infrared Astronomy Research Laboratory), the U.S. center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and Vera C. Rubin Observatory (operated in cooperation with the Department of Energy’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O’odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.

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Links

• Photos of Gemini North
• Videos of Gemini North
• Check out other NOIRLab Photo Releases

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Contacts:

Josie Fenske
Jr. Public Information Officer
NSF NOIRLab
Email: josie.fenske@noirlab.edu

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Rings and things Rings and things

MCG+07-07-072

A glowing bar stretching across its core; from the ends of the bar, thin spiral arms wrap around the galaxy to form a closed disc. The arms are fuzzy from the dust and stars they contain. The galaxy is on a black, mostly-empty background. A few foreground stars with cross-shaped diffraction spikes can be seen, as well as some distant galaxies in the background. Credit: ESA/Hubble & NASA, I. Chilingarian

The subject of this week’s circular Hubble Picture of the Week is situated in the Perseus Cluster, also known as Abell 426, 320 million light-years from Earth. It’s a barred spiral galaxy known as MCG+07-07-072, seen here among a number of photobombing stars that are much closer to Earth than it is.

MCG+07-07-072 has quite an unusual shape, for a spiral galaxy, with thin arms emerging from the ends of its barred core to draw a near-circle around its disc. It is classified, using a common extension of the basic Hubble scheme, as an SBc(r) galaxy: the c denotes that its two spiral arms are loosely wound, each only performing a half-turn around the galaxy, and the (r) is for the ring-like structure they create. Rings in galaxies come in quite a few forms, from merely uncommon, to rare and astrophysically important!

Lenticular galaxies are a type that sit between elliptical and spiral galaxies. They feature a large disc, unlike an elliptical galaxy, but lack any spiral arms. Lenticular means lens-shaped, and these galaxies often feature ring-like shapes in their discs. Meanwhile, the classification of “ring galaxy” is reserved for peculiar galaxies with a round ring of gas and star formation, much like spiral arms look, but completely disconnected from the galactic nucleus - or even without any visible nucleus! They’re thought to be formed in galactic collisions. Finally, there are the famous gravitational lenses, where the ring is in fact a distorted image of a distant, background galaxy, formed by the ‘lens’ galaxy bending light around it. Ring-shaped images, called Einstein rings, only form when the lensing and imaged galaxies are perfectly aligned.

Source: ESA/Hubble/potw

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New NASA Black Hole Sonifications with a Remix

Credit: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)

Black Hole at the Center of the Perseus Galaxy Cluster (above)

Since 2003, the black hole at the center of the Perseus galaxy cluster has been associated with sound. This is because astronomers discovered that pressure waves sent out by the black hole caused ripples in the cluster's hot gas that could be translated into a note — one that humans cannot hear some 57 octaves below middle C. Now a new sonification brings more notes to this black hole sound machine. This new sonification — that is, the translation of astronomical data into sound — is being released for NASA's Black Hole Week this year.

In some ways, this sonification is unlike any other done before (1, 2, 3, 4) because it revisits the actual sound waves discovered in data from NASA's Chandra X-ray Observatory. The popular misconception that there is no sound in space originates with the fact that most of space is essentially a vacuum, providing no medium for sound waves to propagate through. A galaxy cluster, on the other hand, has copious amounts of gas that envelop the hundreds or even thousands of galaxies within it, providing a medium for the sound waves to travel.

In this new sonification of Perseus, the sound waves astronomers previously identified were extracted and made audible for the first time. The sound waves were extracted in radial directions, that is, outwards from the center. The signals were then resynthesized into the range of human hearing by scaling them upward by 57 and 58 octaves above their true pitch. Another way to put this is that they are being heard 144 quadrillion and 288 quadrillion times higher than their original frequency. (A quadrillion is 1,000,000,000,000,000.) The radar-like scan around the image allows you to hear waves emitted in different directions. In the visual image of these data, blue and purple both show X-ray data captured by Chandra.

