Astronomers find evidence for the tightest-knit supermassive <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>black hole duo observed to date.
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 <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>Pluto. When the pair merge in roughly 10,000 years, the titanic collision is expected to shake space and time itself, sending <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>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), <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>MIT’s Haystack Observatory, the National Radio Astronomy Observatory (NRAO), Metsähovi Radio Observatory in Finland, and <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>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 <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>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 <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>LIGO.
In the future, <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>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.
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.
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.
After 45 years, NASA's Voyager 1 space probe encounters mystery issue – CP24 Toronto's Breaking News
(CNN) — The Voyager 1 probe is still exploring interstellar space 45 years after launching, but it has encountered an issue that mystifies the spacecraft’s team on Earth.
Voyager 1 continues to operate well, despite its advanced age and 14.5 billion-mile distance (23.3 billion kilometers) from Earth. And it can receive and execute commands sent from NASA, as well as gather and send back science data.
But the readouts from the attitude articulation and control system, which control the spacecraft’s orientation in space, don’t match up with what Voyager is actually doing. The attitude articulation and control system, or AACS, ensures that the probe’s high-gain antenna remains pointed at Earth so Voyager can send data back to NASA.
Due to Voyager’s interstellar location, it takes light 20 hours and 33 minutes to travel one way, so the call and response of one message between NASA and Voyager takes two days.
So far, the Voyager team believes the AACS is still working, but the instrument’s data readouts seem random or impossible. The system issue hasn’t triggered anything to put the spacecraft into “safe mode” so far. That’s when only essential operations occur so engineers can diagnose an issue that would put the spacecraft at risk.
And Voyager’s signal is as strong as ever, meaning the antenna is still pointed to Earth. The team is trying to determine if this incorrect data is coming directly from this instrument or if another system is causing it.
“Until the nature of the issue is better understood, the team cannot anticipate whether this might affect how long the spacecraft can collect and transmit science data,” according to a NASA release.
“A mystery like this is sort of par for the course at this stage of the Voyager mission,” said Suzanne Dodd, project manager for Voyager 1 and 2 at NASA’s Jet Propulsion Laboratory in Pasadena, California, in a statement.
“The spacecraft are both almost 45 years old, which is far beyond what the mission planners anticipated. We’re also in interstellar space — a high-radiation environment that no spacecraft have flown in before. So there are some big challenges for the engineering team. But I think if there’s a way to solve this issue with the AACS, our team will find it.”
If the team doesn’t determine the source of the issue, they may just adapt to it, Dodd said. Or if they can find it, the issue may be solved by making a software change or relying on a redundant hardware system.
Voyager has already relied on backup systems to last as long as it has. In 2017, the probe fired thrusters that were used during its initial planetary encounters during the 1970s — and they still worked after remaining unused for 37 years.
The aging probes produce very little power per year, so subsystems and heaters have been turned off over the years so that critical systems and science instruments can keep operating.
Voyager 2, a twin spacecraft, continues to operate well in interstellar space 12.1 billion miles (19.5 billion kilometers) from Earth. By comparison, Neptune, the farthest planet from Earth, is, at most, only 2.9 billion miles away. Both probes were launched in 1977 and have far exceeded their original purpose to fly by planets.
Now, they have become the only two spacecraft to gather data from interstellar space and provide insights about the heliosphere, or the bubble created by the sun that extends beyond the planets in our solar system.
Boeing's Starliner ready to launch to space station on 2nd test flight – CBC.ca
Boeing’s new Starliner capsule was set for launch on Thursday on a do-over uncrewed test flight to the International Space Station, aiming to deliver the company a much-needed success after two years of delays and costly engineering setbacks.
The gumdrop-shaped CST-100 Starliner was scheduled for liftoff at 6:54 p.m. ET from the Cape Canaveral Space Force Station in Florida, carried atop an Atlas V rocket furnished by the Boeing-Lockheed Martin joint venture United Launch Alliance (ULA).
ULA said Wednesday evening forecasts called for a 70 per cent chance of favourable weather conditions for an on-time launch.
If all goes as planned, the capsule will arrive at the space station about 24 hours later, docking with the research outpost orbiting some 400 kilometres above Earth at 7:10 p.m. ET on Friday.
The <a href=”https://twitter.com/BoeingSpace?ref_src=twsrc%5Etfw”>@BoeingSpace</a> <a href=”https://twitter.com/hashtag/Starliner?src=hash&ref_src=twsrc%5Etfw”>#Starliner</a> counts down to liftoff at 6:54pm ET today as the Exp 67 crew preps for its Friday arrival and keeps up human research. <a href=”https://t.co/PqF6Pkbf9Z”>https://t.co/PqF6Pkbf9Z</a>
The Boeing craft is to spend four to five days attached to the space station before undocking and flying back to Earth, with a parachute landing cushioned by airbags on the desert floor of White Sands, New Mexico.
