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  • richardmitnick 1:11 pm on January 13, 2020 Permalink | Reply
    Tags: "Influential electrons? Physicists uncover a quantum relationship", How electron energies vary from region to region in a particular quantum state, , , , phys.org, Quantum hybridization in the relationships between moving electrons, , Spectromicroscopy   

    From New York University, the Lawrence Berkeley National Laboratory, Rutgers University, and MIT via phys.org: “Influential electrons? Physicists uncover a quantum relationship” 

    From

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    phys.org

    A team of physicists has mapped how electron energies vary from region to region in a particular quantum state with unprecedented clarity. This understanding reveals an underlying mechanism by which electrons influence one another, termed quantum “hybridization,” that had been invisible in previous experiments.

    1
    Credit: CC0 Public Domain

    The findings, the work of scientists at New York University, the Lawrence Berkeley National Laboratory, Rutgers University, and MIT, are reported in the journal Nature Physics.

    “This sort of relationship is essential to understanding a quantum electron system—and the foundation of all movement—but had often been studied from a theoretical standpoint and not thought of as observable through experiments,” explains Andrew Wray, an assistant professor in NYU’s Department of Physics and one of the paper’s co-authors. “Remarkably, this work reveals a diversity of energetic environments inside the same material, allowing for comparisons that let us spot how electrons shift between states.”

    The scientists focused their work on bismuth selenide, or Bi2Se3, a material that has been under intense investigation for the last decade as the basis of advanced information and quantum computing technologies. Research in 2008 and 2009 identified bismuth selenide to host a rare “topological insulator” quantum state that changes the way electrons at its surface interact with and store information.

    Studies since then have confirmed a number of theoretically inspired ideas about topological insulator surface electrons. However, because these particles are on a material’s surface, they are exposed to environmental factors not present in the bulk of the material, causing them to manifest and move in different ways from region to region.

    The resulting knowledge gap, together with similar challenges for other material classes, has motivated scientists to develop techniques for measuring electrons with micron- or nanometer- scale spatial resolution, allowing researchers to examine electron interaction without external interference.

    The Nature Physics research is one of the first studies to use this new generation of experimental tools, termed “”—and the first spectromicroscopy investigation of Bi2Se3. This procedure can track how the motion of surface electrons differs from region to region within a material. Rather than focusing on average electron activity over a single large region on a sample surface, the scientists collected data from nearly 1,000 smaller regions.

    By broadening the terrain through this approach, they could observe signatures of quantum hybridization in the relationships between moving electrons, such as a repulsion between electronic states that come close to one another in energy. Measurements from this method illuminated the variation of electronic quasiparticles across the material surface.

    “Looking at how the electronic states vary in tandem with one another across the sample surface reveals conditional relationships between different kinds of electrons, and it’s really a new way of studying a material,” explains Erica Kotta, an NYU graduate student and first author on the paper. “The results provide new insight into the physics of topological insulators by providing the first direct measurement of quantum hybridization between electrons near the surface.”

    See the full article here .

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    Mission 12 reasons for reading daily news on Science X Organization Key editors and writersinclude 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 2:06 am on January 13, 2020 Permalink | Reply
    Tags: "New evidence shows that the key assumption made in the discovery of dark energy is in error", , , , , phys.org   

    From phys.org: “New evidence shows that the key assumption made in the discovery of dark energy is in error” 


    From phys.org

    January 6, 2020
    Yonsei University

    1
    Figure 1. Luminosity evolution mimicking dark energy in supernova (SN) cosmology. The Hubble residual is the difference in SN luminosity with respect to the cosmological model without dark energy (the black dotted line). The cyan circles are the binned SN data from Betoule et al. [Astronomy and Astrophysics] (2014). The red line is the evolution curve based on our age dating of early-type host galaxies. The comparison of our evolution curve with SN data shows that the luminosity evolution can mimic Hubble residuals used in the discovery and inference of the dark energy (the black solid line). Credit: Yonsei University

    The most direct and strongest evidence for the accelerating universe with dark energy is provided by the distance measurements using type Ia supernovae (SN Ia) for the galaxies at high redshift. This result is based on the assumption that the corrected luminosity of SN Ia through the empirical standardization would not evolve with redshift.

    New observations and analysis made by a team of astronomers at Yonsei University (Seoul, South Korea), together with their collaborators at Lyon University and KASI, show, however, that this key assumption is most likely in error. The team has performed very high-quality (signal-to-noise ratio ~175) spectroscopic observations to cover most of the reported nearby early-type host galaxies of SN Ia, from which they obtained the most direct and reliable measurements of population ages for these host galaxies. They find a significant correlation between SN luminosity and stellar population age at a 99.5 percent confidence level. As such, this is the most direct and stringent test ever made for the luminosity evolution of SN Ia. Since SN progenitors in host galaxies are getting younger with redshift (look-back time), this result inevitably indicates a serious systematic bias with redshift in SN cosmology. Taken at face values, the luminosity evolution of SN is significant enough to question the very existence of dark energy. When the luminosity evolution of SN is properly taken into account, the team found that the evidence for the existence of dark energy simply goes away (see Figure 1).