Black Hole at the Center of Galaxy M87:

In addition to the Perseus galaxy cluster, a new sonification of another famous black hole is being released. Studied by scientists for decades, the black hole in Messier 87, or M87, gained celebrity status in science after the first release from the Event Horizon Telescope (EHT) project in 2019. This new sonification does not feature the EHT data, but rather looks at data from other telescopes that observed M87 on much wider scales at roughly the same time. The image in visual form contains three panels that are, from top to bottom, X-rays from Chandra, optical light from NASA's Hubble Space Telescope, and radio waves from the Atacama Large Millimeter Array in Chile. The brightest region on the left of the image is where the black hole is found, and the structure to the upper right is a jet produced by the black hole. The jet is produced by material falling onto the black hole. The sonification scans across the three-tiered image from left to right, with each wavelength mapped to a different range of audible tones. Radio waves are mapped to the lowest tones, optical data to medium tones, and X-rays detected by Chandra to the highest tones. The brightest part of the image corresponds to the loudest portion of the sonification, which is where astronomers find the 6.5-billion solar mass black hole that EHT imaged.

More sonifications of astronomical data, as well as additional information on the process, can be found at the "A Universe of Sound" website: https://chandra.si.edu/sound/

These sonifications were led by the Chandra X-ray Center (CXC) and included as part of NASA's Universe of Learning (UoL) program with additional support from NASA's Hubble Space Telescope/Goddard Space Flight Center. The collaboration was driven by visualization scientist Kimberly Arcand (CXC), astrophysicist Matt Russo, and musician Andrew Santaguida (both of the SYSTEMS Sound project). NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science from Cambridge Massachusetts and flight operations from Burlington, Massachusetts. NASA's Universe of Learning materials are based upon work supported by NASA under cooperative agreement award number NNX16AC65A to the Space Telescope Science Institute, working in partnership with Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and the Jet Propulsion Laboratory.

JPEG (232.7 kb) - Large JPEG (1.2 MB) -Tiff (9.6 MB) - More Images

A Tour of TBD - More Animations

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Fast Facts for Perseus Cluster:

Credit X-ray: NASA/CXC/Univ. of Cambridge/C. Reynolds et al.; Sonification: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)

About the Sound:

• This is more than a data sonification, it's actually a re-sonification of a real sound wave
• Researchers identified literal sound waves in earlier images of this cluster (the lowest pitches ever found), we have extracted them and made them audible for the first time
• Waves propagating along each radial direction (and any periodic features) are extracted from the image, sweeping around 360 degrees
• Signals are resynthesized after scaling by 57 and 58 octaves above their true pitch, 144 and 288 quadrillion (million billion) times their true frequency, or about 7 piano-lengths
• The true pitch of the sound waves generated by the black hole is Bb, just over 57 octaves below middle C
• Waves were extracted from blue image here and here
• Purple image used for visualization (radar plus audio spectra)
• Sound contains the actual waves plus some signals from other large scale density fluctuations (such as cavities)

Scale: Image is about 8 arcmin (550,000 light years) across
Category: Groups & Clusters of Galaxies, Black Holes
Coordinates (J2000): RA 03h 19m 47.60s | Dec +41° 30´ 37.00"
Constellation: Perseus
Observation Date: 25 pointings between Sep 1999 and Dec 2009
Observation Time: 416 hours 37 minutes (17 days 8 hours 37 minutes)

Obs. ID: 502, 503, 1513, 3209, 3404, 4289, 4946-4953, 6139, 6145, 6146, 11713-11716, 12025, 12033, 12036, 12037

Instrument: ACIS
Color Code: X-ray: red = 0.5-1.2 keV, green = 1.2-2.0 keV, blue = 2.0-7.0 keV
Distance Estimate: About 240 million light years

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Fast Facts for M87:

Credit X-ray (Chandra): NASA/CXC/SAO; Optical (Hubble): NASA/ESA/STScI; Radio (ALMA): ESO/NAOJ/NRAO; Sonification: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)

About the Sound:

• Left to right scan in which brightness controls volume
• The vertical position controls pitch
• Each wavelength is mapped to notes in a different pitch range
• Radio/optical/x-ray are mapped to low/med/high ranges (Following the ordering of their frequencies of light)
• Radio (ALMA) is played on a brass-like synth
• Optical (HST) is played on a breathy synth (sustained for diffuse gas, plucked for point-like star clusters)
• X-ray (Chandra) is played on string-like synth
• The most intense parts of the core and jet that appear white are also heard as pitch-filtered noise

