Time Domain Astronomy Will Change How We Think About Space

“This is the place to be if you are doing time domain astronomy,” says Andrej Prša, an astronomer at Villanova University. He’s referring to Hotwired 5, short for the fifth annual Hotwiring the Transient Universe conference, being held this week at Villanova University. Researchers from all around the world are gathering in a single place to discuss how to better perfect the study of transient celestial and astrophysical phenomena.

But what the hell is “time domain astronomy?” And why should we care?

According to Prša, one of the Hotwired’s organizers, time domain astronomy is essentially the study of anything in space that is a variable of time. Thats a broad spectrum of things, but they could be phenomena that are periodically variable (and therefore predictable), like pulsating stars or eclipsing binary stars; or things that are wild and seemingly random, like x-ray binaries, gamma ray bursts, supernovae, cataclysmic variables, gravitational waves, or even the behavior and movements of near-Earth objects like asteroids.

In short, time domain astronomy effectively relates to investigating space science that is not necessarily static. “Whenever you want to explore the variability of an object as a function of time, that’s time domain astronomy.”

This sounds pretty simple unless you understand one of the biggest limitations to studying space has to do with the fact that we don’t have eyes on everything all at once. There are telescopes all around the world doing surveys of the night sky and trying to catch a signal or collect data related to very transient events. A star explodes — and you might have an opportunity to catch the explosion at its brightest light. But unless you’ve been focusing your lens in that direction the entire time, you’ll only be able to collect a blip of data that reveals little about how a supernova unfolds as a process.

Hotwired was founded in 2007 when there was a realization that “there are a lot of transient time domain phenomena in astronomy, that we simply are not equipped to deal with as a rapid follow-up time response,” said Prša. New technology allows scientists to detect the aforementioned phenomena as they occur, but those instruments will not stop to conduct follow-up investigations and collect more data — they simply continue along with their general survey of space.

“In order to address that,” he says, “we decided that people who are on the science side of the transients and people who are in charge of the world’s observatories should get together and start talking about the possibilities of introducing robotic telescopes and rapid follow-up systems in order to cover the gap we have in following up these transient phenomena.”

Nine years later, Hotwired boasts over 100 presentations and sessions attended by astronomers and observatory directors from all over the world. This year’s Hotwired is being held for the first time on the East Coast.

Time domain astronomy offers a key to some of the galaxy’s most perplexing problems. “We quite frequently don’t even know what causes these phenomena,” says Prša. For example, gamma ray bursts and gravitational waves have a good model for when they might originate (such as black hole binary system mergers), but we still aren’t sure of what kinds of signals they produce on the electromagnetic spectrum and how we can best measure these. Are these phenomena producing blue-colored wavelengths? Do they have infrared signal emissions? Nobody knows yet.

The goal of Hotwired is to develop response systems that have been shrunken to the order of 15 minutes “from when the survey detects one of the transient phenomenon, to when the follow-up network receives note and can issue an interrupt of the current operation so that [the instrument] can immediately follow-up on what’s called a ‘high science profile case’ … [in which case], we stand the best chance to find out what’s going on” — even with very mysterious and very transient phenomena.

Perhaps the best example of how this might work is with the century-old mystery of gravitational waves — of which there are now two confirmed detections, with another pending detection. But because the signals we’ve picked up are fleeting, there’s no way to actually put that data into a context that helps us understand them beyond a one-dimensional view, so to speak.

Finding an electromagnetic counterpart for gravitational waves would allow us to understand when those waves are more likely to be produced at high signals, and better characterize the kinds of celestial events that make them.

But we shouldn’t pigeon-hole time domain astronomy as a gravitational waves explainer. Sure, they’re what Prša calls “the hottest thing on the block” for the emerging field, but there’s probably a slew of celestial phenomena that we don’t even know about which could benefit from a time domain explanation. Take our shaky understanding of gamma ray bursts, or binary star interactions, which are Prša’s own research interest and could be relevant to understanding planetary formation in star systems like Alpha Centauri. “We’re seeing such a diverse spectrum of topics,” says Prša.

Astrophysics has traditionally suffered as a divided community, one where groups attempted to explain the universe’s infinite mysteries with little consensus. And if Hotwired proves successful in uniting the disparate groups with time domain astronomy, our entire conception of what we think of when it comes to our universe might be forever beholden to Prša’s game-changing ideas.