    Commenting on the result, Prof. Young-Wook Lee (Yonsei Univ., Seoul), who led the project said, “Quoting Carl Sagan, extraordinary claims require extraordinary evidence, but I am not sure we have such extraordinary evidence for dark energy. Our result illustrates that dark energy from SN cosmology, which led to the 2011 Nobel Prize in Physics, might be an artifact of a fragile and false assumption.”

    Other cosmological probes, such as the cosmic microwave background (CMB) and baryonic acoustic oscillations (BAO), are also known to provide some indirect and “circumstantial” evidence for dark energy, but it was recently suggested that CMB from Planck mission no longer supports the concordance cosmological model which may require new physics (Di Valentino, Melchiorri, & Silk [Nature Astronomy] 2019).

    CMB per ESA/Planck


    ESA/Planck 2009 to 2013

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    (BAO)http://www.astro.ucla.edu/~wright/BAO-cosmology.html

    Some investigators have also shown that BAO and other low-redshift cosmological probes can be consistent with a non-accelerating universe without dark energy (see, for example, Tutusaus et al. [Astronomy and Astrophysics] 2017). In this respect, the present result showing the luminosity evolution mimicking dark energy in SN cosmology is crucial and very timely.

    This result is reminiscent of the famous Tinsley-Sandage debate in the 1970s on luminosity evolution in observational cosmology, which led to the termination of the Sandage project originally designed to determine the fate of the universe.

    This work based on the team’s 9-year effort at Las Campanas Observatory 2.5-m telescope and at MMT 6.5 m telescope was presented at the 235th meeting of the American Astronomical Society held in Honolulu on January 5th (2:50 PM in cosmology session, presentation No. 153.05).


    Carnegie Las Campanas 2.5 meter Irénée Dupont telescope, Atacama Desert, over 2,500 m (8,200 ft) high approximately 100 kilometres (62 mi) northeast of the city of La Serena,Chile


    CfA U Arizona Fred Lawrence Whipple Observatory Steward Observatory MMT 6.5-m Telescope at the summit of Mount Hopkins near Tucson, Arizona, USA, Altitude 2,616 m (8,583 ft)

    Their paper is also accepted for publication in The Astrophysical Journal and will be published in January 2020 issue.

    See the full article here .

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  • richardmitnick 12:06 pm on January 12, 2020 Permalink | Reply
    Tags: "Study probes the origin of the very high energy gamma-ray source VER J1907+062", Dame Susan Jocelyn Bell Burnell discovered pulsars with radio astronomy., , Laura Duvidovich of the University of Buenos Aires Argentina, phys.org, The nature of VER J1907+062 is still unknown.   

    From phys.org: “Study probes the origin of the very high energy gamma-ray source VER J1907+062” 


    From phys.org

    January 10, 2020
    Tomasz Nowakowski

    1
    Radio continuum image at 1.5 GHz covering the whole extension of the TeV source VER J1907+062. Credit: Duvidovich et al., 2019.

    A new study based on high-quality radio observations with the Karl G. Jansky Very Large Array (VLA) has investigated the origin of a very high-energy gamma-ray source known as VER J1907+062.

    NRAO/Karl V Jansky Expanded Very Large Array, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

    Results of the study, published December 27 on arXiv.org [MNRAS], suggest that VER J1907+062 consists of two separate gamma-ray sources.

    Sources emitting gamma radiation with photon energies between 100 GeV and 100 TeV are called very high energy (VHE) gamma-ray sources. Observations show that these sources are often blazars or binary star systems containing a compact object. However, the nature of many VHE gamma-ray sources is still not well understood.

    This is the case with VER J1907+062, a TeV source first identified in 2007. Previous studies have shown a strong TeV emission from this source near the location of the pulsar PSR J1907+0602, extending toward the supernova remnant SNR G40.5−0.5.

    Dame Susan Jocelyn Bell Burnell, discovered pulsars with radio astronomy. Jocelyn Bell at the Mullard Radio Astronomy Observatory, Cambridge University, taken for the Daily Herald newspaper in 1968. Denied the Nobel.

    The nature of VER J1907+062 is still unknown. Based on the strong TeV emission around PSR J1907+0602, some astronomers suggest that this source could be a TeV pulsar wind nebula (PWN) powered by this pulsar. Moreover, it was also proposed that VER J1907+062 may be the superposition of two sources, either separated or interacting.

    To clarify these uncertainties and to shed more light on the origin and true nature of VER J1907+062, a team of astronomers led by Laura Duvidovich of the University of Buenos Aires, Argentina, has carried out new high-quality radio observations of this source using VLA.

    “In this paper, we present new high-quality radio images of a large region containing the extended TeV source VER J1907+062 at 1.5 GHz and a region toward the PSR J1907+0602 at 6 GHz, in both cases with data obtained using the VLA in its D configuration,” the astronomers wrote in the paper.

    The VLA observations found no nebular radio emission toward PSR J1907+0602 or the other two pulsars in the region. Moreover, the new images show no evidence of extended radio emission in coincidence with PSR J1907+0602 and also no evidence of extended nor point-like emission toward the pulsar. These results seem to disfavor the scenario suggesting that the non-thermal X-ray emission around the pulsar may be a PWN.

