Tag Archives: National Science Foundation

Standby for a New Round of Gravitational Wave Detection

Since late August 2017, the US LIGO 0bservatories in Washington and Louisiana and the European Gravitational Observatory (EGO), Virgo, in Italy, have been off-line for updating and testing.  These gravitational wave observatories were set to start Observing Run 3 (O3) on 1 April 2019 and conduct continuous observations for one year.  All three of these gravitational wave observatories have improved sensitivities and are capable of “seeing” a larger volume of the universe than in Observing Run 2 (O2).

Later in 2019, the Japanese gravitational wave observatory, KAGRA, is expected to come online for the first time and join O3.  By 2024, a new gravitational wave observatory in India is expected to join the worldwide network.

On the advent of this next gravitational wave detection cycle, here’s is a brief summary of the status of worldwide gravitational wave observatories.

Advanced LIGO 

The following upgrades were implemented at the two LIGO observatories since Observing Run 2 (O2) concluded in 2017:

  • Laser power has been doubled, increasing the detectors’ sensitivity to gravitational waves.
  • Upgrades were made to LIGO’s mirrors at both locations, with five of eight mirrors being swapped out for better-performing versions.
  • Upgrades have been implemented to reduce levels of quantum noise. Quantum noise occurs due to random fluctuations of photons, which can lead to uncertainty in the measurements and can mask faint gravitational wave signals. By employing a technique called quantum “squeezing” (vacuum squeezing), researchers can shift the uncertainty in the laser light photons around, making their amplitudes less certain and their phases, or timing, more certain. The timing of photons is what is crucial for LIGO’s ability to detect gravitational waves.  This technique initially was developed for gravitational wave detectors at the Australian National University, and matured and routinely used since 2010 at the GEO600 gravitational wave detector in Hannover, Germany,

In comparison to its capabilities in 2017 during O2, the twin LIGO detectors have a combined increase in sensitivity of about 40%, more than doubling the volume of the observable universe.

You’ll find more news and information on the LIGO website at the following link:

https://www.ligo.caltech.edu/news

GEO600 

GEO600 is a modest-size laser interferometric gravitational wave detector (600 meter / 1,969 foot arms) located near Hannover, Germany. It was designed and is operated by the Max Planck Institute for Gravitational Physics, along with partners in the United Kingdom.

In mid-2010, GEO600 became the first gravitational wave detector to employ quantum “squeezing” (vacuum squeezing) and has since been testing it under operating conditions using two lasers: its standard laser, and a “squeezed-light” laser that just adds a few entangled photons per second but significantly improves the sensitivity of GEO600.  In a May 2013 paper entitled, “First Long-Term Application of Squeezed States of Light in a Gravitational Wave Observatory,” researchers reported the following results of operational tests in 2011 and 2012.

“During this time, squeezed vacuum was applied for 90.2% (205.2 days total) of the time that science-quality data were acquired with GEO600. A sensitivity increase from squeezed vacuum application was observed broadband above 400 Hz. The time average of gain in sensitivity was 26% (2.0 dB), determined in the frequency band from 3.7 to 4.0 kHz. This corresponds to a factor of 2 increase in the observed volume of the Universe for sources in the kHz region (e.g., supernovae, magnetars).”

The installed GEO600 squeezer (in the foreground) inside the GEO600 clean room together with the vacuum tanks (in the background).  
Source: http://www.geo600.org/15581/1-High-Tech

While GEO600 has conducted observations in coordination with LIGO and Virgo, GEO600 has not reported detecting gravitational waves. At high frequencies GEO600 sensitivity is limited by the available laser power. At the low frequency end, the sensitivity is limited by seismic ground motion.