Listening notes:

• the core near the BH is the brightest/loudest
• rising jet with gaps and clumps can be heard as rising pitch with volume fluctuations
• Glow in HST due to billions of unresolved stars produces sustained chord

Scale: The X-ray image is about 32 arcmin (8,500 light years) across
Category: Black Holes, Quasars & Active Galaxies
Coordinates (J2000): RA 12h 30m 49.40s | Dec +12° 23´ 28.00"
Constellation: Virgo
Observation Date: April 11, 2017 and April 14, 2017
Observation Time: 7 hours 17 minutes
Obs. ID: 20034, 20035
Instrument: ACIS
Color Code: Intensity
Distance Estimate: About 55 million light years

Source: NASA's Chandra X-Ray Observatory

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Cold Horseshoes in Fast

Composite image of the active galaxy NGC 1275, which lies at the center of the Perseus cluster. Credits: [X-ray: NASA/CXC/IoA/A.Fabian et al.; Radio: NRAO/VLA/G. Taylor; Optical: NASA/ESA/Hubble Heritage (STScI/AURA) & Univ. of Cambridge/IoA/A. Fabian

In this annotated image of NGC 1275, outlines and insets identify two filamentary structures: the blue loop (dotted outline and bottom left inset) and the horseshoe filament (dashed outline and top right inset). These two strikingly shaped filaments may both have been created during the same outburst. Annotations: Yu Qiu

The dynamic environments around active galaxies often exhibit delicate filaments of cold gas. In a new study, scientists have explored how these fragile structures are able to form and survive within their hot, fast-moving surroundings.

Curious Structures

The Perseus cluster, located more than 200 million light-years away, is a collection of thousands of galaxies embedded in a cloud of hot gas. At the cluster’s heart lies NGC 1275, an active galaxy that’s rapidly forming stars and contains an accreting supermassive black hole — two factors that result in outbursts of hot, fast outflows that are spewed into the intracluster medium.

In the midst of all this action, there’s a conundrum: we also see cold, outflowing gas that forms slender, elongated filamentary structures extending tens of thousands of light-years. Where does this cold gas come from, and how is it not heated or destroyed by the fast, hot outflows of the active galaxy?

Sweeping Up Old or Forming New?

Two explanations have been proposed for these cold outflows:

1. The hot winds flowing from the active galaxy sweep up existing cold gas and carry it along, drawing it out into filaments. This idea has a challenge: long before the cold gas manages to reach the speeds we observe — more than 100 km/s! — it would likely be destroyed by shocks, preventing the formation of filaments

2. The cold gas forms within the hot outflows as these winds slow, cool, and fragment into filaments. This idea shows promise! In a new study, a team of scientists led by Yu Qiu (邱宇; Peking University, China) has explored this possibility further using a set of detailed simulations of an outbursting active galaxy

The shape and speed of cold gas that forms within the outflows in two of the authors’ simulations (top and bottom) at three different times (left, middle, and right). The two simulations, which had different starting conditions, produce very different shapes of filaments: the top is long and threadlike, whereas the bottom is a perpendicular ring structure. Credits: Qiu et al. 2021, Hi-res image

Threads, Loops, and Horseshoes

Qiu and collaborators’ 3D hydrodynamic simulations model a hot, radial outflow erupting from the center of a cluster similar to Perseus. From these simulations, the authors show how gravity and pressure from the surroundings cause the hot outflow to slow and cool. They confirm that this process eventually leads to fragmentation, forming filaments of cold gas that move at high speeds consistent with what we observe.

One especially interesting result of the authors’ work: the shapes of the resulting filaments depend strongly on the starting conditions of the outflow. This could explain some particularly striking shapes that we observe in Perseus — there are not only radial threads, but also a loop and a horseshoe at opposite sides of the central galaxy.

The authors show that a bipolar outburst with specific physical conditions can create two perpendicular rings of cold gas instead of long filaments — which could easily reproduce the loop and horseshoe we see in Perseus.

