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  • richardmitnick 7:03 am on October 31, 2017 Permalink | Reply
    Tags: , , , , NAOJ Subaru Telescope   

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

    NAOJ

    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.

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    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.

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    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 .

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    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

    NAOJ Subaru Telescope interior
    Subaru

    ALMA Array
    ALMA

    sft
    Solar Flare Telescope

    Nobeyama Radio Telescope - Copy
    Nobeyama Radio Observatory

    Nobeyama Solar Radio Telescope Array
    Nobeyama Radio Observatory: Solar

    Misuzawa Station Japan
    Mizusawa VERA Observatory

    NAOJ Okayama Astrophysical Observatory Telescope
    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.

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  • richardmitnick 3:26 pm on October 5, 2017 Permalink | Reply
    Tags: , , , , NAOJ Cray XC30 ATERUI, NAOJ Subaru Telescope, , ,   

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

    NAOJ

    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

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    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 .

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    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

    NAOJ Subaru Telescope interior
    Subaru

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

    sft
    Solar Flare Telescope

    Nobeyama Radio Telescope - Copy
    Nobeyama Radio Observatory

    Nobeyama Solar Radio Telescope Array
    Nobeyama Radio Observatory: Solar

    Misuzawa Station Japan
    Mizusawa VERA Observatory

    NAOJ Okayama Astrophysical Observatory Telescope
    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.

     
  • richardmitnick 1:17 pm on September 10, 2017 Permalink | Reply
    Tags: , , , , , Explosive Birth of Stars Swells Galactic Cores - ALMA spots transforming disk galaxies, NAOJ Subaru Telescope,   

    From ALMA: “Explosive Birth of Stars Swells Galactic Cores – ALMA spots transforming disk galaxies” 

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

    2017.09.11
    No writer credits

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    NAOJ

    Astronomers found that active star formation upswells galaxies, like yeast helps bread rise. Using three powerful telescopes on the ground and in orbit, they observed galaxies from 11 billion years ago and found explosive formation of stars in the cores of galaxies. This suggests that galaxies can change their own shape without interaction with other galaxies.

    Astronomers found that active star formation upswells galaxies, like yeast helps bread rise. Using three powerful telescopes on the ground and in orbit, they observed galaxies from 11 billion years ago and found explosive formation of stars in the cores of galaxies. This suggests that galaxies can change their own shape without interaction with other galaxies.

    “Massive elliptical galaxies are believed to be formed from collisions of disk galaxies,” said Ken-ichi Tadaki, the lead author of two research papers and a postdoctoral researcher at the National Astronomical Observatory of Japan (NAOJ). “But, it is uncertain whether all the elliptical galaxies have experienced galaxy collision. There may be an alternative path.”

    Aiming to understand galactic metamorphosis, the international team explored distant galaxies 11 billion light-years away. Because it takes time for the light from distant objects to reach us, by observing galaxies 11 billion light-years away, the team can see what the Universe looked like 11 billion years ago, 3 billion years after the Big Bang. This corresponds the peak epoch of galaxy formation; the foundations of most galaxies were formed in this epoch.

    Receiving faint light which has travelled 11 billion years is tough work. The team harnessed the power of three telescopes to anatomize the ancient galaxies. First, they used NAOJ’s 8.2-m Subaru Telescope in Hawai`i and picked out 25 galaxies in this epoch.


    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA

    Then they targeted the galaxies for observations with NASA/ESA’s Hubble Space Telescope (HST) and the Atacama Large Millimeter/submillimeter Array (ALMA).

    NASA/ESA Hubble Telescope

    The astronomers used HST to capture the light from stars which tells us the “current” (as of when the light was emitted, 11 billion years ago) shape of the galaxies, while ALMA observed submillimeter waves from cold clouds of gas and dust, where new stars are being formed. By combining the two, we know the shapes of the galaxies 11 billion years ago and how they are evolving.

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    Observation images of a galaxy 11 billion light-years away. Submillimeter waves detected with ALMA are shown in left, indicating the location of dense dust and gas where stars are being formed. Optical and infrared light seen with the Hubble Space Telescope are shown in the middle and right, respectively. A large galactic disk is seen in infrared, while three young star clusters are seen in optical light.
    Credit: ALMA (ESO/NAOJ/NRAO), NASA/ESA Hubble Space Telescope, Tadaki et al.

    Thanks to their high resolution, HST and ALMA could illustrate the metamorphosis of the galaxies. With HST images the team found that a disk component dominates the galaxies. Meanwhile, the ALMA images show that there is a massive reservoir of gas and dust, the material of stars, so that stars are forming very actively. The star formation activity is so high that huge numbers of stars will be formed at the centers of the galaxies. This leads the astronomers to think that ultimately the galaxies will be dominated by the stellar bulge and become elliptical or lenticular galaxies.

    “Here, we obtained firm evidence that dense galactic cores can be formed without galaxy collisions. They can also be formed by intense star formation in the heart of the galaxy.” said Tadaki. The team used the European Southern Observatory’s Very Large Telescope to observe the target galaxies and confirmed that there are no indications of massive galaxy collisions.

    ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

    Almost 100 years ago, American astronomer Edwin Hubble invented the morphological classification scheme for galaxies. Since then, many astronomers have devoted considerable effort to understanding the origin of the variety in galaxy shapes. Utilizing the most advanced telescopes, modern astronomers have come one step closer to solving the mysteries of galaxies.

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    Evolution diagram of a galaxy. First the galaxy is dominated by the disk component (left) but active star formation occurs in the huge dust and gas cloud at the center of the galaxy (center). Then the galaxy is dominated by the stellar bulge and becomes an elliptical or lenticular galaxy. Credit: NAOJ

    Paper and research team
    These observation results were published as Tadaki et al. Bulge-forming Galaxies with an Extended Rotating Disk at z ~ 2 and Rotating Starburst Cores in Massive Galaxies at z = 2.5 in The Astrophysical Journal Letters in January and May 2017, respectively.

