From National Astronomical Observatory of Japan: “Seeds of Giant Galaxies formed in the Early Universe”

From National Astronomical Observatory of Japan

December 20, 2018

An international research team has shown that the largest galaxies in the Universe may have started out as ultra-dense objects in the very early Universe that then expanded over time.

Figure 1: A wide field-of-view false-color image of a massive quiescent galaxy taken by Surpime-Cam on the Subaru Telescope (main image) and a high resolution close-up (inset) by IRCS (Infrared Camera and Spectrograph) on the Subaru Telescope. The yellow circle shows the point spread function of this observation corrected with the AO188 adaptive optics system. (Credit: NAOJ)

NAOJ Subaru Adaptive Optics system

Modern galaxies show a wide diversity, including dwarf galaxies, irregular galaxies, spiral galaxies, and massive elliptical galaxies. This final type, massive elliptical galaxies, provides astronomers with a puzzle. Although they are the most massive galaxies with the most stars, almost all of their stars are old. At some time during the past the progenitors of massive elliptical galaxies must have rapidly formed many stars and then stopped for some reason.

Fortunately, the finite speed of light gives scientists a way to turn back the clock and view the early Universe. If a galaxy is located 12 billion light-years away, then light from that galaxy must have traveled for 12 billion years before it reached Earth. This means that the light we observe today must have left the galaxy 12 billion years ago. In other words the light is the image of what the galaxy looked like 12 billion years ago. By observing galaxies at various distances from Earth, astronomers can reconstruct the history of the Universe.

An international team including researchers from the National Astronomical Observatory of Japan (NAOJ), the University of Tokyo, and Copenhagen University used data from NAOJ’s Subaru Telescope and other telescopes [name them, please] to search for galaxies located 12 billion light-years away. Among this sample they identified massive quiescent galaxies, meaning massive galaxies without active star formation, as the probable progenitors of modern giant elliptical galaxies. It is surprising that mature giant galaxies already existed very early, when the Universe was only about ~13% of its current age.

The team then used the Subaru Telescope to perform high resolution follow-up observations in near infrared for the 5 brightest massive quiescent galaxies located 12 billion light-years away.

The results show that although the massive quiescent galaxies are compact (only about 2% the size of the Milky Way) they are almost as heavy as modern galaxies. This means that to become modern giant elliptical galaxies they must puff up about 100 times in size, but only increase in mass by about 5 times. Comparing the observations to toy models, the team showed that this would be possible if the growth was driven, not by major mergers where two similar galaxies merge to form a larger one, but by minor mergers where a large galaxy cannibalizes smaller ones.

Figure 2: The stellar mass (x-axis) and size (y-axis) relation derived assuming that the most massive galaxies at each epoch are the progenitors of the modern most massive giant elliptical galaxies (red). Gray solid and dashed curves show the size evolution driven by many minor mergers and major mergers, respectively. (Credit: NAOJ)

“We are very excited about the implications of our findings,” explains corresponding author Mariko Kubo, a post-doctoral researcher at NAOJ. “But we are now at the resolution limit of existing telescopes. The superior spatial resolution of the Thirty Meter Telescope currently under development will allow us to study the morphologies of distant galaxies more precisely. For more distant galaxies beyond 12 billion light-years, we need the next generation James Webb Space Telescope.”

TMT-Thirty Meter Telescope, proposed and now approved for Mauna Kea, Hawaii, USA4,207 m (13,802 ft) above sea level

NASA/ESA/CSA Webb Telescope annotated

These results appeared as Kubo et al. 2018, “The Rest-frame Optical Sizes of Massive Galaxies with Suppressed Star Formation at z∼4” in The Astrophysical Journal on November 20, 2018.

This research is supported by KAKENHI Grant Numbers JP15K17617, JP16K17659, and JP18K13578.

See the full article here .

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NAOJ

The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

ESO/NRAO/NAOJ ALMA Array

Solar Flare Telescope

Nobeyama Radio Observatory

Nobeyama Radio Observatory: Solar

Mizusawa VERA Observatory

Okayama Astrophysical Observatory

From National Astronomical Observatory of Japan: “Subaru Telescope Discovers a New Extremely Distant Solar System Object During Hunt for Planet X”

From National Astronomical Observatory of Japan

Using Hyper Suprime-Cam (HSC) on the Subaru Telescope, astronomers have discovered a new object at the edge of our Solar System. The new extremely distant object far beyond Pluto has an orbit that supports the presence of an even-farther-out Super-Earth, or larger Planet X.

NAOJ Subaru Hyper Suprime-Cam

NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

Movie of the discovery images of 2015 TG387. Two images were taken about 3 hours apart on October 13, 2015 at the Subaru Telescope. 2015 TG387 can be seen moving between the images near the center, while the more distant background stars and galaxies remain stationary. (Credit: Dave Tholen, Chad Trujillo, Scott Sheppard)

The discovery of the newly found object, called 2015 TG387, was made by Carnegie Institution for Sciences’ Scott Sheppard, Northern Arizona University’s Chad Trujillo, and the University of Hawai’i Institute for Astronomy’s David Tholen. 2015 TG387 was discovered about 80 astronomical units (au) from the Sun. One AU is the distance between the Earth and Sun. For context, Pluto is around 34 au, so 2015 TG387 is about two and a half times further away from the Sun than Pluto is right now.

“The objects we’re looking for are both faint and can be pretty much anywhere in the sky, so the ability to reach a faint limiting magnitude (large aperture) and cover a large amount of sky (wide field) is crucial for this work. The Subaru Telescope with its wide-field imaging camera Hyper Suprime-Cam is the facility best suited for this work,” says Tholen.

The new object is on a very elongated orbit and the closest it ever gets to the Sun, a point called perihelion, is about 65 au. Only 2012 VP113 and Sedna, at 80 and 76 au respectively, have more distant perihelia than 2015 TG387. Even though 2015 TG387 has the third-most-distant perihelion, its orbital semi-major axis is larger than that of both 2012 VP113 and Sedna, meaning it travels much farther from the Sun than they do. At its furthest point, it reaches all the way out to about 2300 au. 2015 TG387 is one of the few known objects that never comes close enough to the Solar System’s giant planets, like Neptune and Jupiter, to have significant gravitational interactions with them.

