Month: March 2023

by Rida Fatima

The final breath of a dying star before it was engulfed by a black hole was the light that traversed over 8.5 billion years before reaching the Earth.

(Figure 1: An example of a black hole damaging a star due to tides. (Carl Knox, OzGrav, Swinburne University of Technology’s ARC Center of Excellence for Gravitational Wave Discovery))

Two different groups of researchers came to the conclusion that AT2022cmc, a mystery glint in the darkness of space in February 2022, was the cosmological stream that blasted from the huge black hole as the shattered star fled outside its event horizon.

Since AT2022cmc is currently the farthest object we have observed, it is quite unusual that we witness one of such events in progress. The two publications were released in Nature and Nature Astronomy, respectively. Michael Coughlin, an astronomer at the University of Minnesota Twin Cities in the United States, said:

“The last time scientists discovered one of these jets was well over a decade ago. From the data we have, we can estimate that relativistic jets are launched in only 1 percent of these destructive events, making AT2022cmc an extremely rare occurrence. In fact, the luminous flash from the event is among the brightest ever observed.”

In our chaotic cosmos, there is a great deal of phenomena happening. Many of these occurrences and happenings, such as supernova explosions, rapid radio wave bursts, stars colliding, interplay between compact binaries, and black hole feeding frenzy, are unreliable, spewing out transient flashes of light that blaze across the the depths of space before dissipating.

We can only observe vast areas of the cosmos carefully in order to see the illumination from such enormous but fleeting astronomical phenomena.

(Figure 2: This graphic depicts how a star’s components descended into a faraway galaxy’s black hole, creating streams of debris and energy in the process. The incident, known as AT2022cmc, might be observed for the first time from Earth using an optical telescope since the jets are virtually aimed at us. Credit: M. Kornmesser/ESO)

In the previous year, a surveying telescope noticed an unexpected concentration of light waves and contacted the European Southern Observatory’s Very Large Telescope (ESO’s VLT). The VLT as well as additional telescopes were quickly oriented towards to the origin, which was a supermassive black hole in a far-off galaxy that had sucked up a star and ejected the remains in a jet. The VLT found that it was the farthest instance of a similar occurrence that had ever been seen. This additionally marks the first time the jet has been observed using visible light, opening up a new method of seeing these extreme events because the jet is virtually pointed directly at us.

A tidal disruption event (TDE) takes place when stars approach a black hole too closely and are shattered by the black hole’s powerful tidal forces. About 1% of such events result in the revolving black hole’s polarities ejecting plasma and energy in the form of jets. John Wheeler, a pioneer of black holes, presented the principle of jetted-TDEs as:

“A tube of toothpaste gripped tight about its middle, causing the system to squirt matter out of both ends.”

(Figure 3: This creator’s rendering shows what it would appear like when a star comes too close to a black hole and is crushed by its powerful gravitational attraction. The ring that is visible in this picture is formed when a portion of the star’s debris is drawn in and begins to spiral all around black hole. Streams of material and energy can occasionally be seen shooting out from the black hole’s edges, as in this instance. Several telescopes, including the VLT, observed signs of the streams in the instance of the AT2022cmc occurrence, and this was found to be the farthest instance of a similar incident. Credit: M. Kornmesser/ESO)

Nial Tanvir, who headed the investigations to gauge the entity’s proximity using the VLT, from the University of Leicester in the UK, elaborated:

“We have only seen a handful of these jetted-TDEs and they remain very exotic and poorly understood events”

To learn how the jets are truly formed and why only a limited percentage of TDEs generate them, researchers are therefore continually searching for such intense occurrences.

In order to fulfill this mission, numerous telescopes, like the Zwicky Transient Facility (ZTF) in the US, frequently scan the cosmos for indications of brief, frequently severe occurrences that might later be examined in considerable depth by other telescopes, like the ESO’s VLT in Chile. Igor Andreoni, an astronomer at the University of Maryland in the US, and Michael Coughlin, an astronomer at the University of Minnesota, co-led the research that was released recently in Nature. The researchers stated:

“We developed an open-source data pipeline to store and mine important information from the ZTF survey and alert us about atypical events in real time”

An unexpected origin of visible light was discovered by the ZTF in February last year. The incident, designated AT2022cmc, resembled a gamma-ray burst, the known universe’s most intense source of radiation. Researchers activated numerous telescopes from all over the world to look closer at the enigmatic object in anticipation of seeing this unusual occurrence. Within this was ESO’s VLT that swiftly used the X-shooter equipment to investigate this novel occurrence. The light emitted by AT2022cmc started its voyage when the universe was roughly one-third of its present age, according to the VLT measurements, which put the origin at an unheard-of distance for such occurrences.

