Researchers from the University of Turku, Finland, found that the axis of rotation of a
Artist impression of the X-ray binary system MAXI J1820+070 containing a black hole (small black dot at the center of the gaseous disk) and a companion star. A narrow jet is directed along the black hole spin axis, which is strongly misaligned from the rotation axis of the orbit. Image produced with Binsim. Credit: R. Hynes
Often for the space systems with smaller objects orbiting around the central massive body, the own rotation axis of this body is to a high degree aligned with the rotation axis of its satellites. This is true also for our solar system: the planets orbit around the Sun in a plane, which roughly coincides with the equatorial plane of the Sun. The inclination of the Sun rotation axis with respect to orbital axis of the Earth is only seven degrees.
“The expectation of alignment, to a large degree, does not hold for the bizarre objects such as black hole X-ray binaries. The black holes in these systems were formed as a result of a cosmic cataclysm – the collapse of a massive star. Now we see the black hole dragging matter from the nearby, lighter companion star orbiting around it. We see bright optical and X-ray radiation as the last sigh of the infalling material, and also radio emission from the relativistic jets expelled from the system,” says Juri Poutanen, Professor of Astronomy at the University of Turku and the lead author of the publication.
Artist impression of the X-ray binary system MAXI J1820+070 containing a black hole (small black dot at the center of the gaseous disk) and a companion star. A narrow jet is directed along the black hole spin axis, which is strongly misaligned from the rotation axis of the orbit. Image produced with Binsim. Credit: R. Hynes
By following these jets, the researchers were able to determine the direction of the axis of rotation of the black hole very accurately. As the amount of gas falling from the companion star to the black hole later began to decrease, the system dimmed, and much of the light in the system came from the companion star. In this way, the researchers were able to measure the orbit inclination using spectroscopic techniques, and it happened to nearly coincide with the inclination of the ejections.
“To determine the 3D orientation of the orbit, one additionally needs to know the position angle of the system on the sky, meaning how the system is turned with respect to the direction to the North on the sky. This was measured using polarimetric techniques,” says Juri Poutanen.
The results published in the Science magazine open interesting prospects towards studies of black hole formation and evolution of such systems, as such extreme misalignment is hard to get in many black hole formation and binary evolution scenarios.
“The difference of more than 40 degrees between the orbital axis and the black hole spin was completely unexpected. Scientists have often assumed this difference to be very small when they have modeled the behavior of matter in a curved time space around a black hole. The current models are already really complex, and now the new findings force us to add a new dimension to them,” Poutanen states.
Reference: “Black hole spin–orbit misalignment in the x-ray binary MAXI J1820+070” by Juri Poutanen, Alexandra Veledina, Andrei V. Berdyugin, Svetlana V. Berdyugina, Helen Jermak, Peter G. Jonker, Jari J. E. Kajava, Ilia A. Kosenkov, Vadim Kravtsov, Vilppu Piirola, Manisha Shrestha, Manuel A. Perez Torres and Sergey S. Tsygankov, 24 February 2022, Science. DOI: 10.1126/science.abl4679
The key finding was made using the in-house built polarimetric instrument DIPol-UF mounted at the Nordic Optical Telescope, which is owned by the University of Turku jointly with the
(function(d, s, id){
var js, fjs = d.getElementsByTagName(s)[0];
if (d.getElementById(id)) return;
js = d.createElement(s); js.id = id;
js.src = "https://connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.6";
fjs.parentNode.insertBefore(js, fjs);
}(document, 'script', 'facebook-jssdk'));
Biden will deliver remarks on Friday afternoon announcing the selection, the White House said. CNN first reported Biden’s decision.
She received and accepted Biden’s offer in a call Thursday night, a source familiar with the decision told CNN, but was present for DC Circuit Court hearings Friday morning.
Biden met with Jackson for her Supreme Court interview earlier this month, a senior administration official said, in a meeting that the White House managed to keep secret.
For more than a year, the President had familiarized himself with her work, reading many of her opinions and other writings, along with those of other contenders.
But the official said Biden also was impressed by her life story, including her rise from federal public defender to federal appellate judge — and her upbringing as the daughter of two public school teachers and administrators.
“President Biden sought a candidate with exceptional credentials, unimpeachable character and unwavering dedication to the rule of law,” the senior official said.
From the beginning, Jackson was the leading contender, but the official said the President gave “considerable weight” to other finalists, including Judge J. Michelle Childs and California Supreme Court Justice Leondra Kruger.
The President reached his final decision this week, the official said, and extended the offer to her in a phone call on Thursday evening. She accepted in the call, which lasted several minutes.
The White House considered delaying the announcement, given the Russian invasion in Ukraine, but believed it was critical to get the second phase of the confirmation process moving, the official said.
In a statement, the White House cited Jackson’s “broad experience across the legal profession,” pointing to her career as a federal appellate judge, a federal district court judge, a member of the US Sentencing Commission, an attorney in private practice and as a federal public defender. The White House described Jackson as “an exceptionally qualified” and “historic” nominee, calling on the Senate to “move forward with a fair and timely hearing and confirmation.”