    The research team members are:
    Ken-ichi Tadaki (Max-Planck-Institute for Extraterrestrial Physics [MPE]/National Astronomical Observatory of Japan [NAOJ]), Reinhard Genzel (MPE/University of California, Berkeley), Tadayuki Kodama (NAOJ/The Graduate University for Advanced Studies [SOKENDAI], Tohoku University), Stijn Wuyts (University of Bath), Emily Wisnioski (MPE), Natascha M. Foerster Schreiber (MPE), Andreas Burkert (MPE/Ludwig Maximilian University), Phillip Lang (MPE), Linda J. Tacconi (MPE), Dieter Lutz (MPE), Sirio Belli (MPE), Richard I. Davies (MPE), Bunyo Hatsukade (The University of Tokyo), Masao Hayashi (NAOJ), Rodrigo Herrera-Camus (MPE), Soh Ikarashi (University of Groningen), Shigeki Inoue (The University of Tokyo), Kotaro Kohno (The University of Tokyo), Yusei Koyama (NAOJ), J. Trevor Mendel (MPE / Ludwig Maximilian University), Kouichiro Nakanishi (NAOJ/SOKENDAI), Rhythm Shimakawa (SOEKNDAI/University of California), Tomoko L. Suzuki (SOEKNDAI/NAOJ), Yoichi Tamura (The University of Tokyo/Nagoya University), Ichi Tanaka (NAOJ), Hannah Uebler (MPE), Dave J. Wilman (MPE/ Ludwig Maximilian University), Erica J. Nelson (MPE), Magdalena Lippa (MPE)

    This research was supported by the Japan Society for the Promotion of Science and the German Academic Exchange Service under the Japan-German Research Cooperative Program.

    See the full article here .

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    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

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

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  • richardmitnick 10:03 am on March 29, 2017 Permalink | Reply
    Tags: , , , , NAOJ Subaru Telescope, Subaru Telescope Detects the Shadow of a Gas Cloud in an Ancient Proto-supercluster   

    From NOAJ Subaru: “Subaru Telescope Detects the Shadow of a Gas Cloud in an Ancient Proto-supercluster” 

    NAOJ

    NAOJ

    March 28, 2017

    A team led by researchers from Osaka Sangyo University, with members from Tohoku University, Japan Aerospace Exploration Agency (JAXA) and others, has used the Suprime-Cam on the Subaru Telescope to create the most-extensive map of neutral hydrogen gas in the early universe (Figure 1). This cloud appears widely spread out across 160 million light-years in and around a structure called the proto-supercluster. It is the largest structure in the distant universe, and existed some 11.5 billion years ago. Such a huge gas cloud is extremely valuable for studying large-scale structure formation and the evolution of galaxies from gas in the early universe, and merits further investigation.

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    The distribution of galaxies in the proto-supercluster region 11.5 billion years ago (top left), and the Subaru Telescope Suprime-Cam image used in this work.


    NAOJ Subaru Hyper Suprime Camera

    Neutral hydrogen gas distribution is superposed on the Subaru image. The red color indicates denser regions of the neutral hydrogen gas. Cyan squares correspond to member galaxies in the proto-supercluster, while objects without cyan squares are foreground galaxies and stars. The distribution of neutral hydrogen gas does not align perfectly with the galaxies. (Credit: Osaka Sangyo University/NAOJ)

    “We are surprised because the dense gas structure is extended much more than expected in the proto-supercluster,” said Dr. Mawatari. “Wider field observations with narrow-band filters are needed to grasp full picture of this largest structure in the young Universe. This is exactly the type of strong research that can be done with Hyper Suprime-Cam (HSC) recently mounted at the Subaru Telescope. We intend to study the gas – galaxy relation in various proto-superclusters using the HSC.”

    Understanding Matter Distribution in the Universe

    Stars assembled to form galaxies, and galaxies are clustered to form larger structures such as clusters or superclusters. Matter in the current universe is structured in a hierarchical manner on scales of ~ 100 million light-years. However, we cannot observe inhomogeneous structure in any direction or distance over scales larger than that. One important issue in modern astronomy is to clarify how perfectly the large-scale uniformity and homogeneity in matter distribution is maintained. In addition, astronomers seek to investigate the properties of the seeds of large-scale structures (i.e., the initial matter fluctuations) that existed at the beginning of the universe. Thus, it is important to observe huge structures at various epochs (which translates to distances). The study of gaseous matter as well as galaxies is needed for an accurate and comprehensive understanding. This is because local superclusters are known to be rich in gas. Furthermore, it is clear that there are many newborn galaxies in ancient (or distant) clusters. A detailed comparison between the spatial distributions of galaxies and gas during the early epochs of the universe is very important to understand process of galaxy formation from the dim (low light-emitting) clumps of gas in the early universe.

    In order to investigate early, dim gas clouds, astronomers take advantage of the fact that light from bright distant objects gets dimmed by foreground gas (giving an effect like a “shadow picture”). Since neutral hydrogen in the gas cloud absorbs and dims light from background objects at a certain wavelength, we can see characteristic absorption feature in the spectrum of the background object. In many previous observations, researchers used quasars (which are very bright and distant) as background light sources. Because bright quasars are very rare, opportunities for such observations are limited. This allows astronomers to get information about the gas that lies only along the line of sight between a single QSO and Earth in a wide survey area. It has long been the goal to obtain “multi-dimensional” information of gas (e.g., spatially resolve the gas clouds) rather than the “one-dimensional” view currently available. This requires a new approach.

    Expanding the View

    To widen their view of these objects in the early universe, Dr. Ken Mawatari at Osaka Sangyo University and his colleagues recently developed a scheme to analyze the spatial distribution of the neutral hydrogen gas using imaging data of galaxies of the distant epoch (Figure 2).

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    Figure 2: Schematic pictures of an analysis scheme of previous work (left) and a new method (right). In the previous approach, basically a single background light source (quasar) can be used in a searched area. On the other hand, with the new scheme, it is easier to spatially resolve the neutral hydrogen gas density by using many normal galaxies in a searched area as background light sources. In the new scheme, absorption strength by the neutral hydrogen gas is estimated by measuring how much flux of the background galaxies becomes dimmed in the narrow-band image, not by using spectrum. By combining this scheme with the wide-area imaging ability of the Subaru Telescope, Mawatari, et al. made the most-extensive map of neutral hydrogen gas ever created. (Credit: Osaka Sangyo University/NAOJ)

    There are two major advantages to this approach. First, instead of rare quasars, the team uses numerous normal galaxies as background light sources to investigate gas distribution at various places in the search area. Second, they use imaging data taken with the narrow-band filter on Suprime-cam. It is fine-tuned so that light with certain wavelengths can be transmitted, to capture evidence of absorption by the neutral hydrogen gas (the shadow picture effect). Compared with the traditional scheme of observations based on spectroscopy of quasars, this new method enables Mawatari and his collaborators to obtain wide-area gas distribution information relatively quickly.

