Tag Archives: Fabio Governato

BOSS and Pleiades figure out the universe

Astronomy these days is something of a tag-team event involving both observers and theorists. We got a look at how it works at the most recent Astronomy on Tap Seattle event at Bad Jimmy’s Brewing Company in Ballard.

Case in point: for a couple of decades cosmologists had been using the cold dark matter theory to explain how the universe evolved from a hot, dense, uniform place right after the Big Bang to the web of galaxies that we see today. The theory worked pretty well, but there were a couple of catches: it predicted that dwarf galaxies would have large central bulges of stars and increasingly dense dark matter at their cores. Neither prediction matched with the observations.

Figuring it out


Look! Up in the sky! Prof. Fabio Governato makes a point during his Astronomy on Tap talk Feb. 17 at Bad Jimmy’s. Photo: Greg Scheiderer.

Dr. Fabio Governato, a research professor in the Department of Astronomy at the University of Washington, said he and a few colleagues, after downing several beers each during an escape from a boring conference, decided to figure out this anomaly. Governato‘s talk at Astronomy on Tap Seattle was titled, “Dark Matter, Black Holes, and other reasons to work with NASA’s fastest supercomputer: Pleiades.”

Eventually, they hit upon the idea that supernova explosions in the dwarf galaxies might push away gas and thus retard star formation, and may also blow dark matter away as well.

“This is very simple physics,” Governato said, “but the problem was to find a numerical experiment that you could run with computers that shows clearly” how it works. They used millions of hours on supercomputers, like NASA’s Pleiades, adding the supernovae into the mix and tweaking the idea until the computer simulation of the cold dark matter theory turned out dwarf galaxies that matched what we actually observe. Their paper about the work was published in the journal Nature, and Governato has some humorous tales about the twists and turns between the work, the publication, and ultimate acceptance of the findings.

His talk also used interesting and sometimes humorous animations to make points. Governato’s movie of a dwarf galaxy formation based on the work is posted below.



Dr. John Parejko, holding a sample of the metal plates used in the BOSS survey, answers questions after his talk. Even pooches love Astronomy on Tap! Photo: Greg Scheiderer.

Dr. John Parejko works on the observation side of the equation. Parejko recently was with the Sloan Digital Sky Survey out of New Mexico. His talk was titled, “Detect the Ancient Universe Like a BOSS.”

“BOSS is measuring distances to millions of galaxies to find wiggles from the early universe, but that doesn’t make a very good acronym,” Parejko quipped. BOSS actually stands for Baryon Oscillation Spectroscopic Survey.

The wiggles or oscillations are evidence of interactions that happened right after the Big Bang.

“Patterns in that hot, dense plasma persist to today in the distribution of galaxies in the universe,” Parejko said.

“These are not gravitational waves,” he noted, as the discoveries from LIGO were fresh in the news. “These are actually the interaction between the dark matter and the baryons very early in the universe.”

The process was simple enough, as they took spectra of galaxies and computed their redshifts to precisely determine distances. The challenge was that they had to look at a lot of galaxies, and over the years BOSS examined about a third of the sky and took images of about two million galaxies, measuring the redshifts of about half of those. Using the redshift to pin down distances to and between galaxies, and examining the patterns that emerge, helps astronomers figure out galaxy formation and learn how dark energy is causing the expansion of the universe to speed up.

Part of the tool that BOSS uses is made at the University of Washington, where telescope plates are created for the project. Each metal plate, about three feet wide, has a thousand holes drilled into it, each one corresponding to a specific object in the sky. Humans plug a fiberoptic cable into each hole by hand, and the cable collects the light from targeted galaxies.

Birthday party!

Astronomy on Tap Seattle is organized by astronomy graduate students at the University of Washington. The next event, scheduled for March 23, will celebrate the first birthday of the program. Speakers will update the subjects of their talks from the first year. Attendees will be able to purchase a commemorative AoT beer glass and sample Bad Jimmy’s barrel-aged Big Sipper, a Scotch ale named as a salute to Astronomy on Tap.