    The research found molecular clouds in the vicinity of SNR G40.5−0.5, which match the eastern, southern and western borders of the remnant and partially overlap peaks of the TeV emission from VER J1907+062. The finding suggests an association of the studied TeV source with this SNR.

    Summing up the results, the astronomers proposed two hypotheses that could explain the origin of VER J1907+062. According to them, this source could be the superposition in the line of sight of two distinct gamma-ray sources powered by different emission mechanisms and located at different distances. They find this scenario as the most plausible, but do not exclude the possibility that VER J1907+062 could be a single source whose VHE emission is produced by two particle accelerators (the pulsar and the supernova remnant) located at the same distance.

    See the full article here .

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    Mission 12 reasons for reading daily news on Science X Organization Key editors and writersinclude 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 11:29 am on January 12, 2020 Permalink | Reply
    Tags: A novel type of detector that enables the oscillation profile of light waves to be precisely determined., , Laboratory for Attosecond Physics at Ludwig-Maximilians-Universitaet, , , phys.org,   

    Max Planck Institute of Quantum Optics via phys.org: “Laser physics- At the pulse of a light wave” 

    Max Planck Institute of Quantum Optics

    Max Planck Institute of Quantum Optics

    via


    phys.org

    January 10, 2020
    Ludwig Maximilian University of Munich

    1
    How a novel type of detector enables the oscillation profile of light waves to be precisely determined. Credit: Philipp Rosenberger

    Physicists in the Laboratory for Attosecond Physics at Ludwig-Maximilians-Universitaet (LMU) in Munich and at the Max Planck Institute for Quantum Optics (MPQ) have developed a novel type of detector that enables the oscillation profile of light waves to be precisely determined.

    Light is hard to get a hold on. Light waves propagate with a velocity of almost 300,000 km per second, and the wavefront oscillates several hundred trillion times in that same interval. In the case of visible light, the physical distance between successive peaks of the light wave is less than 1 micrometer, and peaks are separated in time by less than 3 millionths of a billionth of a second (< 3 femtoseconds). To work with light, one must control it—and that requires precise knowledge of its behaviour. It may even be necessary to know the exact position of the crests or valleys of the light wave at a given instant. Researchers based at the Laboratory for Attosecond Physics (LAP) at the LMU Munich and the Max Planck Institute for Quantum Optics are now in a position to measure the exact location of such peaks within single ultrashort pulses of infrared light with the aid of a newly developed detector.

    Such pulses, which encompass only a few oscillations of the wave, can be used to investigate the behaviour of molecules and their constituent atoms, and the new detector is a very valuable tool in this context. Ultrashort laser pulses allow scientists to study dynamic processes at molecular and even subatomic levels. Using trains of these pulses, it is possible first to excite the target particles and then to film their responses in real time. In intense light fields, however, it is crucial to know the precise waveform of the pulses. Since the peak of the oscillating (carrier) light field and that of the pulse envelope can shift with respect to each other between different laser pulses, it is important to know the precise waveform of each pulse.

    The team at LAP, which was led by Dr. Boris Bergues and Professor Matthias Kling, head of the Ultrafast Imaging and Nanophotonics Group, has now made a decisive breakthrough in the characterization of light waves. Their new detector allows them to determine the 'phase," i.e. the precise positions of the peaks of the few oscillation cycles within each and every pulse, at repetition rates of 10,000 pulses per second. To do so, the group generated circularly polarized laser pulses in which the orientation of the propagating optical field rotates like a clock hand, and then focused the rotating pulse in ambient air.

    The interaction between the pulse and molecules in the air results in a short burst of electric current, whose direction depends on the position of the peak of the light wave. By analyzing the exact direction of the current pulse, the researchers were able to retrieve the phase of the 'carrier-envelope offset," and thus reconstruct the form of the light wave. Unlike the method conventionally employed for phase determination, which requires the use of a complex vacuum apparatus, the new technique works in ambient air and the measurements require very few extra components. "The simplicity of the setup is likely to ensure that it will become a standard tool in laser technology," explains Matthias Kling.

    “We believe that this technique can also be applied to lasers with much higher repetition rates and in different spectral regions”; says Boris Bergues.”Our methodology is of particular interest in the context of the characterization of extremely short laser pulses with high repetition rates, such as those generated at Europe’s Extreme Light Infrastructure (ELI)” adds Prof. Matthias Kling. When applied to the latest sources of ultrashort laser pulses, this new method of waveform analysis could pave the way to technological breakthroughs, as well as permitting new insights into the behaviour of elementary particles & in the fast lane.

    Science paper:
    Single-shot carrier–envelope-phase measurement in ambient air
    Optica

    See the full article here .

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    Research at the Max Planck Institute of Quantum Optics
    Light can behave as an electromagnetic wave or a shower of particles that have no mass, called photons, depending on the conditions under which it is studied or used. Matter, on the other hand, is composed of particles, but it can actually exhibit wave-like properties, giving rise to many astonishing phenomena in the microcosm.