Jackson clerked for Breyer and served as a federal public defender in Washington — an experience that her backers say is fitting, given Biden’s commitment to putting more public defenders on the federal bench. She was also a commissioner on the US Sentencing Commission and served on the federal district court in DC, as an appointee of President Barack Obama, before Biden elevated her to the DC Circuit last year.
Opportunity for Biden to excite Democrats
Biden’s pick is a chance for him to fire up a Democratic base that is less excited to vote in this year’s midterm elections than it has been over the past several election cycles. It’s also a welcome change of topic for the President, whose approval ratings have been sagging in recent months as the Covid-19 pandemic has dragged on and inflation has affected consumers across the nation. The selection gives Biden a chance to deliver on one of his top campaign promises, and he’ll hope that the Black voters who were crucial to his election win will see this as a return on their investment.
Though it is historic, the choice of Jackson will not change the ideological makeup of the court. The court currently has six conservative justices and three liberal justices — and the retiring Breyer comes from the liberal camp. The court is already poised to continue its turn toward the right with high-profile cases and rulings expected from the court in the coming months on abortion, gun control and religious liberty issues.
Eyes will now turn to the Senate, where Biden’s Democratic Party holds the thinnest possible majority. The President will hope that Jackson can garner bipartisan support, but Democrats will need all their members in Washington to ensure her confirmation. Unlike for most major pieces of legislation, Democrats do not need Republican help to confirm a Supreme Court justice and can do it with their 50 votes and Vice President Kamala Harris breaking a deadlock. When Jackson was confirmed to the appellate bench, she had the support of three Republican senators.
Jackson is expected to have her courtesy meetings with senators next week, according to a person familiar with the plans. It’s common for Supreme Court nominees to meet with the leadership on both sides, then members of the Senate Judiciary Committee.
As a judge in DC — where some of the most politically charged cases are filed — Jackson’s issued notable rulings touching on Congress’ ability to investigate the White House. As a district court judge, she wrote a 2019 opinion siding with House lawmakers who sought the testimony of then-White House Counsel Don McGahn. Last year, she was on the unanimous circuit panel that ordered disclosure of certain Trump White House documents to the House January 6 committee.
The White House indicated her time in the federal public defenders’ office was critical to Biden’s selection, setting her apart from other candidates. Biden sought “an individual who is committed to equal justice under the law and who understands the profound impact that the Supreme Court’s decisions have on the lives of the American people,” the White House said.
Following Breyer’s retirement announcement in late January, Biden began reviewing background materials, such as legal records and writings, about his potential picks.
Biden first committed to nominating a Black female US Supreme Court justice when he was running for president in 2020. On a debate stage in South Carolina, Biden argued that his push to make “sure there’s a Black woman on the Supreme Court” was rooted in an effort to “get everyone represented.”
Coming from ‘a background of public service’
Jackson was born in the nation’s capital but grew up in the Miami area. She was a member of the debate team at Miami Palmetto Senior High School before earning both her undergraduate degree and law degree at Harvard.
At her 2021 confirmation hearing for the appellate court, she connected her family’s professions — her parents worked in public schools — to her decision to work as a public defender.
“I come from a background of public service. My parents were in public service, my brother was a police officer and (was) in the military,” she said at the time, “and being in the public defenders’ office felt very much like the opportunity to help with my skills and talents.”
Former House Speaker Paul Ryan, a Republican, is a relative by marriage and introduced her at the 2013 hearing for her district court nomination.
Conservatives have already previewed how they will scrutinize her record defending Guantanamo Bay detainees as a public defender. The role she played in her uncle’s successful efforts to seek a commutation from former President Barack Obama has also attracted attention. When she was in private practice in 2008, she referred her uncle’s file to the firm Wilmer Hale, which several years later submitted the file.
As a judge, some other notable cases she has in her record are a 2018 case brought federal employee unions where she blocked parts of executive orders issued by former President Donald Trump, and a case where she ruled against Trump policies that expand the categories of non-citizens who could be subject to expedited removal procedures without being able to appear before a judge.
Jackson penned more than 500 opinions in the eight years she spent on the district court.
Republicans signal potential opposition
Though Biden has said that he’d pick a nominee with bipartisan appeal who is “worthy of Justice Breyer’s legacy of excellence and decency,” his decision to name the first Black woman to the court is already facing Republican opposition. Several Senate Republicans have told CNN they disagreed with the President’s decision to name a Black woman to the court rather than judging a nominee squarely on their credentials, even though Ronald Reagan and Trump both said they’d name a female justice to the Supreme Court when they were on the campaign trail.
Even before Biden nominated Jackson, GOP senators and Senate candidates were already concluding that she’d be far left, throwing cold water on the names floated as being on Biden’s potential short list and calling for a slow confirmation process. Still, Republicans are limited in their ability to block a Supreme Court nominee, and Jackson may win the support of some GOP senators.
Sens. Lisa Murkowski of Alaska, Lindsey Graham of South Carolina and Susan Collins of Maine all voted for Jackson last summer when she was confirmed as a circuit court judge on the US Court of Appeals for the District of Columbia, the second most important court in the country.
