Month: April 2019

Spinning Black Hole Sprays Light-speed Plasma Clouds into Space

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An international team of astronomers, including Dr Alex Tetarenko, a researcher working at the East Asian Observatory in Hilo, Hawai’i, have discovered rapidly swinging jets coming from a black hole within our own Galaxy the Milky Way, almost 8,000 light-years from Earth. This black hole is much closer to us than Pōwehi, a black hole recently imaged with the Event Horizon Telescope, located around 56 million light-years away from Earth in another Galaxy.

Published today in the journal Nature, the research shows jets from V404 Cygni’s black hole behaving in a way never seen before on such short timescales.

The rapidly spinning black hole in V404 Cygni was observed to eject high-speed clouds of plasma, known as jets, travelling at close to the speed of light. These jets appeared to also be rapidly rotating, with multiple clouds of material ejected just minutes apart.

Lead author Associate Professor James Miller-Jones, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said black holes are some of the most extreme objects in the Universe.

“This is one of the most extraordinary black hole systems I’ve ever come across,” Associate Professor Miller-Jones said. “Like many black holes, it’s feeding on a nearby star, pulling gas away from the star and forming a disk of material that encircles the black hole and spirals towards it under gravity”.

An artist’s impression of the binary system that includes the black hole V404 Cygni and a sun-like star that orbit one another. Credit: ICRAR.

“What’s different in V404 Cygni is that we think the disk of material and the black hole are misaligned. This appears to be causing the inner part of the disk to wobble like a spinning top and fire jets out in different directions as it changes orientation.”

V404 Cygni, located in the constellation of Cygnus, was first identified as a black hole in 1989 when it released a big outburst of jets and material.

Astronomers looking at archival photographic plates then found previous outbursts in observations from 1938 and 1956.

Associate Professor Miller-Jones said that when V404 Cygni experienced another very bright outburst in 2015, lasting for two weeks, telescopes around the world tuned in to study what was going on.

“Everybody jumped on the outburst with whatever telescopes they could throw at it. So we have this amazing observational coverage” he said.

When Associate Professor Miller-Jones and his team studied the black hole, they saw its jets behaving in a way never seen before.

Where jets are usually thought to shoot straight out from the poles of black holes, these jets were shooting out in different directions at different times.

And they were changing direction very quickly—over no more than a couple of hours.

An artist’s impression of the inner parts of the accretion disk around the black hole V404 Cygni. Credit: ICRAR.

Associate Professor Miller-Jones said the change in the movement of the jets was because of the accretion disk—the rotating disk of matter around a black hole.

He said V404 Cygni’s accretion disk is 10 million kilometres wide, 7 times the diameter of the Sun, and the inner few thousand kilometres was puffed up and wobbling during the bright outburst.

“The inner part of the accretion disk was precessing and effectively pulling the jets around with it. You can think of it like the wobble of a spinning top as it slows down—only in this case, the wobble is caused by Einstein’s theory of general relativity.” Associate Professor Miller-Jones said.

The research used observations from the Very Long Baseline Array, a continent-sized radio telescope made up of 10 dishes across the United States, from the Virgin Islands in the Caribbean to Maunakea, Hawai’i.

Co-author Alex Tetarenko—an East Asian Observatory Fellow working in Hilo Hawai`i, and a recent PhD graduate from the University of Alberta —said the speed the jets were changing direction meant the scientists had to use a very different approach to most radio observations.

Dr Alex Tetarenko outside of the James Clerk Maxwell Telescope Office in Hilo, Hawaiʻi. Credit: Alyssa Clark

“Typically, radio telescopes produce a single image from several hours of observation. But these jets were changing so fast that in a four-hour image we just saw a blur. It was like trying to take a picture of a waterfall with a one-second long exposure” Dr. Tetarenko said.

Observations taken by Dr. Tetarenko and her team with two more telescopes on Maunakea, Hawai`i, the James Clerk Maxwell Telescope (JCMT) and the Sub-millimeter Array (SMA), also hinted at a rapidly evolving jet. Previously published in the journal Monthly Notices of the Royal Astronomical Society, these observations tracking the brightness of the jet over time, revealed extreme flaring events that coincided with the directly imaged jet ejection events.

“The incredible changes in brightness we saw in this JCMT and SMA data, and the model we designed to explain these changes, provided key information needed to develop our imaging method for this paper” she said.

To directly image these rapidly changing jets, the researchers produced 103 individual images, each about 70 seconds long. Miller-Jones and Tetarenko then led the efforts to combine those images into a continuous video—a difficult task, as each image required its own careful analysis.

“The result has been well worth the effort, illustrating this unique and unusual black hole behaviour” Dr. Tetarenko said.

“We were gobsmacked by what we saw in this system—it was completely unexpected,” said study co-author Gregory Sivakoff, a University of Alberta astrophysicist.  “Finding this astronomical first has deepened our understanding of how matter behaves near black holes”.

