Blackhole and its companion star make up a system called MAXI J1820+070. It is a stellar-mass black hole. The companion star orbiting the black hole has about half the mass of the sun.
Location - Milky Way
10,000 light-years from Earth in the direction of the constellation Leo
Mass about eight times that of the sun
Blackhole MAXI J1820+070 was discovered during its 2018 outburst
It was extensively monitored across the electromagnetic spectrum
MAXI J1820+070 has also been observed at radio wavelengths by a team led by Joe Bright from the University of Oxford.
Footage of this black hole's behavior is based on four observations obtained with Chandra in November 2018 and February, May, and June of 2019. This has been reported in a paper led by Mathilde Espinasse of the Université de Paris. That footage is an incredible cosmic flare-up captured by NASA's Chandra X-ray Observatory.
On 27th November 2020, NASA shared time-lapse footage of a MAXI J1820+070 (stellar-mass black hole) drifting away from its orbiting companion star and carrying out superluminal ejection in space. The outburst activity was occurring at 80 percent the speed of light. The black hole X-ray binary was discovered by the AstroSat spacecraft. The hot gas ejected from the nucleus of the stellar-mass black hole would undergo a phenomenon called the event horizon where the gaseous material falls back into the black hole and diminishes forever. The other type of short beams of material or jets is ejected away from the black hole in the magnetic lines surrounding the disk outside the event horizon.
Observing the MAXI J1820+070 location from the Milky Way with PanSTARRS optical telescope in Hawaii, scientists found that the massive stellar-mass black hole was a point source of X-rays and jets that grew faint towards the south. Scientists studied the speed of jets composed of the hot material from the Earth's perspective.
MAXI J1820+070 is the bright X-ray source in the middle of the image and sources of X-rays can be seen moving away from the black hole in jets to the north and south. MAXI J1820+070 is a point source of X-rays, although it appears to be larger than a point source because it is much brighter than the jet sources. The southern jet is too faint to be detected in the May and June 2019 observations. It looks as if the northern jet is moving at 60% the speed of light and the southern one is traveling at an impossible-sounding 160% of light speed. This is an example of superluminal motion. It is a phenomenon that occurs when something travels towards us near the speed of light along a direction close to our line of sight.
MAXI J1820+070, the southern jet is pointing towards us and the northern jet is pointing away from us, so the southern jet appears to be moving faster than the northern one. The actual velocity of the particles in both jets is greater than 80% of the speed of light. Only two other examples of such high-speed expulsions have been seen in X-rays from stellar-mass black holes.
The study published in The Astrophysical Journal Letters
Radio observations conducted with the Karl G. Jansky Very Large Array and the MeerKAT array were also used to study MAXI J1820+070's jets. The researchers estimate that about 400 million billion pounds of material were blown away from the black hole in these two jets launched in July 2018. This amount of mass is comparable to what could be accumulated on the disk around the black hole in the space of a few hours and is equivalent to about a thousand Halley's Comets or about 500 million times the mass of the Empire State Building.
Most of the energy in the jets is not converted into radiation but is instead released when particles in the jets interact with the surrounding material. These interactions might be the cause of the jets' deceleration. When the jets collide with surrounding material in interstellar space, shock waves akin to the sonic booms caused by supersonic aircraft occur. This process generates particle energies that are higher than that of the Large Hadron Collider.
The discovery of X-ray sources associated with the radio jets moving at relativistic velocities with a possible deceleration at late times. The broadband spectra of the jets are consistent with synchrotron radiation from particles accelerated up to very high energies (>10 TeV) by shocks produced by the jets interacting with the interstellar medium. The minimal internal energy estimated from the X-ray observations for the jets is ∼1041 erg, significantly larger than the energy calculated from the radio flare alone, suggesting most of the energy is possibly not radiated at small scales but released through late-time interactions.
Another team led by Joe Bright from the University of Oxford observed the radio wavelengths of MAXI J1820+070 and discovered the superluminal motion in the stellar-mass black hole that occurred due to the launch of the jets. According to the observation, most of the energy in the jets is not converted into radiation but is released when jets particles interact with the surrounding material. These jets collided with surrounding material in interstellar space, shock waves were created like the sonic booms caused by supersonic aircraft. This causes an estimated 400 million billion pounds of material to eject out of the black hole including the material accumulated on the disk.
Finally, scientists concluded that the studies of MAXI J1820+070 and similar systems promise to teach us more about the jets produced by stellar-mass black holes and how they release their energy once their jets interact with their surroundings.
The researchers presented the results of BVR polarisation measurements of the black hole X-ray binary MAXI J1820+070 during the period of March-April 2018. Researchers detect small ∼0.7% statistically significant polarisation, part of which is of interstellar origin. Depending on the interstellar polarisation estimate, the intrinsic polarisation degree of the source is between ∼0.3% and 0.7%, and the polarisation position angle is between ∼10 ° −30°. The research shows that the polarisation increases after MJD 58222 (2018 April 14). The change is of the order of 0.1% and is most pronounced in the R band. The change of the source Stokes parameters occurs simultaneously with the drop of the observed V-band flux and a slow softening of the X-ray spectrum. The Stokes vectors of intrinsic polarisation before and after the drop are parallel, at least in the V and R filters.