But on Friday, Graham, who had expressed support for Childs, suggested Jackson does not have his approval, saying in a tweet that the choice of Jackson “means the radical Left has won President Biden over yet again.” Graham added that he expects a “respectful but interesting hearing in the Senate Judiciary Committee.”
Senate Minority Leader Mitch McConnell called for a “rigorous, exhaustive” review of Jackson in a statement.
“I also understand Judge Jackson was the favored choice of far-left dark-money groups that have spent years attacking the legitimacy and structure of the Court itself,” McConnell said.
Senate Majority Leader Chuck Schumer has indicated that he wants to push a nominee through the process quickly, using Supreme Court Justice Amy Coney Barrett’s Senate proceedings as a model for Jackson’s confirmation timeline. And Sen. Dick Durbin, the chairman of the Senate Judiciary Committee, told CNN recently that he expects to have a hearing within a few weeks of the selection. The goal of the leadership is to have the nominee confirmed by the April 11 recess.
This story has been updated with additional developments, reaction and background information.
CNN’s John Harwood, and Manu Raju contributed to this report.
Astronomers believe they have spotted two colossal black holes orbiting each other that are set to collide in the future—an event so energetic it will shake the fabric of space and time.
The discovery was made by scientists observing a quasar, which is the name given to extremely bright cores of galaxies where gas is superheated to millions of degrees by a supermassive black hole.
The quasar in question, PKS 2131-021, has been studied extensively with radio observations spanning 45 years. Over time, researchers had noticed that the brightness of PKS 2131-021 would sometimes change.
Not only was the light varying periodically, but sinusoidally. In other words, there was a pattern that the researchers could trace.
They think the reason for this is that a jet of light from the quasar is moving back and forth like a ticking clock. They also believe the most likely reason for this is that this quasar is not the result of one huge black hole, but two spinning around each other.
Astronomers knew this was possible, but finding direct evidence of the phenomenon has proven difficult.
The black holes, located around 9 billion light-years from Earth, are thought to be huge. Each has a mass hundreds of millions of times the mass of our sun.
In a study published in The Astrophysical Journal Letters on Wednesday, scientists from several research institutions including CalTech describe how the two black holes of PKS 2131-021 appear to be orbiting each other once every two years, separated by a distance of around 2,000 astronomical units, or 2,000 times the distance from the sun to the Earth.
This may sound large, but in astronomical terms it’s practically a hair’s breadth. The only other known candidate for supermassive black holes in the process of merging is the quasar OJ 287, in which the two black holes are thought to be 10 to 100 times further apart than the pair in PKS 2131-021, according to a CalTech press release.
NASA’s Jet Propulsion Laboratory in California estimates that if one were to take into account the many millions of years these black holes have likely been orbiting each other, they are now more than 99 percent of the way to a collision. In real terms, that means a collision around 10,000 years from now.
It should be noted that the two black holes have not been conclusively identified. As the study says: “While we have not yet proven definitively that PKS 2131–021 is a [supermassive black hole binary], we believe that this is by far the most likely scenario.”
Black hole mergers are of interest to astronomers since they are believed to be sources of gravitational waves—ripples in space time caused by highly energetic events that were predicted by Albert Einstein in 1916. Almost 100 years later in 2015, scientists physically sensed these waves using the Laser Interferometer Gravitational-Wave Observatory experiment.
Gravitational waves provide clues to the nature of gravity itself, which is one of the mysteries of the universe.
We don’t have to worry about them, though. By the time gravitational waves reach Earth, they are thousands of billions of times smaller than they were at their source. As such, these ripples tend to be 1,000 times smaller than the nucleus of an atom and are incredibly hard to detect.
Illustration of a black hole. Colliding black holes are thought to be sources of gravitational waves. solarseven/Getty
Evidence that this supermassive black hole may have a companion comes from observations by radio telescopes on Earth. Black holes don’t emit light, but their gravity can gather disks of hot gas around them and eject some of that material into space. These jets can stretch for millions of light-years. A jet pointed toward Earth appears far brighter than a jet pointed away from Earth. Astronomers call supermassive black holes with jets oriented toward Earth blazars, and a blazar named PKS 2131-021 is at the heart of this recent paper.
Located about 9 billion light-years from Earth, PKS 2131-021 is one of 1,800 blazars that a group of researchers at Caltech in Pasadena has been monitoring with the Owens Valley Radio Observatory in Northern California for 13 years as part of a general study of blazar behavior. But this particular blazar exhibits a strange behavior: Its brightness shows regular ups and downs as predictably as the ticking of a clock.
Researchers now think this regular variation is the result of a second black hole tugging on the first as they orbit each other about every two years. Each of the two black holes in PKS 2131-021 is estimated to be a few hundred million times the mass of our Sun. To confirm the finding, scientists will try to detect gravitational waves – ripples in space – coming from the system. The first detection of gravitational waves from black hole binaries was announced in 2016.
To confirm that the oscillations weren’t random or the cause of a temporary effect around the black hole, the team had to look beyond the decade (2008 to 2019) of data from the Owens Valley Observatory. After learning that two other radio telescopes had also studied this system – the University of Michigan Radio Observatory (1980 to 2012) and the Haystack Observatory (1975 to 1983) – they dug into the additional data and found that it matched predictions for how the blazar’s brightness should change over time.
