Tag Archives: Caltech

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:

Simulating Extreme Spacetimes

Thanks to Dave Groce for sending me the following link to the Caltech-Cornell Numerical Relativity collaboration; Simulating eXtreme Spacetimes (SXS):

http://www.black-holes.org

Caltech SXSSource: SXS

From the actual website (not the image above), click on the yellow “Admit One” ticket and you’re on your way.

Under the “Movies” tab, you’ll find many video simulations that help visualizes a range of interactions between two black holes and between a black hole and a neutron star. Following is a direct link:

http://www.black-holes.org/explore/movies

A movie visualizing GW150914, the first ever gravitational wave detection on 14 September 2015, is at the following SXS link:

https://www.black-holes.org/gw150914

At the above link, you also can listen to the sound of the GW150914 “in-spiral” event (two black holes spiraling in on each other).  You can read more about the detection of GW150914 in my 11 February 2016 post.

On the “Sounds” tab on the SXS website, you’ll find that different types of major cosmic events are expected to emit gravitational waves with waveforms that will help characterize the original event. You can listen to the expected sounds from a variety of extreme cosmic events at the following SXS link:

http://www.black-holes.org/explore/sounds

Have fun exploring SXS.

 

Anyone Can Quantum

Nobel Laureate Dr. Richard Feynman is famously quoted as saying, “I think I can safely say that nobody understands quantum mechanics.” University of Southern California (USC) graduate student Chris Cantwell, the inventor of Quantum Chess, is seeking to change that view by demonstrating that, in the right framework, anyone can grapple with some of the basic concepts of quantum mechanics. In particular, Chris Cantwell views Quantum Chess as a means of “demystifying the quantum world through play.” In Quantum Chess, all of the conventional chess moves are allowed as well as certain quantum moves for all pieces except pawns.

Quantum Chess isn’t a game you can purchase right now, but the short video, “Anyone Can Quantum,” provides an entertaining demonstration of what quantum gameplay will be like in the near future. This video was created by Caltech’s Institute for Quantum Information and Matter (IQIM) (‪http://iqim.caltech.edu) in association with Trouper Productions (‪http://trouper.net). In the video, actor Paul Rudd (Ant Man) challenges Stephen Hawking to a game of Quantum Chess for the right to give the keynote address at Caltech’s 26 – 27 January 2016 special event, “One Entangled Evening: A Celebration of Richard Feynman’s Quantum Legacy.”

You can view the almost 12 minute video at the following link.

https://www.youtube.com/watch?v=Hi0BzqV_b44

Here are a few of screenshots from the video.

Quantum chess match announcement

Quantum chess players

Quantum superposition is demonstrated by “Schrodinger’s king”, which could be in two places at one time.

Without superposition                                                      With superposition

Without superposition             With superposition

Quantum entanglement of the king & bishop enabled a bishop to move through a king.

Without entanglement                                                  With entanglement

Without entanglement           With entangelement

Resolution of the game required a quantum measurement to determine the winner.

For those of you who can’t wait to play a real game of Quantum Chess, Chris Cantwell has launched a Kickstarter funding program. Find out details at the following link:

https://www.kickstarter.com/projects/507726696/quantum-chess

You can find out more about the 26 – 27 January 2016 Caltech event, One Entangled Evening: A Celebration of Richard Feynman’s Quantum Legacy,” at the following link:

https://www.caltech.edu/content/one-entangled-evening-celebration-richard-feynmans-quantum-legacy

 

 

100th Anniversary of Einstein’s General Theory of Relativity and the Advent of a New Generation of Gravity Wave Detectors

One hundred years ago, Albert Einstein presented his General Theory of Relativity in November 1915, at the Prussian Academy of Science. Happy Anniversary, Dr. Einstein!

Today, general relativity is being tested with unprecedented accuracy with a new generation of gravity-wave “telescopes” in the U.S., Italy, Germany, and Japan. All are attempting to directly detect gravity waves, which are the long-predicted quakes in space-time arising from cataclysmic cosmic sources.

The status of four gravity-wave telescopes is summarized below.