    At our institute we explore the interaction of light and quantum systems, exploiting the two extreme regimes of the wave-particle duality of light and matter. On the one hand we handle light at the single photon level where wave-interference phenomena differ from those of intense light beams. On the other hand, when cooling ensembles of massive particles down to extremely low temperatures we suddenly observe phenomena that go back to their wave-like nature. Furthermore, when dealing with ultrashort and highly intense light pulses comprising trillions of photons we can completely neglect the particle properties of light. We take advantage of the large force that the rapidly oscillating electromagnetic field exerts on electrons to steer their motion within molecules or accelerate them to relativistic energies.

     
  • richardmitnick 10:32 am on January 12, 2020 Permalink | Reply
    Tags: "Volcano erupts near Manila; airport shut and villagers flee", , , phys.org,   

    From phys.org: “Volcano erupts near Manila; airport shut, villagers flee” 


    From phys.org

    January 12, 2020
    Aaron Favila
    Jim Gomez

    1
    People watch as the Taal volcano spews ash and smoke during an eruption in Tagaytay, Cavite province south of Manila, Philippines on Sunday. Jan. 12, 2020. A tiny volcano near the Philippine capital that draws many tourists for its picturesque setting in a lake belched steam, ash and rocks in a huge plume Sunday, prompting thousands of residents to flee and officials to temporarily suspend flights. (AP Photo/Bullit Marquez)

    A small volcano south of the Philippine capital that draws many tourists for its picturesque setting in a lake erupted with a massive plume of ash and steam Sunday, prompting thousands of people to flee and officials to shut Manila’s international airport.

    The Philippine Institute of Volcanology and Seismology said Taal Volcano in Batangas province south of Manila blasted steam, ash and pebbles up to 10 to 15 kilometers (6 to 9 miles) into the sky in a dramatic escalation of its growing restiveness, which began last year.

    The volcanology institute raised the danger level around Taal three notches on Sunday to level 4, indicating “a hazardous eruption may happen within hours or days,” said Renato Solidum, who heads the volcanology institute. Level 5, the highest, means a hazardous eruption is underway and could affect a larger area.

    There were no immediate reports of injuries or damage, but authorities scrambled to evacuate more than 6,000 villagers from an island in the middle of a lake, where the volcano lies, and tens of thousands more from nearby coastal towns, officials said.

    “We have asked people in high-risk areas, including the volcano island, to evacuate now ahead of a possible hazardous eruption,” Solidum said.

    Renelyn Bautista, a 38-year-old housewife who was among thousands of residents who fled from Batangas province’s Laurel town, said she hitched a ride to safety from her home with her two children, including a 4-month-old baby, after Taal erupted and the ground shook mildly.

    “We hurriedly evacuated when the air turned muddy because of the ashfall and it started to smell like gunpowder,” Bautista said by phone.

    International and domestic flights were suspended Sunday night at Manila’s international airport “due to volcanic ash in the vicinity of the airport” and nearby air routes, the Civil Aviation Authority of the Philippines said.

    Taal lies more than 60 kilometers (37 miles) south of Manila.

    The institute reminded the public that the small island where the volcano lies is a “permanent danger zone,” although fishing villages have existed there for years. It asked nearby coastal communities “to take precautionary measures and be vigilant of possible lake water disturbances related to the ongoing unrest.”

    Heavy to light ashfall was reported in towns and cities several kilometers (miles) from the volcano, and officials advised residents to stay indoors and don masks and goggles for safety. Motorists were hampered by poor visibility, which was worsened by rainy weather.

    2
    Plumes of smoke and ash rise from as Taal Volcano erupts Sunday Jan. 12, 2020, in Tagaytay, Cavite province, outside Manila, Philippines (AP Photo/Aaron Favila)

    Hotels, shopping malls and restaurants line an upland road along a ridge overlooking the lake and the volcano in Tagaytay city, a key tourism area that could be affected by a major eruption.

    Authorities recorded a swarm of earthquakes, some of them felt with rumbling sounds, and a slight inflation of portions of the 1,020-foot (311-meter) volcano ahead of Sunday’s steam-driven explosion, officials said.

    Classes in a wide swath of towns and cities were suspended Monday, including in Manila, to avoid health risks posed by the ashfall.

    One of the world’s smallest volcanoes, Taal is among two dozen active volcanoes in the Philippines, which lies along the so-called Pacific “Ring of Fire,” a seismically active region that is prone to earthquakes and volcanic eruptions.

    About 20 typhoons and other major storms each year also lash the Philippines, which lies between the Pacific and the South China Sea, making it one of the world’s most disaster-prone countries.

    See the full article here .

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    Science X™ is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004 (Physorg.com), Science X’s readership has grown steadily to include 5 million scientists, researchers, and engineers every month. Science X publishes approximately 200 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Science X community members enjoy access to many personalized features such as social networking, a personal home page set-up, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.
    Mission 12 reasons for reading daily news on Science X Organization Key editors and writersinclude 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 11:37 am on January 11, 2020 Permalink | Reply
    Tags: "On the hunt for primordial black holes", , , , , phys.org,   

    From University of Tokyo via phys.org: “On the hunt for primordial black holes” 

    From University of Tokyo

    via


    From phys.org

    January 10, 2020
    Motoko Kakubayashi, University of Tokyo

    1
    The Andromeda Galaxy is the Milky Way’s closest neighbour galaxy, 2.5 million light years away. Credit: HSC Project / NAOJ

    The theory that dark matter could be made of primordial black holes a fraction of a millimeter in size has been ruled out by a team of researchers led by the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU).