“This work is a testament to the importance of perseverance,” said Lazio. “It took 45 years of radio observations to produce this result. Small teams, at different observatories across the country, took data week in and week out, month in and month out, to make this possible.”
To learn more, read the news release from Caltech.
An artist’s impression of the binary system, with the angled black hole projecting jets from within the accretion disk of material surrounding it.Illustration: Rob Hynes
A team of astronomers recently observed an askew black hole just 10,000 light-years from Earth. The black hole’s spin axis is out of alignment with the plane of debris orbiting it by at least 40 degrees, the most extreme misalignment of its kind yet seen by astronomers.
The system is called MAXI J1820+70, and it contains a small black hole (about eight times more massive than the Sun) and a star that’s about half the size of the Sun. Astrophysicists recently calculated that the black hole, an incredibly dense object with a gravitational field so intense that not even light can escape, is spinning at an awkward angle compared to stuff orbiting it; the researchers think its tilt may be a relic of how the object was born, in the violent death of a star.
“The main result is that, for the first time, we measure a large (>40 degrees) misalignment between the black hole spin and the orbital spin,” said Juri Poutanen, an astrophysicist at the University of Turku in Finland and the paper’s lead author, in an email to Gizmodo. “In this case, the likely formation channel is a large kick (due to asymmetric neutrino emission) to the black hole during the collapse of the core of a massive star.”
The “kick” Poutanen refers to is the result of the supernova—the collapse of a massive star—that birthed the black hole. The ejection of material from the dying star gave the black hole something called a natal kick, which can knock the massive object out of alignment with neighboring objects.
“It is not much the ‘hit’ by the explosion itself, but the sudden change in the gravitation field that keeps the two objects together, coupled to the fact that the black hole, during its formation in the supernova explosion, acquires an extreme rotation speed,” said Ferdinando Patat, an astrophysicist at the European Southern Observatory who wrote an accompanying Perspectives article about the new paper, in an email to Gizmodo.
The black hole is slowly pulling material off a neighboring star thanks to its strong gravitational field, forming an accretion disk around the dense abyss. Some of the star’s material is swallowed by the black hole, but some of it is also ejected in the form of two massive jets of material, spewing out at about 80% the speed of light.
By looking at the angle of those jets and the incline of the orbital plane of the system, the researchers figured out things were off-kilter. “What was missing was the position angle of the orbital plane,” Patat said, “and this was provided by the polarization of light coming from the material on the orbital plane.”
“This is the novelty of the approach,” Patat added. “Polarization carries with it geometrical information that often no other signal carries. It can tell you what is the orientation of an emitting surface, even if you cannot discern the details of the surface.”
More of these misaligned black holes probably exist, Poutanen said, but they’re difficult to measure. The team is planning to look for more, and they’ll also further investigate the structure of this one using data from NASA’s new IXPE satellite, launched in December 2021, to better understand how its tilt became so extreme.
More: See a Black Hole’s Magnetic Fields in New Image From the Event Horizon Telescope
This artist’s concept shows two candidate supermassive black holes at the heart of a quasar called PKS 2131-021. In this view of the system, gravity from the foreground black hole (right) can be seen twisting and distorting the light of its companion, which has a powerful jet. Each black hole is about a hundred million times the mass of our sun, with the black hole in the foreground being slightly less massive. Credit: Caltech/R. Hurt (IPAC)
Astronomers find evidence for the tightest-knit supermassive
Two supermassive black holes are seen orbiting each other in this artist’s loopable animation. The more massive black hole, which is hundreds of millions times the mass of our sun, is shooting out a jet that changes in its apparent brightness as the duo circles each other. Astronomers found evidence for this scenario in a quasar called PKS 2131-021 after analyzing 45-years-worth of radio observations that show the system periodically dimming and brightening. The observed cyclical pattern is thought to be caused by the orbital motion of the jet. Credit: Caltech/R. Hurt (IPAC)
Reporting in The Astrophysical Journal Letters, the researchers argue that PKS 2131-021 is now the second known candidate for a pair of supermassive black holes caught in the act of merging. The first candidate pair, within a quasar called OJ 287, orbit each other at greater distances, circling every nine years versus the two years it takes for the PKS 2131-021 pair to complete an orbit.
The telltale evidence came from radio observations of PKS 2131-021 that span 45 years. According to the study, a powerful jet emanating from one of the two black holes within PKS 2131-021 is shifting back and forth due to the pair’s orbital motion. This causes periodic changes in the quasar’s radio-light brightness. Five different observatories registered these oscillations, including Caltech’s Owens Valley Radio Observatory (OVRO), the University of Michigan Radio Astronomy Observatory (UMRAO),
Artist’s animation of a supermassive black hole circled by a spinning disk of gas and dust. The black hole is shooting out a relativistic jet—one that travels at nearly the speed of light. Credit: Caltech/R. Hurt (IPAC)
The combination of the radio data yields a nearly perfect sinusoidal light curve unlike anything observed from quasars before.
