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Black holes do the tango
Animation: Excerpts from the solo multimedia concert “Einstein’s Cosmic Messengers”, by Andrea Centazzo and Michele Vallisneri, illustrate a galaxy and black hole merger. Animation and audio courtesy of Andrea Centazzo and Michele Vallisneri, Caltech. Please send your comments on this issue of Cosmic Matters to .(JavaScript must be enabled to view this email address).
Two dancers waltzing in a darkened ballroom are invisible to an observer standing in the room. Similarly, two inspiralling black holes in a merger-remnant galaxy can be invisible to astronomers. Now imagine the two ballroom dancers picking up sparklers; suddenly their dance becomes very visible. A similar concept holds true for black holes—if a black hole is surrounded by gas from its host galaxy, this gas can fall onto the black hole and cause it to light up. In this way, the inspiralling of two black holes can become very visible to astronomers. —Julie Comerford, UC Berkeley astronomer
Despite the vastness of space, many galaxies interact and eventually merge with one another. Understanding how often this happens provides astronomers with information about how galaxies evolve in the Universe.
However, observing two galaxies as they merge is difficult. Images from the Hubble Space Telescope hint at past and future mergers, but these images have limitations. From them, it is not clear how to accurately classify a galaxy merger.
Julie Comerford and her colleagues at the University of California Berkeley have developed a new technique to study galaxy mergers. Using the Keck II telescope and its DEIMOS instrument, the astronomers observe spectra from material accreting onto black holes as they inspiral in merger-remnant galaxies. The data shed light on the dynamics of galaxy mergers and black hole mergers, as well as how often the black holes do the tango.
Keck Observatory Interferometry
Video. Watch how interferometry and a technique called nulling might help astronomers discover developing planets. Courtesy of the Jet Propulsion Laboratory.
Adding ten plus ten usually equals twenty. At Keck Observatory, ten plus ten gives astronomers 85.
The technique that makes this math possible is called optical interferometry. It is based on the interference of light waves and combines the power of the Observatory’s twin, ten-meter telescopes to open up new areas of research in extremely high-resolution astronomy.
When the Keck Interferometer is used, light from distant objects enters each telescope and is then sent into the basement of the Observatory, where the light is eventually merged to form a single signal—a uniform, zebra-striped pattern called interference fringes.
Seeing those fringes, whether it’s the first time or the five-hundredth, “always seems like a miracle,” said astronomer Rafael Millan-Gabet, who specializes in research that uses the two Keck telescopes as one extremely large, 85-meter telescope.
Defending dark skies of Hawai’i
By Ashley Yeager
This satellite image shows the city lights of Hawai’i. Courtesy of NASA
Hawai’i State Governor Linda Lingle approved legislation requiring business leaders to strategize plans to preserve dark skies across the state. The new law, passed in June 2009, supports astronomy in Hawai’i and stresses the need to limit light pollution to protect the health of natural habitats, wildlife and even humans.
The county’s citizens have benefited from the foresight of former law-makers who, in 1988, established a lighting ordinance to keep the Big Island’s skies dark. But, the original ordinance was last updated in 1989, when the largest potentially impacted telescope on Mauna Kea was 3.8 meters in diameter and fewer people resided on the island.
Over the last 25 years, the size of the telescopes at the summit has grown to include the two 10-meter Keck telescopes and Hawai’i County’s population has increased by nearly 80,000 people or 86 percent in the last 25 years.
In response to these changes, dark sky advocates have been lobbying state legislatures to preserve nighttime skies, especially during this International Year of Astronomy, or IYA 2009. In Hawai’i, lawmakers and lobbyists drafted legislation that required the Department of Business, Economic Development & Tourism, or DBEDT, assisted by a temporary advisory committee, to construct starlight reserves.
These designated sites have a core dark zone surrounded by a buffer and external zone. The dark zone will be an unpolluted area where natural night sky light conditions remain intact. The intermediate buffer zone would surround the dark zone to minimize adverse effects of air and light pollution. The external zone would surround the inner two regions to protect the interior night sky quality from pollution. This outer region would also have to follow “intelligent and responsible lighting criteria,” according to Hawai’i State Bill 536.
University of Hawaii’s Institute for Astronomy researcher Richard Wainscoat supported this initiative and testified before the Hawai’i State Legislature that “air molecules and dust scatter artificial light into the telescopes.” He explained that a ten percent increase in artificial light compared to its natural value makes the effective size of a telescope ten percent smaller. The starlight preserves, which would most likely include Mauna Kea and Haleakala on Maui, could envelope the two mountains to preserve darkness for astronomy.
Hawai’i DBEDT Director Ted Liu testified that the starlight preserves would protect and promote cultural heritages associated with the night sky and help safeguard the equilibrium of the biosphere. Office of Hawaiian Affairs, or OHA, representatives also argued that the night sky is important to native culture for identifying the stars used in navigation and also for planting, fishing and harvesting. The dark regions would provide darkness for these uses of the sky, and OHA has therefore requested to have a representative on the advisory committees that plan the reserves.
Image: The Milky Way arches over Mauna Kea. Haleakalā is in the distance as is the light pollution from Waimea, Kahului on Maui, and Honolulu on Oahu. Credit: Wally Pacholka.
The testimonies convinced the House and Senate to pass the dark skies legislation in May 2009.
After passing both the House and Senate, the bill moved to Gov. Lingle’s desk in early June of 2009, and state residents were urged to comment on the potential law.
On behalf of Keck Observatory, Director Taft Armandroff responded, advocating the scientific aspect that dark skies provide to astronomy and to the state. Director of Advancement Debbie Goodwin also called on friends of the Observatory to lend their voice.
“Starlight over our state is a precious resource for science, scientific leadership, for beauty and yes, for romance,” Keck Observatory friends Doug and Linda Lanterman wrote in a letter to the Governor.
Mainland resident Sam McClung wrote: “I am one of thousands of visitors to the Big Island of Hawai’i that find the Observatories on Mauna Kea a wonderful symbol of some of the unique advantages our fiftieth state provides. Please keep the skies dark at night so that the telescopes can continue their uninhibited exploration of our universe,” he testified.
McClung, a California resident, also explained that his state’s “big telescopes (Wilson & Palomar) are severely restricted in their performance by the huge population growth and the unrestricted light that we send into the sky. Don’t let this happen to Hawai’i!”
If the law is enacted as written, it won’t.
Leaving a Legacy to the Stars
By Debbie Goodwin
Throughout history humans have gazed up at the night sky with curiosity and wonder. Polynesian navigators looked to the stars for direction. Galileo sparked the tradition of observing the heavens for understanding. Today astronomers continue to explore the cosmos for answers to explain our ultimate origins and our fate.
This illustration captures the human connection to the stars and their legacy of wonder. Credit: (c) Kadi Igawa.
Supporting the W. M. Keck Observatory through a planned gift ensures this rigorous and noble endeavor will continue far into the future. Including Keck Observatory in your estate plan offers you financial benefits, entitles you to receive a charitable income tax deduction, and most importantly ensures support for the strategic goals of an organization that is aligned with your vision of how you wish to better the world in a lasting way.
Tax law provides a diverse selection of charitable gift options which include bequests, gift annuities, pooled income funds, and charitable trusts. You can use a blend of assets including cash, securities, and real estate to make your gift. By working with your professional advisor, you can benefit yourself, family members, or other individuals and the charitable organization of your choice.
For more information about supporting Keck Observatory through your will, trust, or planned gift, please contact Debbie Goodwin at 808.881.3814.
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