You’ll find more information on GEO600 at the following link:

http://www.geo600.org/3020/About-GEO600

Advanced Virgo, the European Gravitational Observatory (EGO)

At Virgo, the following upgrades were implemented since Observing Run 2 (O2) concluded in 2017:

  • The steel wires used during O2 observation campaign to suspend the four main mirrors of the interferometer have been replaced.  The 42 kg (92.6 pound) mirrors now are suspended with thin fused-silica (glass) fibers, which are expected to increase the sensitivity in the low-medium frequency region.  The mirrors in Advanced LIGO have been suspended by similar fused-silica fibers since those two observatories went online in 2015.
  • A more powerful laser source has been installed, which should improve sensitivity at high frequencies. 
  • Quantum “squeezing” has been implemented in collaboration with the Albert Einstein Institute in Hannover, Germany.  This should improve the sensitivity at high frequencies.
Virgo mirror suspension with fused-silica fibers.  
Source: EGO/Virgo Collaboration/Perciballi

In comparison to its capabilities in 2017 during O2, Virgo sensitivity has been improved by a factor of about 2, increasing the volume of the observable universe by a factor of about 8.

You’ll find more information on Virgo at the following link:

http://www.virgo-gw.eu

Japan’s KAGRA 

KAGRA is a cryogenically-cooled laser interferometer gravitational wave detector that is sited in a deep underground cavern in Kamioka, Japan.  This gravitational wave observatory is being developed by the Institute for Cosmic Ray Research (ICRR) of the University of Tokyo.  The project website is at the following link:

https://gwcenter.icrr.u-tokyo.ac.jp/en/

One leg of the KAGRA interferometer.  
Source: ICRR, University of Tokyo

The cryogenic mirror cooling system is intended to cool the mirror surfaces to about 20° Kelvin (–253° Celsius) to minimize the motion of molecules (jitter) on the mirror surface and improve measurement sensitivity.   KAGRA’s deep underground site is expected to be “quieter” than the LIGO and VIRGO sites, which are on the surface and have experienced effects from nearby vehicles, weather and some animals.

The focus of work in 2018 was on pre-operational testing and commissioning of various systems and equipment at the KAGRA observatory. In December 2018, the KAGRA Scientific Congress reported that, “If our schedule is kept, we expect to join (LIGO and VIRGO in) the latter half of O3…”   You can follow the latest news from the KAGRA team here:

https://gwcenter.icrr.u-tokyo.ac.jp/en/category/latestnews

LIGO-India

IndIGO, the Indian Initiative in Gravitational-wave Observations, describes itself as an initiative to set up advanced experimental facilities, with appropriate theoretical and computational support, for a multi-institutional Indian national project in gravitational wave astronomy.  The IndIGO website provides a good overview of the status of efforts to deploy a gravitational wave detector in India.  Here’s the link:

http://www.gw-indigo.org/tiki-index.php?page=Welcome

On 22 January 2019, T. V. Padma reported on the Naturewebsite that India’s government had given “in-principle” approval for a LIGO gravitational wave observatory to be built in the western India state of Maharashtra. 

“India’s Department of Atomic Energy and its Department of Science and Technology signed a memorandum of understanding with the US National Science Foundation for the LIGO project in March 2016. Under the agreement, the LIGO Laboratory — which is operated by the California Institute of Technology (Caltech) in Pasadena and the Massachusetts Institute of Technology (MIT) in Cambridge — will provide the hardware for a complete LIGO interferometer in India, technical data on its design, as well as training and assistance with installation and commissioning for the supporting infrastructure. India will provide the site, the vacuum system and other infrastructure required to house and operate the interferometer — as well as all labor, materials and supplies for installation.”

India’s LIGO observatory is expected to cost about US$177 million.  Full funding is expected in 2020 and the observatory currently is planned for completion in 2024.  India’s Inter-University Centre for Astronomy and Astrophysics (IUCAA), also in Maharashtra  state, will lead the project’s gravitational-wave science and the new detector’s data analysis.

For T. V. Padma’s complete article, refer to: 

https://www.nature.com/articles/d41586-019-00184-z.

Spatial resolution of gravitational wave events

Using only the two US LIGO detectors, it is not possible to localize the source of gravitational waves beyond a broad sweep through the sky.  On 1 August 2017, Virgo joined LIGO during the second Observation Run, O2. While the LIGO-Virgo three-detector network was operational for only three-and-a-half weeks, five gravitational wave events were observed.  As shown in the following figure, the spatial resolution of the source was greatly improved when a triple detection was made by the two LIGO observatories and Virgo. These events are labeled with the suffix “HLV”.  