“These so-called Inner Oort Cloud objects like 2015 TG387, 2012 VP113, and Sedna are isolated from most of the Solar System’s known mass, which makes them immensely interesting,” Sheppard explained. “They can be used as probes to understand what is happening at the edge of our Solar System.”

Oort Cloud, The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA, Universe Today

The orbits of the new extreme object 2015 TG387 and its fellow Inner Oort Cloud objects 2012 VP113 and Sedna, as compared with the rest of the Solar System. The of 2015 TG387 orbit has a larger semi-major axis than both 2012 VP11 and Sedna, so it travels much farther from the Sun, out to 2,300 au. (Credit: Roberto Molar Candanosa and Scott Sheppard / Carnegie Institution for Science)

The object with the most distant orbit at perihelion, 2012 VP113, was also discovered by Sheppard and Trujillo, in 2014. The discovery of 2012 VP113 led Sheppard and Trujillo to notice similarities of the orbits of several extremely distant Solar System objects, and they proposed the presence of an unknown planet several times larger than Earth — sometimes called Planet X or Planet 9 — orbiting the Sun, well beyond Pluto at hundreds of au.

“We think there could be thousands of small bodies like 2015 TG387 out on the Solar System’s fringes, but their distance makes finding them very difficult,” Tholen said. “Currently we would only detect 2015TG387 when it is near its closest approach to the Sun. For some 99 percent of its 40,000-year orbit, it would be too faint to see, even with today’s largest telescopes.”

The object was discovered as part of the team’s ongoing hunt for unknown dwarf planets and Planet X. It is the largest and deepest survey ever conducted for distant Solar System objects.

“These distant objects are like breadcrumbs leading us to Planet X. The more of them we can find, the better we can understand the outer Solar System and the possible planet that we think is shaping their orbits — discovery that would redefine our knowledge of the Solar System’s evolution,” Sheppard added.

It took the team a few years of observations to obtain a good orbit for 2015 TG387 because it moves so slowly and has such a long orbital period. They first observed 2015 TG387 in October of 2015 at the Subaru Telescope. Follow-up observations at the Magellan telescope at Carnegie’s Las Campanas Observatory in Chile, and the Discovery Channel Telescope in Arizona, were obtained in 2015, 2016, 2017 and 2018, to determine 2015 TG387’s orbit.

Carnegie 6.5 meter Magellan Baade and Clay Telescopes located at Carnegie’s Las Campanas Observatory, Chile. over 2,500 m (8,200 ft) high

Discovery Channel Telescope at Lowell Observatory, Happy Jack AZ, USA, Altitude 2,360 m (7,740 ft)

2015 TG387 is likely on the small end of being a dwarf planet, since it has a diameter of roughly 300 kilometers. The location in the sky where 2015 TG387 reaches perihelion is similar to 2012 VP113, Sedna, and most other known extremely distant trans-Neptunian objects, suggesting that something is pushing them into similar types of orbits.

Trujillo and University of Oklahoma’s Nathan Kaib ran computer simulations to see how different hypothetical Planet X orbits would affect the orbit of 2015 TG387. The simulations included a super-Earth-mass planet at several hundred au on an elongated orbit, as proposed by Caltech’s Konstantin Batygin and Michael Brown in 2016. Most of the simulations showed that not only was 2015 TG387’s orbit stable for the age of the Solar System, but it was actually shepherded by Planet X’s gravity, which keeps the smaller 2015 TG387 away from the massive planet. This gravitational shepherding could explain why the most distant objects in our Solar System have similar orbits. These orbits keep them from ever approaching the proposed planet too closely, similar to how Pluto never gets too close to Neptune even though their orbits cross.

“What makes this result really interesting is that Planet X seems to affect 2015 TG387 the same way as all the other extremely distant Solar System objects. These simulations do not prove that there is another massive planet in our Solar System, but they are further evidence that something big could be out there,” Trujillo concludes.

2015 TG387 was announced in the Minor Planet Electronic Circular issued by the International Astronomical Union’s Minor Planet Center on October 1, 2018 (Tholen, D., Sheppard, S., and Trujillo, C. 2018, MPEC, 2018-T05). The research paper with the full details of the discovery is available as a preprint (Scott S. Sheppard, Chadwick A. Trujillo, David J. Tholen, Nathan Kaib 2018, arXiv:1810.00013, “A New High Perihelion Inner Oort Cloud Object”), and has also been submitted to The Astronomical Journal.

Links:

Press Release from Carnegie Institution for Science
Press release from the University of Hawai’i Institute for Astronomy

See the full article here .

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NAOJ

The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

ESO/NRAO/NAOJ ALMA Array

Solar Flare Telescope

Nobeyama Radio Observatory

Nobeyama Radio Observatory: Solar

Mizusawa VERA Observatory

Okayama Astrophysical Observatory

From UC Riverside: “Early Opaque Universe Linked to Galaxy Scarcity”

From UC Riverside

August 14, 2018
Iqbal Pittalwala

Computer simulation of a region of the universe wherein a low-density “void” (dark blue region at top center) is surrounded by denser structures containing numerous galaxies (orange/white). The research done by Becker and his team suggests that early in cosmic history, these void regions would have been the murkiest places in the universe even though they contained the least amount of dark matter and gas. Image credit: TNG Collaboration.

A team of astronomers led by George Becker at the University of California, Riverside, has made a surprising discovery: 12.5 billion years ago, the most opaque place in the universe contained relatively little matter.

It has long been known that the universe is filled with a web-like network of dark matter and gas. This “cosmic web” accounts for most of the matter in the universe, whereas galaxies like our own Milky Way make up only a small fraction.

Cosmic web Millenium Simulation Max Planck Institute for Astrophysics

Today, the gas between galaxies is almost totally transparent because it is kept ionized— electrons detached from their atoms—by an energetic bath of ultraviolet radiation.

Over a decade ago, astronomers noticed that in the very distant past — roughly 12.5 billion years ago, or about 1 billion years after the Big Bang — the gas in deep space was not only highly opaque to ultraviolet light, but its transparency varied widely from place to place, obscuring much of the light emitted by distant galaxies.