The scientists analyzed this information with various known events, such as kilonovae and collapsing supernovae. However, the information merely supported the possibility of an unusual jetted-TDE heading in our direction. Co-author of this work and astronomer Giorgos Leloudas from DTU Space in Denmark says:

“Because the relativistic jet is pointing at us, it makes the event much brighter than it would otherwise appear, and visible over a broader span of the electromagnetic spectrum.”

AT2022cmc was revealed as the most remote TDE currently identified by the Wohl distance measurement, yet this is not the sole record-breaking feature of this entity. Co-author of the paper and astronomer at Liverpool John Moores University in the UK, Daniel Perley, states:

“Until now, the small number of jetted-TDEs that are known were initially detected using high energy gamma-ray and X-ray telescopes, but this was the first discovery of one during an optical survey”

This shows a novel method for identifying jetted-TDEs, enabling future research into such unusual occurrences and exploration of the harsh conditions near black holes.

References

1. Andreoni, I., Coughlin, M.W., Perley, D.A. et al. A very luminous jet from the disruption of a star by a massive black hole. Nature 612, 430–434 (2022). https://doi.org/10.1038/s41586-022-05465-8
2. Rees, M. J. Tidal disruption of stars by black holes of 10⁶–10⁸ solar masses in nearby galaxies. Nature 333, 523–528 (1988).

by Rida Fatima

(Figure 1: Asteroid moonlet Dimorphos as seen by the DART spacecraft 11 seconds before impact. DART’s DRACO imager captured this image from a distance of 42 miles (68 kilometers). This image was the last to contain all of Dimorphos in the field of view. Dimorphos)

Since asteroids preserve a history of our solar system’s past 4.6 billion years, many international researchers have dedicated their efforts to investigating them. Researchers can get knowledge about how our solar system developed into the Sun and planets we see today by studying asteroids, as well as how asteroid strikes can influence us in the long term.

A rock which descends to Earth from outer space is the fundamental definition of an asteroid. Although asteroids are rocks, they differ from rocks on Earth. The majority of these asteroids are far more ancient, and thus offer some of the sole specimens scientists possess of distant solar system bodies, including asteroids, meteors, as well as other planets. Even minuscule fragments that developed around different stars that originated before our Sun are found in certain asteroids.

Stardust, which is found in certain asteroids, was created by stars that existed before our own Solar System came into being. Research into such pre-solar particles can help us better grasp how stars begin and evolve. The earliest solidified substance to develop within our solar system can be found in some so-called “primitive” asteroids. The age of this substance, 4.568 billion years, has been used to calculate the age of our very own planetary system. Several ancient asteroids haven’t altered much at all since they were created, providing us with a glimpse into the ancient solar system’s environment.

Because organic substances like carbonyl compounds, complex amino acids, aliphatic amines, acetic acid, and formate could travel considerable distances within space debris, it is possible that asteroids carried the building blocks for life to Earth. Huge asteroids can cause massive extinction events and alter the trajectory of our existence on Earth. One such asteroid hit 65 million years ago and infamously wiped out the dinosaurs.

In a new research, a big, multinational team employed the UK’s national synchrotron facility, Diamond Light Source, to analyze particles retrieved from a near-Earth asteroid to increase our knowledge of the history of our planetary system.

(Figure 2: The asteroid Ryugu, as seen by Japan’s Hayabusa2 spacecraft on June 26, 2018. (Image credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST))

A specimen of fragments collected from the Ryugu asteroid was brought to Diamond’s Nanoprobe beamline I14 by scientists from the University of Leicester. There, a specialized method known as X-ray Absorption Near Edge Spectroscopy (XANES) was employed to plot the chemical states of the elements present inside the asteroid contents and investigate its constituents in considerable depth. The research group also analyzed the asteroid’s contents with the help of an electron microscope at Diamond’s electron Physical Science Imaging Centre (ePSIC).