Study co-author Dr Gemma Anderson, who is also based at ICRAR’s Curtin University node, said the wobble of the inner accretion disk could happen in other extreme events in the Universe too.

“Anytime you get a misalignment between the spin of black hole and the material falling in, you would expect to see this when a black hole starts feeding very rapidly,” Dr Anderson said.

“That could include a whole bunch of other bright, explosive events in the Universe, such as supermassive black holes feeding very quickly or tidal disruption events, when a black hole shreds a star.”

Narrated V404 Cygni Black Hole Animation from ICRAR on Vimeo.

An animation of the precessing jets and accretion flow in V404 Cygni narrated by Associate Professor James Miller-Jones of Curtin University and ICRAR. Zooming in from the high-speed plasma clouds observed with our radio telescope, we see the binary system itself. Mass from the star spirals in towards the black hole via an accretion disk, whose inner regions are puffed up by intense radiation. The spinning black hole pulls spacetime (the green gridlines) around with it, causing the inner disk to precess like a spinning top, redirecting the jets as it does so. Credit: ICRAR.

V404 Cygni Black Hole Jets Simulation from ICRAR on Vimeo.

High-speed plasma clouds ejected from V404 Cygni over a four-hour period on 22nd June, 2015. This movie is made directly from our high-resolution radio images taken with the National Science Foundationʻs Very Long Baseline Array. It shows clouds of plasma in the precessing jets moving away from the black hole in different directions. The scale of the images is approximately the size of our Solar System, and time is shown by the clock in the bottom right-hand corner. Credit: ICRAR and the University of Alberta.

Media Contacts:

  • James Clerk Maxwell Telescope
    • Alex Tetarenko
    • 1-808-969-6519
    • a.tetarenko at eaobservatory.org
  • James Clerk Maxwell Telescope
    • Jessica Dempsey
    • 1-808-969-6512
    • j.dempsey at eaobservatory.org

 

About East Asian Observatory/James Clerk Maxwell Telescope

The EAO (East Asian Observatory) is formed  by EACOA (East Asian Core Observatories Association) for the purpose of pursuing joint projects in astronomy within the East Asian region. The EAO is chartered as a non-profit Hawai`i corporation. Its first task is to assume the operation of the James Clerk Maxwell Submillimetre Telescope (JCMT) on the summit of Maunakea, Hawai`i. Pursuant to an agreement with the University of Hawai`i, the EAO also provides engineering and IT support to the UKIRT Observatory (UKIRT). The JCMT is run by the non-profit organization the East Asian Observatory.

A new dimmconfig that uses PCA

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The $STARLINK_DIR/share/smurf directory includes several “dimmconfig” files that package up commonly used groups of configuration parameter values for use by the makemap command.  A new file called dimmconfig_pca.lis has recently been added, which can be combined with  other dimmconfig files to tell makemap to include a PCA model in its iterative algorithm (the PCA model removes noise signals that are correlated between multiple bolometer time-streams). For instance, to use a PCA model when creating a map of a bright extended source, you could run makemap as follows:

% more conf
^$STARLINK_DIR/share/smurf/dimmconfig_bright_extended.lis
^$STARLINK_DIR/share/smurf/dimmconfig_pca.lis
% makemap config=^conf

To process compact sources, change “bright_extended” above to “bright_compact“.

Using a PCA model can help to reduce the spurious extended structures that often appear in SCUBA-2 maps (although this benefit is bought at the cost of a much extended run time). For instance, below are four 850 um maps of DR 21 – the top row shows the maps made with the basic “bright extended” dimmconfig, and the bottom shows eh results of adding in the new PCA dimmconfig:

Below are the mosaics of the four observations, with the difference map shown in between:

As another example, the following panes show similar maps for three observations of the Serpens South field:

JCMT Plays Critical Role in Producing World’s First Image of a Black Hole – Pōwehi

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MAUNAKEA, HAWAIʻI –– Two of the world’s most powerful telescopes, located atop Maunakea, played a vital role in producing the world’s very first image of a black hole. Hawai‘i-based James Clerk Maxwell Telescope (JCMT) and Submillimeter Array (SMA) are part of the unprecedented Event Horizon Telescope (EHT) project. JCMT is operated by the East Asian Observatory; SMA is operated by the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics.

In April 2017, a groundbreaking observational campaign brought together eight telescopes at six locations around the globe to capture an image of Pōwehi, a supermassive black hole at the center of the Messier 87 galaxy.

Pōwehi

Using the Event Horizon Telescope, scientists obtained an image of the black hole at the center of galaxy M87, outlined by emission from hot gas swirling around it under the influence of strong gravity near its event horizon.

“Maunakea makes this discovery and the spectacular image of Pōwehi possible,” said Dr. Jessica Dempsey, deputy director of East Asian Observatory’s James Clerk Maxwell Telescope. “It’s perfect remote position, and the dry conditions on Maunakea’s summit, allow JCMT and SMA to collect the tiny amount of light that only touches our planet in a few very special places. Like the mountain itself, every drop of light we gather is precious.”