Busy Presidents Day week ahead

Happy Presidents Day from Seattle Astronomy. We celebrate the birthdays of George Washington and Abraham Lincoln this week. Perhaps, though, we should observe Astronomers Day, because some big-name birthdays fall this week as well. Nicholas Copernicus was born Feb. 19, 1473—he would be 543—and Galileo was born Feb. 15, 1564—452 years ago this day. Maybe it is because of these two most important scientists that there are so many great astronomy events on the calendar this week!

Show me a rose

Rose City AstronomersWe’re planning a road trip to Portland, where the Rose City Astronomers will hold their monthly meeting at 7:30 p.m. Monday, Feb. 15 at the OMSI auditorium. Dr. Gregory Bothun of the University of Oregon will give a talk titled, “Astronomy, Big Data, and the Future.” The premise: we’re collecting astronomical data at an astronomically increasing pace, but human processing and thinking about all of this information can’t keep up. Is astronomy in danger of becoming a “pixel archive science?”

Silent Sky and These Things Abide

Silent SkyTaproot Theatre in Greenwood continues its run of Silent Sky, Lauren Gunderson‘s play about astronomer Henrietta Leavitt, through Feb. 27. This Tuesday, Feb. 16 at 7:30 p.m. the theatre will host a special conversation with the play’s director, Karen Lund, and Adrian Wyard of the Counterbalance Foundation as they discuss the search for truth by both science and religion, the history of the conversation between faith and science, and the possibilities for future dialogue. It’s free, but seating is limited, so contact the theatre if you wish to attend.

Watch for a post about our conversation with Wyard coming soon!

Decisions, decisions

There are two good events coming up on Wednesday, Feb. 17, but alas, you can only be in one place at a time, unless this whole multiverse thing is true.

AOT SeattleThe fine folks from Astronomy on Tap Seattle, organized by astronomy graduate students from the University of Washington, will host their monthly confab of astronomy, trivia, prizes, and beer at 7 p.m. at Bad Jimmy’s Brewing Company in Ballard. This month UW astronomer Dr. John Parejko will give a talk titled, “Detect the Ancient Universe Like a BOSS,” and Dr. Fabio Governato will speak about “Dark Matter, Black Holes and other reasons to work with NASA’s fastest supercomputer: Pleiades.” It’s free, but bring beer money.

Meanwhile the Seattle Astronomical Society will hold its monthly meeting at 7:30 p.m. Wednesday in room A102 of the Physics/Astronomy Building on the UW campus in Seattle. Astronomy Ph.D. student Phoebe Upton Sanderbeck will give a presentation about how measuring the temperature of the universe can help us understand its development.

Saturn’s moons of promise

Pacific PlanetariumPacific Planetarium in Bremerton will feature its monthly third Friday astronomy talk this Friday, Feb. 19 with hourly presentations at 5 p.m., 6 p.m., and 7 p.m. NASA Solar System Ambassador Ron Hobbs will share the latest findings about the environments on Saturn’s moons Enceledus and Titan, where liquid water and methane flow, which might provide the necessary conditions for life to develop. Tickets are $5 and are available at the door or in advance online.

The Mercury 13

Mercury 13Sally Ride became the first American woman in space when she flew on a space shuttle mission in 1983. More than two decades earlier 13 U.S. women were training for flight in the Woman in Space program. Of course, the Mercury 13 never got off the ground. At 2 p.m. this Saturday, Feb. 20 at the Museum of Flight aviation expert Philip Tartalone will explore the genesis of the Woman in Space Program, the personalities involved, the testing, and the social mores of the early 1960s that ultimately doomed the program. The presentation is free with admission to the Museum.

Up in the sky

Jupiter will be at opposition next month, but it’s already placed pretty well for viewing in the late evening these days. The Sky This Week from Astronomy magazine and This Week’s Sky at a Glance from Sky & Telescope have other observing highlights for the week.