    In 1974, physicist Stephen Hawking described how primordial black holes could have formed in the fraction of a second after the Big Bang. Primordial black holes could have masses ranging from a tiny speck to 100,000 times our sun. In contrast, supermassive black holes detected by astronomical observations started forming at least hundreds of thousands of years later, and are millions or billions times larger than our sun. Since primordial black holes of any size have not been detected, they have been an intriguing candidate for elusive dark matter.

    As far as we currently know, baryonic matter only makes up 5 percent of all matter in the universe. The rest is either dark matter (27 percent) or dark energy (68 percent), both of which have not yet been physically detected. But researchers are confident that dark matter exists because we can see its effect on our universe. Without the gravitational force from dark matter, the stars in our Milky Way Galaxy would be flying apart.

    To test the theory that primordial black holes, specifically those about the mass of the moon or less, could be dark matter, Kavli IPMU researchers Masahiro Takada, Naoki Yasuda, Hiroko Niikura and collaborators from Japan, India and the U.S. searched for these tiny black holes between Earth and the Andromeda Galaxy, the Milky Way’s closest neighbor galaxy, 2.5 million light years away.

    2
    Data from the star which showed characteristics of being magnified by a potential gravitational lens, possibly by a primordial black hole. About 4 hours after data taking on the Subaru Telescope began, one star began to shine brighter. Less than an hour later, the star reached peak brightness before becoming dimmer. (From left to right) the original image, the brightened image, the differential image and the residual image. Niikura et al.

    “What made me interested in this project was the tremendous impact it would have on uncovering the nature of dark matter,” says Niikura. “Discovering primordial black holes would be a historical achievement. Even a negative result would be valuable information for researchers piecing together the scenario of how the universe began.”

    To look for black holes, the team used the gravitational lensing effect.

    Gravitational Lensing NASA/ESA

    Gravitational lenses were first explained by Albert Einstein, who said it was possible for an image of a distant object, such as a star, to become distorted due to the gravitational effect of a massive object between the star and Earth. The massive object’s gravity could act like a magnifying glass lens, bending the star’s light and making it appear brighter or distorted to human observers on Earth.

    Because a star, a black hole and the Earth are constantly moving in interstellar space, a star would gradually grow brighter, then dimmer to observers on Earth, as it moves across the path of a gravitational lens. So the researchers captured 190 consecutive images of the entire Andromeda Galaxy, thanks to the Hyper Suprime-Cam digital camera on the Subaru Telescope in Hawaii.

    NAOJ Subaru Hyper Suprime-Cam

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

    If dark matter is made of primordial black holes and, in this case, ones lighter than the moon, the researchers expected to find 1,000 gravitational microlenses. They calculated this estimate by assuming dark matter in the entire galaxy’s halo is made up of primordial black holes, and taking into consideration the number of stars in the Andromeda Galaxy that could be affected by a primordial black hole, and finally the chances of their equipment capturing a gravitational microlens event.

    Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835

    The telescope photographed 90 million stars. It took two years for the team to filter out all of the noise and non-gravitational lens events from the data. In the end, they could only identify one star that brightened then dimmed—suggesting a possible primordial black hole—meaning it is unlikely that they make up all of dark matter.

    Even so, Niikura explains that there is still a lot to learn about primordial black holes. The researchers had only debunked the theory for a specific mass: black holes with a mass similar to or less than the moon. Previous studies have ruled out other masses, or to what extent they could account for dark matter. But there is still a chance that primordial black holes of varying sizes might be out there. The analytical approach developed by the Kavli team could be used in future primordial black hole studies, including trying to determine if black holes discovered by the Laser Interferometer Gravitational Wave-Observatory (LIGO) in the U.S. could in fact be primordial.

    MIT /Caltech Advanced aLigo


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Science paper:
    Microlensing constraints on primordial black holes with Subaru/HSC Andromeda observations
    Nature Astronomy

    See the full article here .

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    About Science X in 100 words

    Science X™ is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004 (Physorg.com), Science X’s readership has grown steadily to include 5 million scientists, researchers, and engineers every month. Science X publishes approximately 200 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Science X community members enjoy access to many personalized features such as social networking, a personal home page set-up, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.
    Missionnetworking, a personal home page set-up, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options. include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

    The University of Tokyo aims to be a world-class platform for research and education, contributing to human knowledge in partnership with other leading global universities. The University of Tokyo aims to nurture global leaders with a strong sense of public responsibility and a pioneering spirit, possessing both deep specialism and broad knowledge. The University of Tokyo aims to expand the boundaries of human knowledge in partnership with society. Details about how the University is carrying out this mission can be found in the University of Tokyo Charter and the Action Plans.