Then a few years ago, a team led by Becker, then at the University of Cambridge, found that these differences in opacity were so large that either the amount of gas itself, or more likely the radiation in which it is immersed, must vary substantially from place to place.

“Today, we live in a fairly homogeneous universe,” said Becker, an expert on the intergalactic medium, which includes dark matter and the gas that permeates the space between galaxies. “If you look in any direction you find, on average, roughly the same number of galaxies and similar properties for the gas between galaxies, the so-called intergalactic gas. At that early time, however, the gas in deep space looked very different from one region of the universe to another.”

To find out what created these differences, the team of University of California astronomers from the Riverside, Santa Barbara, and Los Angeles campuses turned to one of the largest telescopes in the world: the Subaru telescope on the summit of Mauna Kea in Hawaii.

NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

Using its powerful camera, the team looked for galaxies in a vast region, roughly 300 million light years in size, where they knew the intergalactic gas was extremely opaque.

For the cosmic web more opacity normally means more gas, and hence more galaxies. But the team found the opposite: this region contained far fewer galaxies than average. Because the gas in deep space is kept transparent by the ultraviolet light from galaxies, fewer galaxies nearby might make it murkier.

“Normally it doesn’t matter how many galaxies are nearby; the ultraviolet light that keeps the gas in deep space transparent often comes from galaxies that are extremely far away. That’s true for most of cosmic history, anyway,” said Becker, an assistant professor in the Department of Physics and Astronomy. “At this very early time, it looks like the UV light can’t travel very far, and so a patch of the universe with few galaxies in it will look much darker than one with plenty of galaxies around.”

This discovery, reported in the August 2018 issue of the Astrophysical Journal, may eventually shed light on another phase in cosmic history. In the first billion years after the Big Bang, ultraviolet light from the first galaxies filled the universe and permanently transformed the gas in deep space. Astronomers believe that this occurred earlier in regions with more galaxies, meaning the large fluctuations in intergalactic radiation inferred by Becker and his team may be a relic of this patchy process, and could offer clues to how and when it occurred.

“There is still a lot we don’t know about when the first galaxies formed and how they altered their surroundings,” Becker said.

By studying both galaxies and the gas in deep space, astronomers hope to get closer to understanding how this intergalactic ecosystem took shape in the early universe.

The research was funded by the National Science Foundation and NASA.

Becker was joined in the research by Frederick B. Davies of UC Santa Barbara; Steven R. Furlanetto and Matthew A. Malkan of UCLA; and Elisa Boera and Craig Douglass of UCR.

See the full article here .

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The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

From National Astronomical Observatory of Japan: “New IR Instrument Searches for Habitable Planets”

From National Astronomical Observatory of Japan

July 2, 2018

Test observation of a red dwarf. Comparing the star’s spectrum (broken line) to the laser frequency comb (dots) allows researchers to calculate the motion of the star.

A new instrument to search for potentially habitable/inhabited planets has started operation at the Subaru Telescope. This instrument, IRD (InfraRed Doppler), will look for habitable planets around red dwarf stars. Astronomers are hoping that investigating these small but numerous stars will uncover a plethora of new planets.

IRD schematic. https://www.spiedigitallibrary.org

Red dwarfs are smaller than the Sun and emit most of their energy as infrared (IR) rather than visible light. But because they are smaller, it is easier to find planets around them. Also, in the neighborhood around the Sun there are many late-M-type stars (a type of red dwarf) ripe for investigation. The sheer number of candidates raises the odds of finding potentially habitable or otherwise interesting planets.

But red dwarfs are enough different from the Sun that a new instrument was needed before they could be surveyed for planets. Researchers at NINS Astrobiology Center, National Astronomical Observatory of Japan, University of Tokyo, Tokyo University of Agriculture and Technology, and Tokyo Institute of Technology created IRD to observe the IR light which is emitted strongly by red dwarf stars. Combined with the large light gathering power of the Subaru Telescope to capture the faint light from red dwarfs, IRD will allow astronomers to survey hundreds of stars looking for planets.

New technology, known as a laser frequency comb, provides a standard ruler for measuring the line-of-sight movement of a star to within a few meters per second. Watching this motion for effects caused by planets around the star reveals not only the presence of a planet, but also its characteristics, like its mass and distance from the star. By comparing this information to models, researchers can choose the most interesting planets for detailed follow up observations.

IRD had successful test observations earlier this year and will be available to the world-wide astronomical community starting from August 2018.

See the full article here .

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Please help promote STEM in your local schools.

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NAOJ

The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

ESO/NRAO/NAOJ ALMA Array

Solar Flare Telescope

Nobeyama Radio Observatory

Nobeyama Radio Observatory: Solar

Mizusawa VERA Observatory

Okayama Astrophysical Observatory

From National Astronomical Observatory of Japan : “Next generation of telescope equipment begins arriving in Hawai`i”

National Astronomical Observatory of Japan

April 27, 2018

Summary of PFS, including the Metrology Camera.

An instrument that will help astronomers study dark matter and galaxies in detail has begun to be assembled at NAOJ’s Subaru Telescope in Hawai`i.

The Metrology Camera is the first of several sub-components currently under construction worldwide to be assembled at its final destination in order to create the Prime Focus Spectrograph (PFS). When the PFS is mounted on the telescope, it will be able to measure spectra of up to 2400 celestial objects in the night sky all at once. This is important because it will help astronomers understand how stars and galaxies are distributed, and how they move around us, affected by the presence of dark matter. Studying millions of stars and galaxies across large areas of sky will therefore help create a dark matter map of our Universe.

The camera arrived in Hawai`i last Friday (April 20) from the Academia Sinica, Institute of Astronomy and Astrophysics in Taiwan, the collaborators in the PFS project who developed it. After checks to make sure the Metrology Camera is not damaged during transportation, the camera will be shipped to the Subaru Telescope on the summit of Mauna Kea for further tests in the telescope’s dome in May, and on the telescope in June and July. Other subcomponents will then follow, and the PFS will be completed.