    The researchers applied their scheme to the Subaru Telescope Suprime-Cam imaging data taken in their previous large survey of galaxies. The fields investigated in this work include the SSA22 field, an ancestor of a supercluster of galaxies (proto-supercluster), where young galaxies are formed actively, in the universe 11.5 billion years ago in the early universe.

    New Maps of Neutral Hydrogen Distribution

    The researchers’ work resulted in very wide-area maps of the neutral hydrogen gas in the three fields studied (Figure 3).

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    Figure 3: Sky distribution of the neutral hydrogen gas in the three fields studied in this work. While in the normal fields (SXDS and GOODS-N) the neutral hydrogen gas density is consistent with the average density in the entire universe at 11.5 billion years ago, the neutral hydrogen gas density is higher than the average over the entire SSA22 proto-supercluster field. Contours correspond to the galaxies’ number density. Bold, solid thin, and dashed contours mean the average, high density, and low density regions, respectively. (Credit: Osaka Sangyo University/NAOJ)

    It appears that the neutral hydrogen gas absorption is significantly strong over the entire SSA22 proto-supercluster field compared with those in the normal fields (SXDS and GOODS-N). It is clearly confirmed that the proto-supercluster environment is rich in neutral hydrogen gas, which is the major building block of galaxies.

    The team’s work also revealed that gas distribution in the proto-supercluster region does not align with the galaxies’ distribution perfectly (see Figure 1 and Figure 3). While the proto-supercluster is rich in both galaxies and gas, there is no local-scale dependency of gas amount correlated with the density of galaxies inside the proto-supercluster. This result may mean that the neutral hydrogen gas not only is associated with the individual galaxies but also spreads out diffusely across intergalactic space only within the proto-supercluster. Since the neutral hydrogen gas excess in the SSA22 field is detected over the entire searched area, this overdense gas structure is actually extended more than 160 million light-years. In the traditional view of structure formation, matter density fluctuation is thought to be smaller and large-scale high-density structure was rarer in the early universe. The discovery that a gas structure that extends across more than 160 million light-years (which is roughly same as present-day superclusters in scale) already existed in the universe 11.5 billion years ago is a surprising result of this study.

    By investigating spatial distribution of the neutral hydrogen gas in a very large area, the researchers have provided a new window on the relation between gas and galaxies in the young universe. The SSA22 huge gas structure revealed by this work is considered a key object to test the standard theory of structure formation, and so further investigation is anticipated.

    This research will be published in the journal of the British Royal Astronomical Society (Monthly Notices of the Royal Astronomical Society, publisher Oxford University Press) in its June, 2017 issue of the printed version (Mawatari et al. 2017, MNRAS, 467, 3951, “Imaging of diffuse HI absorption structure in the SSA22 protocluster region at z = 3.1”). This work is supported by JSPS Grant-in-Aid JP26287034 and JP16H06713.

    See the full article here .

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    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

    NAOJ Subaru Telescope interior
    Subaru

    ALMA Array
    ALMA

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    Solar Flare Telescope

    Nobeyama Radio Telescope - Copy
    Nobeyama Radio Observatory

    Nobeyama Solar Radio Telescope Array
    Nobeyama Radio Observatory: Solar

    Misuzawa Station Japan
    Mizusawa VERA Observatory

    NAOJ Okayama Astrophysical Observatory Telescope
    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.

     
  • richardmitnick 1:55 pm on February 24, 2017 Permalink | Reply
    Tags: NAOJ Subaru Telescope, Saturn's rings   

    From NAOJ: “Saturn’s Rings Viewed in the Mid-infrared Show Bright Cassini Division” 

    NAOJ

    NAOJ

    1
    Figure 1: A three-color composite of the mid-infrared images of Saturn on January 23, 2008 captured with COMICS on the Subaru Telescope. The Cassini Division and the C ring appear bright. Color differences reflect the temperatures; the warmer part is blue, the cooler part is red. (Credit: NAOJ)

    A team of researchers has succeeded in measuring the brightnesses and temperatures of Saturn’s rings using the mid-infrared images taken by the Subaru Telescope in 2008. The images are the highest resolution ground-based views ever made. They reveal that, at that time, the Cassini Division and the C ring were brighter than the other rings in the mid-infrared light and that the brightness contrast appeared to be the inverse of that seen in the visible light (Figure 1). The data give important insights into the nature of Saturn’s rings.

    The beautiful appearance of Saturn and its rings has always fascinated people. The rings consist of countless numbers of ice particles orbiting above Saturn’s equator. However, their detailed origin and nature remain unknown. Spacecraft- and ground-based telescopes have tackled that mystery with many observations at various wavelengths and methods. The international Cassini mission led by NASA has been observing Saturn and its rings for more than 10 years, and has released a huge number of beautiful images.

    Subaru Views Saturn

    The Subaru Telescope also has observed Saturn several times over the years. Dr. Hideaki Fujiwara, Subaru Public Information Officer/Scientist, analyzed data taken in January 2008 using the Cooled Mid-Infrared Camera and Spectrometer (COMICS) on the telescope to produce a beautiful image of Saturn for public information purposes. During the analysis, he noticed that the appearance of Saturn’s rings in the mid-infrared part of the spectrum was totally different from what is seen in the visible light.

    Saturn’s main rings consist of the C, B, and A rings, each with different populations of particles. The Cassini Division separates the B and A rings. The 2008 image shows that the Cassini Division and the C ring are brighter in the mid-infrared wavelengths than the B and A rings appear to be (Figure 1). This brightness contrast is the inverse of how they appear in the visible light, where the B and A rings are always brighter than the Cassini Division and the C ring (Figure 2).

    2
    Figure 2: Comparison of the images of Saturn’s rings in the 2008 view in the mid-infrared (left) and the visible light (right). The visible light image was taken on March 16, 2008 with the 105-cm Murikabushi telescope at Ishigakijima Astronomical Observatory. The radial brightness contrast of Saturn’s rings is the inverse between the two wavelength ranges. (Credit: NAOJ)

    “Thermal emission” from ring particles is observed in the mid-infrared, where warmer particles are brighter. The team measured the temperatures of the rings from the images, which revealed that the Cassini Division and the C ring are warmer than the B and A rings. The team concluded that this was because the particles in the Cassini Division and C ring are more easily heated by solar light due to their sparser populations and darker surfaces.

