Thursday, February 28, 2019

Hiding Black Hole Found

Artist’s impression of a gas cloud swirling around a black hole
Credit: NAOJ.  Hi-res image

Astronomers have detected a stealthy black hole from its effects on an interstellar gas cloud. This intermediate mass black hole is one of over 100 million quiet black holes expected to be lurking in our galaxy. These results provide a new method to search for other hidden black holes and help us understand the growth and evolution of black holes.

Black holes are objects with such strong gravity that everything, including light, is sucked in and cannot escape. Because black holes do not emit light, astronomers must infer their existence from the effects their gravity produce in other objects. Black holes range in mass from about 5 times the mass of the Sun to supermassive black holes millions of times the mass of the Sun. Astronomers think that small black holes merge and gradually grow into large ones, but no one had ever found an intermediate mass, hundreds or thousands of times the mass of the Sun.

A research team led by Shunya Takekawa at the National Astronomical Observatory of Japan noticed HCN–0.009–0.044, a gas cloud moving strangely near the center of the Galaxy 25,000 light-years away from Earth in the constellation Sagittarius. They used ALMA (Atacama Large Millimeter/submillimeter Array) to perform high resolution observations of the cloud and found that it is swirling around an invisible massive object.

Takekawa explains, “Detailed kinematic analyses revealed that an enormous mass, 30,000 times that of the Sun, was concentrated in a region much smaller than our Solar System. This and the lack of any observed object at that location strongly suggests an intermediate-mass black hole. By analyzing other anomalous clouds, we hope to expose other quiet black holes. ”

Tomoharu Oka, a professor at Keio University and coleader of the team, adds, “It is significant that this intermediate mass black hole was found only 20 light-years from the supermassive black hole at the Galactic center. In the future, it will fall into the supermassive black hole; much like gas is currently falling into it. This supports the merger model of black hole growth.”



Aditional Information


These results were published as Takekawa et al. “Indication of Another Intermediate-mass Black Hole in the Galactic Center” in The Astrophysical Journal Letters on January 20, 2019.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.




Contacts

Valeria Foncea
Education and Public Outreach Officer
Joint ALMA Observatory Santiago - Chile
Phone: +56 2 2467 6258
Cell phone: +56 9 7587 1963
Email: valeria.foncea@alma.cl

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory
, Tokyo - Japan
Phone: +81 422 34 3630
Email: hiramatsu.masaaki@nao.ac.jp

Calum Turner
ESO Assistant Public Information Officer
Garching bei München, Germany
Phone: +49 89 3200 6670
Email: calum.turner@eso.org

Charles E. Blue
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia - USA
Phone: +1 434 296 0314
Cell phone: +1 202 236 6324
Email: cblue@nrao.edu




Wednesday, February 27, 2019

Dark Matter May be Hitting the Right Note in Small Galaxies

Fig 1: Astronomers observed that the dark matter does not seem to clump very much in small galaxies, but their density peaks sharply in bigger systems such as clusters of galaxies. It has been a puzzle why different systems behave differently. (Credit: Kavli IPMU - Kavli IPMU modified this figure based on the image credited by NASA, STScI)

Dark matter may scatter against each other only when they hit the right energy, say researchers in Japan, Germany, and Austria in a new study. Their idea helps explain why galaxies from the smallest to the biggest have the shapes they do.

Dark matter is a mysterious and unknown form of matter that comprises more than 80 per cent of matter in the Universe today. Its nature is unknown, but it is believed to be responsible for forming stars and galaxies by its gravitational pull, which led to our existence.

“Dark matter is actually our mom who gave birth to all of us. But we haven’t met her; somehow, we got separated at birth. Who is she? That is the question we want to know,” says paper author Hitoshi Murayama, a University of California Berkeley Professor and Kavli Institute for the Physics and Mathematics of the Universe Principal Investigator.

Astronomers have already found dark matter does not seem to clump together as much as computer simulations suggest. If gravity is the only force that drives dark matter, only pulling and never pushing, then dark matter should become very dense towards the center of galaxies. However, especially in small faint galaxies called dwarf spheroidals, dark matter does not seem to become as dense as expected toward their centers.

This puzzle could be solved if dark matter scatters with each other like billiard balls, allowing them to spread out more evenly after a collision.

But one problem with this idea is that dark matter does seem to clump in bigger systems such as clusters of galaxies. What makes dark matter behave differently between dwarf spheroidals and clusters of galaxies? An international team of researchers has developed an explanation that could solve this riddle, and reveal what dark matter is.

Fig 2a: When two dark matter particles approach each other, then tend to simply pass each other. 
Credit: Kavli IPMU

Fig 2b: But when they come at a special speed, they “resonate” and stick with each other for a brief moment, and move out to different directions afterwards, causing them to scatter. This way, dark matter can spread out so that we can understand smooth profile in small galaxies. (Credit: Kavli IPMU)

“If dark matter scatters with each other only at a low but very special speed, it can happen often in dwarf spheroidals where it is moving slowly, but it is rare in clusters of galaxies where it is moving fast. It needs to hit a resonance” says Chinese physicist Xiaoyong Chu, a postdoctoral researcher at the Austrian Academy of Sciences.

Resonance is a phenomenon that appears every day. To swirl wine in a glass to get it more oxygen so that it lets out more aroma and softens its taste, you need to find the right speed to circle the wine glass. Or you dial old analog radios to the right frequency to tune into your favorite station. These are all examples of resonance, says Murayama. The team suspects this is precisely what dark matter is doing.

“As far as we know, this is the simplest explanation to the puzzle. We are excited because we may know what dark matter is sometime soon,” says Murayama.

However, the team was not convinced that such a simple idea would explain the data correctly.

“First, we were a bit skeptical that this idea will explain the observational data; but once we tried it, it worked like a charm!” says Colombian researcher Camilo Garcia Cely, a postdoctoral researcher at the Deutsches Elektronen-Synchrotron (DESY) in Germany.

The team believes it is no accident that dark matter can hit the exact right note.

“There are many other systems in nature that show similar accidents: in stars alpha particles hit a resonance of beryllium, which in turn hits a resonance of carbon, producing the building blocks that gave rise to life on Earth. A similar process happens for a subatomic particle called phi,” says Garcia Cely.

Fig 3: Using the idea of resonance, the plot demonstrates that we can explain all systems at the same time.
Credit: Xiaoyong Chu, Camilo Garcia Cely, Hitoshi Murayama

“It may also be a sign that our world has more dimensions than we see. If a particle moves in extra dimensions, it has energy. For us who don’t see the extra dimension, we think the energy is actually a mass, thanks to Einstein’s E=mc2. Perhaps some particle moves twice as fast in extra dimension, making its mass precisely twice as much as the mass of dark matter,” says Chu.

The team’s next step will be to find observational data that backs their theory.