Led by the University of Tokyo Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), the PFS project is an international collaboration to conduct an unprecedented census of the Universe, taking advantage of the Subaru Telescope to take a wide shot of the night sky with great depth. Combining data from the PFS and Hyper Suprime-Cam, astronomers hope to learn more about the nature of dark matter, dark energy, galaxy growth history, and challenge our understanding of the Universe and underlying physics.

NAOJ Subaru Hyper Suprime-Cam

In the current schedule, the PFS is anticipated to start its experimental run at the Subaru Telescope in 2019, before starting a formal survey in 2021.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition
The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

NAOJ

NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

ESO/NRAO/NAOJ ALMA Array

Solar Flare Telescope

Nobeyama Radio Observatory

Nobeyama Radio Observatory: Solar

Mizusawa VERA Observatory

Okayama Astrophysical Observatory

From Science Node: Women in STEM – “Burçin’s galaxy” Burçin Mutlu-Pakdil

Science Node

30 Mar, 2018
Ellen Glover

Burçin Mutlu-Pakdil

As a little girl growing up in Turkey, Burçin Mutlu-Pakdil loved the stars.

Burçin’s galaxy, AKA PGC 1000714, is a unique, double-ringed, Hoag-type galaxy exhibiting features never observed before. Courtesy North Carolina Museum of Natural Sciences.

“How is it possible not to fall in love with stars?” wonders Mutlu-Pakdil. “I find it very difficult not to be curious about the Universe, about the Milky Way and how everything got together. I really want to learn more. I love my job because of that.”

Young or old? The object’s blue outer rings suggests it may have formed more recently than the center.

Her job is at The University of Arizona’s Steward Observatory, one of the world’s premier astronomy facilities, where she works as a postdoctoral astrophysics research associate.

U Arizona Steward Observatory at Kitt Peak, AZ, USA, altitude 2,096 m (6,877 ft)

Just a few years ago, while earning her Ph.D. at the University of Minnesota, Mutlu-Pakdil and her colleagues discovered PGC 1000174, a galaxy with qualities so rare they’ve never been observed anywhere else. For now, it’s known as Burçin’s Galaxy.

The object was originally detected by Patrick Treuthardt, who was observing a different galaxy when he spotted it in the background. It piqued the astronomers’ attention because of an initial resemblance to Hoag’s Object. This rare galaxy is known for its yellow-orange center surrounded by a detached outer ring.

“Our object looks very similar to Hoag’s Object. It has a very symmetric central body with a very symmetric outer ring,” explains Mutlu-Pakdil. “But my work showed that there is actually a second ring on this object. This makes it much more complex.”

Through extensive imaging and analysis, Mutlu-Pakdil found that, unlike Hoag’s Object, this new galaxy has two rings with no visible materials attaching them, a phenomenon not seen before. It offered the first-ever observation and description of a double-ringed elliptical galaxy.

Eye on the universe. Sophisticated instruments like the 8.2 meter optical-infrared Subaru Telescope on the summit of Mauna Kea in Hawaii allow astronomers to peer ever further into the stars–and into the origins of the universe.

NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

Since spotting the intriguing galaxy, Mutlu-Pakdil and her team have evaluated it in several ways. They initially observed it via the Irénéé du Pont two-meter telescope at the Las Campanas observatory in Chile. And they recently captured infrared images with the Magellan 6.5-meter telescope also at Las Campanas.

Carnegie Las Campanas Dupont telescope, Atacama Desert, over 2,500 m (8,200 ft) high approximately 100 kilometres (62 mi) northeast of the city of La Serena,Chile

Carnegie 6.5 meter Magellan Baade and Clay Telescopes located at Carnegie’s Las Campanas Observatory, Chile. over 2,500 m (8,200 ft) high

The optical images reveal that the components of Burçin’s Galaxy have different histories. Some parts of the galaxy are significantly older than others. The blue outer ring suggests a newer formation, while the red inner ring indicates the presence of older stars.

Mutlu-Pakdil and her colleagues suspect that this galaxy was formed as some material accumulated into one massive object through gravitational attraction, AKA an accretion event.

However, beyond that, PGC1000174’s unique qualities largely remain a mystery. There are about three trillion galaxies in our observable universe and more are being found all the time.

“In such a vast universe, finding these rare objects is really important,” says Mutlu-Pakdil. “We are trying to create a complete picture of how the Universe works. These peculiar systems challenge our understanding. So far, we don’t have any theory that can explain the existence of this particular object, so we still have a lot to learn.”

Challenging norms and changing lives

In a way, Mutlu-Pakdil has been challenging the norms of science all her life.

Though her parents weren’t educated beyond elementary school, they supported her desire to pursue her dreams of the stars.

“When I was in college, I was the only female in my class, and I remember I felt so much like an outsider. I felt like I wasn’t fitting in,” she recalls of her time studying physics at Bilkent University in Ankara, Turkey.

Bilkent University

Astronomical ambassador. Mutlu-Pakdil believes in sharing her fascination for space and works to encourage students from all backgrounds to explore astronomy and other STEM fields.

Throughout her education and career, Mutlu-Pakdil has experienced being a minority in an otherwise male-dominated field. It hasn’t slowed her down, but it has made her more passionate about promoting diversity in science and being a mentor to young people.

“I realized, it is not about me, it is society that needs to change,” she says. “Now I really want to inspire people to do similar things. So kids from all backgrounds will be able to understand they can do science, too.”

That’s why she serves as an ambassador for the American Astronomical Society and volunteers to mentor children in low-income neighborhoods to encourage them to pursue college and, hopefully, a career in STEM.

She was also recently selected to be a 2018 TED Fellow and will present a TED talk about her discoveries and career on April 10.

Through her work, Mutlu-Pakdil hopes to show people how important it is to learn about our universe. It behooves us all to take an interest in the night sky and the groundbreaking discoveries being made by astronomers like her around the world.

“We are a part of this Universe, and we need to know what is going on in it. We have strong theories about how common galaxies form and evolve, but, for rare ones, we don’t have much information,” says Mutlu-Pakdil. “Those unique objects present the extreme cases, so they really give us a big picture for the Universe’s evolution — they stretch our understanding of everything.”