Julia Parker is the Principal Beamline Scientist for I14 at Diamond. She said:

“The X-ray Nanoprobe allows scientists to examine the chemical structure of their samples at micron to nano length scales, which is complemented by the nano to atomic resolution of the imaging at ePSIC. It’s very exciting to be able to contribute to the understanding of these unique samples, and to work with the team at Leicester to demonstrate how the techniques at the beamline, and correlatively at ePSIC, can benefit future sample return missions.”

The information gathered at Diamond helped researchers better understand the asteroid’s signs of space weathering. The researchers were able to investigate how cosmic aging could change the morphological and molecular content of the surfaces of carbon containing asteroids like Ryugu thanks to the pure asteroid specimens.

The dehydration of Ryugu’s crust was observed by the researchers, and they concluded that space weathering is almost certainly to blame. According to the report’s results, which were just released in Nature Astronomy, asteroids that seem barren on the exterior might actually be water-rich, which could force us to revise current theories about the relative abundances of different sorts of asteroids and the origin of the asteroid belt.

Ryugu, a near-Earth asteroid with a diameter of about 900 meters, was found for the first time in the asteroid belt between Mars and Jupiter in 1999. It is called after the Japanese mythological underwater temple of the Dragon God. In order to interact with the Ryugu asteroid and gather mineral specimens from its exterior and interior, the Japanese state space agency JAXA deployed Hayabusa2 in 2014. In 2020, the spaceship made its way back to Earth and released a container carrying valuable asteroid pieces. These tiny specimens were dispersed to different laboratories worldwide for analytical investigation, such as the School of Physics & Astronomy at the University of Leicester and Space Park, where John Bridges, one of the paper’s writers and a professor of planetary science, works.

John stated:

“This unique mission to gather samples from the most primitive, carbonaceous, building blocks of the Solar System needs the world’s most detailed microscopy, and thats why JAXA and the Fine Grained Mineralogy team wanted us to analyse samples at Diamond’s X-ray nanoprobe beamline. We helped reveal the nature of space weathering on this asteroid with micrometeorite impacts and the solar wind creating dehydrated serpentine minerals, and an associated reduction from oxidised Fe3+ to more reduced Fe2+.

It’s important to build up experience in studying samples returned from asteroids, as in the Hayabusa2 mission, because soon there will be new samples from other asteroid types, the Moon and within the next 10 years Mars, returned to Earth. The UK community will be able to perform some of the critical analyses due to our facilities at Diamond and the electron microscopes at ePSIC.”

In the ancient Solar System, before Earth formed, water, rocks, and organic material interacted to generate the basic components of Ryugu. The formation of the initial solar system and the later formation of the Earth could both be better understood by comprehending the makeup of asteroids. Given that asteroids are thought to have brought most of the planet’s water as well as biochemical compounds like amino acids that serve as the basic components from which all human life is built, they also might aid in understanding how life on this planet first originated. We would be able to properly comprehend the history of life itself as a consequence of the data being gathered from such small asteroid fragments. A device that is 10,000 times stronger than a conventional microscope can be used by researchers at the synchrotron to examine their specimens, whether they are bits of asteroids or unidentified viral complexes.

References

1. Noguchi, T., Matsumoto, T., Miyake, A. A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu. Nat Astron, 2022 DOI: 10.1038/s41550-022-01841-6
2. Diamond Light Source. “Ancient asteroid grains provide insight into the evolution of our solar system.” ScienceDaily. ScienceDaily, 19 December 2022. .
3. https://en.prothomalo.com/science-technology/science/tryxskiue0

4. Arizona State University meteorites.asu.edu. Retrieved on 20 June 2018.
5. American Museum of Natural History amnh.org. Retrieved on 20 June 2018.
6. https://www.amnh.org/exhibitions/permanent/meteorites/meteorites/what-is-a-meteorite

by Rida Fatima

(Figure 1: The adjacent dwarf galaxy Leo I contains the second nearest SMBH. Credit: Scott Anttila Anttler.)