Astronomers collaborated with renowned Hawaiian language and cultural practitioner Dr. Larry Kimura for the Hawaiian naming of the black hole. Pōwehi, meaning embellished dark source of unending creation, is a name sourced from the Kumulipo, the primordial chant describing the creation of the Hawaiian universe. Pō, profound dark source of unending creation, is a concept emphasized and repeated in the Kumulipo, while wehi, or wehiwehi, honored with embellishments, is one of many descriptions of pō in the chant.

“It is awesome that we, as Hawaiians today, are able to connect to an identity from long ago, as chanted in the 2,102 lines of the Kumulipo, and bring forward this precious inheritance for our lives today,” said Dr. Kimura, associate professor at University of Hawai‘i at Hilo Ka Haka ‘Ula o Ke‘elikolani College of Hawaiian Language. “To have the privilege of giving a Hawaiian name to the very first scientific confirmation of a black hole is very meaningful to me and my Hawaiian lineage that comes from pō, and I hope we are able to continue naming future blackholes from Hawai‘i astronomy according to the Kumulipo.”

Dr Jessica Dempsey, Dr Larry Kimura, Dr Geoff Bower discuss the results at the JCMT, in front of the 15m dish.

The SMA and JCMT telescopes are key members of the Event Horizon Telescope project, which links together strategically placed radio telescopes across the globe to form a larger, Earth-sized telescope powerful enough to see a Lehua flower petal on the moon.

“SMA and JCMT, working together as one ‘ohana, pioneered the revolutionary technique to see such tiny and faint objects and they were critical in capturing the image of Pōwehi,” said Geoff Bower, chief scientist for Hawai‘i operations of Academia Sinica Institute of Astronomy and Astrophysics. “The spirit of aloha required to unite scientists and observatories across the world was born right here on Maunakea. And powerful new capabilities coming soon at SMA and JCMT mean that Hawai‘i’s groundbreaking contributions to understanding our universe are just beginning.”

The participation of the SMA and JCMT as the far-west anchor point of EHT’s telescope array allowed astronomers to effectively observe and “photograph” supermassive black holes, among the most mysterious and powerful objects in the cosmos.

About James Clerk Maxwell Telescope
Operated by the East Asian Observatory, the James Clerk Maxwell Telescope (JCMT) is the largest astronomical telescope in the world designed specifically to operate in the submillimeter wavelength region of the spectrum. The JCMT has a diameter of 15 meters and is used to study our Solar System, interstellar and circumstellar dust and gas, and distant galaxies. It is situated near the summit of Maunakea, Hawai‘i, at an altitude of 4,092 meters.

The JCMT is operated by the East Asian Observatory on behalf of The National Astronomical Observatory of Japan; Academia Sinica Institute of Astronomy and Astrophysics, Taiwan; the Korea Astronomy and Space Science Institute; Center for Astronomical Mega-Science, China. Additional funding support is provided by the Science and Technology Facilities Council of the United Kingdom and participating universities in the United Kingdom and Canada. The East Asian Observatory also proudly partners with Vietnam, Thailand, Malaysia, Indonesia, and India. Click here for more information.

About Event Horizon Telescope

The EHT collaboration involves more than 200 researchers from Africa, Asia, Europe, North and South America. The international collaboration is working to capture the first-ever image of a black hole by creating a virtual Earth-sized telescope. Supported by considerable international investment, the EHT links existing telescopes using novel systems — creating a fundamentally new instrument with the highest angular resolving power that has yet been achieved.

The individual telescopes involved are; ALMA, APEX, the IRAM 30-meter Telescope, the IRAM NOEMA Observatory, the James Clerk Maxwell Telescope (JCMT), the Large Millimeter Telescope Alfonso Serrano (LMT), the Submillimeter Array (SMA), the Submillimeter Telescope (SMT), the South Pole Telescope (SPT), the Kitt Peak Telescope, and the Greenland Telescope (GLT).

The EHT collaboration consists of 13 stakeholder institutes; the Academia Sinica Institute of Astronomy and Astrophysics, the University of Arizona, the University of Chicago, the East Asian Observatory, Goethe-Universitaet Frankfurt, Institut de Radioastronomie Millimétrique, Large Millimeter Telescope, Max Planck Institute for Radio Astronomy, MIT Haystack Observatory, National Astronomical Observatory of Japan, Perimeter Institute for Theoretical Physics, Radboud University and the Smithsonian Astrophysical Observatory.

This research was presented in a series of six papers published today in a special issue of The Astrophysical Journal Letters.

More information on the Event Horizon Telescope can be found on the EHT website. For a copy of the Press release in `ōlelo Hawai’i click here.

MEDIA CONTACT:

Dylan Beesley, Director, Bennet Group Strategic Communications

dylan at bennetgroup.com

Dr Jessica Dempsey, Deputy Director

j.dempsey at eaobservatory.org

 

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