“If this is true, future and more detailed observation of different galaxies will reveal that scattering of dark matter indeed depends on its speed,” says Murayama, who is also leading a separate international group that intends to do precisely this using the under construction Prime Focus Spectrograph. The US$80 million instrument will be mounted on the Subaru telescope atop Mauna Kea on Big Island, Hawaii, and will be capable of measuring the speeds of thousands of stars in dwarf spheroidals.

The team’s paper was published online on 22 February by Physical Review Letters.

Fig 4: Paper authors (from left) Xiaoyong Chu, Camilo Garcia Cely, and Hitoshi Murayama 
Credit from left: Xiaoyong Chu, DESY, Kavli IPMU




Paper details

Journal: Physical Review Letters
Title: Velocity Dependence from Resonant Self-Interacting Dark Matter
Authors: Xiaoyong Chu (1), Camilo Garcia-Cely (2), Hitoshi Murayama (3, 4, 5, 2)



Author affiliations:

1. Institute of High Energy Physics, Austrian Academy of Sciences, Nikolsdorfer Gasse 18, 1050 Vienna, Austria
2. Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
3. Department of Physics, University of California, Berkeley, CA 94720, USA
4. Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan
5. Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA

DOI: 10.1103/PhysRevLett.122.071103 (Published 22 February, 2019)



Images & Video


Click here to download images and video.



Research contact

Hitoshi Murayama
Principal Investigator
Kavli Institute for the Physics and Mathematics of the Universe
University of Tokyo
E-mail: hitoshi.murayama@ipmu.jp



Media contact

Motoko Kakubayashi
Press officer
Kavli Institute for the Physics and Mathematics of the Universe
University of Tokyo
Tel:04-7136-5980
E-mail: press@ipmu.jp


Tuesday, February 26, 2019

ALMA Differentiates Two Birth Cries from a Single Star

ALMA image of the protostar MMS5/OMC-3. The protostar is located at the center and the gas streams are ejected to the east and west (left and right). The slow outflow is shown in orange and the fast jet is shown in blue. It is obvious that the axes of the outflow and jet are misaligned. Credit: ALMA (ESO/NAOJ/NRAO), Matsushita et al. Hi-res image

Artist’s impression of the baby star MMS5/OMC-3. ALMA observations identified two gas streams from the protostar, a collimated fast jet and a wide-angle slow outflow, and found that the axes of the two gas flows are misaligned. Credit: NAOJ. Hi-res image

Astronomers have unveiled the enigmatic origins of two different gas streams from a baby star. Using ALMA, they found that the slow outflow and the high speed jet from a protostar have misaligned axes and that the former started to be ejected earlier than the latter. The origins of these two flows have been a mystery, but these observations provide telltale signs that these two streams were launched from different parts of the disk around the protostar.

Stars in the Universe have a wide range of masses, ranging from hundreds of times the mass of the Sun to less than a tenth of that of the Sun. To understand the origin of this variety, astronomers study the formation process of the stars, that is the aggregation of cosmic gas and dust.

Baby stars collect the gas with their gravitational pull, however, some of the material is ejected by the protostars. This ejected material forms a stellar birth cry which provides clues to understand the process of mass accumulation.

Yuko Matsushita, a graduate student at Kyushu University and her team used ALMA to observe the detailed structure of the birth cry from the baby star MMS5/OMC-3 and found two different gaseous flows: a slow outflow and a fast jet. There have been a handful of examples with two flows seen in radio waves, but MMS5/OMC-3 is exceptional.

“Measuring the Doppler shift of the radio waves, we can estimate the speed and lifetime of the gas flows,” said Matsushita, the lead author of the research paper that appeared in the Astrophysical Journal. “We found that the jet and outflow were launched 500 years and 1300 years ago, respectively. These gas streams are quite young.”

More interestingly, the team found that the axes of the two flows are misaligned by 17 degrees. The axis of the flows can be changed over long time periods due to the precession of the central star. But in this case, considering the extreme youth of the gas streams, researchers concluded that the misalignment is not due to precession but is related to the launching process.

There are two competing models for the formation mechanism of the protostellar outflows and jets. Some researchers assume that the two streams are formed independently in different parts of the gas disk around the central baby star, while others propose that the collocated jet is formed first, then it entrains the surrounding material to form the slower outflows. Despite extensive research, astronomers had not yet reached a conclusive answer.

A misalignment in the two flows could occur in the ‘independent model,’ but is difficult in the ‘entrainment model.’ Moreover, the team found that the outflow was ejected considerably earlier than the jet. This clearly backs the ‘independent model.’

“The observation well matches the result of my simulation,” said Masahiro Machida, a professor at Kyushu University. A decade ago, he performed pioneering simulation studies using a supercomputer operated by the National Astronomical Observatory of Japan. In the simulation, the wide-angle outflow is ejected from the outer area of the gaseous disk around a prototar, while the collimated jet is launched independently from the inner area of the disk. Machida continues, “An observed misalignment between the two gas streams may indicate that the disk around the protostar is warped.”

“ALMA’s high sensitivity and high angular resolution will enable us to find more and more young, energetic outflow-and-jet-systems like MMS 5/OMC-3,” said Satoko Takahashi, an astronomer at the National Astronomical Observatory of Japan and the Joint ALMA Observatory and co-author of the paper. “They will provide clues to understand the driving mechanisms of outflows and jets. Moreover studying such objects will also tell us how the mass accretion and ejection processes work at the earliest stage of star formation.”



Additional Information


These observation results were published as Matsushita et al. “Very Compact Extremely High Velocity Flow toward MMS 5 / OMC-3 Revealed with ALMA” in the Astrophysical Journal issued in February 2019.

The research team members are:


Yuko Matsushita (Kyushu University), Satoko Takahashi (Joint ALMA Observatory/National Astronomical Observatory of Japan/SOKENDAI), Masahiro Machida (Kyushu University), and Koji Tomisaka (National Astronomical Observatory of Japan/SOKENDAI)

This research was supported by JSPS KAKENHI (No. 17K05387, 17H06360, 17H02869, 15K05032) and the Science Visitor Program of the Joint ALMA Observatory.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI). ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.



Contacts

Valeria Foncea
Education and Public Outreach Officer
Joint ALMA Observatory Santiago - Chile
Phone: +56 2 2467 6258
Cell phone: +56 9 7587 1963
Email: valeria.foncea@alma.cl

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory
, Tokyo - Japan
Phone: +81 422 34 3630
Email: hiramatsu.masaaki@nao.ac.jp

Charles E. Blue
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia - USAv 
Phone: +1 434 296 0314
Cell phone: +1 202 236 6324
Email: cblue@nrao.edu

Calum Turner
ESO Assistant Public Information Officer
Garching bei München, Germany
Phone: +49 89 3200 6670
Email: calum.turner@eso.org




Monday, February 25, 2019

Past and future generations of stars in NGC 300

Past and future generations of stars in NGC 300
Copyright: ESA/XMM-Newton (X-rays); MPG/ESO (optical); NASA/Spitzer (infrared)
Acknowledgement: S. Carpano, Max-Planck Institute for Extraterrestrial Physics

 JPG - (1.48 MB) / PNG - (7.99 MB)

This swirling palette of colours portrays the life cycle of stars in a spiral galaxy known as NGC 300.