A successful mission will move the long-delayed Starliner a major step closer to providing NASA with a second reliable means of ferrying astronauts to and from the International Space Station (ISS).
Since resuming crewed flights to orbit from American soil in 2020, nine years after the space shuttle program ended, the U.S. space agency has had to rely solely on the Falcon 9 rockets and Crew Dragon capsules flown by Elon Musk’s company SpaceX.
Payload and model passenger
The Starliner will not be flying to orbit empty. The capsule will carry a research mannequin to collect data on crew cabin conditions during the journey, plus 500 pounds of cargo for delivery to the space station’s crew — three NASA astronauts, a European Space Agency astronaut from Italy and three Russian cosmonauts.
Two of the U.S. astronauts will be tasked with boarding the capsule during Starliner’s stay to take measurements of its interior environment and unload the supplies.
Thursday’s launch marks a repeat of a 2019 test mission that failed to achieve a successful rendezvous with the space station because of a flight-software malfunction. Subsequent problems with Starliner’s propulsion system, supplied by Aerojet Rocketdyne, led Boeing to scrub an attempt to launch the capsule last summer.
The spacecraft remained grounded for nine more months while the two companies sparred over what caused its fuel valves to stick shut and which firm was responsible for fixing them.
Boeing says it has since resolved the glitch with a temporary workaround and plans to redesign the propulsion system’s fuel valves system after this week’s flight.
Starliner was developed with a $4.5 billion US fixed-price NASA contract to provide the U.S. space agency a second avenue to low-Earth orbit, along with SpaceX, and has proven costly to Boeing.
Delays and engineering setbacks with Starliner have led the aerospace giant to take $595 million US in charges since the capsule’s 2019 failure, even as the company strives to climb out of successive crises in its jetliner business and its space-defence unit.
If the second uncrewed trip to orbit succeeds, Starliner could fly its first team of astronauts in the fall, though NASA officials caution that time frame could get pushed back.
NASA astronauts Butch Wilmore and Mike Fincke had been designated to fly Starliner’s maiden crewed mission. But NASA officials, reluctant to tie down two astronauts to a flight whose launch date is uncertain, said Wednesday the mission could end up carrying at least two of any of the four astronauts now training to test-fly Starliner.
Dusty demise for NASA Mars lander in July; power dwindling – CGTN
A NASA spacecraft on Mars is headed for a dusty demise.
The InSight lander is losing power because of all the dust on its solar panels. NASA said Tuesday it will keep using the spacecraft’s seismometer to register marsquakes until the power peters out, likely in July. Then flight controllers will monitor InSight until the end of this year, before calling everything off.
“There really hasn’t been too much doom and gloom on the team. We’re really still focused on operating the spacecraft,” said Jet Propulsion Laboratory’s Bruce Banerdt, the principal scientist.
Since landing on Mars in 2018, InSight has detected more than 1,300 marsquakes; the biggest one, a magnitude 5, occurred two weeks ago.
It will be NASA’s second Mars lander lost to dust: A global dust storm took out Opportunity in 2018. In InSight’s case, it’s been a gradual gathering of dust, especially over the past year.
NASA’s two other functioning spacecraft on the Martian surface – rovers Curiosity and Perseverance – are still going strong thanks to nuclear power. The space agency may rethink solar power in the future for Mars, said planetary science director Lori Glaze, or at least experiment with new panel-clearing tech or aim for the less-stormy seasons.
InSight currently is generating one-tenth of the power from the sun that it did upon arrival. Deputy project manager Kathya Zamora Garcia said the lander initially had enough power to run an electric oven for one hour and 40 minutes; now it’s down to 10 minutes max.
The InSight team had anticipated this much dust buildup, but hoped a gust of wind or dust devil might clean off the solar panels. That has yet to happen, despite several thousand whirlwinds coming close.
“None of them have quite hit us dead-on yet enough to blow the dust off the panels,” Banerdt told reporters.
Another science instrument, dubbed the mole, was supposed to burrow 16 feet (5 meters) underground to measure the internal temperature of Mars. But the German digger never got deeper than a couple of feet (a half-meter) because of the unexpected composition of the red dirt, and it finally was declared dead at the beginning of last year.
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Europe kicks off vaccination programs | All media content | DW | 27.12.2020 – Deutsche Welle
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