USA: Laser Interferometer Gravitational-Wave Observatory (LIGO)

LIGO is a multi-kilometer-scale gravitational wave detector that uses laser interferometry to, hopefully, measure the minute ripples in space-time caused by passing gravitational waves. LIGO consists of two widely separated interferometers within the United States; one in Hanford, WA and the other in Livingston, LA. These facilities are operated in unison to detect gravitational waves. The Livingston and Hanford LIGO sites are shown in the following photos (Hanford above, Livingston below):

ligo-hanford-aerial-02Source LIGO Caltechligo-livingston-aerial-03Source: LIGO Caltech

LIGO is operated by Caltech and MIT and is supported by the National Academy of Sciences. For more information, visit the LIGO website at the following link:

https://ligo.caltech.edu/page/about

Basically, LIGO is similar to the traditional interferometer used in 1887 in the famous Michelson-Morley experiment (https://en.wikipedia.org/wiki/Michelson–Morley_experiment). However, the LIGO interferometer incorporates novel features to greatly increase its sensitivity. The basic arrangement of the interferometer is shown in the following diagram.

LIGO experiment setupSource: LIGO Caltech

Each leg of the interferometer has a physical length of 4 km and is a resonant Fabry-Perot cavity that uses a complex set of mirrors to extend the effective arm length by a factor of 400 to 1,600 km.

On 18 September 2015, the first official “observing run” using LIGO’s advanced detectors began. This “observing run” is planned to last three months. LIGO’s advanced detectors are already three times more sensitive than Initial LIGO was by the end of its observational lifetime in 2007. You can read about this milestone event at the following link:

https://ligo.caltech.edu/news/ligo20150918

You also can find much more information on the LIGO Scientific Collaboration (LSC) at the following link:

http://www.ligo.org

Italy: VIRGO

VIRGO is installed near Pisa, Italy, at the site of the European Gravitational Observatory (http://www.ego-gw.it/public/virgo/virgo.aspx). VIRGO is intended to directly observe gravitational waves using a Michelson interferometer with arms that are 3 km long, with resonant Fabry-Perot cavities that increase the effective arm length by a factor of 50 to 150 km. The initial version of VIRGO operated from 2007 to 2011 and the facility currently is being upgraded with a new, more sensitive detector. VIRGO is expected to return to operation in 2018.

You can find much more information on VIRGO at the following link:

http://www.virgo-gw.eu

Germany: GEO600

GEO600 is installed near Hanover, Germany. It, too, uses a Michelson interferometer with arms that are 600 meters long, with resonant Fabry-Perot cavities that double the effective arm length to 1,200 meters.

You can find much more information on the GEO600 portal at the following link:

http://www.geo600.org

Japan: KAGRA Large-scale Cryogenic Gravitational Wave Telescope

The KAGRA telescope is installed deep underground, in tunnels of Kamioka mine, as shown in the following diagram.

img_abt_lcgtSource: KAGARA

Like the other facilities described previously, KAGRA is a Michelson interferometer with resonant Fabry-Perot cavities. The physical length of each arm is of 3 km (1.9 mi). KAGRA is expected to be in operation in 2018.

You can find much more information on KAGARA at the following links:

http://www.astro.umd.edu/~miller/Compact/lcgt.pdf

and,

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

 

 

Spitzer Space Telescope “Warm Mission” Continues

The Spitzer Space Telescope, an infrared space observatory, was launched on 8 August 2003 into an “earth-trailing” orbit around the Sun. It is one of four “Great Observatories” launched by NASA; the others being the Hubble Space Telescope, the Compton Gamma-ray Observatory; and the Chandra X-ray Observatory.

Spitzer_Telescope_Handbook013   Diagram source: NASA

The primary mirror is 85 cm in diameter, made of beryllium, and until May 2009, was cooled by liquid helium to 5.5 degrees K. With the on-board liquid helium supply exhausted, most of the instruments were no longer usable. However, the two shortest wavelength modules of the Infrared Science Archive (IRAC) camera remained operable at their original sensitivities. This allowed the mission team to continue with the “Spitzer Warm Mission”.

You can read about the design of the Spitzer Space Telescope at the following link:

http://irsa.ipac.caltech.edu/data/SPITZER/docs/spitzermission/missionoverview/spitzertelescopehandbook/9/

An example of an image from the Spitzer Space Telescope is this view of Eta Carinae:

The tortured clouds of Eta Carinae  Photo source: NASA

You can see this and many other images from the Spitzer telescope, and related image data, at the following NASA / JPL / Caltech website:

http://www.spitzer.caltech.edu