Located some six million light-years away, NGC 300 is relatively nearby. It is one of the closest galaxies beyond the Local Group – the hub of galaxies to which our own Milky Way galaxy belongs. Due to its proximity, it is a favourite target for astronomers to study stellar processes in spiral galaxies.

The population of stars in their prime is shown in this image in green hues, based on optical observations performed with the Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope at La Silla, Chile. Red colours indicate the glow of cosmic dust in the interstellar medium that pervades the galaxy: this information derives from infrared observations made with NASA’s Spitzer space telescope, and can be used to trace stellar nurseries and future stellar generations across NGC 300.

A complementary perspective on this galaxy’s composition comes from data collected in X-rays by ESA’s XMM-Newton space observatory, shown in blue. These represent the end points of the stellar life cycle, including massive stars on the verge of blasting out as supernovas, remnants of supernova explosions, neutron stars, and black holes. Many of these X-ray sources are located in NGC 300, while others – especially towards the edges of the image – are foreground objects in our own Galaxy, or background galaxies even farther away.

The sizeable blue blob immediately to the left of the galaxy’s centre is especially interesting, featuring two intriguing sources that are part of NGC 300 and shine brightly in X-rays.

One of them, known as NGC 300 X-1, is in fact a binary system, consisting of a Wolf-Rayet star – an ageing hot, massive and luminous type star that drives strong winds into its surroundings – and a black hole, the compact remains of what was once another massive, hot star. As matter from the star flows towards the black hole, it is heated up to temperatures of millions of degrees or more, causing it to shine in X-rays.

The other source, dubbed NGC 300 ULX1, was originally identified as a supernova explosion in 2010. However, later observations prompted astronomers to reconsider this interpretation, indicating that this source also conceals a binary system comprising a very massive star and a compact object – a neutron star or a black hole – feeding on material from its stellar companion.

Data obtained in 2016 with ESA’s XMM-Newton and NASA’s NuSTAR observatories revealed regular variations in the X-ray signal of NGC 300 ULX1, suggesting that the compact object in this binary system is a highly magnetized, rapidly spinning neutron star, or pulsar.
The large blue blob in the upper left corner is a much more distant object: a cluster of galaxies more than one billion light years away, whose X-ray glow is caused by the hot diffuse gas interspersed between the galaxies.

Explore NGC 300 in ESASky



Sunday, February 24, 2019

SOFIA Uncovers Clues to the Evolution of Universe and Search for Life

Magnetic fields in the Orion Nebula, shown as stream lines over an infrared image taken by the Very Large Telescope in Chile, are regulating the formation of new stars. SOFIA’s HAWC+ instrument is sensitive to the alignment of dust grains, which line up along magnetic fields, letting researchers infer the direction and strength. Credits: NASA/SOFIA/D. Chuss et al. and European Southern Observatory/M.McCaughrean et al.

A compilation of scientific results from The Stratospheric Observatory for Infrared Astronomy, SOFIA, reveal new clues to how stars form and galaxies evolve, and closer to understanding the environment of Europa and its subsurface ocean. The airborne observatory carries a suite of instruments, each sensitive to different properties of infrared light, that gives astronomers insights into the flow of matter in galaxies.

“Much of the light in the universe is emitted as infrared light that does not reach Earth’s surface,” said Bill Reach, chief science advisor at the University Space Research Association’s SOFIA Science Center. “Infrared observations from SOFIA, which flies above most of the atmosphere, let us study what’s happening deep inside cosmic clouds, analyze celestial magnetic fields and investigate the chemical universe in ways that are not possible with visible light.”

Unlike space-based telescopes, SOFIA’s instruments can be exchanged, serviced or upgraded to harness new technologies. Its newest instrument, called the High-resolution Airborne Wideband Camera-Plus, or HAWC+, enables studies of celestial magnetic fields with ground-breaking precision.

“How magnetic fields affect the process of star formation has not been well understood, though it has long been suspected that they play an important role,” said David Chuss, professor of physics at Villanova University in Pennsylvania. “With SOFIA’s HAWC+ instrument, we can now begin to understand how these fields influence the dynamics of regions where gas and dust are collapsing to produce new stars."

Some observations highlighted in the Astrophysical Journal “Focus on Results from SOFIA” include:
  • The magnetic fields in the Orion Nebula are preventing star-forming clouds from collapsing under gravity, thereby regulating the formation of new stars. This can help better explain the number of stars in our galaxy and those that may form in the future. If magnetic fields inhibit the gravitational collapse of celestial clouds in other regions of the galaxy, the number of new stars may be lower than current models predict.
  • Magnetic fields are trapping material, keeping it close enough to be fed into the black hole in the Cygnus A Galaxy. These findings may mean that magnetic fields regulate black hole activity and explain why some are actively gobbling up material from their surroundings, while others, like the one in our own Milky Way Galaxy, are not.
  • A map of the entire grand-design spiral galaxy M51 (also known as the Whirlpool Galaxy), including its small companion galaxy, reveals that the companion is not forming new stars at the same rate as the its larger neighbor. Understanding how stars are born in different celestial environments is key to learning how star birth evolved from the early universe to the present day.
  • The region called Sagittarius B1 — near the black hole at the center of our Milky Way Galaxy — must be part of a large, young star-formation complex, but the stars were formed elsewhere and are remnants of a previous generation of star formation, which includes the Arches cluster. Observations like these are helping researchers develop a template to understand distant galaxies, which are often too far away for even the most powerful telescopes to see clearly, and ultimately learn how the universe works.
  • Water plumes that may be erupting from Jupiter’s moon Europa, suggested by data from NASA’s Galileo and Hubble spacecraft, contain, at most, the amount of water in an Olympic-sized swimming pool. SOFIA’s observations in 2017 did not directly detect the plume, but established an upper limit on how much water could be in the plumes. This upper limit is crucial to ongoing studies that will analyze the contents of the plumes and investigate their origins, which will help reveal if Europa has the ingredients to support life.
SOFIA is a Boeing 747SP jetliner modified to carry a 106-inch diameter telescope. It is a joint project of NASA and the German Aerospace Center, DLR. NASA’s Ames Research Center in California’s Silicon Valley manages the SOFIA program, science and mission operations in cooperation with the Universities Space Research Association headquartered in Columbia, Maryland, and the German SOFIA Institute (DSI) at the University of Stuttgart. The aircraft is maintained and operated from NASA’s Armstrong Flight Research Center Hangar 703, in Palmdale, California.