    On the other hand, in the visible light, observers see sunlight being reflected by the ring particles. Therefore, the B and A rings, with their dense populations of particles, always seem bright in the visible wavelengths, while the Cassini Division and the C ring appear faint. The difference in the emission process explains the inverse brightnesses of Saturn’s rings between the mid-infrared and the visible-light views.

    Changing Angles Change the Brightnesses

    3
    Figure 3: Comparison of the mid-infrared images of Saturn’s rings on April 30, 2005 (top) and January 23, 2008 (bottom). Although both of the images were taken in the mid-infrared, the radial contrast of Saturn’s rings is the inverse of each other. (Credit: NAOJ)

    The team concluded that the “inversion” of the brightness of Saturn’s rings between 2005 and 2008 was caused by the seasonal change in the ring opening angle to the Sun and Earth. Since the rotation axis of Saturn inclines compared to its orbital plane around the Sun, the ring opening angle to the Sun changes over a 15-year cycle. This makes a seasonal variation in the solar heating of the ring particles. The change in the opening angle viewed from the Earth affects the apparent filling factor of the particles in the rings. These two variations – the temperature and the observed filling factor of the particles – led to the change in the mid-infrared appearance of Saturn’s rings.

    The data taken with the Subaru Telescope revealed that the Cassini Division and the C ring are sometimes bright in the mid-infrared though they are always faint in visible light. “I am so happy that the public information activities of the Subaru Telescope, of which I am in charge, led to this scientific finding,” said Dr. Fujiwara. “We are going to observe Saturn again in May 2017 and hope to investigate the nature of Saturn’s rings further by taking advantages of observations with space missions and ground-based telescopes.”

    This research is published in Astronomy & Astrophysics, Volume 599, A29 and posted on-line on February 23, 2017 (Fujiwara et al., 2017, Seasonal variation of the radial brightness contrast of Saturn’s rings viewed in mid-infrared by Subaru/COMICS). This work is supported JSPS KAKENHI Grant Numbers JP23103002 and JP26800110.

    The research team:

    Hideaki Fujiwara: Subaru Telescope, National Astronomical Observatory of Japan, USA
    Ryuji Morishima: University of California, Los Angeles/Jet Propulsion Laboratory, California Institute of Technology, USA
    Takuya Fujiyoshi: Subaru Telescope, National Astronomical Observatory of Japan, USA
    Takuya Yamashita: National Astronomical Observatory of Japan, Japan

    See the full article here .

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    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

    NAOJ Subaru Telescope interior
    Subaru

    ALMA Array
    ALMA

    sft
    Solar Flare Telescope

    Nobeyama Radio Telescope - Copy
    Nobeyama Radio Observatory

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    Nobeyama Radio Observatory: Solar

    Misuzawa Station Japan
    Mizusawa VERA Observatory

    NAOJ Okayama Astrophysical Observatory Telescope
    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.

     
  • richardmitnick 8:44 am on January 31, 2017 Permalink | Reply
    Tags: , , , , MMT telescope, NAOJ Subaru Telescope, Weak lensing   

    From Subaru: “Tracing the Cosmic Web with Star-forming Galaxies in the Distant Universe” 

    NAOJ

    NAOJ

    January 30, 2017
    No writer credit

    A research group led by Hiroshima University has revealed a picture of the increasing fraction of massive star-forming galaxies in the distant universe. Massive star-forming galaxies in the distant universe, about 5 billion years ago, trace large-scale structure in the universe. In the nearby universe, about 3 billion years ago, massive star-forming galaxies are not apparent. This change in the way star-forming galaxies trace the matter distribution is consistent with the picture of galaxy evolution established by other independent studies.

    1
    Figure 1: A close-up view of the cluster of galaxies observed. The image is a compotie of the i-band data (in red) from the Hyper Suprime-Cam at the Subaru Telescope and R-band (in green) and V-band (in blue) images from the Mayall 4-m telescope at the Kitt Peak National Observatory of National Optical Astronomy Observatory. Contour lines show the mass distribution. Red and blue circles show galaxies that stopped star formation and galaxies with star formation, respectively. The research team was able to study the evolution of the large scale structure in the Universe by comparing the mass distribution in the Universe and the distribution of the galaxies. (Credit: Hiroshima University/NAOJ)

    Galaxies in the universe trace patterns on very large scales; there are large empty regions (called “voids”) and dense regions where the galaxies exist. This distribution is called the cosmic web. The most massive concentrations of galaxies are clusters. The formation of the cosmic web is governed by the action of gravity on the invisible mysterious “dark matter” that exists throughout the universe. The normal baryonic material one can see falls into the dark matter halos and forms galaxies. The action of gravity over about 14-billion-year history of the universe makes the halos cluster together. The location of galaxies or clusters in this enormous cosmic web tests our understanding of the way structure forms in the universe.

    Increasingly, deeper and more extensive observations with telescopes like Subaru Telescope provide a clearer picture of the way galaxies evolve within the cosmic web. Of course, one cannot see the dark matter directly. However, one can use the galaxies that are seen to trace the dark matter. It is also possible to use the way the gravity of clusters of galaxies distort more distant background galaxies, weak gravitational lensing, as another tracer.

    The Hiroshima group combined these two tracers: galaxies and their weak lensing signal to map the changing role of massive star-forming galaxies as the universe evolves.

    Weak lensing is a phenomenon that provides a powerful technique for mapping the changing contribution of star-forming galaxies as tracers of the cosmic web. The cluster of galaxies and surrounding dark matter halo act as a gravitational lens. The lens bends the light passing through from more distant galaxies and distorts the images of them. The distortions of the appearance of the background galaxies provide a two-dimensional image of the foreground dark matter distribution that acts as a huge lens. The excellent imaging of the Subaru Telescope covering large regions of the sky provides exactly the data needed to construct maps of this weak lensing.

    Dr. Yousuke Utsumi, a member of Hyper Suprime-Cam building team and a project assistant professor at Hiroshima University, conducted a 1-hour observation of a 4-deg2 patch of sky in the direction of the constellation Cancer. Figure 1 shows a close-up view of a cluster of galaxies with the weak lensing map tracing the matter distribution. The highest peaks in the maps correspond the foreground massive clusters of galaxies that lie 5 billion light-years away.

    To map the three-dimensional distribution of the foreground galaxies, spectrographs on large telescopes like the 6.5-meter MMT disperse the light with a grating.