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

Science Node is an international weekly online publication that covers distributed computing and the research it enables.

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From NAOJ: “Double or Nothing: Astronomers Rethink Quasar Environment”

NAOJ

March 12, 2018
No writer credit

Using Hyper Suprime-Cam (HSC) mounted on the Subaru Telescope, astronomers have identified nearly 200 “protoclusters,” the progenitors of galaxy clusters, in the early Universe, about 12 billion years ago, about ten times more than previously known.

NAOJ Subaru Hyper Suprime-Cam

NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

They also found that quasars don’t tend to reside in protoclusters; but if there is one quasar in a protocluster, there is likely a second nearby. This result raises doubts about the relation between protoclusters and quasars.

In the Universe, galaxies are not distributed uniformly. There are some places, known as clusters, where dozens or hundreds of galaxies are found close together. Other galaxies are isolated. To determine how and why clusters formed, it is critical to investigate not only mature galaxy clusters as seen in the present Universe but also observe protoclusters, galaxy clusters in the process of forming.

Because the speed of light is finite, observing distant objects allows us to look back in time. For example, the light from an object 1 billion light-years away was actually emitted 1 billion years ago and has spent the time since then traveling through space to reach us. By observing this light, astronomers can see an image of how the Universe looked when that light was emitted.

Even when observing the distant (early) Universe, protoclusters are rare and difficult to discover. Only about 20 were previously known. Because distant protoclusters are difficult to observe directly, quasars are sometimes used as a proxy. When a large volume of gas falls towards the super massive black hole in the center of a galaxy, it collides with other gas and is heated to extreme temperatures. This hot gas shines brightly and is known as a quasar. The thought was that when many galaxies are close together, a merger, two galaxies colliding and melding together, would create instabilities and cause gas to fall into the super massive black hole in one of the galaxies, creating a quasar. However, this relationship was not confirmed observationally due to the rarity of both quasars and protoclusters.

In order to understand protoclusters in the distant Universe a larger observational sample was needed. A team including astronomers from the National Astronomical Observatory of Japan, the University of Tokyo, the Graduate University for Advanced Studies, and other institutes is now conducting an unprecedented wide-field systematic survey of protoclusters using the Subaru Telescope’s very wide-field camera, Hyper Suprime-Cam (HSC). By analyzing the data from this survey, the team has already identified nearly 200 regions where galaxies are gathering together to form protoclusters in the early Universe 12 billion years ago.

Figure 1: Galaxy distribution and close-ups of some protoclusters revealed by HSC. Higher- and lower-density regions are represented by redder and bluer colors, respectively. In the close-ups, white circles indicate the positions of distant galaxies. The red regions are expected to evolve into galaxy clusters. From the close-ups, we can see various morphologies of the overdense regions: some have another neighboring overdense region, or are elongated like a filament, while there are also isolated overdense regions. (Credit: NAOJ)

The team also addressed the relationship between protoclusters and quasars. The team sampled 151 luminous quasars at the same epoch as the HSC protoclusters and to their surprise found that most of those quasars are not close to the overdense regions of galaxies. In fact, their most luminous quasars even avoid the densest regions of galaxies. These results suggest that quasars are not a good proxy for protoclusters and more importantly, mechanisms other than galactic mergers may be needed to explain quasar activity. Furthermore, since they did not find many galaxies near the brightest quasars, that could mean that hard radiation from a quasar suppresses galaxy formation in its vicinity.

On the other hand, the team found two “pairs” of quasars residing in protoclusters. Quasars are rare and pairs of them are even rarer. The fact that both pairs were associated with protoclusters suggests that quasar activity is perhaps synchronous in protocluster environments. “We have succeeded in discovering a number of protoclusters in the distant Universe for the first time and have witnessed the diversity of the quasar environments thanks to our wide-and-deep observations with HSC,” says the team’s leader Nobunari Kashikawa (NAOJ).

Figure 2: The two quasar pairs and surrounding galaxies. Stars indicate quasars and bright (faint) galaxies at the same epoch are shown as circles (dots). The galaxy overdensity with respect to the average density is shown by the contour. The pair members are associated with high density regions of galaxies. (Credit: NAOJ)

“HSC observations have enabled us to systematically study protoclusters for the first time.” says Jun Toshikawa, lead author of the a paper reporting the discovery of the HSC protoclusters, “The HSC protoclusters will steadily increase as the survey proceeds. Thousands of protoclusters located 12 billion light-years away will be found by the time the observations finish. With those new observations we will clarify the growth history of protoclusters.”

These results were published on January 1, 2018 in the HSC special issue of the Publications of the Astronomical Society of Japan (Toshikawa et al. 2018, GOLDRUSH. III. A Systematic Search of Protoclusters at z~4 Based on the >100 deg2 Area, PASJ, 70, S12; Uchiyama et al. 2018, Luminous Quasars Do Not Live in the Most Overdense Regions of Galaxies at z~4, PASJ, 70, S32; Onoue et al. 2018, Enhancement of Galaxy Overdensity around Quasar Pairs at z<3.6 based on the Hyper Suprime-Cam Subaru Strategic Program Survey, PASJ, 70, S31). These projects are supported by Grants-In-Aid JP15H03645, JP15K17617, and JP15J02115.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition
The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

ESO/NRAO/NAOJ ALMA Array

Solar Flare Telescope

Nobeyama Radio Observatory

Nobeyama Radio Observatory: Solar

Mizusawa VERA Observatory

Okayama Astrophysical Observatory

The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

From Quanta: “Discoveries Fuel Fight Over Universe’s First Light”

Quanta Magazine

Light from the first galaxies clears the universe. ESO/L. Calçada.

May 19, 2017 n[Just put up in social media.]
Ashley Yeager

Not long after the Big Bang, all went dark. The hydrogen gas that pervaded the early universe would have snuffed out the light of the universe’s first stars and galaxies. For hundreds of millions of years, even a galaxy’s worth of stars — or unthinkably bright beacons such as those created by supermassive black holes — would have been rendered all but invisible.