The nearest supermassive black hole (SMBH) to us is in the center of our Milky Way galaxy. The adjacent dwarf galaxy Leo I contains the second nearest SMBH. Roughly 820,000 light years, or about 30 times farther than the centre of the galaxy, separate Leo I from Earth. SMBHs are enormous objects, between 100,000 and ten billion times the mass of the Sun, but they are difficult to see. This year was the first that the one at the galactic core was imaged. In 2019, when Messier 87* was photographed, the first picture of an SMBH was captured. In 2021, the existence of the “Leo I*” supermassive black hole in the heart of Leo I was first hypothesized. Independent astronomers noted that as stars got closer to the dwarf galaxy’s centre, their orbits accelerated, which is a clear indication of a strong gravitational attraction. A SMBH is most likely to be the cause. (Pacucci et al., 2022).

The scientists calculated the acceleration of the stars as they are drawn into the SMBH’s gravitational field and estimated the black hole’s mass to be about three million times that of the Sun. Compared to the Sagittarius A* SMBH, which is four million times more massive than our Sun, this object is just somewhat smaller. It is now impossible to observe the black hole, which is a completely different thing than simply observing its gravitational effects.

A PROBABLE METHOD TO DETECT LEO I* IN FUTURE

(Fig 2: The ultra-faint Milky Way companion galaxy Leo I appears as a faint patch to the right of the bright star, Regulus. Credit: Scott Anttila Anttler.

The Astrophysical Journal Letters describes a novel approach developed by researchers at the Center for Astrophysics at the Harvard Smithsonian that tries to solve this issue. Lead researcher Dr. Fabio Pacucci claims that black holes are notoriously elusive objects and occasionally love playing hide-and-seek with us. The world surrounding them can be quite brilliant if enough material falls into their gravitational well, but light cannot escape from their event horizons. However, if a black hole is not accreting mass, it stops emitting light and is no longer visible to our telescopes (Pacucci et al., 2022).

Leo I* is difficult to see because of this. There is hardly any gas or other matter in its host dwarf galaxy, thus the black hole has nothing to accrete. It is said that the galaxy is a “fossil.” But according to the astronomers, there is still a chance of detecting the SMBH. According to Pacucci, “in our analysis, we proposed that a modest amount of mass lost from stars circling the black hole could give the accretion rate required to witness it.” “Old stars grow extremely large and crimson; we refer to them as red giant stars. Strong winds are generally present in red giants, which disperse a portion of their mass into the surrounding space. (Yazgin, 2022).

According to co-author Professor Avi Loeb, “observing Leo I* could be revolutionary.” With a very similar mass to the one at the heart of our galaxy, but being hosted by a galaxy that is a thousand times smaller than the Milky Way, it would be the second-closest supermassive black hole after that one. This discovery calls into question everything we’ve learned about how galaxies and the supermassive black holes at their centres co-evolve. How did a parent who was so thin wind up having a baby who was so big? The existence of a supermassive black hole at the heart of the majority of big galaxies has been thoroughly established in recent decades. However, the mass of the black hole is typically 0.1% of the combined mass of the stars that surround it. (Yazgin, 2022).

Loeb adds, “We would predict a significantly smaller black hole in the case of Leo I. Instead, Leo I seems to house a black hole similar to the Milky Way’s, with a mass a few million times that of the Sun. This is thrilling since unexpected events frequently result in the greatest achievements in science. We aren’t yet ready, according to the experts, to obtain a photograph of Leo I*. New data from the Very Large Array radio telescope in New Mexico and the Chandra X-ray Observatory space observatory are now being examined by the team.

Leo I* is probably playing hide and seek, but it produces too much radiation to go unnoticed for very long, according to Pacucci.

References

• Fabio Pacucci, Abraham Loeb. Accretion from Winds of Red Giant Branch Stars May Reveal the Supermassive Black Hole in Leo I. The Astrophysical Journal Letters, 2022; 940 (2): L33 DOI: 10.3847/2041-8213/ac9b21
• Yazgin, Evrim. “Hunt for Second Closest Supermassive Black Hole Begins.” Cosmos, Dec. 2022, cosmosmagazine.com/space/leo-supermassive-black-hole.