    MMT Telescope at the summit of Mount Hopkins near Tucson, Arizona, USA
    MMT Telescope at the summit of Mount Hopkins near Tucson, Arizona, USA

    The expansion of the universe shifts the light to the red and by measuring this shift one measures the distances to the galaxies. Using spectroscopy places the galaxies in the cosmic web. The observations locate star-forming galaxies and those that are no longer forming stars.

    Collaborators led by Dr. Margaret Geller (Harvard-Smithsonian Center for Astrophysics) conducted spectroscopic measurements for galaxies. The Hectospec instrument on the MMT enables measurements of redshifts for 250 galaxies at a time. The survey contains measurements for 12,000 galaxies.

    The MMT redshift survey provides the map for the way all types of galaxies might contribute to the weak lensing map. Because the MMT survey provides distances to the galaxies, slices of the map at different distances corresponding to different epochs in the history of the universe can also be made and compared with the lensing map.

    The MMT survey provides a predicted map of the cosmic web based on the positions of galaxies in three-dimensional space. Research team compared this map with the weak lensing map to discover the similarities. Figure 2 shows that both the highest peak and the largest empty regions are similar in the two maps. In other words, the matter distribution traced by the foreground galaxies and the distribution traced by the Subaru weak lensing map are similar. There are two complementary views of the cosmic web in this patch of the universe.

    2
    Figure 2: Distribution of mass (left) and galaxies (right) in the corresponding area. The conspicuous feature in the galaxy distribution also is visible in the left side, mass distribution, while the areas with no structure in the right also has no feature in the left. (Credit: Hiroshima University/NAOJ)

    If they slice up the three-dimensional map in different redshift or time slices, they can examine the way the correspondence between these maps and the weak lensing map changes for different slices (Figure 3). Remarkably, the distribution of star-forming galaxies around a cluster of galaxies in the more distant universe (5 billion years ago) corresponds much more closely with the weak lensing map than a slice of the more nearby universe (3 billion years ago). In other words, the contribution of star-forming galaxies to the cosmic web is more prominent in the distant universe. These maps are the first demonstration of this effect in the weak lensing signal (Figure 4).

    3
    Figure 3: The distribution of galaxies with respect to the distance. The panels show the three-dimensional distribution of the galaxies, viewed from the observer on Earth. Red points represent quiescent galaxies and blue points are star-forming galaxies. Boxes in the cone are 3 and 5 billion light-years from the observer. The maps next to the enclosed areas show the corresponding distribution of galaxies. (Credit: Hiroshima University/NAOJ)

    4
    Figure 4: Close-ups of the cluster of galaxies at 3 billion light years (top) and 5 billion light years (bottom). These panels show the distribution of mass (left), quiescent galaxies (middle), and star forming galaxies (right), respectively. Three billion years ago, it is hard to see any similarity between the star-forming galaxies and the mass distribution, but there is much greater similarity in the maps of 5 billion years ago. (Credit: Hiroshima University/NAOJ)

    The research team provides a new window on galaxy evolution by comparing the three-dimensional galaxy distribution mapped with a redshift survey including star-forming galaxies to a weak lensing map based on Subaru imaging.

    “It turns out that the contribution of star-forming galaxies as tracers of the mass distribution in the distant universe is not negligible,” said Dr. Utsumi. “The HSC weak lensing map should contain signals from more distant galaxies in the 8 billion-year-old universe. Deeper redshift surveys combined with similar weak lensing maps should reveal an even greater contribution of star-forming galaxies as tracers of the matter distribution in this higher redshift range. Using the next generation spectrograph for the Subaru Telescope, Prime Focus Spectrograph (PFS), we hope to extend our maps to the interesting era.”

    naoj-subaru-prime-focus-sectrograph
    NAOJ Subaru Prime Focus Spectrograph

    This research is published in the Astrophysical Journal in its December 14, 2016 on-line version and December 20, 2016 in the printed version, Volume 833, Number 2. The title of the paper is A weak lensing view of the downsizing of star-forming galaxies by Y. Utsumi et al., which is also available in preprint from arXiv:1606.07439v2. This work is supported by a JSPS Grant-in-Aid for Young Scientists (B) (JP26800103) and a MEXT Grant-in-Aid for Scientific Research on Innovative Areas (JP24103003).

    See the full article here .

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    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

    NAOJ Subaru Telescope interior
    Subaru

    ALMA Array
    ALMA

    sft
    Solar Flare Telescope

    Nobeyama Radio Telescope - Copy
    Nobeyama Radio Observatory

    Nobeyama Solar Radio Telescope Array
    Nobeyama Radio Observatory: Solar

    Misuzawa Station Japan
    Mizusawa VERA Observatory

    NAOJ Okayama Astrophysical Observatory Telescope
    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.

     
  • richardmitnick 3:21 pm on November 22, 2016 Permalink | Reply
    Tags: , , , NAOJ Subaru Telescope, New record-breaking Milky Way satellite, Virgo I   

    From EarthSky: “New record-breaking Milky Way satellite” 

    1

    EarthSky

    November 21, 2016
    Deborah Byrd

    It’s record-breaking because it’s so faint. Could this galaxy be a sign of many yet-unknown dwarf galaxies orbiting our Milky Way? And do we now have a way to detect them? Astronomical theorists hope so!

    1
    Satellite galaxies associated with the Milky Way, which is shown here as the gray oval in the center of the diagram. Squares are Large and Small Magellanic Clouds and circles are dwarf spheroidal galaxies. Via subarutelescope.org.

    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA
    NAOJ Subaru Telescope interior
    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA

    An international team led by astronomers from Tohoku University in Japan said on November 21, 2016 that it has found an extremely faint dwarf satellite galaxy orbiting the center of our Milky Way galaxy. They’ve named the satellite Virgo I, because it lies in the direction of the constellation Virgo the Maiden. The galaxy is very faint, perhaps the faintest satellite galaxy yet found. Its discovery suggests the presence of a large number of yet-undetected dwarf satellites in the halo of the Milky Way. That would be good news to astronomical theorists, whose leading theories about our universe require many more dwarf galaxies for our Milky Way and other galaxies than have been observed so far.

    The team’s discovery is part of the ongoing Subaru Strategic Survey using a gigantic digital still camera called Hyper Suprime-Cam.