Eventually this fog burned off as high-energy ultraviolet light broke the atoms apart in a process called reionization. But the questions of exactly how this happened — which celestial objects powered the process and how many of them were needed — have consumed astronomers for decades.

Now, in a series of studies, researchers have looked further into the early universe than ever before. They’ve used galaxies and dark matter as a giant cosmic lens to see some of the earliest galaxies known, illuminating how these galaxies could have dissipated the cosmic fog. In addition, an international team of astronomers has found dozens of supermassive black holes — each with the mass of millions of suns — lighting up the early universe. Another team has found evidence that supermassive black holes existed hundreds of millions of years before anyone thought possible. The new discoveries should make clear just how much black holes contributed to the reionization of the universe, even as they’ve opened up questions as to how such supermassive black holes were able to form so early in the universe’s history.

First Light

In the first years after the Big Bang, the universe was too hot to allow atoms to form. Protons and electrons flew about, scattering any light. Then after about 380,000 years, these protons and electrons cooled enough to form hydrogen atoms, which coalesced into stars and galaxies over the next few hundreds of millions of years.

Starlight from these galaxies would have been bright and energetic, with lots of it falling in the ultraviolet part of the spectrum. As this light flew out into the universe, it ran into more hydrogen gas. These photons of light would break apart the hydrogen gas, contributing to reionization, but as they did so, the gas snuffed out the light.

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To find these stars, astronomers have to look for the non-ultraviolet part of their light and extrapolate from there. But this non-ultraviolet light is relatively dim and hard to see without help.

A team led by Rachael Livermore, an astrophysicist at the University of Texas at Austin, found just the help needed in the form of a giant cosmic lens.

Gravitational Lensing NASA/ESA

These so-called gravitational lenses form when a galaxy cluster, filled with massive dark matter, bends space-time to focus and magnify any object on the other side of it. Livermore used this technique with images from the Hubble Space Telescope to spot extremely faint galaxies from as far back as 600 million years after the Big Bang — right in the thick of reionization.

In a recent paper that appeared in The Astrophysical Journal, Livermore and colleagues also calculated that if you add galaxies like these to the previously known galaxies, then stars should be able to generate enough intense ultraviolet light to reionize the universe.

Yet there’s a catch. Astronomers doing this work have to estimate how much of a star’s ultraviolet light escaped its home galaxy (which is full of light-blocking hydrogen gas) to go out into the wider universe and contribute to reionization writ large. That estimate — called the escape fraction — creates a huge uncertainty that Livermore is quick to acknowledge.

In addition, not everyone believes Livermore’s results. Rychard Bouwens, an astrophysicist at Leiden University in the Netherlands, argues in a paper submitted to The Astrophysical Journal that Livermore didn’t properly subtract the light from the galaxy clusters that make up the gravitational lens. As a result, he said, the distant galaxies aren’t as faint as Livermore and colleagues claim, and astronomers have not found enough galaxies to conclude that stars ionized the universe.

Supremacy of Supermassive Black Holes

If stars couldn’t get the job done, perhaps supermassive black holes could. Beastly in size, up to a billion times the mass of the sun, supermassive black holes devour matter. They tug it toward them and heat it up, a process that emits lots of light and creates luminous objects that we call quasars. Because quasars emit way more ionizing radiation than stars do, they could in theory reionize the universe.

The trick is finding enough quasars to do it. In a paper posted to the scientific preprint site arxiv.org last month, astronomers working with the Subaru Telescope announced the discovery of 33 quasars that are about a 10th as bright as ones identified before.

NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

With such faint quasars, the astronomers should be able to calculate just how much ultraviolet light these supermassive black holes emit, said Michael Strauss, an astrophysicist at Princeton University and a member of the team. The researchers haven’t done the analysis yet, but they expect to publish the results in the coming months.

The oldest of these quasars dates back to around a billion years after the Big Bang, which seems about how long it would take ordinary black holes to devour enough matter to bulk up to supermassive status.

This is why another recent discovery [The Astrophysical Journal] is so puzzling. A team of researchers led by Richard Ellis, an astronomer at the European Southern Observatory, was observing a bright, star-forming galaxy seen as it was just 600 million years after the Big Bang.

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

The galaxy’s spectrum — a catalog of light by wavelength — appeared to contain a signature of ionized nitrogen. It’s hard to ionize ordinary hydrogen, and even harder to ionize nitrogen. It requires more higher-energy ultraviolet light than stars emit. So another strong source of ionizing radiation, possibly a supermassive black hole, had to exist at this time, Ellis said.

One supermassive black hole at the center of an early star-forming galaxy might be an outlier. It doesn’t mean there were enough of them around to reionize the universe. So Ellis has started to look at other early galaxies. His team now has tentative evidence that supermassive black holes sat at the centers of other massive, star-forming galaxies in the early universe. Studying these objects could help clarify what reionized the universe and illuminate how supermassive black holes formed at all. “That is a very exciting possibility,” Ellis said.

All this work is beginning to converge on a relatively straightforward explanation for what reionized the universe. The first population of young, hot stars probably started the process, then drove it forward for hundreds of millions of years. Over time, these stars died; the stars that replaced them weren’t quite so bright and hot. But by this point in cosmic history, supermassive black holes had enough time to grow and could start to take over. Researchers such as Steve Finkelstein, an astrophysicist at the University of Texas at Austin, are using the latest observational data and simulations of early galactic activity to test out the details of this scenario, such as how much stars and black holes contribute to the process at different times.

His work — and all work involving the universe’s first billion years — will get a boost in the coming years after the 2018 launch of the James Webb Space Telescope, Hubble’s successor, which has been explicitly designed to find the first objects in the universe. Its findings will probably provoke many more questions, too.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

Formerly known as Simons Science News, Quanta Magazine is an editorially independent online publication launched by the Simons Foundation to enhance public understanding of science. Why Quanta? Albert Einstein called photons “quanta of light.” Our goal is to “illuminate science.” At Quanta Magazine, scientific accuracy is every bit as important as telling a good story. All of our articles are meticulously researched, reported, edited, copy-edited and fact-checked.

