CU study: ‘Sideline quasars’ helped to stifle early galaxy formation
Mar 21st
CU-Boulder Professor Michael Shull and Research Associate David Syphers used the Hubble Space Telescope to look at the quasar — the brilliant core of an active galaxy that acted as a “lighthouse” for the observations — to better understand the conditions of the early universe. The scientists studied gaseous material between the telescope and the quasar with a $70 million ultraviolet spectrograph on Hubble designed by a team from CU-Boulder’s Center for Astrophysics and Space Astronomy.
During a time known as the “helium reionization era” some 11 billion years ago, blasts of ionizing radiation from black holes believed to be seated in the cores of quasars stripped electrons from primeval helium atoms, said Shull. The initial ionization that charged up the helium gas in the universe is thought to have occurred sometime shortly after the Big Bang.
“We think ‘sideline quasars’ located out of the telescope’s view reionized intergalactic helium gas from different directions, preventing it from gravitationally collapsing and forming new generations of stars,” he said. Shull likened the early universe to a hunk of Swiss cheese, where quasars cleared out zones of neutral helium gas in the intergalactic medium that were then “pierced” by UV observations from the space telescope.
The results of the new study also indicate the helium reionization era of the universe appears to have occurred later than thought, said Shull, a professor in CU-Boulder’s astrophysical and planetary sciences department. “We initially thought the helium reionization era took place about 12 billion years ago,” said Shull. “But now we think it more likely occurred in the 11 to 10 billion-year range, which was a surprise.”
A paper on the subject by Shull and Syphers was published online this week in the Astrophysical Journal.
The Cosmic Origins Spectrograph used for the quasar observations aboard Hubble was designed to probe the evolution of galaxies, stars and intergalactic matter. The COS team is led by CU Professor James Green of CASA and was installed on Hubble by astronauts during its final servicing mission in 2009. COS was built in an industrial partnership between CU and Ball Aerospace & Technologies Corp. of Boulder.
“While there are likely hundreds of millions of quasars in the universe, there are only a handful you can use for a study like this,” said Shull. Quasars are nuclei in the center of active galaxies that have “gone haywire” because of supermassive black holes that gorged themselves in the cores, he said. “For our purposes, they are just a really bright background light that allows us to see to the edge of the universe, like a headlight shining through fog.”
The universe is thought to have begun with the Big Bang that triggered a fireball of searing plasma that expanded and then become cool neutral gas at about 380,000 years, bringing on the “dark ages” when there was no light from stars or galaxies, said Shull. The dark ages were followed by a period of hydrogen reionization, then the formation of the first galaxies beginning about 13.5 billion years ago. The first galaxies era was followed by the rise of quasars some 2 billion years later, which led to the helium reionization era, he said.
The radiation from the huge quasars heated the gas to 20,000 to 40,000 degrees Fahrenheit in intergalactic realms of the early universe, said Shull. “It is important to understand that if the helium gas is heated during the epoch of galaxy formation, it makes it harder for proto-galaxies to hang on to the bulk of their gas. In a sense, it’s like intergalactic global warming.”
The team is using COS to probe the “fossil record” of gases in the universe, including a structure known as the “cosmic web” believed to be made of long, narrow filaments of galaxies and intergalactic gas separated by enormous voids. Scientists theorize that a single cosmic web filament may stretch for hundreds of millions of light years, an eye-popping number considering that a single light-year is about 5.9 trillion miles.
COS breaks light into its individual components — similar to the way raindrops break sunlight into the colors of the rainbow — and reveals information about the temperature, density, velocity, distance and chemical composition of galaxies, stars and gas clouds.
For the study, Shull and Syphers used 4.5 hours of data from Hubble observations of the quasar, which has a catalog name of HS1700+6416. While some astronomers define quasars as feeding black holes, “We don’t know if these objects feed once, or feed several times,” Shull said. They are thought to survive only a few million years or perhaps a few hundred million years, a brief blink in time compared to the age of the universe, he said.
“Our own Milky Way has a dormant black hole in its center,” said Shull. “Who knows? Maybe our Milky Way used to be a quasar.”
The first quasar, short for “quasi-stellar radio source,” was discovered 50 years ago this month by Caltech astronomer Maarten Schmidt. The quasar he observed, 3C-273, is located roughly 2 billion years from Earth and is 40 times more luminous than an entire galaxy of 100 billion stars. That quasar is receding from Earth at 15 percent of the speed of light, with related winds blowing millions of miles per hour, said Shull.
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Lyndi McCartney, wife of former CU coach Bill McCartney, dies of emphysema
Mar 21st
WESTMINSTER – Lyndi McCartney, the wife of former University of Colorado football coach Bill McCartney, passed away Thursday afternoon after a lengthy, hard-fought battle with emphysema. She was 70.
“We have four children and 10 grandchildren and we all loved her very much,” Bill McCartney said of his wife for a half century; the two celebrated their 50th wedding anniversary last Dec. 29.
Lyndi spent her last days in Hospice care and was surrounded by family when she finally succumbed after decade-plus long battle against the disease. Grandsons, the sons of daughter Kristy, T.C., a CU graduate assistant coach, and Derek, a freshman on the football team, were among those present when she passed.
The eldest McCartney son, Mike, announced his mother’s passing on his Facebook page with simply, “RIP Mom. I am who I am because of you. Love you.” He works as a player’s representative with Priority Sports out of Chicago.
The youngest son, Marc, posted this on Facebook: “Today I mourn, but my mom suffers no more. She is forever in heaven now and that gives me a great peace that surpasses all understanding. Thank you to all of the people who loved my mom and have been praying for her. Your thoughts and prayers have been a great encouragement and comfort to me and my family.” Marc is the vice president for special events with RightNow, a non-profit ministry in Rockwall, Texas
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The couples’ other son, Tom, is the football coach at Fairview High School in Boulder.
Services are pending.
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Smoking ban on Pearl Street Mall has Teeth
Mar 21st
The ordinance banning smoking on the Pearl Street Mall went into effect on Jan. 18, 2013. The ordinance bans all smoking between 11th and 15th streets on the Pearl Street Mall, and on the lawn of the Boulder County Courthouse. The maximum penalty for a first or second offense within two years is a fine of $500; a third and subsequent conviction within two years triggers the general penalty provision of a maximum $1,000 fine and/or maximum of 90 days in jail.
Boulder police officers who patrol on the Pearl Street Mall have been educating people about the smoking ban since it went into effect, and have not written any tickets while the signs were being manufactured. On Monday, April 1, the ordinance will be fully implemented, and enforcement will begin.
Signs were ordered after City Council approved the ordinance in December; however there was a delay in the sign manufacturing. The signs on the mall are custom enameled and take longer to fabricate. The enamel signs are more resistant to graffiti and other tampering.
The city is collaborating with several partners, including Boulder County Public Health and Downtown Boulder, Inc. (DBI), to create a coordinated educational campaign for downtown employees and visitors about the smoking ban on the mall. A celebration event will be held from 11:30 a.m. to 1:30 p.m. on Friday, April 12, on the 1300 block of the Pearl Street Mall, where county, city and DBI staff will be available to answer questions about the smoking ban and about free resources available for individuals who wish to quit smoking.