Qiu and collaborators demonstrate how we can use the morphology and locations of the filaments to probe the history of the active galaxy’s outbursts, inferring their energetics and properties. Further study of these delicate threads, loops, and horseshoes is sure to provide a wealth of new information about distant, active galaxies and clusters.

Citation

“Dynamics and Morphology of Cold Gas in Fast, Radiatively Cooling Outflows: Constraining AGN Energetics with Horseshoes,” Yu Qiu et al 2021 ApJL 917 L7. doi:10.3847/2041-8213/ac16d9

Source:  American Astronomical Society (AAS/Nova)

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Galaxies in the Perseus Cluster

NGC 1275, NGC 1265 and IC 310

Credit: M. Gendron-Marsolais et al.; S. Dagnello, NRAO/AUI/NSF; Sloan Digital Sky Survey.
Hi-res image

The giant galaxy NGC 1275, at the core of the cluster, is seen in new detail, including a newly-revealed wealth of complex, filamentary structure in its radio lobes. Credit: CREDIT: M. Gendron-Marsolais et al.; S. Dagnello, NRAO/AUI/NSF; Sloan Digital Sky Survey. Hi-res image

The galaxy NGC 1265 shows the effects of its motion through the tenuous material between the galaxies. Its radio jets are bent backward by that interaction, then merge into a single, broad "tail." The tail then is further bent, possibly by motions within the intergalactic material. Credit:  M. Gendron-Marsolais et al.; S. Dagnello, NRAO/AUI/NSF; Sloan Digital Sky Survey. Hi-res image

The jets of the galaxy IC 310 are bent backward, similarly to NGC 1265, but appear closer because of the viewing angle from Earth. That angle also allows astronomers to directly observe energetic gamma rays generated near the supermassive black hole at the galaxy's core. Credit: M. Gendron-Marsolais et al.; S. Dagnello, NRAO/AUI/NSF; SDSS. Hi-res image

 

For galaxies, as for people, living in a crowd is different from living alone. Recently, astronomers used the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) to learn how a crowded environment affects galaxies in the Perseus Cluster, a collection of thousands of galaxies some 240 million light-years from Earth.

Left: The giant galaxy NGC 1275, at the core of the cluster, is seen in new detail, including a newly-revealed wealth of complex, filamentary structure in its radio lobes.

Center: The galaxy NGC 1265 shows the effects of its motion through the tenuous material between the galaxies. Its radio jets are bent backward by that interaction, then merge into a single, broad “tail.” The tail then is further bent, possibly by motions within the intergalactic material.

Right: The jets of the galaxy IC 310 are bent backward, similarly to NGC 1265, but appear closer because of the viewing angle from Earth. That angle also allows astronomers to directly observe energetic gamma rays generated near the supermassive black hole at the galaxy’s core.

Such images can help astronomers better understand the complex environment of galaxy clusters, which are the largest gravitationally-bound structures in the universe, and which harbor a variety of still poorly-understood phenomena.

“These images show us previously-unseen structures and details and that helps our effort to determine the nature of these objects,” said Marie-Lou Gendron-Marsolais, an ESO/ALMA Fellow in Santiago, Chile. She and a number of international collaborators are announcing their results in the Monthly Notices of the Royal Astronomical Society.

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Source: National Radio Astronomy Observatory (NRAO)/News

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Abell 2384: Bending the Bridge Between Two Galaxy Clusters

Abell 2384
Credit: X-ray: NASA/CXC/SAO/V.Parekh, et al. & ESA/XMM-Newton; Radio: NCRA/GMRT

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A Tour of Abell 2384 - More Animations

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Several hundred million years ago, two galaxy clusters collided and then passed through each other. This mighty event released a flood of hot gas from each galaxy cluster that formed an unusual bridge between the two objects. This bridge is now being pummeled by particles driven away from a supermassive black hole.

Galaxy clusters are the largest objects in the universe held together by gravity. They contain hundreds or thousands of galaxies, vast amounts of multi-million-degree gas that glow in X-rays, and enormous reservoirs of unseen dark matter.