From NAOJ Subaru: “Minor Merger Kicks Supermassive Black Hole into High Gear”

NAOJ

October 30, 2017
Press release
No writer credit found

The galaxy Messier 77 (M77) is famous for its super-active nucleus that releases enormous energy across the electromagnetic spectrum, ranging from x-ray to radio wavelengths. Yet, despite its highly active core, the galaxy looks like any normal quiet spiral. There’s no visual sign of what is causing its central region to radiate so extensively. It has long been a mystery why only the center of M77 is so active. Astronomers suspect a long-ago event involving a sinking black hole, which could have kicked the core into high gear.

To test their ideas about why the central region of M77 beams massive amounts of radiation, a team of researchers at the National Astronomical Observatory of Japan and the Open University of Japan used the Subaru Telescope to study M77. The unprecedented deep image of the galaxy reveals evidence of a hidden minor merger billions of years ago. The discovery gives crucial evidence for the minor merger origin of active galactic nuclei.

Figure 1: The deep image of Messier 77 taken with the Hyper Suprime-Cam (HSC) mounted at the Subaru Telescope. The picture is created by adding the color information from the Sloan Digital Sky Survey (Note 1) to the monochromatic image acquired by the HSC. (Credit: NAOJ/SDSS/David Hogg/Michael Blanton. Image Processing: Ichi Tanaka)

NAOJ Subaru Hyper Suprime-Cam

SDSS Telescope at Apache Point Observatory, NM, USA, Altitude2,788 meters (9,147 ft)

The Mystery of Seyfert Galaxies

The galaxy Messier 77 (NGC 1068) is famous for harboring an active nucleus at its core that releases an enormous amount of energy. The existence of such active galaxies in the nearby universe was first noted by the American astronomer Carl Seyfert more than 70 years ago. Nowadays they are called the Seyfert galaxies (Note 2). Astronomers think that the source of such powerful activity is the gravitational energy released from superheated matter falling onto a supermassive black hole (SMBH) that resides in the center of the host galaxy. The estimated mass of such a SMBH for M77 is about 10 million times that of the Sun.

It takes a massive amount of gas dumped on the galaxy’s central black hole to create such strong energies. That may sound like an easy task, but it’s actually very difficult. The gas in the galactic disk will circulate faster and faster as it spirals into the vicinity of the SMBH. Then, at some point the “centrifugal force” balances with the gravitational pull of the SMBH. That actually prevents the gas from falling into the center. The situation is similar to water draining out of a bathtub. Due to the centrifugal force, the rapidly rotating water will not drain out rapidly. So, how can the angular momentum be removed from the gas circling near an active galactic nucleus? Finding the answer to that question is one of the big challenges for researchers today.

A Prediction Posed 18 Years Ago

In 1999, Professor Yoshiaki Taniguchi (currently at the Open University of Japan), the team leader of the current Subaru study, published a paper about the driving mechanism of the active nucleus of Seyfert galaxies such as M 77. He pointed out that a past event – a “minor merger” where the host galaxy ate up its “satellite” galaxy (a small low-mass galaxy orbiting it) – would be the key to activating the Seyfert nucleus (Note 3).

Usually, a minor merger event simply breaks up a low-mass satellite galaxy. The resulting debris is absorbed into the disk of the more massive host galaxy before it approaches the center. Therefore, it was not considered as the main driver of the nuclear activity. “However, the situation could be totally different if the satellite galaxy has a (smaller) SMBH in its center (Note 4),” Professor Taniguchi suggests, “because the black hole can never be broken apart. If it exists, it should eventually sink into the center of the host galaxy.”

The sinking SMBH from the satellite galaxy would eventually create a disturbance in the rotating gas disk around the main galaxy’s SMBH. Then, the disturbed gas would eventually rush into the central SMBH while releasing enormous gravitational energy. “This must be the main ignition mechanism of the active Seyfert nuclei,” Taniguchi argued. “The idea can naturally explain the mystery about the morphology of the Seyfert galaxies,” said Professor Taniguchi, pointing out the advantage of the model of normal-looking galaxies also being very active at their cores. (Note 5).

Probing the Theory Using the Subaru Telescope

Recent advances in observational technique allow the detection of the extremely faint structure around galaxies, such as loops or debris that are likely made by dynamical interactions with satellite galaxies.. The outermost parts of galaxies are often considered as relatively “quiet” with a longer dynamical timescale than anywhere inside. Simulations show that the faint signature of a past minor merger can remain several billion years after the event. “Such a signature can be a key test for our minor merger hypothesis for Seyfert galaxies. Now it is time to revisit M77,” said Taniguchi.

The team’s choice to look for ‘the past case’ was, of course, the Subaru Telescope and its powerful imaging camera, Hyper Suprime-Cam. The observing proposal was accepted and executed on Christmas night 2016. “The data was just amazing,” said Dr. Ichi Tanaka, the primary investigator of the project. “Luckily, we could also retrieve the other data that was taken in the past and just released from the Subaru Telescope’s data archive. Thus, the combined data we got finally is unprecedentedly deep.”

Figure 2 shows the result. The team has identified several notable features outside the bright disk as seen in Figure 1, most of which were not known prior to the observation. There is a faint outer one-arm structure outside the disk to the west. The opposite part of the disk has a ripple-like structure which is clearly different from the spiral pattern. The detected signatures amazingly match to the result of a minor-merger simulation published by other research teams. What is more, the observing team discovered three extremely diffuse and large blobby structures farther outside of the disk. Intriguingly, it seems that two of these diffuse blobs actually constitute a gigantic loop around M77 with a diameter of 250,000 light years. These structures are compelling evidence that M77 ate up its satellite galaxy at least several billion years ago.