    NAOJ Subaru Hyper Suprime-Cam
    NAOJ Subaru Hyper Suprime-Cam

    Astronomers have been pondering the puzzle of dwarf galaxies for some years. Standard cosmology predicts there should be hundreds of dwarf galaxies in orbit around galaxies like our Milky Way galaxy. But, so far, astronomers know of only about 50 small galaxies within about 1.4 million light-years of the Milky Way, and it’s possible they’re not all true Milky Way satellites. A statement issued by Tohoku University astronomers on November 21, 2016 explained:

    “Formation of galaxies like the Milky Way is thought to proceed through the hierarchical assembly of dark matter, forming dark halos, and through the subsequent infall of gas and star formation affected by gravity. Standard models of galaxy formation in the context of the so-called cold dark matter (CDM) theory predict the presence of hundreds of small dark halos orbiting in a Milky Way-sized dark halo and a comparable number of luminous satellite companions. However, only tens of satellites have ever been identified. This falls well short of a theoretical predicted number, which is part of the so-called missing satellite problem.”

    In other words, if what we think we understand about the universe is correct, where are the rest of the dwarf galaxies?

    About 40 of the 50 known dwarf galaxies orbiting our Milky Way belong to a category that astronomers call dwarf spheroidal galaxies. However, many recently discovered dwarf galaxies are much fainter. These are called ultra-faint dwarf galaxies by astronomers. Obviously, the much-fainter ones are much harder to detect. So one idea has been that the dwarf galaxies are there, and we just haven’t seen them yet.

    If that’s the case, then the detection of Virgo 1 might be a sign we can now detect much-fainter galaxies than before. If so, astronomers might begin detecting many more of them.

    And, if that happens, many astronomical theorists will be glad! It’ll mean their theories are on the right track.

    3
    white -> yellow -> red indicates increasing density. (Credit: Tohoku University/National Astronomical Observation of Japan/ subarutelescope.org.” width=”800″ height=”340″ class=”size-full wp-image-251652″ /> The position of Virgo I in the constellation of Virgo the Maiden (left). Image via Tohoku University/ National Astronomical Observation of Japan/ subarutelescope.org.

    Astronomy graduate studentDaisuke Homma Tohoku University made the discovery. He commented:

    “We have carefully examined the early data of the Subaru Strategic Survey with HSC and found an apparent over density of stars in Virgo with very high statistical significance … Surprisingly, this is one of the faintest satellites, with absolute magnitude of -0.8 in the optical waveband.”

    Homma worked under the guidance of his advisor, Masashi Chiba, and their international collaborators. According to Chiba, the discovery has profound implications:

    This discovery implies hundreds of faint dwarf satellites waiting to be discovered in the halo of the Milky Way.

    How many satellites are indeed there and what properties they have, will give us an important clue of understanding how the Milky Way formed and how dark matter contributed to it.

    The team’s finding is published in the peer-reviewed Astrophysical Journal in its November 14, 2016 on-line version and November 20, 2016 in the printed version.

    Bottom line: Astronomers said on November 21, 2016 that they’ve found a record-breakingly faint dwarf satellite galaxy orbiting the center of our Milky Way galaxy. They’ve named the satellite Virgo I. It might be a sign that many more faint galaxies like this one orbit the Milky Way, and, if so, it will help confirm leading astronomical theories.

    See the full article here .

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  • richardmitnick 8:52 am on August 10, 2016 Permalink | Reply
    Tags: Astronomers discover new substellar companion to the Pleiades member star, , , NAOJ Subaru Telescope,   

    From phys.org: “Astronomers discover new substellar companion to the Pleiades member star” 

    physdotorg
    phys.org

    August 10, 2016
    Tomasz Nowakowsk

    1
    Final Pleiades HII 3441 images. (Left) reduced HS -band image taken in the 2011 observation. (Middle) reduced HL-band image taken in the 2011 observation. (Right) reduced H-band image taken in the 2014 observation. All images were analyzed using standard ADI. Pleiades HII 3441B can be seen southeast of the primary star. There is no methane absorption in Pleiades HII 3441B when left and middle panels are compared. Credit: Konishi et al., 2016.

    An international team of astronomers has found a new substellar mass companion to one of the stars in the Pleiades open cluster. The discovery could contribute to our understanding of stellar and substellar multiplicity as well as formation mechanisms in this cluster. A study detailing the new findings was published Aug. 5 on the arXiv pre-print server.

    Due to its proximity, the well-known Pleiades cluster is frequently observed and studied by amateur and professional astronomers. The cluster, located some 440 light years away, is about 120 million years old, which makes it one of the nearest young open clusters. It is also a great target for searching new low-mass substellar objects such as brown dwarfs.

    From 2011 to 2015, an international team of researchers led by Mihoko Konishi of the National Astronomical Observatory of Japan conducted a series of observations of the cluster’s member star, designated Pleiades HII 3441, looking for planetary-mass and substellar companions. These observations were part of the Strategic Explorations of Exoplanets and Disks with Subaru (SEEDS) survey, which uses adaptive optics assisted high contrast imaging for studying planets and disks, including primordial systems, transitional systems and mature systems. The survey utilizes the 8.2 Subaru Telescope located on Mauna Kea, Hawaii.

    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA
    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA

    The newly detected object was named Pleiades HII 3441B. According to the study, it was found southeast of the primary star with a projected separation of about 66 AU.

    “A companion candidate was detected southeast of the primary star, and subsequently confirmed as a companion object to the primary star. (…) The projected separation and position angle are 0.′′49 ± 0.′′02 (66 ± 2 AU) and 136.4° ± 3.2°, respectively. These values were derived by averaging all observations,” the researchers wrote in the paper.

    The mass of Pleiades HII 3441B was calculated to be approximately 68 Jupiter masses and its temperature was estimated to be 2,700 K. Moreover, the team found that there is no methane absorption in the atmosphere of this substellar companion. They emphasized that methane is considered to condense below 1,300 K.

    The object was classified an M7-type brown dwarf, due to the fact that its mass is below the hydrogen-burning limit (72 Jupiter masses). Its spectral type was deducted from the photometry-derived temperature. However, as the researchers noted, Pleiades HII 3441B is “close to the boundary between the stellar and substellar regime.”

    The scientists have also taken into account the possibility that the object is another faint Pleiades member along the same line of sight; it cannot be ruled out completely as the observations could not detect the orbital motion.

