Scientists reach Back in Time to Discover some of the most Power-packed Galaxies

In the heart of an active galaxy, matter falling toward a supermassive black hole generates jets of particles traveling near the speed of light.Credit: NASA's Goddard Space Flight Center Scientific Visualization Studio

When the universe was young, a supermassive black hole heaved out a jet of particle-infused energy that raced through space at nearly the speed of light. Billions of years later, scientists has identified this black hole and four others similar to it that range in age from 1.4 billion to 1.9 billion years old.

When the universe was young, a supermassive black hole -- bloated to the bursting point with stupendous power -- heaved out a jet of particle-infused energy that raced through the vastness of space at nearly the speed of light.

Billions of years later, a trio of Clemson University scientists, led by College of Science astrophysicist Marco Ajello, has identified this black hole and four others similar to it that range in age from 1.4 billion to 1.9 billion years old. These objects emit copious gamma rays, light of the highest energy, that are billions of times more energetic than light that is visible to the human eye.

The previously known earliest gamma-ray blazars -- a type of galaxy whose intense emission is powered by extremely powerful relativistic jets launched by monstrous black holes -- were more than 2 billion years old. Currently, the universe is estimated to be approximately 14 billion years old.



"The discovery of these supermassive black holes, which launch jets that emit more energy in one second than our sun will produce in its entire lifetime, was the culmination of a yearlong research project," said Ajello, who has spent much of his career studying the evolution of distant galaxies. "Our next step is to increase our understanding of the mechanisms involved in the formation, development and activities of these amazing objects, which are the most powerful accelerators in the universe. We can't even come close to replicating such massive outputs of energy in our laboratories. The complexities we're attempting to unravel seem almost as mysterious as the black holes themselves."

Ajello conducted his research in conjunction with Clemson post-doc Vaidehi Paliya and Ph.D candidate Lea Marcotulli. The trio worked closely with the Fermi-Large Area Telescope collaboration, which is an international team of scientists that includes Roopesh Ojha, an astronomer at NASA's Goddard Space Flight Center in Greenbelt, Maryland; and Dario Gasparrini of the Italian Space Agency.

The Clemson team's breakthroughs were made possible by recently juiced-up software on NASA's Fermi Gamma-ray Telescope. The refurbished software significantly boosted the orbiting telescope's sensitivity to a level that made these latest discoveries possible.



"People are calling it the cheapest refurbishment in history," Ajello said. "Normally, for the Hubble Space Telescope, NASA had to send someone up to space to physically make these kinds of improvements. But in this case, they were able to do it remotely from an Earth-bound location. And of equal importance, the improvements were retroactive, which meant that the previous six years of data were also entirely reprocessed. This helped provide us with the information we needed to complete the first step of our research and also to strive onward in the learning process."

Using Fermi data, Ajello and Paliya began with a catalog of 1.4 million quasars, which are
galaxies that harbor at their centers active supermassive black holes. Over the course of a year, they narrowed their search to 1,100 objects. Of these, five were finally determined to be newly discovered gamma-ray blazars that were the farthest away -- and youngest -- ever identified.

"After using our filters and other devices, we were left with about 1,100 sources. And then we did the diagnostics for all of these and were able to narrow them down to 25 to 30 sources," Paliya said. "But we still had to confirm that what we had detected was scientifically authentic. So we performed a number of other simulations and were able to derive properties such as black hole mass and jet power. Ultimately, we confirmed that these five sources were guaranteed to be gamma-ray blazars, with the farthest one being about 1.4 billion years old from the beginning of time."



Marcotulli, who joined Ajello's group as a Ph.D student in 2016, has been studying the blazars' mechanisms by using images and data delivered from another orbiting NASA telescope, the Nuclear Spectroscopic Telescope Array (NuSTAR). At first, Marcotulli's role was to understand the emission mechanism of gamma-ray blazars closer to us. Now she is turning her attention toward the most distant objects in a quest to understand what makes them so powerful.

"We're trying to understand the full spectrum of the energy distribution of these objects by using physical models," Marcotulli said. "We are currently able to model what's happening far more accurately than previously devised, and eventually we'll be able to better understand what processes are occurring in the jets and which particles are radiating all the energy that we see. Are they electrons? or protons? How are they interacting with surrounding photons? All these parameters are not fully understood right now. But every day we are deepening our understanding."