“When we realized that the peaks and troughs of the light curve detected from recent times matched the peaks and troughs observed between 1975 and 1983, we knew something very special was going on,” says Sandra O’Neill, lead author of the new study and an undergraduate student at Caltech who is mentored by Tony Readhead, Robinson Professor of Astronomy, Emeritus.
Ripples in Space and Time
Most, if not all, galaxies possess monstrous black holes at their cores, including our own
Three sets of radio observations of the quasar PKS 2131-02, spanning 45 years, are plotted here, with data from Owens Valley Radio Observatory (OVRO) in blue; University of Michigan Radio Astronomical Observatory (UMRAO) in brown; and Haystack Observatory in green. The observations match a simple sine wave, indicated in blue. Astronomers believe that the sine wave pattern is caused by two supermassive black holes at the heart of the quasar orbiting around each other every two years. (A period of five years was actually observed due to a Doppler effect caused by the expansion of the universe.) One of the black holes is shooting out a relativistic jet that dims and brightens periodically. Note that data from OVRO and UMRAO match for the peak in 2010, and the UMRAO and Haystack data match for the peak in 1981. The magnitudes of the peaks observed around 1980 are twice as large as those observed in recent times, presumably because more material was falling towards the black hole and being ejected at that time. Credit: Tony Readhead/Caltech
In the future,
Sandra O’Neill. Credit: Caltech
Revealing the 45-Year Light Curve
Readhead says the discoveries unfolded like a “good detective novel,” beginning in 2008 when he and colleagues began using the 40-meter telescope at OVRO to study how black holes convert material they “feed” on into relativistic jets, or jets traveling at speeds up to 99.98 percent that of light. They had been monitoring the brightness of more than 1,000 blazars for this purpose when, in 2020, they noticed a unique case.
“PKS 2131 was varying not just periodically, but sinusoidally,” Readhead says. “That means that there is a pattern we can trace continuously over time.” The question, he says, then became how long has this sine wave pattern been going on?
The research team then went through archival radio data to look for past peaks in the light curves that matched predictions based on the more recent OVRO observations. First, data from NRAO’s Very Long Baseline Array and UMRAO revealed a peak from 2005 that matched predictions. The UMRAO data further showed there was no sinusoidal signal at all for 20 years before that time—until as far back as 1981 when another predicted peak was observed.
“The story would have stopped there, as we didn’t realize there were data on this object before 1980,” Readhead says. “But then Sandra picked up this project in June of 2021. If it weren’t for her, this beautiful finding would be sitting on the shelf.”
O’Neill began working with Readhead and the study’s second author Sebastian Kiehlmann, a postdoc at the University of Crete and former staff scientist at Caltech, as part of Caltech’s Summer Undergraduate Research Fellowship (SURF) program. O’Neill began college as a chemistry major but picked up the astronomy project because she wanted to stay active during the pandemic. “I came to realize I was much more excited about this than anything else I had worked on,” she says.
With the project back on the table, Readhead searched through the literature and found that the Haystack Observatory had made radio observations of PKS 2131-021 between 1975 and 1983. These data revealed another peak matching their predictions, this time occurring in 1976.
“This work shows the value of doing accurate monitoring of these sources over many years for performing discovery science,” says co-author Roger Blandford, Moore Distinguished Scholar in Theoretical Astrophysics at Caltech who is currently on sabbatical from Stanford University.
Tony Readhead. Credit: Caltech
Like Clockwork
Readhead compares the system of the jet moving back and forth to a ticking clock, where each cycle, or period, of the sine wave corresponds to the two-year orbit of the black holes (though the observed cycle is actually five years due to light being stretched by the expansion of the universe). This ticking was first seen in 1976 and it continued for eight years before disappearing for 20 years, likely due to changes in the fueling of the black hole. The ticking has now been back for 17 years.
“The clock kept ticking,” he says, “The stability of the period over this 20-year gap strongly suggests that this blazar harbors not one supermassive black hole, but two supermassive black holes orbiting each other.”
The physics underlying the sinusoidal variations were at first a mystery, but Blandford came up with a simple and elegant model to explain the sinusoidal shape of the variations.
“We knew this beautiful sine wave had to be telling us something important about the system,” Readhead says. “Roger’s model shows us that it is simply the orbital motion that does this. Before Roger worked it out, nobody had figured out that a binary with a relativistic jet would have a light curve that looked like this.”
Says Kiehlmann: “Our study provides a blueprint for how to search for such blazar binaries in the future.”