Researchers suggest that the increased polarization is due to the decreasing contribution of the non-polarized component, which is associated with the hot flow or jet emission. The low polarization can result from the tangled geometry of the magnetic field or from the Faraday rotation in the dense, ionized, and magnetized medium close to the black hole. The polarized optical emission is likely produced by the irradiated disc or by scattering of its radiation in the optically thin outflow.
MAXI J1820+070 with NuSTAR I
MAXI J1820+070 (optical counterpart ASASSN-18ey) is a black hole candidate discovered through its recent very bright outburst. The low extinction column and long duration at high flux allow detailed measurements of the accretion process to be made. In this work, researchers compare the evolution of X-ray spectral and timing properties through the initial hard state of the outburst. Researchers show that the inner accretion disc as measured by relativistic reflection remains steady throughout this period of the outburst. Nevertheless, subtle spectral variability is observed which is well explained by a change in coronal geometry. However, characteristic features of the temporal variability low-frequency roll over and quasi-periodic oscillation frequency increase drastically in frequency as the outburst proceeds. This suggests that the variability time scales are governed by coronal conditions rather than solely by the inner disc radius. Researchers also find a strong correlation between X-ray luminosity and coronal temperature. This can be explained by electron pair production with a changing effective radius and a non-thermal electron fraction of ∼20 percent.
The soft state of the black hole transient source MAXI J1820+070
The Galactic black hole X-ray binary MAXI J1820+070 had a bright outburst in 2018 when it became the second brightest X-ray source in the sky. It was too bright for X-ray CCD instruments such as XMM–Newton, and Chandra but was well observed by photon counting instruments such as Neutron star Inner Composition Explorer (NICER) and Nuclear Spectroscopic Telescope Array(NuSTAR). We report here on the discovery of an excess-emission component during the soft state. It is best modeled with a blackbody spectrum in addition to the regular disc emission, modeled as either diskbb or kerrbb. Its temperature varies from about 0.9 to 1.1 keV, which is about 30–80 percent higher than the inner disc temperature of diskbb. Its flux varies between 4 and 12 percent of the disc flux. Simulations of magnetized accretion discs have predicted the possibility of excess emission associated with a non-zero torque at the innermost stable circular orbit (ISCO) about the black hole, which, from other NuSTAR studies, lies at about 5 gravitational radii or about 60 km (for a black hole, mass is 8M⊙). In this case, the emitting region at the ISCO has a width varying between 1.3 and 4.6 km and would encompass the start of the plunge region where matter begins to fall freely into the black hole.
Violent Flaring Revealed At The Heart Of A Black Hole System
An international team of astronomers led by the University of Southampton used state-of-the-art cameras to create a high frame rate movie of a growing black hole system at a level of detail never seen before. In the process, they uncovered new clues to understanding the immediate surroundings of these enigmatic objects.
This radiation was detected in visible light by the HiPERCAM instrument on the Gran Telescopio Canarias (La Palma, Canary Islands) and in X-rays by NASA’s NICER observatory aboard the International Space Station. The black hole system studied is named MAXI J1820+070. Investigating these systems is usually very difficult as their distances make them too faint and too small to see not even using the Event Horizon Telescope.
The HiPERCAM and NICER instruments let the researcher's record movies of the changing light from the system at over three hundred frames per second capturing violent crackling and flaring of visible and X-ray light. The movie was made using real data but slowed down to 1/10th of actual speed to allow the most rapid flares to be discerned by the human eye. Researchers can see how the material around the black hole is so bright. It’s outshining the star that it is consuming and the fastest flickers last only a few milliseconds that’s the output of a hundred Suns and more being emitted in the blink of an eye.
Researchers also found that dips in X-ray levels are accompanied by a rise in visible light and vice-versa. And the fastest flashes in visible light were found to emerge a fraction of a second after X-rays. Such patterns indirectly reveal the presence of distinct plasma extremely hot material where electrons are stripped away from atoms in structures deep in the embrace of the black hole’s gravity, otherwise too small to resolve.
An instrument aboard the International Space Station has helped reveal how black holes release brilliant flares of X-rays. Scientists have debated where these bright flares come from. One possibility involves changes in the swirling ring of debris falling into the black hole, known as its accretion disk whose inner edges can experience so much friction that they can reach 18 million degrees Fahrenheit (10 million degrees Celsius) or more. Another option involves the coronas of black holes blobs of highly energetic particles floating above the poles of black holes that can heat up to about 1.8 billion degrees F (1 billion degrees C).
To help resolve this controversy, scientists examined a transient event from a black hole MAXI J1820+070 with help of the Monitor of All-sky X-ray Image (MAXI) instrument onboard the International Space Station. The black hole is about 10 times the sun's mass and lies nearly 10,000 light-years away from Earth in the direction of the constellation Leo.