Editor: Kassandra Bell

Source: NASA/Galaxies


Saturday, February 23, 2019

New Horizons Spacecraft Returns Its Sharpest Views of Ultima Thule

The most detailed images of Ultima Thule -- obtained just minutes before the spacecraft's closest approach at 12:33 a.m. EST on Jan. 1 -- have a resolution of about 110 feet (33 meters) per pixel. Their combination of higher spatial resolution and a favorable viewing geometry offer an unprecedented opportunity to investigate the surface of Ultima Thule, believed to be the most primitive object ever encountered by a spacecraft.  This processed, composite picture combines nine individual images taken with the Long Range Reconnaissance Imager (LORRI), each with an exposure time of 0.025 seconds, just 6 ½ minutes before the spacecraft's closest approach to Ultima Thule (officially named 2014 MU69). The image was taken at 5:26 UT (12:26 a.m. EST) on Jan. 1, 2019, when the spacecraft was 4,109 miles (6,628 kilometers) from Ultima Thule and 4.1 billion miles (6.6 billion kilometers) from Earth. The angle between the spacecraft, Ultima Thule and the Sun – known as the "phase angle" – was 33 degrees. Credit: NASA/Johns Hopkins Applied Physics Laboratory/Southwest Research Institute, National Optical Astronomy Observatory

This processed, composite picture combines seven individual images taken with the New Horizons Long Range Reconnaissance Imager (LORRI), each with an exposure time of 0.025 seconds, just 19 minutes before the spacecraft’s closest approach to Ultima Thule (officially named 2014 MU69).The image was taken at 5:14 UT (12:14 a.m. EST) on Jan. 1, 2019, when the spacecraft was 10,350 miles (16,694 kilometers) from Ultima Thule, yielding a resolution of 273 feet (83 meters) per pixel. The spacecraft was 4.1 billion miles (6.6 billion kilometers) from Earth. The angle between the spacecraft, Ultima Thule and the Sun – known as the “phase angle” – was 16 degrees.  Credit: NASA/Johns Hopkins Applied Physics Laboratory/Southwest Research Institute, National Optical Astronomy Observatory

New Horizons scientists created this movie from 14 different images taken by the New Horizons Long Range Reconnaissance Imager (LORRI) shortly before the spacecraft flew past the Kuiper Belt object nicknamed Ultima Thule (officially named 2014 MU69) on Jan. 1, 2019. The central frame of this sequence was taken on Jan. 1 at 5:26:54 UT (12:26 a.m. EST), when New Horizons was 4,117 miles (6,640 kilometers) from Ultima Thule, some 4.1 billion miles (6.6 billion kilometers) from Earth. Ultima Thule nearly completely fills the LORRI image and is perfectly captured in the frames, an astounding technical feat given the uncertain location of Ultima Thule and the New Horizons spacecraft flying past it at over 32,000 miles per hour. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.  Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.  View MP4


The mission team called it a "stretch goal" – just before closest approach, precisely point the cameras on NASA's New Horizons spacecraft to snap the sharpest possible pics of the Kuiper Belt object nicknamed Ultima Thule, its New Year's flyby target and the farthest object ever explored.

Now that New Horizons has sent those stored flyby images back to Earth, the team can enthusiastically confirm that its ambitious goal was met.

These new images of Ultima Thule – obtained by the telephoto Long-Range Reconnaissance Imager (LORRI) just 6½ minutes before New Horizons' closest approach to the object (officially named 2014 MU69) at 12:33 a.m. EST on Jan. 1 – offer a resolution of about 110 feet (33 meters) per pixel. Their combination of high spatial resolution and a favorable viewing angle gives the team an unprecedented opportunity to investigate the surface, as well as the origin and evolution, of Ultima Thule – thought to be the most primitive object ever encountered by a spacecraft.

"Bullseye!" said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute (SwRI). "Getting these images required us to know precisely where both tiny Ultima and New Horizons were — moment by moment – as they passed one another at over 32,000 miles per hour in the dim light of the Kuiper Belt, a billion miles beyond Pluto. This was a much tougher observation than anything we had attempted in our 2015 Pluto flyby.

"These 'stretch goal' observations were risky, because there was a real chance we'd only get part or even none of Ultima in the camera's narrow field of view," he continued. "But the science, operations and navigation teams nailed it, and the result is a field day for our science team! Some of the details we now see on Ultima Thule's surface are unlike any object ever explored before."

The higher resolution brings out a many surface features that weren't readily apparent in earlier images. Among them are several bright, enigmatic, roughly circular patches of terrain. In addition, many small, dark pits near the terminator (the boundary between the sunlit and dark sides of the body) are better resolved. "Whether these features are craters produced by impactors, sublimation pits, collapse pits, or something entirely different, is being debated in our science team," said John Spencer, deputy project scientist from SwRI.

Project Scientist Hal Weaver, of the Johns Hopkins Applied Physics Laboratory, noted that the latest images have the highest spatial resolution of any New Horizons has taken – or may ever take – during its entire mission. Swooping within just 2,200 miles (3,500 kilometers), New Horizons flew approximately three times closer to Ultima than it zipped past its primary mission target, Pluto, in July 2015.

Ultima Thule is smaller than Pluto, but the Ultima flyby was done with the highest navigation precision ever achieved by any spacecraft. This unprecedented precision was achieved thanks to the ground-based occultation campaigns from 2017 and 2018 conducted in Argentina, Senegal, South Africa and Colombia, as well as the European Space Agency's Gaia mission, which provided the locations of the stars that were used during the occultation campaigns.

Look for these and other LORRI images on the New Horizons LORRI website this week. Raw images from the camera are posted to the site each Friday.

Mission operations manager Alice Bowman, of APL, reports that the spacecraft continues to operate flawlessly. New Horizons is nearly 4.13 billion miles (6.64 billion kilometers) from Earth; at that distance, radio signals, traveling at light speed, reach the large antennas of NASA's Deep Space Network six hours and nine minutes after New Horizons sends them. Follow New Horizons on its trek through the Kuiper Belt.


Source:  New Horizons - NASA's Mission to Pluto and the Kuiper Belt


Friday, February 22, 2019

Solar Tadpole-Like Jets Seen With NASA’S IRIS Add New Clue to Age-Old Mystery

Images from IRIS show the tadpole-shaped jets containing pseudo-shocks streaking out from the Sun
Credits: Abhishek Srivastava IIT (BHU)/Joy Ng, NASA’s Goddard Space Flight Center

For 150 years scientists have been trying to figure out why the wispy upper atmosphere of the Sun — the corona — is over 200 times hotter than the solar surface. This region, which extends millions of miles, somehow becomes superheated and continually releases highly charged particles, which race across the solar system at supersonic speeds.