Reference: “The Unanticipated Phenomenology of the Blazar PKS 2131–021: A Unique Supermassive Black Hole Binary Candidate” by S. O’Neill, S. Kiehlmann, A. C. S. Readhead, M. F. Aller, R. D. Blandford, I. Liodakis, M. L. Lister, P. Mróz, C. P. O’Dea, T. J. Pearson, V. Ravi, M. Vallisneri, K. A. Cleary, M. J. Graham, K. J. B. Grainge, M. W. Hodges, T. Hovatta, A. Lähteenmäki, J. W. Lamb, T. J. W. Lazio, W. Max-Moerbeck, V. Pavlidou, T. A. Prince, R. A. Reeves, M. Tornikoski, P. Vergara de la Parra and J. A. Zensus, 23 February 2022, The Astrophysical Journal Letters. DOI: 10.3847/2041-8213/ac504b
The Astrophysical Journal Letters study titled “The Unanticipated Phenomenology of the Blazar PKS 2131-021: A Unique Super-Massive Black hole Binary Candidate” was funded by Caltech, the Max Planck Institute for Radio Astronomy, NASA, National Science Foundation (NSF), the Academy of Finland, the European Research Council, ANID-FONDECYT (Agencia Nacional de Investigación y Desarrollo-Fondo Nacional de Desarrollo Científico y Tecnológico in Chile), the Natural Science and Engineering Council of Canada, the Foundation for Research and Technology – Hellas in Greece, the Hellenic Foundation for Research and Innovation in Greece, and the University of Michigan. Other Caltech authors include Tim Pearson, Vikram Ravi, Kieran Cleary, Matthew Graham, and Tom Prince. Other authors from the Jet Propulsion Laboratory, which is managed by Caltech for NASA, include Michele Vallisneri and Joseph Lazio.
Joe Biden has interviewed at least three potential supreme court nominees and is expected to reveal his decision by the end of this month, according to multiple sources close to the president.
Ketanji Brown Jackson, Leondra Kruger and J Michelle Childs – all Black women – were among the contenders who spoke with the president, those familiar with the matter told CNN and the Washington Post.
Jackson, who has widely been considered the frontrunner, currently sits on the US court of appeals for the DC circuit after replacing the attorney general, Merrick Garland, in June 2021.
Kruger is an associate justice of the California supreme court and has served as the acting principal deputy solicitor general under the Barack Obama administration.
Childs currently sits on the US district court for the district of South Carolina and was previously nominated by Biden for a seat on the DC circuit court of appeals.
The impending retirement of supreme court associate justice Stephen Breyer has given Biden has the opportunity to fulfill one of his campaign promises: to appoint a Black woman to the supreme court.
On Sunday evening Cedric L Richmond, director of the White House office of public engagement, told members of the organization Win With Black Women that “we’re close”.
“We know what some of the attacks are going to be: not qualified, affirmative action pick … Well, it wasn’t ‘affirmative action pick’ when we just picked friends, white friends of the president, for all these decades. You know, it was just patronage or whatever they wanted to call it,” Richmond said, according to a source who has direct knowledge of the private conference call.
Biden, who is dealing with a growing crisis between Ukraine and Russia, has set the end of February as his deadline to pick a nominee. According to CNN, White House officials have reached out to liberal groups to inform them that Biden will not be shifting from his timeline and urged them to support “top tier” candidates against critics’ attacks.
In a statement on Tuesday, Andrew Bates, a White House spokesperson, said Biden has not yet made a decision.
“The president has not yet chosen a nominee. He continues to evaluate eminently qualified individuals in the mold of Justice [Stephen] Breyer who have the strongest records, intellect, character, and dedication to the rule of law that anyone could ask for – and all of whom would be deserving of bipartisan support. He looks forward to announcing a nominee this month.”
This artist’s concept shows two candidate supermassive black holes at the heart of a quasar called PKS 2131-021. In this view of the system, gravity from the foreground black hole (right) can be seen twisting and distorting the light of its companion, which has a powerful jet. Each black hole is about a hundred million times the mass of our sun, with the black hole in the foreground being slightly less massive. Credit: Caltech/R. Hurt (IPAC)
Locked in an epic cosmic waltz 9 billion light years away, two supermassive black holes appear to be orbiting around each other every two years. The two giant bodies each have masses that are hundreds of millions of times larger than that of our sun, and the objects are separated by a distance roughly 50 times that which separates our sun and Pluto. When the pair merge in roughly 10,000 years, the titanic collision is expected to shake space and time itself, sending gravitational waves across the universe.
A Caltech-led team of astronomers has discovered evidence for this scenario taking place within a fiercely energetic object known as a quasar. Quasars are active cores of galaxies in which a supermassive black hole is siphoning material from a disk encircling it. In some quasars, the supermassive black hole creates a jet that shoots out at near the speed of light. The quasar observed in the new study, PKS 2131-021, belongs to a subclass of quasars called blazars in which the jet is pointing toward the Earth. Astronomers already knew quasars could possess two orbiting supermassive black holes, but finding direct evidence for this has proved difficult.
Reporting in The Astrophysical Journal Letters, the researchers argue that PKS 2131-021 is now the second known candidate for a pair of supermassive black holes caught in the act of merging. The first candidate pair, within a quasar called OJ 287, orbit each other at greater distances, circling every nine years versus the two years it takes for the PKS 2131-021 pair to complete an orbit.
The telltale evidence came from radio observations of PKS 2131-021 that span 45 years. According to the study, a powerful jet emanating from one of the two black holes within PKS 2131-021 is shifting back and forth due to the pair’s orbital motion. This causes periodic changes in the quasar’s radio-light brightness. Five different observatories registered these oscillations, including Caltech’s Owens Valley Radio Observatory (OVRO), the University of Michigan Radio Astronomy Observatory (UMRAO), MIT’s Haystack Observatory, the National Radio Astronomy Observatory (NRAO), Metsähovi Radio Observatory in Finland, and NASA’s Wide-field Infrared Survey Explorer (WISE) space satellite.