Source:  http://www.virgo-gw.eu, 3 December 2018

The greatly reduced areas of the triple event localizations demonstrate the capabilities of the current global gravitational wave observatory network to resolve the source of a gravitational-wave detection.  The LIGO and Virgo Collaboration reports that it can send Open Public Alerts within five minutes of a gravitational wave detection.

With timely notification and more precise source location information, other land-based and space observatories can collaborate more rapidly and develop a comprehensive, multi-spectral (“multi-messenger”) view of the source of the gravitational waves.

When KAGRA and LIGO-India join the worldwide gravitational wave detection network, it is expected that source localizations will become 5 to 10 times more accurate than can be accomplished with just the LIGO and Virgo detectors.

For more background information on gravitational-wave detection, see the following Lyncean posts:

A Newcomer at the Top of the June 2016 TOP500 Ranking of the World’s Supercomputers

The latest TOP500 ranking of the world’s 500 most powerful supercomputers was released on 20 June 2016. Since June 2013, China’s Tianhe-2 supercomputer topped this ranking at 33 petaflops [PFLOPS; 1015  floating-point operations per second (FLOPS)]. Now there is a new leader, and once again it is a Chinese supercomputer the Sunway TaihuLight.

sunway-taihulightSource: Jack Dongarra, Report on the Sunway TaihuLight System, June 2016

Details are available at the TOP500 website:

https://www.top500.org

On this website, Michael Feldman commented on the new leader in the TOP500 ranking:

“A new Chinese supercomputer, the Sunway TaihuLight, captured the number one spot on the latest TOP500 list of supercomputers released on Monday morning at the ISC High Performance conference (ISC) being held in Frankfurt, Germany.  With a Linpack mark of 93 petaflops, the system outperforms the former TOP500 champ, Tianhe-2, by a factor of three. The machine is powered by a new ShenWei processor and custom interconnect, both of which were developed locally, ending any remaining speculation that China would have to rely on Western technology to compete effectively in the upper echelons of supercomputing.”

Remarkably, the Sunway TaihuLight’s significant performance increase is delivered with lower power consumption than Tihane-2: 15,371 kW for TihauLight vs. 17,808 kW for Tihane-2.

You can read Michael Feldman’s complete article at the following link:

https://www.top500.org/news/china-tops-supercomputer-rankings-with-new-93-petaflop-machine/

You also can read the press release for the new TOP500 listing at the following link:

https://www.top500.org/news/new-chinese-supercomputer-named-worlds-fastest-system-on-latest-top500-list/

You’ll find the list of the top 10 supercomputers at the following link:

https://www.top500.org/lists/2016/06/

From here, you can navigate to the complete listing of all 500 supercomputers by going to the grey box titled RELEASE and selecting The List.

U.S supercomputers Titan and Sequoia are ranked 3rd and 4th, respectively, each with about 17% of the RMAX rating of the Sunway TaihuLight and half the power consumption. In comparison, the Sunway TaihuLight is significantly more power efficient than Titan and Sequoia.

15 July 2016 Update: National Science Foundation (NSF) examines the future directions for NSF advanced computing infrastructure

The NSF recently published the new report entitled, “Future Directions for NSF Advanced Computing Infrastructure to Support U.S. Science and Engineering in 2017-2020.”

NSF adv computing infrastructure report cover   Source: NAP

As described by the authors, this report “offers recommendations aimed at achieving four broad goals: (1) position the U.S. for continued leadership in science and engineering, (2) ensure that resources meet community needs, (3) aid the scientific community in keeping up with the revolution in computing, and (4) sustain the infrastructure for advanced computing.”

The report addresses the TOP500 listing, pointing to several known limitations, and concludes that:

“Nevertheless, the list is an excellent source of historical data, and taken in the aggregate gives insights into investments in advanced computing internationally.”