When those particles encounter Earth, they have the potential to harm satellites and astronauts, disrupt telecommunications, and even interfere with power grids during particularly strong events. Understanding how the corona gets so hot can ultimately help us understand the fundamental physics behind what drives these disruptions.

In recent years, scientists have largely debated two possible explanations for coronal heating: nanoflares and electromagnetic waves. The nanoflare theory proposes bomb-like explosions, which release energy into the solar atmosphere. Siblings to the larger solar flares, they are expected to occur when magnetic field lines explosively reconnect, releasing a surge of hot, charged particles. An alternative theory suggests a type of electromagnetic wave called Alfvén waves might push charged particles into the atmosphere like an ocean wave pushing a surfer. Scientists now think the corona may be heated by a combination of phenomenon like these, instead of a single one alone. 

The new discovery of pseudo-shocks adds another player to that debate. Particularly, it may contribute heat to the corona during specific times, namely when the Sun is active, such as during solar maximums — the most active part of the Sun’s 11-year cycle marked by an increase in sunspots, solar flares and coronal mass ejections.

The discovery of the solar tadpoles was somewhat fortuitous. When recently analyzing data from NASA’s Interface Region Imaging Spectrograph, or IRIS, scientists noticed unique elongated jets emerging from sunspots ­— cool, magnetically-active regions on the Sun’s surface — and rising 3,000 miles up into the inner corona. The jets, with bulky heads and rarefied tails, looked to the scientists like tadpoles swimming up through the Sun’s layers.

“We were looking for waves and plasma ejecta, but instead, we noticed these dynamical pseudo-shocks, like disconnected plasma jets, that are not like real shocks but highly energetic to fulfill Sun's radiative losses,” said Abhishek Srivastava, scientist at the Indian Institute of Technology (BHU) in Varanasi, India, and lead author on the new paper in Nature Astronomy.

Using computer simulations matching the events, they determined these pseudo-shocks could carry enough energy and plasma to heat the inner corona.

A computer simulation shows how the pseudo-shock is ejected and becomes disconnected from the plasma below (green)
Credits: Abhishek Srivastava IIT (BHU)/Joy Ng, NASA’s Goddard Space Flight Center

The scientists believe the pseudo-shocks are ejected by magnetic reconnection — an explosive tangling of magnetic field lines, which often occurs in and around sunspots. The pseudo-shocks have only been observed around the rims of sunspots so far, but scientists expect they’ll be found in other highly magnetized regions as well.

The tadpole-shaped pseudo-shocks, shown in dashed white box, are ejected from highly magnetized regions on the solar surface. Credits: Abhishek Srivastava IIT (BHU)/Joy Ng, NASA’s Goddard Space Flight Center

Over the past five years, IRIS has kept an eye on the Sun in its 10,000-plus orbits around Earth. It’s one of several in NASA’s Sun-staring fleet that have continually observed the Sun over the past two decades. Together, they are working to resolve the debate over coronal heating and solve other mysteries the Sun keeps.

“From the beginning, the IRIS science investigation has focused on combining high-resolution observations of the solar atmosphere with numerical simulations that capture essential physical processes,” said Bart De Pontieu research scientist at Lockheed Martin Solar & Astrophysics Laboratory in Palo Alto, California. “This paper is a nice illustration of how such a coordinated approach can lead to new physical insights into what drives the dynamics of the solar atmosphere.”

The newest member in NASA’s heliophysics fleet, Parker Solar Probe, may be able to provide some additional clues to the coronal heating mystery. Launched in 2018, the spacecraft flies through the solar corona to trace how energy and heat move through the region and to explore what accelerates the solar wind as well as solar energetic particles. Looking at phenomena far above the region where pseudo-shocks are found, Parker Solar Probe’s investigation hopes to shed light on other heating mechanisms, like nanoflares and electromagnetic waves. This work will complement the research conducted with IRIS.

“This new heating mechanism could be compared to the investigations that Parker Solar Probe will be doing,” said Aleida Higginson, deputy project scientist for Parker Solar Probe at Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. “Together they could provide a comprehensive picture of coronal heating.”

Related Links:

By Mara Johnson-Groh
NASA’s Goddard Space Flight Center, Greenbelt, Md.




Editor: Rob Garner

Source: NASA/IRIS


Thursday, February 21, 2019

Hubble helps uncover origin of Neptune’s smallest moon Hippocamp

Neptune and its smallest moon Hippocamp (artist’s impression)
Hubble data showing Neptune’s inner moons
Orbits of Neptune’s inner moons



Videos

Animation of Neptune’s moon Hippocamp
Animation of Neptune’s moon Hippocamp 




Astronomers using the NASA/ESA Hubble Space Telescope, along with older data from the Voyager 2 probe, have revealed more about the origin of Neptune’s smallest moon. The moon, which was discovered in 2013 and has now received the official name Hippocamp, is believed to be a fragment of its larger neighbour Proteus.

A team of astronomers, led by Mark Showalter of the SETI Institute, have used the NASA/ESA Hubble Space Telescope to study the origin of the smallest known moon orbiting the planet Neptune, discovered in 2013.

“The first thing we realised was that you wouldn’t expect to find such a tiny moon right next to Neptune’s biggest inner moon,” said Mark Showalter. The tiny moon, with an estimated diameter of only about 34 km, was named Hippocamp and is likely to be a fragment from Proteus, Neptune’s second-largest moon and the outermost of the inner moons. Hippocamp, formerly known as S/2004 N 1, is named after the sea creatures of the same name from Greek and Roman mythology [1].

The orbits of Proteus and its tiny neighbour are incredibly close, at only 12 000 km apart. Ordinarily, if two satellites of such different sizes coexisted in such close proximity, either the larger would have  kicked the smaller out of orbit or the smaller would crash into the larger one.

Instead, it appears that billions of years ago a comet collision chipped off a chunk of Proteus. Images from the Voyager 2 probe from 1989 show a large impact crater on Proteus, almost large enough to have shattered the moon. “In 1989, we thought the crater was the end of the story,” said Showalter. “With Hubble, now we know that a little piece of Proteus got left behind and we see it today as Hippocamp.”

Hippocamp is only the most recent result of the turbulent and violent history of Neptune’s satellite system. Proteus itself formed billions of years ago after a cataclysmic event involving Neptune’s satellites. The planet captured an enormous body from the Kuiper belt, now known to be Neptune’s largest moon, Triton. The sudden presence of such a massive object in orbit tore apart all the other satellites in orbit at that time. The debris from shattered moons re-coalesced into the second generation of natural satellites that we see today.

Later bombardment by comets led to the birth of Hippocamp, which can therefore be considered a third-generation satellite. “Based on estimates of comet populations, we know that other moons in the outer Solar System have been hit by comets, smashed apart, and re-accreted multiple times,” noted Jack Lissauer of NASA’s Ames Research Center, California, USA, a coauthor of the new research. “This pair of satellites provides a dramatic illustration that moons are sometimes broken apart by comets.”