The combination of the radio data yields a nearly perfect sinusoidal light curve unlike anything observed from quasars before.
“When we realized that the peaks and troughs of the light curve detected from recent times matched the peaks and troughs observed between 1975 and 1983, we knew something very special was going on,” says Sandra O’Neill, lead author of the new study and an undergraduate student at Caltech who is mentored by Tony Readhead, Robinson Professor of Astronomy, Emeritus.
Ripples in Space and Time
Most, if not all, galaxies possess monstrous black holes at their cores, including our own Milky Way galaxy. When galaxies merge, their black holes “sink” to the middle of the newly formed galaxy and eventually join together to form an even more massive black hole. As the black holes spiral toward each other, they increasingly disturb the fabric of space and time, sending out gravitational waves, which were first predicted by Albert Einstein more than 100 years ago.
The National Science Foundation’s LIGO (Laser Interferometer Gravitational-Wave Observatory), which is managed jointly by Caltech and MIT, detects gravitational waves from pairs of black holes up to dozens of times the mass of our sun. However, the supermassive black holes at the centers of galaxies have millions to billions of times as much mass as our sun, and give off lower frequencies of gravitational waves than those detected by LIGO.
In the future, pulsar timing arrays—which consist of an array of pulsing dead stars precisely monitored by radio telescopes—should be able to detect the gravitational waves from supermassive black holes of this heft. (The upcoming Laser Interferometer Space Antenna, or LISA, mission would detect merging black holes whose masses are 1,000 to 10 million times greater than the mass of our sun.) So far, no gravitational waves have been registered from any of these heavier sources, but PKS 2131-021 provides the most promising target yet.
In the meantime, light waves are the best option to detect coalescing supermassive black holes.
The first such candidate, OJ 287, also exhibits periodic radio-light variations. These fluctuations are more irregular, and not sinusoidal, but they suggest the black holes orbit each other every nine years. The black holes within the new quasar, PKS 2131-021, orbit each other every two years and are 2,000 astronomical units apart, about 50 times the distance between our sun and Pluto, or 10 to 100 times closer than the pair in OJ 287. (An astronomical unit is the distance between Earth and the sun.)
Revealing the 45-Year Light Curve
Readhead says the discoveries unfolded like a “good detective novel,” beginning in 2008 when he and colleagues began using the 40-meter telescope at OVRO to study how black holes convert material they “feed” on into relativistic jets, or jets traveling at speeds up to 99.98 percent that of light. They had been monitoring the brightness of more than 1,000 blazars for this purpose when, in 2020, they noticed a unique case.
“PKS 2131 was varying not just periodically, but sinusoidally,” Readhead says. “That means that there is a pattern we can trace continuously over time.” The question, he says, then became how long has this sine wave pattern been going on?
The research team then went through archival radio data to look for past peaks in the light curves that matched predictions based on the more recent OVRO observations. First, data from NRAO’s Very Long Baseline Array and UMRAO revealed a peak from 2005 that matched predictions. The UMRAO data further showed there was no sinusoidal signal at all for 20 years before that time—until as far back as 1981 when another predicted peak was observed.
“The story would have stopped there, as we didn’t realize there were data on this object before 1980,” Readhead says. “But then Sandra picked up this project in June of 2021. If it weren’t for her, this beautiful finding would be sitting on the shelf.”
O’Neill began working with Readhead and the study’s second author Sebastian Kiehlmann, a postdoc at the University of Crete and former staff scientist at Caltech, as part of Caltech’s Summer Undergraduate Research Fellowship (SURF) program. O’Neill began college as a chemistry major but picked up the astronomy project because she wanted to stay active during the pandemic. “I came to realize I was much more excited about this than anything else I had worked on,” she says.
With the project back on the table, Readhead searched through the literature and found that the Haystack Observatory had made radio observations of PKS 2131-021 between 1975 and 1983. These data revealed another peak matching their predictions, this time occurring in 1976.
“This work shows the value of doing accurate monitoring of these sources over many years for performing discovery science,” says co-author Roger Blandford, Moore Distinguished Scholar in Theoretical Astrophysics at Caltech who is currently on sabbatical from Stanford University.
Like Clockwork
Readhead compares the system of the jet moving back and forth to a ticking clock, where each cycle, or period, of the sine wave corresponds to the two-year orbit of the black holes (though the observed cycle is actually five years due to light being stretched by the expansion of the universe). This ticking was first seen in 1976 and it continued for eight years before disappearing for 20 years, likely due to changes in the fueling of the black hole. The ticking has now been back for 17 years.
“The clock kept ticking,” he says, “The stability of the period over this 20-year gap strongly suggests that this blazar harbors not one supermassive black hole, but two supermassive black holes orbiting each other.”
The physics underlying the sinusoidal variations were at first a mystery, but Blandford came up with a simple and elegant model to explain the sinusoidal shape of the variations.
“We knew this beautiful sine wave had to be telling us something important about the system,” Readhead says. “Roger’s model shows us that it is simply the orbital motion that does this. Before Roger worked it out, nobody had figured out that a binary with a relativistic jet would have a light curve that looked like this.”