    According to the researchers, their study provides an important input for the determination of the initial mass function in Pleiades, and might help us understand the formation mechanisms in the cluster. Substellar multiplicity in Pleiades is also discussed in the paper, with the aim to estimate the general fraction of substellar companions in star clusters. However, as the team noted, further studies are needed in order to get comprehensive answers.

    “A much larger survey of the Pleiades would be needed to draw general conclusion on the multiplicity differences between open clusters and field star populations,” the astronomers concluded.

    Read more at: http://phys.org/news/2016-08-astronomers-substellar-companion-pleiades-member.html#jCp

    See the full article here .

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  • richardmitnick 6:43 am on July 26, 2016 Permalink | Reply
    Tags: Ancient Eye in the Sky, , , , NAOJ Subaru Telescope   

    From NAOJ Subaru: “Ancient Eye in the Sky” 

    NAOJ

    NAOJ

    July 25, 2016
    No writer credit found

    Light from a distant galaxy can be strongly bent by the gravitational influence of a foreground galaxy. That effect is called strong gravitational lensing. Normally a single galaxy is lensed at a time. The same foreground galaxy can – in theory – simultaneously lens multiple background galaxies. Although extremely rare, such a lens system offers a unique opportunity to probe the fundamental physics of galaxies and add to our understanding of cosmology. One such lens system has recently been discovered and the discovery was made not in an astronomer’s office, but in a classroom. It has been dubbed the Eye of Horus (Fig. 1), and this ancient eye in the sky will help us understand the history of the universe.

    1
    Figure 1: Eye of Horus in pseudo color. Enlarged image to the right (field of view of 23 arcseconds x 19 arcseconds) show two arcs/rings with different colors. The inner arc has a reddish hue, while the outer arc has a blue tint. These arcs are lensed images of the two background galaxies. There are blobs in and around the arcs/rings, which are also the lensed images of those background galaxies. The yellow-ish object at the center is a massive galaxy at z = 0.79 (distance 7 billion light years), which bends the light from the two background galaxies. The wide field image in the background is here. Enlarged image of the Eye of Horus is here and the image with labels is here. (Credit: NAOJ)

    Classroom Research Pays Off

    Subaru Telescope organizes a school for undergraduate students each year. One such session was held in September 2015 at the NAOJ headquarters in Mitaka, Tokyo (Fig. 2). Subaru is currently undertaking a massive survey to image a large area of the sky at an unprecedented depth with Hyper Suprime-Cam as part of the Subaru Strategic Program. A group of astronomers and young students were analyzing some of that Hyper Suprime-Cam data at the school when they found a unique lens system. It was a classic case of a serendipitous discovery.

    “When I was looking at HSC images with the students, we came across a ring-like galaxy and we immediately recognized it as a strong-lensing signature,” said Masayuki Tanaka, the lead author of a science paper on the system’s discovery. “The discovery would not have been possible without the large survey data to find such a rare object, as well as the deep, high quality images to detect light from distant objects.”

    Arsha Dezuka, a student who was working on the data, was astonished at the find. “It was my first time to look at the astronomical images taken with Hyper Suprime-Cam and I had no idea what the ring-like galaxy is,” she said. “It was a great surprise for me to learn that it is such a rare, unique system!”

    What They Saw

    A close inspection of the images revealed two distinct arcs/rings of light with different colors. This strongly suggested that two distinct background galaxies were being lensed by the foreground galaxy. The lensing galaxy has a spectroscopic redshift of z = 0.79 (which means it’s 7.0 billion light-years away, Note 1) based on data from the Sloan Digital Sky Survey. Follow-up spectroscopic observations of the lensed objects using the infrared-sensitive FIRE spectrometer on the Magellan Telescope confirmed that there are actually two galaxies behind the lens. One lies at z = 1.30 and the other is at z = 1.99 (9.0 and 10.5 billion light-years away, respectively).

    “The spectroscopic data reveal some very interesting things about the background sources,” said Kenneth Wong from NAOJ, the second author of the scientific paper describing the system. “Not only do they confirm that there are two sources at different distances from us, but the more distant source seems to consist of two distinct clumps, which could indicate an interacting pair of galaxies. Also, one of the multiple images of that source is itself being split into two images, which could be due to a satellite galaxy that is too faint for us to see.”

    The distinct features for the system (several bright knots, an arc, a complete Einstein ring) arise from the nice alignment of the central lens galaxy and both sources, creating an eye-like structure (Fig.3). The astronomers dubbed it Eye of Horus, for the sacred eye of an ancient Egyptian god, since the system has an uncanny resemblance to it.

    2
    Figure 3: A schematic diagram showing the location of galaxies creating the gravitational lens effect of Eye of Horus. A galaxy 7 billion light years from the Earth bends the light from the two galaxies behind it at a distance of 9 billion light years and 10.5 billion light years, respectively. (Credit: NAOJ)

    The survey with Hyper Suprime-Cam is only 30% complete and it will collect data for several more years. Astronomers expect to find roughly 10 more such systems in the survey, which will provide important insights into the fundamental physics of galaxies as well as how the universe expanded over the last several billion years.

    This research was supported by JSPS KAKENHI Grant Numbers JP15K17617, JP26800093, and JP15H05892. The research paper appeared on-line in the Astrophysical Journal Letters on July 25, 2016.

    Note:
    1. Conversion of the distance from the redshift uses the following cosmological parameters – H0=67.3km/s/Mpc, Ωm=0.315, Λ=0.685, based on Planck 2013 Results.

    Research Team

    Masayuki Tanaka: National Astronomical Observatory of Japan, Japan
    Kenneth Wong: National Astronomical Observatory of Japan, Japan
    Anupreeta More: Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), University of Tokyo, Japan
    Arsha Dezuka: Department of Astronomy, University of Kyoto, Japan
    Eiichi Egami: Steward Observatory, University of Arizona, USA
    Masamune Oguri: Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), University of Tokyo, Japan; Department of Physics, University of Tokyo, Japan; Research Center for the Early Universe, University of Tokyo, Japan
    Sherry H. Suyu: Max Planck Institute for Astrophysics, Germany; Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan
    Alessandro Sonnenfeld: Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), University of Tokyo, Japan
    Ryou Higuchi: Institute for Cosmic Ray Research, The University of Tokyo, Japan
    Yutaka Komiyama: National Astronomical Observatory of Japan, Japan
    Satoshi Miyazaki: National Astronomical Observatory of Japan, Japan; SOKENDAI (The Graduate University for Advanced Studies), Japan
    Masafusa Onoue: SOKENDAI (The Graduate University for Advanced Studies), Japan; National Astronomical Observatory of Japan, Japan
    Shuri Oyamada: Japan Women’s University, Japan
    Yousuke Utsumi: Hiroshima Astrophysical Science Center, Hiroshima University, Japan

    See the full article here .
    See the IPMU article here .