All galaxies have black holes at their centers -- some actively feeding on the matter surrounding them, others lying relatively dormant. Our own galaxy has at its center a super-sized black hole that is currently dormant. Ajello said that only one of every 10 black holes in today's universe are active. But when the universe was much younger, it was closer to a 50-50 ratio.

The supermassive black holes at the center of the five newly discovered blazar galaxies are among the largest types of black holes ever observed, on the order of hundreds of thousands to billions of times the mass of our own sun. And their accompanying accretion disks -- rotating swirls of matter that orbit the black holes -- emit more than two trillion times the energy output of our sun.

One of the most surprising elements of Ajello's research is how quickly -- by cosmic measures -- these supersized black holes must have grown in only 1.4 billion years. In terms of our current knowledge of how black holes grow, 1.4 billion years is barely enough time for a black hole to reach the mass of the ones discovered by Ajello's team.

"How did these incomprehensibly enormous and energy-laden black holes form so quickly?" Ajello said. "Is it because one black hole ate a lot all the time for a very long time? Or maybe because it bumped into other black holes and merged into one? To be honest, we have no observations supporting either argument. There are mechanisms at work that we have yet to unravel. Puzzles that we have yet to solve. When we do eventually solve them, we will learn amazing things about how the universe was born, how it grew into what it has become, and what the distant future might hold as the universe continues to progress toward old age."
Source: Materials provided by Clemson University

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The Time Reality: How its Rules Your Body—and Your Social Life

Time is inescapable, even if you try to ignore it, as author Alan Burdick did, by not wearing a watch.

We can’t smell it, we can’t taste it, we can’t hear it or touch it, but time is with us every second of our lives. And for thousands of years, philosophers and psychologists, from St. Augustine to William James, have pondered its meaning and how we perceive it. For his book Why Time Flies: A Mostly Scientific Investigation, Alan Burdick, who refused to wear a watch for much of his life, set off on a journey in search of time, which took him from a research station in the Arctic to the office of Coordinated Universal Time in Paris.

Speaking from his home in Hastings-on-Hudson, New York, Burdick explains how having twins changed his ideas about time, why as far back as the Romans people have complained about being slaves to time, and how new discoveries in neuroscience show that our bodies are filled with clocks.

It’s ironic that, for many years, the author of a book about time refused to wear a watch. Why was that? And how did your perception of time change after you finally relented?

I started this book some time ago, when I was rather a different person. I really was of the mind that if I could take the time off of me physically, that I somehow made it go away. Part of it was that I am prone to think about mortality. Having a watch on me felt like being a grown up! It meant plugging into, and being subject to, all the things that time requires, like being on time, and it made me feel like my day was chopped up into little bits and my watch was going to parse them out to me, like pellets to a rat.



I used to think that this was a modern outlook but I came across a great quote from a Roman poet, complaining about the sundial and how awful it is that it chops our days up into hours.
A lot of other things changed, too. In my case, I had a family—two fraternal twin boys, ten years old—and that forced me to be on time and get more things done than I used to be able to. I had to come to peace with it in that regard. Also, the more I learned about my subject, the more I came to appreciate the extent to which time and timing is embedded in every aspect of our social lives. You and I are going to have a conversation on such-and-such date at such-and-such time and, in order to do that, the time on your watch in the U.K. has to exactly match my time in the U.S. That’s all made possible by this incredible process that goes into making universal coordinated time, which involves atomic clocks and this global coordinated.



One of the most original ideas in your book is that “time is contagious” and even leads us to feel empathy for one another. Unpack that idea for us.

Yes, it’s super weird! We can come at it from a bunch of different ways. One is that research has found that when people are in conversation in person, there are all these things we do without even noticing. If we’re having lunch, you and I will unconsciously pick up our forks more or less at the same time. There’s a great study about two people playing the game Whack-A-Mole. Even though they were competing against each other, their movements fell into synch, even at the expense of losing points. They would unconsciously work toward this synchrony. The more affiliated and friendly you are with that other person, the more you are in synch.



If I watch a video of two people talking, I will be able to tell, unconsciously, how friendly they are, based on the extent to which their movements fall into synch with each other. The difference between a fake and real smile is a matter of milliseconds. It’s incredibly important to know the difference, right? And, in order to tell the difference, you need, as a viewer, to have a really sensitive timing mechanism that can parse one from the other. We have these clocks in us, which are operating all the time. It’s a very open question where exactly in the brain they are and how they work. But it’s clear that they’re there and utterly essential to making our social interactions go smoothly.