Kiehlmann says their “study provides a blueprint for how to search for such blazar binaries in the future.”
Pulsar timing arrays take us closer to figuring out supermassive black holes
More information:
S. O’Neill et al, The Unanticipated Phenomenology of the Blazar PKS 2131–021: A Unique Supermassive Black Hole Binary Candidate, The Astrophysical Journal Letters (2022). DOI: 10.3847/2041-8213/ac504b
Provided by
California Institute of Technology
Citation:
Colossal black holes locked in dance at heart of galaxy (2022, February 23)
retrieved 23 February 2022
from https://phys.org/news/2022-02-colossal-black-holes-heart-galaxy.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
No crew members or skiers at the Snowbird ski resort were injured, according to Jared Jones, chief warrant officer 5 with the Utah National Guard.
“Everyone is safe,” Jones said. “It was a blessing that everyone was OK.”
The accident occurred near the Mineral Basin area of Snowbird, “about 150 yards off of Snowbird proper,” Jones said.
The resort, almost 30 miles from Salt Lake City, has the capacity to carry more than 17,000 skiers and snowboarders uphill per hour on its many lifts, according to Snowbird’s website.
Both helicopters suffered some damage because of the crash, the Utah National Guard said in a tweet.
“As the first aircraft landed … portions of the blade of the lead helicopter separated and it appears struck the second helicopter,” Jones said.
Black carbon pollution from tourism and research activities in Antarctica is likely increasing snowmelt on the continent by an estimated 83 tonnes for each visitor, according to new research.
Scientists have estimated that the black carbon produced by vessels, planes and diesel generators results in 23mm of additional snowmelt each summer in the most frequently visited areas of the ice-covered landmass.
More than 74,000 tourists visited Antarctica in the 2019–2020 season, nearly double the figures from a decade ago.
A team of researchers sampled the snow yearly between 2016 and 2020 at 28 sites spanning 2000km from Antarctica’s northern tip to the Ellsworth Mountains.
They focused primarily on the Antarctic peninsula, where about half of the research facilities on the continent are located and where an estimated 95% of Antarctic tourist trips are made.
The team estimated that 53,000 tourists visited Antarctica annually between 2016 and 2020.
Study co-author Dr Raúl Cordero, of the University of Santiago Chile, said Antarctic snow was the cleanest on Earth, typically with baseline levels of black carbon around one part in a billion.
“That is 1000 times less than what you would find in the Himalayas, and 100 times less than what you can find in the Andes or in the Rocky Mountains,” he said.
“,”caption”:”Sign up to receive the top stories from Guardian Australia every morning.”,”isTracking”:false,”isMainMedia”:false,”source”:”The Guardian”,”sourceDomain”:”theguardian.com”}”>
Sign up to receive the top stories from Guardian Australia every morning.
Black carbon levels at sites on the Antarctic peninsula were between two and four times higher than on other parts of the continent.
“What black carbon is doing is making the snow darker [so it] is absorbing more solar radiation,” Cordero said. “That extra energy is accelerating the melting of the snow.”
He believes a limit on the number of tourists to Antarctica may need to be adopted.
The team quantified the likely snowmelt by calculating how black carbon pollution reduced the snow’s albedo – a measure of how well a surface reflects solar energy.
Researchers suggest that alternatives to diesel be used to power Antarctic facilities, such as wind. Photograph: Raul Cordero/University of Santiago, Chile
They calculated that an Antarctic researcher’s black carbon footprint was about 10 times greater than a tourist’s.
“We estimated that … the snow that is melting faster because of the activities carried out by a researcher would be closer to 1000 tonnes,” Cordero said. “Every researcher is using vessels, planes, helicopters, generators – and everybody’s using diesel for powering these.”
Cordero said that while the amount of pollution-induced snowmelt is far less than the ice and snow lost to global warming, the study highlighted the need for a transition to renewable energy sources.
“There are technical alternatives to diesel that could be used in Antarctica,” he said, citing the Belgian research station, Princess Elisabeth Antarctica, which is primarily powered by wind.
Prof Andrew Mackintosh, head of the school of earth atmosphere and environment at Monash University, who was not involved in the research, said the link between black carbon pollution and increased surface melt was well established in other parts of the world.
“In the Antarctic peninsula the two major processes [affecting melting] would still be warming oceans melting ice shelves from beneath, or warming surface air temperatures that are melting the ice from above,” Mackintosh said.
“If we have even greater surface warming in [the] decades to centuries ahead, as is projected for the Antarctic peninsula, then the additional black carbon on the surface will cause even more melt than would have occurred otherwise,” he said.
“Human activity is causing the polar regions to warm, but the burning of … [fossil] fuels has a direct consequence in terms of surface melt as well.”
“If you can get rid of the greenhouse gases in the first place, you’ll reduce the temperature increase,” he said. “There’s also the added benefit of less darkening of the snow surfaces.”
Cordero said: “Antarctica is the last continent more or less unpolluted. I think we should try to keep it that way.”
The study was published in the peer-reviewed journal Nature Communications.