The system known as Abell 2384 shows the giant structures that can result when two galaxy clusters collide. A superheated gas bridge in Abell 2384 is shown in this composite image of X-rays from NASA's Chandra X-ray Observatory and ESA's XMM-Newton (blue), as well as the Giant Metrewave Radio Telescope in India (red). This new multi-wavelength view reveals the effects of a jet shooting away from a supermassive black hole in the center of a galaxy in one of the clusters. The jet is so powerful that it is bending the shape of the gas bridge, which extends for over 3 million light years and has the mass of about 6 trillion Suns.

Abell 2384
Credit: Radio Image, Labeled (Credit: NASA/CXC/NCRA/GMRT)

A labeled version of the image traces the shape of the bridge, marks the position of the supermassive black hole, and shows where the jet is pushing the hot gas in the bridge sideways at the collision site. The lobe of radio emission marking the end of each jet is also shown. At the collision site, astronomers found evidence for a shock front, similar to a sonic boom from a supersonic aircraft, which can keep the gas hot and prevent it from cooling to form new stars.

The radio emission extends about 1.2 million light years from the black hole to the north and about 1.7 million light years to the south. The northern radio emission is also fainter than the southern emission. These differences might be explained by the radio emission to the north being slowed down by the jet's impact with the hot gas in the bridge.

Chandra has often observed cavities in hot gas created by jets in the centers of galaxy clusters, such as the Perseus cluster, MS 0735 and the Ophiuchus Cluster. However, Abell 2384 offers a rare case of such an interaction occurring in the outer region of a cluster. It is also unusual that the supermassive black hole driving the jet is not in the largest galaxy located in the center of the cluster.

Astronomers consider objects like Abell 2384 to be important for understanding the growth of galaxy clusters. Based on computer simulations, it has been shown that after a collision between two galaxy clusters, they oscillate like a pendulum and pass through each other several times before merging to form a larger cluster. Based on these simulations, astronomers think that the two clusters in Abell 2384 will eventually merge.

Abell 2384 is located 1.2 billion light years from Earth. Based on previous work, scientists estimate the total mass of Abell 2384 is 260 trillion times the mass of the Sun. This includes the dark matter, hot gas and the individual galaxies.

A paper describing this work was published in the January 2020 issue of the Monthly Notices of the Royal Astronomical Society, and is available online. The authors are Viral Parekh (South African Radio Astronomy Observatory and Rhodes University, South Africa); Tatiana Lagana (Universidade Cruzeiro do Sul/Universidade Cidade de São Paulo, Brazil); Kshitij Thorat (Rhodes University); Kurt van der Heyden (University of Cape Town, South Africa); Asif Iqbal Ahanger (Raman Research Institute, India); and Florence Durret (Institut d'Astrophysique de Paris and Sorbonne Université, France).

NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science and flight operations from Cambridge and Burlington, bf9000 Massachusetts.

A Quick Look at Bending the Bridge Between Two Galaxy Clusters

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Fast Facts for Abell 2384:

Scale: Image is about 50 arcmin (17 million light years) across.
Category: Groups & Clusters of Galaxies
Coordinates (J2000): RA 21h 52m 18.9s | Dec -19° 34´ 42"
Constellation: Capricornus
Observation Date: November 18, 2002
Observation Time: 8 hours 4 min
Obs. ID: 4202
Instrument: ACIS
References: Parekh et al., 2020, MNRAS, 491, 2605. arXiv:1910.12955
Color Code: X-ray: Blue/white; Radio: Magenta; Optical: yellow
Distance Estimate: About 1.2 billion light years (z=0.0943)

Source: NASA's Chandra X-ray Observatory

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Chandra Data Tests "Theory of Everything"

Perseus Cluster

Credit: NASA/CXC/Univ. of Cambridge/C. Reynolds et al.

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A Tour of Chandra Data Tests "Theory of Everything" - More Animations 

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Astronomers using NASA's Chandra X-ray Observatory have made one of the first experimental tests of string theory, a set of models intended to tie together all known forces, particles, and interactions. As described in our latest press release, researchers used Chandra to look for signs of an as-yet undetected particle predicted by string theory. The lack of a detection in these Chandra observations helps rule out some versions of string theory.