Notes

[1] The mythological Hippocampus possesses the upper body of a horse and the lower body of a fish. The Roman god Neptune would drive a sea-chariot pulled by Hippocampi. The name Hippocamp was approved by the International Astronomical Union (IAU). The rules of the International Astronomical Union require that the moons of Neptune are named after Greek and Roman mythology of the undersea world.




The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
The team of astronomers in this study consists of M. R. Showalter (SETI Institute, Mountain View, USA), I. de Pater (Department of Astronomy, University of California, Berkeley, USA), J. J. Lissauer (NASA Ames Research Center, Moffett Field, USA), and R. S. French (SETI Institute, Mountain View, USA).

Image credit: ESA/Hubble, NASA, L. Calçada, A. Feild, M. Showalter et al. 



Links



Contacts

Marc Showalter
SETI Institute
Mountain View, USA
Tel: +1 650 810 0234
Email: mshowalter@seti.org

Mathias Jäger
ESA/Hubble, Public Information Officer
Garching, Germany
Cell: +49 176 62397500
Email: mjaeger@partner.eso.org



Wednesday, February 20, 2019

In Colliding Galaxies, a Pipsqueak Shines Bright

Bright green sources of high-energy X-ray light captured by NASA's NuSTAR mission are overlaid on an optical-light image of the Whirlpool galaxy (in the center of the image) and its companion galaxy, M51b (the bright greenish-white spot above the Whirlpool), taken by the Sloan Digital Sky Survey.Credit: NASA/JPL-Caltech, IPAC.  › Larger view

In the nearby Whirlpool galaxy and its companion galaxy, M51b, two supermassive black holes heat up and devour surrounding material. These two monsters should be the most luminous X-ray sources in sight, but a new study using observations from NASA's NuSTAR (Nuclear Spectroscopic Telescope Array) mission shows that a much smaller object is competing with the two behemoths.

The most stunning features of the Whirlpool galaxy - officially known as M51a - are the two long, star-filled "arms" curling around the galactic center like ribbons. The much smaller M51b clings like a barnacle to the edge of the Whirlpool. Collectively known as M51, the two galaxies are merging. 

At the center of each galaxy is a supermassive black hole millions of times more massive than the Sun. The galactic merger should push huge amounts of gas and dust into those black holes and into orbit around them. In turn, the intense gravity of the black holes should cause that orbiting material to heat up and radiate, forming bright disks around each that can outshine all the stars in their galaxies. 

But neither black hole is radiating as brightly in the X-ray range as scientists would expect during a merger. Based on earlier observations from satellites that detect low-energy X-rays, such as NASA's Chandra X-ray Observatory, scientists believed that layers of gas and dust around the black hole in the larger galaxy were blocking extra emission. But the new study, published in the Astrophysical Journal, used NuSTAR's high-energy X-ray vision to peer below those layers and found that the black hole is still dimmer than expected. 

"I'm still surprised by this finding," said study lead author Murray Brightman, a researcher at Caltech in Pasadena, California. "Galactic mergers are supposed to generate black hole growth, and the evidence of that would be strong emission of high-energy X-rays. But we're not seeing that here."

Brightman thinks the most likely explanation is that black holes "flicker" during galactic mergers rather than radiate with a more or less constant brightness throughout the process. 

"The flickering hypothesis is a new idea in the field," said Daniel Stern, a research scientist at NASA's Jet Propulsion Laboratory in Pasadena and the project scientist for NuSTAR. "We used to think that the black hole variability occurred on timescales of millions of years, but now we're thinking those timescales could be much shorter. Figuring out how short is an area of active study."

Small but  Brilliant

Along with the two black holes radiating less than scientists anticipated in M51a and M51b, the former also hosts an object that is millions of times smaller than either black hole yet is shining with equal intensity. The two phenomena are not connected, but they do create a surprising X-ray landscape in M51. 

The small X-ray source is a neutron star, an incredibly dense nugget of material left over after a massive star explodes at the end of its life. A typical neutron star is hundreds of thousands of times smaller in diameter than the Sun - only as wide as a large city - yet has one to two times the mass. A teaspoon of neutron star material would weigh more than 1 billion tons. 

Despite their size, neutron stars often make themselves known through intense light emissions. The neutron star found in M51 is even brighter than average and belongs to a newly discovered class known as ultraluminous neutron stars. Brightman said some scientists have proposed that strong magnetic fields generated by the neutron star could be responsible for the luminous emission; a previous paper by Brightman and colleagues about this neutron star supports that hypothesis. Some of the other bright, high-energy X-ray sources seen in these two galaxies could also be neutron stars. 

NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corporation in Dulles, Virginia (now part of Northrop Grumman). NuSTAR's mission operations center is at UC Berkeley, and the official data archive is at NASA's High Energy Astrophysics Science Archive Research Center. ASI provides the mission's ground station and a mirror archive. Caltech manages JPL for NASA

News Media Contact

Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.
626-808-2469

calla.e.cofield@jpl.nasa.gov


Source: NuSTAR/News


Citizen Scientist Finds Ancient White Dwarf Star Encircled by Puzzling Rings


Citizen scientists working on Backyard Worlds: Planet 9 scrutinize “flipbooks” of images from NASA’s Wide-field Infrared Survey Explorer. This animation shows a flipbook containing the ring-bearing white dwarf LSPM J0207+3331 (circled). Credits: Backyard Worlds: Planet 9/NASA’s Goddard Space Flight Center
A volunteer working with the NASA-led Backyard Worlds: Planet 9 project has found the oldest and coldest known white dwarf — an Earth-sized remnant of a Sun-like star that has died — ringed by dust and debris. Astronomers suspect this could be the first known white dwarf with multiple dust rings.    

The star, LSPM J0207+3331 or J0207 for short, is forcing researchers to reconsider models of planetary systems and could help us learn about the distant future of our solar system.

“This white dwarf is so old that whatever process is feeding material into its rings must operate on billion-year timescales,” said John Debes, an astronomer at the Space Telescope Science Institute in Baltimore. “Most of the models scientists have created to explain rings around white dwarfs only work well up to around 100 million years, so this star is really challenging our assumptions of how planetary systems evolve.”

A paper detailing the findings, led by Debes, was published in the Feb. 19 issue of The Astrophysical Journal Letters and is now available online.
J0207 is located around 145 light-years away in the constellation Capricornus. White dwarfs slowly cool as they age, and Debes’ team calculated J0207 is about 3 billion years old based on a temperature just over 10,500 degrees Fahrenheit (5,800 degrees Celsius). A strong infrared signal picked up by NASA’s Wide-field Infrared Survey Explorer (WISE) mission — which mapped the entire sky in infrared light — suggested the presence of dust, making J0207 the oldest and coldest white dwarf with dust yet known. Previously, dust disks and rings had only been observed surrounding white dwarfs about one-third J0207’s age.