     
  • richardmitnick 10:36 am on January 11, 2020 Permalink | Reply
    Tags: "Stellar black holes- When David poses as Goliath", , , , , phys.org   

    From phys.org: “Stellar black holes: When David poses as Goliath” 


    From phys.org

    January 10, 2020
    University of Erlangen-Nuremberg

    1
    Credit: CC0 Public Domain

    Stellar black holes form when massive stars end their life in a dramatic collapse. Observations have shown that stellar black holes typically have masses of about ten times that of the Sun, in accordance with the theory of stellar evolution. Recently, a Chinese team of astronomers claimed to have discovered a black hole as massive as 70 solar masses, which, if confirmed, would severely challenge the current view of stellar evolution. The publication immediately triggered theoretical investigations as well as additional observations by other astrophysicists. Among those to take a closer look at the object was a team of astronomers from the Universities of Erlangen-Nürnberg and Potsdam.

    2

    They discovered that it may not necessarily be a black hole at all, but possibly a massive neutron star or even an ‘ordinary’ star. Their results have now been published as a highlight-paper in the renowned journal Astronomy & Astrophysics.

    The putative black hole was detected indirectly from the motion of a bright companion star, orbiting an invisible compact object over a period of about 80 days. From new observations, a Belgian team showed that the original measurements were misinterpreted and that the mass of the black hole is, in fact, very uncertain. The most important question, namely how the observed binary system was created, remains unanswered. A crucial aspect is the mass of the visible companion, the hot star LS V+22 25. The more massive this star is, the more massive the black hole has to be to induce the observed motion of the bright star. The latter was considered to be a normal star, eight times more massive than the Sun.

    A team of astronomers from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) and the University of Potsdam had a closer look at the archival spectrum of LS V+22 25, taken by the Keck telescope at Mauna Kea, Hawaii. In particular, they were interested in studying the abundances of the chemical elements on the stellar surface. Interestingly, they detected deviations in the abundances of helium, carbon, nitrogen, and oxygen compared to the standard composition of a young massive star. The observed pattern on the surface showed ashes resulting from the nuclear fusion of hydrogen, a process that only happens deep in the core of young stars and one that would not be expected to be detected at its surface.

    “At first glance, the spectrum did indeed look like one from a young massive star. However, several properties appeared rather suspicious. This motivated us to have a fresh look at the archival data,” said Andreas Irrgang, the leading scientist of this study and a member of the Dr. Karl Remeis-Observatory in Bamberg, the Astronomical Institute of FAU.

    The authors concluded that LS V+22 25 must have interacted with its compact companion in the past. During this episode of mass-transfer, the outer layers of the star were removed and now the stripped helium core is visible, enriched with the ashes from the burning of hydrogen.

    However, stripped helium stars are much lighter than their normal counterparts. Combining their results with recent distance measurements from the Gaia space telescope, the authors determined a most likely stellar mass of only 1.1 (with an uncertainty of +/-0.5) times that of the Sun. This yields a minimum mass of only 2-3 solar masses for the compact companion, suggesting that it may not necessarily be a black hole at all, but possibly a massive neutron star or even an ‘ordinary’ star.

    The star LS V+22 25 has become famous for possibly having a massive black hole companion. However, a closer look at the star itself reveals that it is a very intriguing object in its own right, as whilst stripped helium stars of intermediate mass have been predicted in theory, only very few have been discovered so far. They are key objects to understanding binary star interactions.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    About Phys.org in 100 Words

    Phys.org™ is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 9:55 am on January 4, 2020 Permalink | Reply
    Tags: "Scientists find evidence that Venus has active volcanoes", , , , , phys.org, Universities Space Research Association,   

    From Universities Space Research Association via phys.org: “Scientists find evidence that Venus has active volcanoes” 

    usra-bloc

    From Universities Space Research Association

    via


    phys.org

    January 3, 2020
    Suraiya Farukhi

    1
    This figure shows the volcanic peak Idunn Mons (at 46 degrees south latitude, 214.5 degrees east longitude) in the Imdr Regio area of Venus. The colored overlay shows the heat patterns derived from surface brightness data collected by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS), aboard the European Space Agency’s Venus Express spacecraft. Credit: NASA

    ESA VIRTIS Visible and Infrared Thermal Imaging Spectrometer

    ESA/Venus Express

    New research led by Universities Space Research Association (USRA) and published today in Science Advances shows that lava flows on Venus may be only a few years old, suggesting that Venus could be volcanically active today—making it the only planet in our solar system, other than Earth, with recent eruptions.

    “If Venus is indeed active today, it would make a great place to visit to better understand the interiors of planets,” says Dr. Justin Filiberto, the study’s lead author and a Universities Space Research Association (USRA) staff scientist at the Lunar and Planetary Institute (LPI). “For example, we could study how planets cool and why the Earth and Venus have active volcanism, but Mars does not. Future missions should be able to see these flows and changes in the surface and provide concrete evidence of its activity.”

    Radar imaging from NASA’s Magellan spacecraft in the early 1990s revealed Venus, our neighboring planet, to be a world of volcanoes and extensive lava flows.

