How do Astronomers Precisely Determine Distances to Objects on the Other Side of the Milky Way Galaxy?

By studying light echoes, rings of x-rays observed around binary star system Circinus X-1

A light echo in X-rays detected by NASA’s Chandra X-ray Observatory has provided a rare opportunity to precisely measure the distance to an object on the other side of the Milky Way galaxy. The rings exceed the field-of-view of Chandra’s detectors, resulting in a partial image of X-ray data. Credits: NASA/CXC/U. Wisconsin/S. Heinz
The image above shows a light echo in x-rays detected by NASA’s Chandra X-ray Observatory which astronomers used to precisely measure the distance to a stellar object across the spiral disk of the Milky Way galaxy. The sizes of the light echoes detected in this image exceed the ability of the detectors, which has resulted in a partial construction of X-ray data. Credits: NASA/CXC/U. Wisconsin/S. Heinz

Space news (astrophysics: measuring distances of objects; light echoes) – 30,700 light-years from Earth in the plane of the Milky Way Galaxy, observing X-rays emitted by a neutron star in double star system Circinus X-1 reflecting off massive, surrounding clouds of gas and dust –

The youngest member of an important class of objects has been found using data from NASA's Chandra X-ray Observatory and the Australia Compact Telescope Array. A composite image shows the X-rays in blue and radio emission in purple, which have been overlaid on an optical field of view from the Digitized Sky Survey. This discovery, described in the press release, allows scientists to study a critical phase after a supernova and the birth of a neutron star.
The youngest member of an important class of objects has been found using data from NASA’s Chandra X-ray Observatory and the Australia Compact Telescope Array. A composite image shows the X-rays in blue and radio emission in purple, which have been overlaid on an optical field of view from the Digitized Sky Survey. This discovery allows scientists to study a critical phase after a supernova and the birth of a neutron star. Credits: NASA/Chandra

Determining the apparent distance of objects tens of thousands of light-years from Earth across the breadth of the Milky Way was a difficult problem to solve during the early days of the human journey to the beginning of space and time. During the years since these early days, astronomers have developed a few techniques and methods to help calculate distances to stellar objects on the other side of the galaxy. 

The most recently measured distance to an object on the other side of the Milky Way used the newest method developed. By detecting the rings from X-ray light echoes around the star Circinus X-1, a double star system containing a neutron star. Astronomers were able to determine the apparent distance to this system is around 30,700 light-years from Earth.

“It’s really hard to get accurate distance measurements in astronomy and we only have a handful of methods,” said Sebastian Heinz of the University of Wisconsin in Madison, who led the study. “But just as bats use sonar to triangulate their location, we can use the X-rays from Circinus X-1 to figure out exactly where it is.”

 Sebastian Heinz of the University of Wisconsin in Madison
Sebastian Heinz of the University of Wisconsin in Madison Credits: University of Wisconsin in Madison.

The rings are faint echoes from an outburst of x-rays emitted by Circinus X-1 near the end of 2013. The x-rays reflected off of separate clouds of gas and dust surrounding the star system, with some being sent toward Earth. The reflected x-rays arrived from different angles over a three month period, which created the observed X-ray rings. Using radio data scientists were able to determine the distance to each cloud of gas and dust, while detected X-ray echoes and simple geometry allowed for an accurate measurement of the distance to Circinus X-1 from Earth.

“We like to call this system the ‘Lord of the Rings,’ but this one has nothing to do with Sauron,” said co-author Michael Burton of the University of New South Wales in Sydney, Australia. “The beautiful match between the Chandra X-ray rings and the Mopra radio images of the different clouds is really a first in astronomy.”

Michael Burton of the University of New South Wales Credits: University of New South Wales
Michael Burton of the University of New South Wales Credits: University of New South Wales

In addition to this new distance measurement to Circinus X-1, astrophysicists determined this binary system’s naturally brighter in X-rays and other light than previously thought. This points to a star system that has repeatedly passed the threshold of brightness where the outward pressure of emitted radiation is balanced by the inward force of gravity. Astronomers have witnessed this equilibrium more often in binary systems containing a black hole, not a neutron star as in this case. The jet of high-energy particles emitted by this binary system’s also moving at 99.9 percent of the speed of light, which is a feature normally associated with a

The jet of high-energy particles emitted by this binary system’s also moving at 99.9 percent of the speed of light, which is a feature normally associated with a relativistic jet produced by a system containing a black hole. Scientists are currently studying this to see if they can determine why this system has such an unusual blend of characteristics.  

“Circinus X-1 acts in some ways like a neutron star and in some like a black hole,” said co-author Catherine Braiding, also of the University of New South Wales. “It’s extremely unusual to find an object that has such a blend of these properties.”

Astronomers think Circinus X-1 started emitting X-rays observers on Earth could have detected starting about 2,500 years ago. If this is true, this X-ray binary system’s the youngest detected, so far, during the human journey to the beginning of space and time.

This new X-ray data is being used to create a detailed three-dimensional map of the dust clouds between Circinus X-1 and Earth. 

What’s next?

Astrophysicists are preparing to measure distances to other stellar objects on the other side of the Milky Way using the latest distance measurement method. This new astronomy tool’s going to come in handy during the next leg of the human journey to the beginning of space and time.

Become a NASA Disk Detective and help classify embryonic planetary systems.

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You can view the published results of this study in The Astrophysical Journal and online here.

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Learn more about Circinus X-1.