When a Sun-like star runs out of fuel, it swells into a red giant, ejects at least half of its mass, and leaves behind a very hot white dwarf. Over the course of the star’s giant phase, planets and asteroids close to the star become engulfed and incinerated. Planets and asteroids farther away survive, but move outward as their orbits expand. That’s because when the star loses mass, its gravitational influence on surrounding objects is greatly reduced.

This scenario describes the future of our solar system. 

Around 5 billion years from now, Mercury, then Venus and possibly Earth will be swallowed when the Sun grows into a red giant. Over hundreds of thousands to millions of years, the inner solar system will be scrubbed clean, and the remaining planets will drift outward.

Yet some white dwarfs — between 1 and 4 percent — show infrared emission indicating they’re surrounded by dusty disks or rings. Scientists think the dust may arise from distant asteroids and comets kicked closer to the star by gravitational interactions with displaced planets. As these small bodies approach the white dwarf, the star’s strong gravity tears them apart in a process called tidal disruption. The debris forms a ring of dust that will slowly spiral down onto the surface of the star.

J0207 was found through Backyard Worlds: Planet 9, a project led by Marc Kuchner, a co-author and astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, that asks volunteers to sort through WISE data for new discoveries.

Melina Thévenot, a co-author and citizen scientist in Germany working with the project, initially thought the infrared signal was bad data. She was searching through the ESA’s (European Space Agency’s) Gaia archives for brown dwarfs, objects too large to be planets and too small to be stars, when she noticed J0207. When she looked at the source in the WISE infrared data, it was too bright and too far away to be a brown dwarf. Thévenot passed her findings along to the Backyard Worlds: Planet 9 team. Debes and Kuchner contacted collaborator Adam Burgasser at the University of California, San Diego to obtain follow-up observations with the Keck II telescope at the W. M. Keck Observatory in Hawaii.

“That is a really motivating aspect of the search,” said Thévenot, one of more than 150,000 citizen scientists on the Backyard Worlds project. “The researchers will move their telescopes to look at worlds you have discovered. What I especially enjoy, though, is the interaction with the awesome research team. Everyone is very kind, and they are always trying to make the best out of our discoveries.”

The Keck observations helped confirm J0207’s record-setting properties. Now scientists are left to puzzle how it fits into their models.

Debes compared the population of asteroid belt analogs in white dwarf systems to the grains of sand in an hourglass. Initially, there’s a steady stream of material. The planets fling asteroids inward towards the white dwarf to be torn apart, maintaining a dusty disk. But over time, the asteroid belts become depleted, just like grains of sand in the hourglass. Eventually, all the material in the disk falls down onto the surface of the white dwarf, so older white dwarfs like J0207 should be less likely to have disks or rings.

J0207’s ring may even be multiple rings. Debes and his colleagues suggest there could be two distinct components, one thin ring just at the point where the star’s tides break up the asteroids and a wider ring closer to the white dwarf. Follow-up with future missions like NASA's James Webb Space Telescope may help astronomers tease apart the ring’s constituent parts.

“We built Backyard Worlds: Planet 9 mostly to search for brown dwarfs and new planets in the solar system,” Kuchner said. “But working with citizen scientists always leads to surprises. They are voracious — the project just celebrated its second birthday, and they’ve already discovered more than 1,000 likely brown dwarfs. Now that we’ve rebooted the website with double the amount of WISE data, we’re looking forward to even more exciting discoveries.”  

Backyard Worlds: Planet 9 is a collaboration between NASA, the American Museum of Natural History in New York, Arizona State University, National Optical Astronomy Observatory, the Space Telescope Science Institute in Baltimore, the University of California San Diego, Bucknell University, the University of Oklahoma, and Zooniverse, a collaboration of scientists, software developers and educators who collectively develop and manage citizen science projects on the internet.

NASA's Jet Propulsion Laboratory in Pasadena, California, manages and operates WISE for NASA's Science Mission Directorate. The WISE mission was selected competitively under NASA's Explorers Program managed by the agency's Goddard Space Flight Center. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah. The spacecraft was built by Ball Aerospace & Technologies Corp. in Boulder, Colorado. Placed in hibernation in 2011, the spacecraft was reactivated in 2013 and renamed NEOWISE. Science operations and data processing take place at the Infrared Processing and Analysis Center at Caltech, which manages JPL for NASA.

For more information about Backyard Worlds: Planet 9, visit: http://backyardworlds.org

For more information about NASA's WISE mission, visit: http://www.nasa.gov/wise



Editor: Rob Garner

Source: NASA/Stars


Tuesday, February 19, 2019

Hundreds of Thousands of New Galaxies

Galaxy cluster Abell 1314 in the constellation „Ursa Major“ in a distance of approximately 460 million light years. The LOFAR observations reveal radio emission from high-speed cosmic electrons (marked in red) resulting from collisions with other galaxy clusters. The overlay onto an optical image also shows hot X-ray gas (marked in grey) from observations with the Chandra satellite. © Amanda Wilber/LOFAR Surveys Team

Astronomers publish new sky map detecting a vast number of previously unknown galaxies

An international team of more than 200 astronomers from 18 countries including scientists from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has published the first phase of a major new radio sky survey at unprecedented sensitivity using the Low Frequency Array (LOFAR) telescope. The survey reveals hundreds of thousands of previously undetected galaxies, shedding new light on many research areas including the physics of black holes and how clusters of galaxies evolve.

A special issue of the scientific journal Astronomy & Astrophysics is dedicated to the first twenty-six research papers describing the survey and its first results.

Radio astronomy reveals processes in the Universe that we cannot see with optical instruments. In this first part of the sky survey, LOFAR observed a quarter of the northern hemisphere at low radio frequencies. At this point, approximately ten percent of that data is now made public. It maps three hundred thousand sources, almost all of which are galaxies in the distant Universe; their radio signals have travelled billions of light years before reaching Earth.

Black holes

Huub Röttgering, Leiden University (The Netherlands): “If we take a radio telescope and we look up at the sky, we see mainly emission from the immediate environment of massive black holes. With LOFAR we hope to answer the fascinating question: where do those black holes come from?” What we do know is that black holes are pretty messy eaters. When gas falls onto them they emit jets of material that can be seen at radio wavelengths.

Philip Best, University of Edinburgh (UK), adds: “LOFAR has a remarkable sensitivity and that allows us to see that these jets are present in all of the most massive galaxies, which means that their black holes never stop eating.”

Clusters of galaxies

Clusters of galaxies are ensembles of hundreds to thousands of galaxies and it has been known for decades that when two clusters of galaxies merge, they can produce radio emission spanning millions of light years. This emission is thought to come from particles that are accelerated during the merger process. Amanda Wilber, University of Hamburg (Germany), elaborates: “With radio observations we can detect radiation from the tenuous medium that exists between galaxies. This radiation is generated by energetic shocks and turbulence. LOFAR allows us to detect many more of these sources and understand what is powering them."