    NASA/Magellan spacecraft mission to Venus, May 4, 1989-Oct. 13, 1994

    In the 2000s, the European Space Agency’s (ESA’s) Venus Express [above] orbiter shed new light on volcanism on Venus by measuring the amount of infrared light emitted from part of Venus’ surface (during its nighttime).

    These new data allowed scientists to identify fresh versus altered lava flows on the surface of Venus. However, until recently, the ages of lava eruptions and volcanoes on Venus were not well known because the alteratiion rate of fresh lava was not well constrained.

    Dr. Filiberto and his colleagues recreated Venus’ hot caustic atmosphere in the laboratory to investigate how the observed Venusian minerals react and change over time. Their experimental results showed that an abundant mineral in basalt—olivine—reacts rapidly with the atmosphere and within weeks becomes coated with the iron oxide minerals—magnetite and hematite. They further found that the Venus Express observations of this change in minerology would only take a few years to occur. Thus, the new results by Filiberto and coauthors suggest that these lava flows on Venus are very young, which in turn would imply that Venus does indeed have active volcanoes.

    See the full article here .

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    USRA is an independent, nonprofit research corporation where the combined efforts of in-house talent and university-based expertise merge to advance space science and technology.

    SIGNIFICANCE & PURPOSE

    USRA was founded in 1969, near the beginning of the Space Age, driven by the vision of two individuals, James Webb (NASA Administrator 1961-1968) and Frederick Seitz (National Academy of Sciences President 1962-1969). They recognized that the technical challenges of space would require an established research base to develop novel concepts and innovative technologies. Together, they worked to create USRA to satisfy not only the ongoing need for innovation in space, but also the need to involve society more broadly so the benefits of space activities would be realized.

     
  • richardmitnick 11:50 am on January 3, 2020 Permalink | Reply
    Tags: (SALT)-Southern African Large Telescope, , , , , NASA/WISE NEOWISE Telescope, phys.org, Planetary nebula WR 72 has hydrogen-poor knots,   

    From phys.org: “Planetary nebula WR 72 has hydrogen-poor knots, study finds” 


    From phys.org

    January 3, 2020
    Tomasz Nowakowski

    1
    SALT image of hydrogen-poor knots around WR72. Credit: Gvaramadze et al., 2019.

    Using the Southern African Large Telescope (SALT), astronomers have conducted spectroscopic and imaging observations of the planetary nebula WR 72. They discovered hydrogen-poor knots in the central part of the nebula, which could be helpful in improving knowledge about the nature of this object. The finding is detailed in a paper published December 23 on arXiv.org.


    South African Large Telescope, close to the town of Sutherland in the semi-desert region of the Karoo, South Africa, Altitude 1,798 m (5,899 ft)

    Planetary nebulae (PNe) are expanding shells of gas and dust that have been ejected from a star during the process of its evolution from main sequence star into a red giant or white dwarf. They are relatively rare, but important for astronomers studying the chemical evolution of stars and galaxies.

    Of special interest are PNe exhibiting hydrogen-poor material in their central regions. In some cases, the hydrogen-poor material appears as a fan of knots with cometary tails stretched radially from the central star. Detailed investigations of PNe of this type could shed more light on the process of low-mass star evolution.

    Now, a team of astronomers led by Vasilii Gvaramadze of the Lomonosov Moscow State University, Russia, reports that the planetary nebula around WR 72 [above], a Wolf–Rayet star of spectral type WO1 located some 4,630 light years away, is the newest addition to the shortlist of PNe with hydrogen-poor knots.

    “We report the discovery of a handful of optical hydrogen-poor knots in the central part of an extended infrared nebula centered on the [WO1] star WR 72, obtained by spectroscopic and imaging observations with the Southern African Large Telescope,” the astronomers wrote in the paper.

    The study, complemented by data from NASA’s Wide-field Infrared Survey Explorer (WISE), shows that the WR 72 nebula consists of an extended, nearly circular halo (about 7,800 light years in diameter) and an elongated and apparently bipolar inner shell that contains the hydrogen-poor knots.

    NASA/WISE NEOWISE Telescope

    The observations identified a bright knot to the southwest from WR 72 and a number of faint knots scattered around the star. The astronomers noted that some of the knots are elongated in the radial direction, as in the fan-like systems of hydrogen-poor knots detected in the central regions of other PNe known as A 30 and A 78.

    The research found that the linear radius of the shell of WR 72 is around 0.75 light years and the typical radial velocity of knots is 100 km/s. According to the scientists, these results suggest that the shell is about 1,000 years old.

    More studies of the knots are required, especially deeper and higher-resolution spectroscopy and imaging, in order to determine their abundances and to check whether their spatial distribution and kinematics are axially symmetric. The astronomers clarified that the detection of axial symmetry could mean that WR72 is a binary system.

    Summing up the results, the authors of the paper suggested the most plausible hypothesis that could explain the origin of WR 72.