The team looked for extraordinarily low-mass "axion-like" particles in the Perseus galaxy cluster, shown in a Chandra image in the main panel of this graphic (red, green and blue colors are low, medium and high X-ray energies respectively). Galaxy clusters, the largest structures in the Universe held together by gravity, offer an excellent opportunity to search for these particles. In a galaxy cluster, X-ray photons from an embedded or a background source can travel through a large amount of hot gas permeated with magnetic field lines. Some of the X-ray photons may undergo conversion into axion-like particles, or the other way around, along this journey. A simplified illustration shows this process, with shorter wavelength X-ray photons (in blue) converting into axion-like particles (yellow) and back to photons, as they travel across magnetic field lines (grey) in the cluster. Longer wavelength X-ray photons (red) are converting into axion-like particles, but not back into photons. Such conversions would cause a distortion in the X-ray spectrum (the amount of X-rays at different energies) of a bright or embedded source of X-rays.

Photon/Particle Illustration

Credit: Amanda Smith/Institute of Astronomy/University of Cambridge 

Astronomers obtained a long Chandra observation, lasting over five days, of the central supermassive black hole in the center of the Perseus galaxy cluster (shown in the inset.) The spectrum of the region around the black hole showed no distortions, allowing the team to rule out the presence of most types of axion-like particles in the relatively low mass range their search was sensitive to.

Here the Chandra spectrum (red) of Perseus' central black hole shows the intensity of X-rays as a function of X-ray energy, along with an example (black) of a model X-ray spectrum predicted if axion-like particles were actually being converted from and into photons. To highlight the distortions that could have been detected, the data divided by the example model are also shown.

Chandra Spectrum

Credit: NASA/CXC/Univ. of Cambridge/C. Reynolds et al. 

One possible interpretation of this work is that axion-like particles do not exist. Another possible interpretation is that the particles undergo conversion from and into photons less easily than some particle physicists have expected. They also could have higher masses than probed with the Chandra data.

There has been a surge of interest in studies of these particles in recent years for three reasons: First, despite a lot of work, there continues to be no detection of Weakly Interacting Massive Particles (WIMPs), either with gamma-ray observations, or earth-based experiments that could explain the nature of dark matter. These particles are predicted to interact with normal matter only via the weak force, and have been considered to be one of the strongest candidates for dark matter. Secondly, scientists have realized that axions and axion-like particles are predicted by string theory. Finally, there are a large number of experiments or observations that can be done to search for these particles.

A paper describing these results appeared in the February 10th, 2020 issue of The Astrophysical Journal and is available online. The authors are Christopher Reynolds (University of Cambridge, UK), David Marsh (Stockholm University, Sweden), Helen Russell (University of Nottingham, UK), Andrew C. Fabian (University of Cambridge), Robyn Smith (University of Maryland in College Park, Francesco Tombesi (University of Rome, Italy), and Sylvain Veilleux (University of Maryland).

NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science and flight operations from Cambridge and Burlington, Massachusetts.

A Quick Look at Chandra Data Tests "Theory of Everything"

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Fast Facts for Perseus Cluster:


Scale: Main image is about 8 arcmin (550,000 light years) across. Inset image is about 11 arcsec (13,000 light years) across.
Category: Groups & Clusters of Galaxies, Black Holes
Coordinates (J2000): RA 03h 19m 47.60s | Dec +41° 30´ 37.00"
Constellation: Perseus

Observation Date: Main image: 25 pointings between Sep 1999 and Dec 2009; Inset: 15 pointings between Jun 2017 and Dec 2017

Observation Time: Main Image: 17 days 8 hours 37 minutes; Inset: 5 days 16 hours 30 minutes

Obs. ID: Main Image: 502, 503, 1513, 3209, 3404, 4289, 4946-4953, 6139, 6145, 6146, 11713-11716, 12025, 12033, 12036, 12037; Inset: 20449-20451, 20823-20827, 20837-20844

Instrument: ACIS
Also Known As: Abell 426
References: Reynolds, C.S., et. al., 2020, ApJ, 890, 59; arXiv:1907.05475
Color Code: Red = 0.5-1.2 keV, Green = 1.2-2.0 keV, Blue = 2.0-7.0 keV
Distance Estimate: About 240 million light years