    Please help promote STEM in your local schools.

    STEM Icon

    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

    NAOJ Subaru Telescope interior
    Subaru

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array
    sft
    Solar Flare Telescope

    Nobeyama Radio Telescope - Copy
    Nobeyama Radio Observatory

    Nobeyama Solar Radio Telescope Array
    Nobeyama Radio Observatory: Solar

    Misuzawa Station Japan
    Mizusawa VERA Observatory

    NAOJ Okayama Astrophysical Observatory Telescope
    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.

     
  • richardmitnick 2:52 pm on May 11, 2016 Permalink | Reply
    Tags: , , NAOJ Subaru Telescope, New test by deepest galaxy map finds Einstein’s theory stands true   

    From IPMU: “New test by deepest galaxy map finds Einstein’s theory stands true” 

    KavliFoundation

    The Kavli Foundation

    Kavli IPMU
    Kavli IMPU

    May 11, 2016
    Media contact:
    Motoko Kakubayashi
    Press Officer
    Kavli Institute for the Physics and Mathematics of the Universe
    The University of Tokyo Institutes for Advanced Study,
    The University of Tokyo
    TEL: +81-04-7136-5980
    E-mail: press@ipmu.jp

    Research contact:
    Teppei Okumura
    Project Researcher
    Kavli Institute for the Physics and Mathematics of the Universe
    TEL: +81-04-7136-6539
    E-mail: teppei.okumura@ipmu.jp

    Chiaki Hikage
    Project Assistant Professor
    Kavli Institute for the Physics and Mathematics of the Universe
    TEL: +81-04-7136-6532
    E-mail: chiaki.hikage@ipmu.jp

    Tomonori Totani
    Professor
    Department of Astronomy, University of Tokyo
    TEL: +81-03-5841-4257
    E-mail: totani@astron.s.u-tokyo.ac.jp

    1
    Image 1: A 3D map of the Universe spanning 12 to 14.5 billion light years (Credit: NAOJ; Partial data supplied by: CFHT, SDSS)

    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA
    NAOJ Subaru Telescope interior
    NAOJ Subaru FMOS
    NAOJ/Subaru, Mauna Kea Hawaii, USA, and FMOS on Subaru used in this study.

    CFHT Telescope, Mauna Kea, Hawaii, USA
    CFHT nterior
    CFHT, Mauna Kea Hawaii, USA

    SDSS Telescope at Apache Point, NM, USA
    SDSS Telescope at Apache Point, NM, USA

    An international team led by Japanese researchers has made a 3D map of 3000 galaxies 13 billion light years from Earth, and found that Einstein’s general theory of relativity is still valid.

    Since it was discovered in the late 1990s that the universe is expanding at an accelerated rate, scientists have been trying to explain why. The mysterious dark energy could be driving acceleration, or Einstein’s theory of general relativity, which says gravity warps space and time, could be breaking down.

    To test Einstein’s theory, a team of researchers led by Kavli Institute for the Physics and Mathematics (Kavli IPMU) Project Researcher Teppei Okumura, Kavli IPMU Project Assistant Professor Chiaki Hikage, University of Tokyo Department of Astronomy Professor Tomonori Totani, and together with Tohoku University Astronomical Institute Associate Professor Masayuki Akiyama and Kyoto University Department of Astronomy Associate Professor Fumihide Iwamuro and Professor Kouji Ohta, used FastSound Survey data on more than 3000 distant galaxies to analyze their velocities and clustering.

    Their results indicated that even far into the universe, general relativity is valid, giving further support that the expansion of the universe could be explained by a cosmological constant, as proposed by Einstein in his theory of general relativity.

    “We tested the theory of general relativity further than anyone else ever has. It’s a privilege to be able to publish our results 100 years after Einstein proposed his theory,” said Okumura.

    “Having started this project 12 years ago it gives me great pleasure to finally see this result come out,” said Karl Glazebrook, Professor at Swinburne University of Technology, who proposed the survey.

    No one has been able to analyze galaxies more than 10 billion light years away, but the team managed to break this barrier thanks to the FMOS (Fiber Multi-Object Spectrograph) on the Subaru Telescope, which can analyze galaxies 12.4 to 14.7 billion light years away. The Prime Focus Spectrograph, currently under construction, is expected to be able to study galaxies even further away.

    Details of this study were published* online on April 27 in the Publications of the Astronomical Society of Japan.

    1
    Image 2: Experimental results looking at the expansion of the universe, in comparison to that predicted by Einstein’s theory of general relativity in green. (Credit: Okumura et al.)

    *Science paper:
    The Subaru FMOS galaxy redshift survey (FastSound). IV. New constraint on gravity theory from redshift space distortions at z∼1.4

    Useful links
    All images can be downloaded from this page: http://web.ipmu.jp/press/201605-fastsound

    About the FastSound (FMOS Acceleration Samping Test Subaru Observation Understanding Nature of Dark energy) Survey: http://www.kusastro.kyoto-u.ac.jp/Fastsound/index.html

    About the Prime Focus Spectrograph: http://pfs.ipmu.jp/

    Video of the FastSound Survey map (Japanese text): https://www.youtube.com/watch?v=FSsjQsjOQDw

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Kavli IPMU (Kavli Institute for the Physics and Mathematics of the Universe) is an international research institute with English as its official language. The goal of the institute is to discover the fundamental laws of nature and to understand the Universe from the synergistic perspectives of mathematics, astronomy, and theoretical and experimental physics. The Institute for the Physics and Mathematics of the Universe (IPMU) was established in October 2007 under the World Premier International Research Center Initiative (WPI) of the Ministry of Education, Sports, Science and Technology in Japan with the University of Tokyo as the host institution. IPMU was designated as the first research institute within the University of Tokyo Institutes for Advanced Study (UTIAS) in January 2011. It received an endowment from The Kavli Foundation and was renamed the “Kavli Institute for the Physics and Mathematics of the Universe” in April 2012. Kavli IPMU is located on the Kashiwa campus of the University of Tokyo, and more than half of its full-time scientific members come from outside Japan. http://www.ipmu.jp/
    Stem Education Coalition
    The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

    The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

     
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