Annalisa Bonafede, University of Bologna and INAF (Italy), adds: “What we are beginning to see with LOFAR is that, in some cases, clusters of galaxies that are not merging can also show this emission, albeit at a very low level that was previously undetectable. This discovery tells us that, besides merger events, there are other phenomena that can trigger particle acceleration over huge scales.”

Magnetic fields

The unprecedented accuracy of the LOFAR measurements allows to measure the effect of cosmic magnetic fields on radio waves. Researchers from Germany investigated magnetic fields in the halos of galaxies. They could show the existence of enormous magnetic structures also between galaxies. „The LOFAR data are providing hints that the space between galaxies could be completely magnetic“, says Rainer Beck from MPIfR Bonn, Germany.

High-quality images

Creating low-frequency radio sky maps takes both significant telescope and computational time and requires large teams to analyse the data. “LOFAR produces enormous amounts of data - we have to process the equivalent of ten million DVDs of data. The LOFAR surveys were recently made possible by a mathematical breakthrough in the way we understand interferometry”, says Cyril Tasse, Observatoire de Paris - Station de radioastronomie à Nançay (France).

“We have been working together with SURF in the Netherlands to efficiently transform the massive amounts of data into high-quality images. These images are now public and will allow astronomers to study the evolution of galaxies in unprecedented detail”, says Timothy Shimwell, Netherlands Institute for Radio Astronomy (ASTRON) and Leiden University.

SURF's compute and data centre located at SURFsara in Amsterdam runs on 100 percent renewable energy and hosts over 20 petabytes of LOFAR data. “This is more than half of all data collected by the LOFAR telescope to date. It is the largest astronomical data collection in the world. Processing the enormous data sets is a huge challenge for scientists. What normally would have taken centuries on a regular computer was processed in less than one year using the high throughput compute cluster (Grid) and expertise”, says Raymond Oonk (SURFsara).

LOFAR

The LOFAR telescope, the Low Frequency Array, is unique in its capabilities to map the sky in fine detail at metre wavelengths. LOFAR is operated by ASTRON in The Netherlands and is considered to be the world’s leading telescope of its type. “This sky map will be a wonderful scientific legacy for the future. It is a testimony to the designers of LOFAR that this telescope performs so well”, says Carole Jackson, Director General of ASTRON.

The next step

The 26 research papers in the special issue of Astronomy & Astrophysics were done with only the first two percent of the sky survey. The team aims to make sensitive high-resolution images of the whole northern sky, which will reveal 15 million radio sources in total. “Just imagine some of the discoveries we may make along the way. I certainly look forward to it”, says Jackson. “And among these there will be the first massive black holes that formed when the Universe was only a ‘baby’, with an age a few percent of its present age”, adds Röttgering.

LOFAR station Effelsberg, shown from 50 m above ground. In front: LOFAR lowband antennas (LBA) for 10-80 MHz, in the back: LOFAR highband antennas (HBA) for 110-240 MHz. © W. Reich/MPIfR




Local Contact:

Dr. Rainer Beck
Phone:+49 228 525-323
Email: rbeck@mpifr-bonn.mpg.de
Max-Planck-Institut für Radioastronomie, Bonn

Prof. Dr. Michael Kramer
Director and Head of "Fundamental Physics in Radio Astronomy" Research Dept.
Phone:+49 228 525-278
Email: mkramer@mpifr-bonn.mpg.de
Max-Planck-Institut für Radioastronomie, Bonn

Dr. Norbert Junkes
Press and Public Outreach
Phone:+49 228 525-399
Email: njunkes@mpifr-bonn.mpg.de
Max-Planck-Institut für Radioastronomie, Bonn



Original Papers:

LOFAR Surveys - 26 papers in special issue of „Astronomy and Astrophysics“ 2019.



Links:

Radioastro­nomische Fundamental­physik
Research Department "Fundamental Physics in Radio Astronomy" at MPIfR, Bonn, Germany

Images and Videos - Additional images and video clips

Image Gallery LOFAR Surveys - Images from LOFAR surveys

LOFAR - International LOFAR Telescope (ILT)

LOFAR MPIfR - LOFAR website at Max Planck Institute for Radio Astronomy (MPIfR)

GLOW - German Long Wavelength Consortium (GLOW)



LOFAR: The international LOFAR telescope (ILT) consists of a European network of radio antennas, connected by a high-speed fibre optic network spanning seven countries. LOFAR was designed, built and is now operated by ASTRON (Netherlands Institute for Radio Astronomy), with its core located in Exloo in the Netherlands. LOFAR works by combining the signals from more than 100,000 individual antenna dipoles, using powerful computers to process the radio signals as if it formed a ‘dish’ of 1900 kilometres diameter. LOFAR is unparalleled given its sensitivity and ability to image at high resolution (i.e. its ability to make highly detailed images), such that the LOFAR data archive is the largest astronomical data collection in the world and is hosted at SURFsara (The Netherlands), Forschungszentrum Juelich (Germany) and the Poznan Super Computing Center (Poland). LOFAR is a pathfinder of the Square Kilometre Array (SKA), which will be the largest and most sensitive radio telescope in the world.

Institutes publishing the results:

Australia: CSIRO

Canada: University of Montreal, University of Calgary, Queen’s University

Denmark: University of Copenhagen

France: Observatoire de Paris PSL, Station de radioastronomie de Nançay, Université Côte d'Azur, Université de Strasbourg

Germany: Hamburg University, Ruhr-University Bochum, Karl Schwarzschild Observatory Tautenburg, European Southern Observatory, University of Bonn, Max Planck Institut für Extraterrestrische Physik, Garching, Bielefeld University, Max Planck Institute for Radio Astronomy, Bonn

Iceland: University of Iceland

India: Savitribai Phule Pune University

Ireland: University College Dublin

Italy: National Institute for Astrophysics (INAF), University of Bologna

Mexico: Universidad de Guanajuato


The Netherlands: ASTRON, the NOVA (Netherlands Research School for Astronomy) institutes at Leiden University, Groningen University, University of Amsterdam and Radboud University Nijmegen, SURFsara, SRON, Ampyx Power B.V, JIVE

Poland: Jagiellonian University, Nicolaus Copernicus University Toruń

South Africa: University of Western Cape, Rhodes University, SKA South Africa

Spain: Universidad de La Laguna

Sweden: Chalmers University

Uganda: Mbarara University of Science & Technology


United Kingdom: University of Hertfordshire, University of Edinburgh, Open University, University of Oxford, Univerity of Southampton, University of Bristol, University of Manchester, The Rutherford Appleton Laboratory, University of Portsmouth, University of Nottingham

USA: Harvard University, Naval Research Laboratory, University of Massachusetts