Source: NASA’s Chandra X-ray Observatory

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Perseus Cluster: Scientists Surprised by Relentless Cosmic Cold Front

Perseus Cluster

Credit NASA/CXC/GSFC/S. Walker, ESA/XMM, ROSAT

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A Tour of the cold front in Perseus - More Animations

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A gigantic and resilient "cold front" hurtling through the Perseus galaxy cluster has been studied using data from NASA's Chandra X-ray Observatory. This cosmic weather system spans about two million light years and has been traveling for over 5 billion years, longer than the existence of our Solar System.

This graphic shows the cold front in the Perseus cluster. The image above contains X-ray data from Chandra — for regions close to the center of the cluster —along with data from ESA's XMM-Newton and the now-defunct German Roentgen (ROSAT) satellite for regions farther out. The Chandra data have been specially processed to brighten the contrast of edges to make subtle details more obvious.

The cold front is the long vertical structure on the left side of the image (rollover the image above to view labels). It is about two million light years long and has traveled away from the center of the cluster at about 300,000 miles per hour.

The inset below shows a close-up view of the cold front from Chandra. This image is a temperature map, where blue represents relatively cooler regions (30 million degrees) while the red is where the hotter regions (80 million degrees) are.

Close-up view of the cold front; 

Credit: NASA/CXC/GSFC/S.Walker, ESA/XMM, ESA/ROSAT

The cold front has not only survived for over a third of the age of the Universe, but it has also remained surprisingly sharp and split into two different pieces. Astronomers expected that such an old cold front would have been blurred out or eroded over time because it has traveled for billions of years through a harsh environment of sound waves and turbulence caused by outbursts from the huge black hole at the center of Perseus.

Instead, the sharpness of the Perseus cold front suggests that the structure has been preserved by strong magnetic fields that are wrapped around it. The comparison of the Chandra X-ray data to theoretical models also gives scientists an indication of the strength of the cold front's magnetic field for the first time.

Perseus Cluster Temperature Animation (Labeled)
Credit: John ZuHone

While cold fronts in the Earth's atmospheres are driven by rotation of the planet, those in the atmospheres of galaxy clusters like Perseus are caused by collisions between the cluster and other clusters of galaxies. These collisions typically occur as the gravity of the main cluster pulls the smaller cluster inward towards its central core. As the smaller cluster makes a close pass by the central core, the gravitational attraction between both structures causes the gas in the core to slosh around like wine swirled in a glass. The sloshing produces a spiral pattern of cold fronts moving outward through the cluster gas.

Aurora Simionescu and collaborators originally discovered the Perseus cold front in 2012 using data from ROSAT (the ROentgen SATellite), ESA's XMM-Newton Observatory, and Japan's Suzaku X-ray satellite. Chandra's high-resolution X-ray vision allowed this more detailed work on the cold front to be performed.

The results of this work appear in a paper that will be published in the April issue of Nature Astronomy and is available online. The authors of the paper are Stephen Walker (Goddard Space Flight Center), John ZuHone (Harvard-Smithsonian Center for Astrophysics), Jeremy Sanders (Max Planck Institute for Extraterrestrial Physics), and Andrew Fabian (Institute of Astronomy, Cambridge, England.)

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

A Quick Look at the Cold Front in the Perseus Cluster

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Fast Facts for Perseus Cluster:


Scale: Image is about 42 arcmin (about 3 million light years) across.
Category: Groups & Clusters of Galaxies, Cosmology/Deep Fields/X-ray Background
Coordinates (J2000): RA 03h 19m 47.60s | Dec +41° 30´ 37.00"
Constellation: Perseus
Observation Date: Nov 13, 2016
Observation Time: 25 hours 50 min (1 day 1 hour 60 minutes)
Obs. ID: 19565, 19938
Instrument: ACIS
Also Known As: Abell 426
References: S. Walker et al., 2018, Nature Astronomy, arXiv:1803.00898
Color Code: X-ray (intensity)
Distance Estimate: About 250 million light years

Source: NASA’s Chandra X-ray Observatory