The cool thing about hummingbirds is that their timing mechanism is super sophisticated. In one experiment, they flew around outdoors to different flowers, which recharge their nectar at different rates. The hummingbirds want to get to the flower when it has maximum nectar, before its competitor does. So it’s got to do this elaborate optimization and algorithm to figure out how to get there often enough to get what it wants, without getting there too soon and wasting time, or getting there too late and being beaten to it.

Scientists have known about circadian rhythms for a couple of hundred years in plants. But in the last 20 years, the genetic mechanism has become clear in humans. The idea is that each of our cells can essentially tell the time; they have a 24-hour clock, which enables the cell to organize all the things it needs to do, just like you and I. We need to meet at a certain time, or talk at a certain time. Within yourself, your organelles and proteins and genes have stuff to do. It has to happen in a certain order, and that requires a clock. In humans it’s a little over 24 hours long, pretty close to, but not exactly, the length of a day.



All your cells have this clock. Your stomach and liver, all your organs, have a clock. In order to keep those clocks in synch, mammals and we humans have a master clock in our brains that sends out a neuro-chemical signal on a regular basis. Like the conductor of an orchestra, it keeps all of these clocks in time so your body knows that when you eat, 30 minutes later, your liver’s going to jump into action, then your adrenal glands and kidneys are going to do their thing, and your fat cells are going to absorb energy on a certain schedule.

There’s been a lot of research showing that, for night shift workers, truck drivers and other people who work on schedules that don’t match the circadian rhythm, their metabolism is thrown off. Some cancers may even be associated with night shift work or circadian imbalances. Your body is expecting to metabolize food at certain times of the day but if you are living at a different time of day, you’re eating food when your fat cells want to be sleeping.

Michel Siffre is a French cave explorer. In the 1960s, at the height of the space race, scientists were thinking about whether humans could live for a long time in isolation in deep space. Siffre had this idea: What if I go live in this cave for a period of weeks, and monitor my own heart rate and sleep cycle? What does living in isolation away from the sun do to the body? It was clear that humans have circadian cycles and that our body temperatures go up and down on a reliable 24-hour cycle. But Siffre was the first to show that the circadian
cycle in humans is not exactly 24 hours long.

He went on to repeat a similar experiment in a cave in Texas. He was down there for about 6 months, all by himself. He could talk to people up on the surface every once in a while by message. But he had no idea what time it was. He all but went nuts from loneliness and sensory deprivation, because his sleep cycle went totally out of whack. There were times when he would sleep for 40 hours straight then be awake for a couple of days in a row, without knowing it. When he finally came out, he thought that he had been called out a month too soon because his count of the days was so far off.

Two very good but very separate questions! Time speeds up when we’re having fun for reasons that are going to sound circular and even tautological: i.e. when you’re having fun you aren’t looking at the clock or paying attention to the time. By contrast, when you’re bored and have nothing else to do, you’re thinking about the time.

Why does time seem to speed up as we get old? It’s one of the great paradoxes. The funny thing is, in surveys, whether they’re 20, 40, 60 or 80, 85 percent of people in every range say time is speeding up. All indications seem to be that it’s not so much that the time goes by faster, though. My sense of it is that, as you get older, you become more aware of how little time you have, so the time you have feels more precious.



The neatest experience I had was spending two weeks at a biological research station on the north slope of Alaska, just above the Arctic Circle. We were in constant daylight and I’d never experienced anything like that before. It was amazing and unnerving. Like everyone, I am accustomed to thinking of sleep as this demarcation between one day and the next. But when the sun is always up, I might sleep for 8 hours and it would seem like a nap. Two weeks was really one long day. It was deeply disorienting but that’s what I went there to experience.
I had hoped I would meet people who were studying circadian rhythms but none of them were. They were all studying different aspects of ecology and climate change on a much longer time scale than I had gone there to find. It did make me face the profound reality of the kind of long term change that we are now causing on the planet.

The thing that fascinated me most is the idea of time as a social glue, a language, which is
fundamental to all of our social interactions. We can’t interact and have social lives without it. What we do as a social species is share time. That’s almost the definition of being a social species. Once I understood that, it suddenly felt more important to wear a watch.

Even if I’m lying in bed at night with no clock or watch, I have clocks in every cell. All of those clocks together make a master clock. It’s not like I can get away from time. I might delude myself briefly into thinking so, but I can’t. We are filled with clocks.
By Simon Worrall

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