Figure 2: (Left) The newly-discovered, extremely　diffuse structures around M77. The innermost color part of the picture shows the bright part of the galaxy (from SDSS: see the center of Figure 1). The middle part in red-brown is the contrast-enhanced expression of the faint one-arm structure (labeled as “Banana”) to the right, as well as the ripple structure (labeled as “Ripple”) to the left. All the fore/background objects unrelated to M77 are removed during the process. The outermost monochrome part shows the faint ultra-diffuse structures in yellow circles (labelled as “UDO-SE”, “UDO-NE”, “UDO-SW”). A deep look at them indicates the latter two (“UDO-NE”, “UDO-SW”) constitute a part of the large loop-like structure. (Credit: NAOJ)
(Right) Artist’s impression of M77. The illustration in the right is created and copyrighted by Mr. Akihiro Ikeshita. (Credit: Akihiro Ikeshita)

Subaru’s great photon-collecting power and the superb performance of the Hyper Suprime-Cam were crucial in the discovery of the extremely faint structures in M77. Their discovery reveals the normal-looking galaxy’s hidden violent past.. “Though people may sometimes make a lie, galaxies never do. The important thing is to listen to their small voices to understand the galaxies,” said Professor Taniguchi.

The team will expand its study to more Seyfert galaxies using the Subaru Telescope. Dr. Masafumi Yagi, who leads the next phase of the project said, “We will discover more and more evidences of the satellite merger around Seyfert host galaxies. We expect that the project can provide a critical piece for the unified picture for the triggering mechanism for active galactic nuclei.”

The result is going to be published in the Volume 69 Issue 6 of the Publications of the Astronomical Society of Japan (I. Tanaka, M.Yagi & Y. Taniguchi 2017, “Morphological evidence for a past minor merger in the Seyfert galaxy NGC 1068”). The research is financially supported by the Basic Research A grant JP16H02166 by the Grant-in-Aid for Scientific Research program.

Note1: The color image by the Sloan Digital Sky Survey used for Figure 1 is under the copyright of David W. Hogg and Michael R. Blanton.

Note 2: Seyfert galaxies are actually a subclass of the active galactic nuclei. There are even more powerful active galactic nuclei called quasar in the universe. Usually quasars are found much farther away than M77.

Note 3: Satellite galaxies are common for large galaxies. For example, there are two bright satellite galaxies called Large and Small Magellanic Clouds associated with our Milky Way. The Andromeda galaxy, our nearest neighbor, also has two bright satellites called Messier 32 and NGC 205.

Note 4: Astronomers believe that most galaxies have an SMBH in their central regions, with its mass mysteriously scaled to the mass of the host galaxy. It is also known that some satellite galaxies also have smaller SMBH. For example, Messier 32 (satellite of the Andromeda galaxy) is likely to have a SMBH much heavier than a million times the mass of our Sun. It is however not easy to directly prove the existence of the SMBH for satellite galaxies due to its light weight.

Note 5: Y. Taniguchi 1999, ApJ, 524, 65, for the reference.

The research team:

Ichi Tanaka: Subaru Telescope, National Astronomical Observatory of Japan
Masafumi Yagi: National Astronomical Observatory of Japan
Yoshiaki Taniguchi: The Open University of Japan

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition
The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

Subaru

ALMA

Solar Flare Telescope

Nobeyama Radio Observatory

Nobeyama Radio Observatory: Solar

Mizusawa VERA Observatory

Okayama Astrophysical Observatory

The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

From NOAJ Subaru: “Surface Helium Detonation Spells End for White Dwarf”

NAOJ

October 4, 2017
No writer credit

An international team of researchers has found evidence that the brightest stellar explosions in our Universe could be triggered by helium nuclear detonation near the surface of a white dwarf star. Using Hyper Suprime-Cam mounted on the Subaru Telescope, the team detected a type Ia supernova within a day after the explosion, and explained its behavior through a model calculated using the supercomputer ATERUI.

NAOJ Cray XC30 ATERUI, installed in the NAOJ Mizusawa campus

Figure 1: A type Ia supernova detected within a day after exploding. Taken with Hyper Suprime-Cam mounted on the Subaru Telescope. Figure without the labels is linked here. (Credit: University of Tokyo/NAOJ)

NAOJ Subaru Hyper Suprime-Cam

Some stars end their lives with a huge explosion called a supernova. The most famous supernovae are the result of a massive star exploding, but a white dwarf, the remnant of an intermediate mass star like our Sun, can also explode. This can occur if the white dwarf is part of a binary star system. The white dwarf accretes material from the companion star, then at some point, it might explode as a type Ia supernova.

Because of the uniform and extremely high brightness (about 5 billion times brighter than the Sun) of type Ia supernovae, they are often used for distance measurements in astronomy. However, astronomers are still puzzled by how these explosions are ignited. Moreover, these explosions only occur about once every 100 years in any given galaxy, making them difficult to catch.

An international team of researchers led by Ji-an Jiang, a graduate student of the University of Tokyo, and including researchers from the University of Tokyo, the Kavli Institute for the Physics and Mathematics of the Universe (IPMU), Kyoto University, and the National Astronomical Observatory of Japan (NAOJ), tried to solve this problem. To maximize the chances of finding a type Ia supernova in the very early stages, the team used Hyper Suprime-Cam (HSC) mounted on the Subaru Telescope, a combination which can capture an ultra-wide area of the sky at once. Also they developed a system to detect supernovae automatically in the heavy flood of data during the survey, which enabled real-time discoveries and timely follow-up observations.

They discovered over 100 supernova candidates in one night with Subaru/Hyper Suprime-Cam, including several supernovae that had only exploded a few days earlier. In particular, they captured a peculiar type Ia supernova within a day of it exploding. Its brightness and color variation over time are different from any previously-discovered type Ia supernova. They hypothesized this object could be the result of a white dwarf with a helium layer on its surface. Igniting the helium layer would lead to a violent chain reaction and cause the entire star to explode. This peculiar behavior can be totally explained with numerical simulations calculated using the supercomputer ATERUI. “This is the first evidence that robustly supports a theoretically predicted stellar explosion mechanism!” said Jiang.

This result is a step towards understand the beginning of type Ia supernovae. The team will continue to test their theory against other supernovae, by detecting more and more supernovae just after the explosion. The details of their study are to be published in Nature on October 5, 2017 (Jiang et al. 2017, A hybrid type la supernova with an early flash triggered by helium-shell detonation, Nature).

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition
The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

Subaru

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

Solar Flare Telescope

Nobeyama Radio Observatory

Nobeyama Radio Observatory: Solar

Mizusawa VERA Observatory

Okayama Astrophysical Observatory

The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.