    “Our findings indicate that WR72 is a new member of the rare group of hydrogen-poor planetary nebulae, which may be explained through a very late thermal pulse of a post-AGB star, or by a merger of two white dwarfs,” the astronomers concluded.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    About Phys.org in 100 Words

    Phys.org™ is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 11:34 am on January 3, 2020 Permalink | Reply
    Tags: "Alien life is out there, , , , Biological signatures, but our theories are probably steering us away from it", , , phys.org,   

    From phys.org: “Alien life is out there, but our theories are probably steering us away from it” 


    From phys.org

    January 3, 2020
    Peter Vickers

    1
    Credit: sdecoret/Shutterstock

    If we discovered evidence of alien life, would we even realize it? Life on other planets could be so different from what we’re used to that we might not recognize any biological signatures that it produces.

    Recent years have seen changes to our theories about what counts as a biosignature and which planets might be habitable, and further turnarounds are inevitable. But the best we can really do is interpret the data we have with our current best theory, not with some future idea we haven’t had yet.

    This is a big issue for those involved in the search for extraterrestrial life. As Scott Gaudi of Nasa’s Advisory Council has said: “One thing I am quite sure of, now having spent more than 20 years in this field of exoplanets … expect the unexpected.”

    But is it really possible to “expect the unexpected”? Plenty of breakthroughs happen by accident, from the discovery of penicillin to the discovery of the cosmic microwave background radiation left over from the Big Bang. These often reflect a degree of luck on behalf of the researchers involved. When it comes to alien life, is it enough for scientists to assume “we’ll know it when we see it”?

    Many results seem to tell us that expecting the unexpected is extraordinarily difficult. “We often miss what we don’t expect to see,” according to cognitive psychologist Daniel Simons, famous for his work on inattentional blindness. His experiments have shown how people can miss a gorilla banging its chest in front of their eyes. Similar experiments also show how blind we are to non-standard playing cards such as a black four of hearts. In the former case, we miss the gorilla if our attention is sufficiently occupied. In the latter, we miss the anomaly because we have strong prior expectations.

    There are also plenty of relevant examples in the history of science. Philosophers describe this sort of phenomenon as “theory-ladenness of observation”. What we notice depends, quite heavily sometimes, on our theories, concepts, background beliefs and prior expectations. Even more commonly, what we take to be significant can be biased in this way.

    For example, when scientists first found evidence of low amounts of ozone in the atmosphere above Antarctica, they initially dismissed it as bad data. With no prior theoretical reason to expect a hole, the scientists ruled it out in advance. Thankfully, they were minded to double check, and the discovery was made.

    Could a similar thing happen in the search for extraterrestrial life? Scientists studying planets in other solar systems (exoplanets) are overwhelmed by the abundance of possible observation targets competing for their attention. In the last 10 years scientists have identified more than 3,650 planets—more than one a day. And with missions such as NASA’s TESS exoplanet hunter this trend will continue.

    NASA/MIT TESS replaced Kepler in search for exoplanets

    Each and every new exoplanet is rich in physical and chemical complexity. It is all too easy to imagine a case where scientists do not double check a target that is flagged as “lacking significance,” but whose great significance would be recognized on closer analysis or with a non-standard theoretical approach.

    2
    More than 200,000 stars captured in one small section of the sky by Nasa’s TESS mission. Credit: NASA

    However, we shouldn’t exaggerate the theory-ladenness of observation. In the Müller-Lyer illusion, a line ending in arrowheads pointing outwards appears shorter than an equally long line with arrowheads pointing inwards. Yet even when we know for sure that the two lines are the same length, our perception is unaffected and the illusion remains. Similarly, a sharp-eyed scientist might notice something in her data that her theory tells her she should not be seeing. And if just one scientist sees something important, pretty soon every scientist in the field will know about it.

    History also shows that scientists are able to notice surprising phenomena, even biased scientists who have a pet theory that doesn’t fit the phenomena. The 19th-century physicist David Brewster incorrectly believed that light is made up of particles traveling in a straight line. But this didn’t affect his observations of numerous phenomena related to light, such as what’s known as birefringence in bodies under stress. Sometimes observation is definitely not theory-laden, at least not in a way that seriously affects scientific discovery.

    We need to be open-minded

    Certainly, scientists can’t proceed by just observing. Scientific observation needs to be directed somehow. But at the same time, if we are to “expect the unexpected,” we can’t allow theory to heavily influence what we observe, and what counts as significant. We need to remain open-minded, encouraging exploration of the phenomena in the style of Brewster and similar scholars of the past.

    3
    The Müller-Lyer optical illusion. Credit: Fibonacci/Wikipedia, CC BY-SA

    Studying the universe largely unshackled from theory is not only a legitimate scientific endeavor—it’s a crucial one. The tendency to describe exploratory science disparagingly as “fishing expeditions” is likely to harm scientific progress. Under-explored areas need exploring, and we can’t know in advance what we will find.

    In the search for extraterrestrial life, scientists must be thoroughly open-minded. And this means a certain amount of encouragement for non-mainstream ideas and techniques. Examples from past science (including very recent ones) show that non-mainstream ideas can sometimes be strongly held back. Space agencies such as NASA must learn from such cases if they truly believe that, in the search for alien life, we should “expect the unexpected.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    About Phys.org in 100 Words

    Phys.org™ is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
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