The NSF report further notes the decline in U.S. ranking in the TOP500 list (see pp. 59 – 60):

“The United States continues to dominate the list, with 45 percent of the aggregate performance across all machines on the July 2015 list, but it has dropped substantially from a peak of over 65 percent in 2008. NSF has had systems either high on the list (e.g., Kraken, Stampede) or comparable to the top systems (i.e., Blue Waters), reflecting the importance of computing at this level to NSF-supported science. Although there are fluctuations across other countries, the loss in performance share across this period is mostly explained by the growth in Asia, with China’s share growing from 1 percent to nearly 14 percent today and Japan growing from 3 to 9 percent.”

The report puts TOP500 rankings in perspective as it addresses future national scale advanced computing needs and operational models for delivering advanced computing services.

If you have a MyNAP account, you can download this report for free from National Academies Press (NAP) at the following link:

http://www.nap.edu/catalog/21886/future-directions-for-nsf-advanced-computing-infrastructure-to-support-us-science-and-engineering-in-2017-2020

Just What are Those U.S. Scientists Doing in the Antarctic and the Southern Ocean?

The National Academies Press (NAP) recently published the report, “A Strategic Vision for NSF Investments in Antarctic and Southern Ocean Research”, which you can download for free at the following link if you have established a MyNAP account:

http://www.nap.edu/catalog/21741/a-strategic-vision-for-nsf-investments-in-antarctic-and-southern-ocean-research

Print Source: NAP

NSF states that research on the Southern Ocean and the Antarctic ice sheets is becoming increasingly urgent not only for understanding the future of the region but also its interconnections with and impacts on many other parts of the globe. The research priorities for the next decade, as recommended by the Committee on the Development of a Strategic Vision for the U.S. Antarctic Program; Polar Research Board; Division on Earth and Life Studies; National Academies of Sciences, Engineering, and Medicine, are summarized below:

  • Core Program: Investigator-driven basic research across a broad range of disciplines
    • NSF gives the following rationale: “…it is impossible to predict where the next major breakthroughs or advances will happen. Thus to ensure that the nation is well positioned to take advantage of such breakthroughs, it is important to be engaged in all core areas of scientific research.”
      • NSF notes, “…discoveries are often made by single or small groups of PIs thinking outside the box, or with a crazy new idea, or even just making the first observations from a new place.”
    • Examples of basic research that have led to important findings include:
      • Ross Sea food chain is affected by a high abundance of predator species (whales, penguins and toothfish) all competing for the same limited resource: krill. Decline or recovery of one predator population can be seen in an inverse effect on the other predator populations.  This food chain response is not seen in other areas of the Antarctic ice shelf where predator populations are lower, allowing a larger krill population that adequately supports all predators.
      • Basic research into “curious” very-low frequency (VLF) radio emissions produced by lightning discharges led to a larger program (with a 21.2-km-long VLF antenna) and ultimately to a better understanding of the behavior of plasma in the magnetosphere.
  • Strategic, Large Research Initiatives –  selection criteria:
    • Primary filter: compelling science – research that has the potential for important, transformative steps forward in understanding and discovery
    • Subsequent filters: potential for societal impact; time-sensitive in nature; readiness / feasibility; and key area for U.S. and NSF leadership.
    • Additional factors: partnership potential; impact on program balance; potential to help bridge existing disciplinary divides
  • Strategic, Large Research Initiative – recommendations::
    • Priority I: The Changing Antarctic Ice Sheets Initiative to determine how fast and by how much will sea level rise?
      • A multidisciplinary initiative to understand why the Antarctic ice sheets is changing now and how they will change in the future.
      • Will use multiple records of past ice sheet change to understand rates and processes.
    • Priority II: How do Antarctic biota evolve and adapt to the changing environment?
      • Decoding the genomic (DNA) and transcriptomic (messenger RNA molecules) bases of biological adaptation and response across Antarctic organisms and ecosystems.
    • Priority III: How did the universe begin and what are the underlying physical laws that govern its evolution and ultimate fate?
      • A next-generation cosmic microwave background (CBM) program that builds on the current successful CMB program using telescopes at the South Pole and the high Atacama Plateau in Chile and possibly will add a new site in the Northern Hemisphere to allow observations of the full sky

You will find detailed descriptions of the Priority I to III strategic programs in the Strategic Vision report.