The researchers monitored the evolution of the X-ray flare using the Neutron star Interior Composition Explorer (NICER) instrument on the space station. They mapped the area around the black hole in unprecedented detail as it consumed matter from a companion star. The first thing that was surprising and exciting about this work was just how bright this black hole system got. This black hole went from being completely unobservable to being one of the brightest sources in the X-ray sky over timescales of just a few days.
The scientists were able to collect highly precise measurements of both the energy and timing of X-rays given off during the outburst. This helped them detect echoes within this outburst X-rays from the corona reflected off the accretion disk and zipped toward Earth at different energies and angles than ones that traveled straight from the corona.
The researchers found a significant decrease over the course of the flare in the millisecond-scale time lags between X-rays traveling straight from the corona and ones emitted at the same time that first reflected off the accretion disk. This suggested that either the accretion disk or the corona was changing shape during the outburst and thus perhaps driving the explosion. Researchers measured light echoes to measure the region close to the black hole.
To see which part of the black hole had changed shape during the flare, the scientists examined a pattern of light known as the iron line. The iron atoms in an accretion disk emit this light only when they are energized, such as by X-rays from a corona.
According to Einstein's theory of special relativity, the kind of strong gravitational fields found near black holes can distort time. As such, the iron line should get stretched near the inner boundary of an accretion disk, since time is moving more slowly there. If the accretion disk shifted in shape during the outburst, the iron line would similarly change. The scientists found the accretion disk changed little in size during the outburst. Instead, they estimated the corona shrank dramatically after the outburst, from an initial size of about 60 miles (100 kilometers) to just 6 miles (10 km), in a little more than a month. There has been much debate in the community for many years as to what drives the evolution of the outburst in stellar-mass black holes. Is it driven by the disk moving inwards or by the corona changing? This research show clear evidence that it is the corona that drives the evolution.
It remains uncertain why the corona shrank. One possibility is that it contracted because of the extraordinary pressure from the avalanche of matter falling into the black hole from the accretion disk according to the study co-author Jack Steiner, an astrophysicist at the Massachusetts Institute of Technology.
These findings might shed light on how matter behaves not just as it falls into stellar-mass black holes such as MAXI J1820+070 but also supermassive black holes millions to billions of times the mass of the sun which is thought to lurk at the hearts of virtually every large galaxy. The scientists presented their work on 9th Jan 2019 at the annual meeting of the American Astronomical Society in Seattle. They also detail their findings on the 10th of Jan 2019 in the issue of the journal Nature.
Blackhole X-ray transient
The black hole X-ray transient MAXI J1820+070 was discovered with the Monitor of All sky X-ray Image (MAXI), an X-ray camera installed on the Exposed Facility of the Japanese Experiment Module Kibo aboard the International Space Station (ISS), by the MAXI research group of Megumi Shidatsu, assistant professor at Ehime University, Satoshi Nakahira, JAXA visiting researcher from RIKEN and researchers from other institutes in Japan. The over eight-month monitoring of its transient activity has continued after this discovery using JAXA's MAXI and other Japanese optical and near-infrared telescopes. In November 2018, the discovery of J1820 appeared in the Astrophysical Journal, an American scientific journal of astronomy and astrophysics, and afterward, the result of the subsequent monitoring observations was released in the April 5, 2019 issue of the journal.
Following the discovery in constellation Ophiuchus on March 11, 2018, J1820 rapidly brightened by 50 times only in 2 weeks and then gradually decreased its brightness over three and a half months. At the end of June 2018, however, it started a dramatic increase in its brightness again. In July, it reached twice the brightness of the Crab Nebula and thus became the second brightest X-ray object next to Scorpius X-1 in the whole sky. Such two-step brightening is unusual in black hole X-ray transients. Similar behavior was observed in XTE J1752-223, which was discovered also with the MAXI in 2009, but no other similar sources had been reported ever since.
MAXI's discovery triggered extensive follow-up observations of J1820 by X-ray observatories, including the NASA's Neutron star Interior Composition Explorer (NICER) also aboard the ISS and X-ray telescope (XRT) of the orbiting satellite Swift. The transient was frequently observed in visual light, infrared, and radio with ground-based telescopes as well. Roughly 60 observations have been reported to the Astronomer's Telegram. During the first four months in particular until the peak of the X-ray brightness, the source exhibited rapid variations of its brightness several times in a few seconds or less, in X-rays and visual light. The X-ray flux variation was likely generated at the inner parts of the accretion disk formed around the black hole, while the visible light variation was mainly observed in jets launched near the black hole. Megumi Shidatsu and the team also conducted X-ray, optical, and near-infrared observations with MAXI and Japanese telescopes, in collaboration with the Japanese universities research team, called OISTER (Optical and Infrared Synergetic Telescopes for Education and Research). They successfully detected emissions from the accretion disk and the jets simultaneously and found that the base of the jets is likely to have a strong magnetic field. The series of observations demonstrate that MAXI's rapid detection of X-ray sources offers astronomers around the world opportunities to observe transients and greatly contributes to a better understanding of high energy phenomena in black hole X-ray transients.