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The Plasma Jets of Active Supermassive Black Holes

Transform surrounding regions and actively evolve host galaxies 

This artist's rendition illustrates a rare galaxy that is extremely dusty, and produces radio jets. Scientists suspect that these galaxies are created when two smaller galaxies merge. A few billion years after the Big Bang, astronomers suspect that small galaxies across the Universe regularly collided forcing the gas, dust, stars, and black holes within them to unite. The clashing of galactic gases was so powerful it ignited star formation, while fusing central black holes developed an insatiable appetite for gas and dust. With stellar nurseries and black holes hungry for galactic gas, a struggle ensued. Scientists say this struggle for resources is relatively short-lived, lasting only 10 to 100 million years. Eventually, much of the gas will be pushed out of the galaxy by the powerful winds of newborn stars, stars going supernovae (dying in a cataclysmic explosion), or radio jets shooting out of central supermassive black holes. The removal of gas will stunt the growth of black holes by "starving'' them, and quench star formation. They believe that these early merging structures eventually grew into some of the most massive galaxies in the Universe.
This artist’s rendition illustrates a rare galaxy that is extremely dusty and produces radio jets. Scientists suspect that these galaxies are created when two smaller galaxies merge.
A few billion years after the Big Bang, astronomers suspect that small galaxies across the Universe regularly collided forcing the gas, dust, stars, and black holes within them to unite. The clashing of galactic gasses was so powerful it ignited star formation while fusing central black holes developed an insatiable appetite for gas and dust. With stellar nurseries and black holes hungry for galactic gas, a struggle ensued.
Scientists say this struggle for resources is relatively short-lived, lasting only 10 to 100 million years. Eventually, much of the gas will be pushed out of the galaxy by the powerful winds of newborn stars, stars going supernovae (dying in a cataclysmic explosion), or radio jets shooting out of central supermassive black holes. The removal of gas will stunt the growth of black holes by “starving” them and quench star formation.
They believe that these early emerging structures eventually grew into some of the most massive galaxies in the Universe. Credits: NASA/JPL

Space news (astrophysics: spinning black holes; bigger, brighter plasma jets) – in the core of galaxies across the cosmos, observing the spin of supermassive black holes – 

In this radio image, two jets shoot out of the center of active galaxy Cygnus A. GLAST may solve the mystery of how these jets are produced and what they are made of. Credit: NRAO
In this radio image, two jets shoot out of the center of active galaxy Cygnus A. GLAST may solve the mystery of how these jets are produced and what they are made of. Credit: NRAO

Have you ever had the feeling the world isn’t the way you see it? That reality’s different than the view your senses offer you? The universe beyond the Earth is vast beyond comprehension and weird in ways human imagination struggles to fathom. Beyond the reach of your senses, the fabric of spacetime warps near massive objects, and even light bends to the will of gravity. In the twilight zone where your senses fear to tread, the cosmos twists and turns in weird directions and appears to leave the universe and reality far behind. Enigmas wrapped in cosmic riddles abound and mysteries to astound and bewilder the human soul are found. 

The galaxy NGC 4151 is located about 45 million light-years away toward the constellation Canes Venatici. Activity powered by its central black hole makes NGC 4151 one of the brightest active galaxies in X-rays. Credit: David W. Hogg, Michael R. Blanton, and the Sloan Digital Sky Survey Collaboration. Credits: NASA/JPL
The galaxy NGC 4151 is located about 45 million light-years away toward the constellation Canes Venatici. Activity powered by its central black hole makes NGC 4151 one of the brightest active galaxies in X-rays. Credit: David W. Hogg, Michael R. Blanton, and the Sloan Digital Sky Survey Collaboration. Credits: NASA/JPL

Imagine an object containing the mass of millions even billions of stars like the Sun. Squeeze that matter into a region of infinitely small volume, a region so dense the gravitational force it exerts warps spacetime and prevents even light from escaping its grasp. This object’s what astronomers call a supermassive black hole, a titanic monster your eyes can’t see with a gravitational pull that would stretch your body to infinity as you approached and crossed its outer boundary, the event horizon. Beyond this point, spacetime and reality take a turn toward the extreme, and the rules of science don’t apply. You have entered the realm of one of the most mysterious and enigmatic objects discovered during the human journey to the beginning of space and time.  

In the newly discovered type of AGN, the disk and torus surrounding the black hole are so deeply obscured by gas and dust that no visible light escapes, making them very difficult to detect. This illustration shows the scene from a more distant perspective than does the other image. Click on image for high-res version. Image credit: Aurore Simonnet, Sonoma State University.
In the newly discovered type of AGN, the disk and torus surrounding the black hole are so deeply obscured by gas and dust that no visible light escapes, making them very difficult to detect. This illustration shows the scene from a more distant perspective than does the other image. Click on image for high-res version. Image credit: Aurore Simonnet, Sonoma State University.

Astronomers hunting for supermassive black holes have pinpointed their realms to be the center of massive galaxies and even the center of galaxy clusters. From this central location in each galaxy, the gravitational well of each supermassive black hole appears to act as an anchor point for the billions of stars within, and astronomers believe a force for change and evolution of every galaxy and galaxy cluster in which they exist. Surrounded and fed by massive clouds of gas and matter called accretion disks, with powerful particle jets streaming from opposite sides like the death ray in Star Wars, fierce, hot winds sometimes moving at millions of miles per hour blow from these supermassive monsters in all directions. 

These galaxy clusters show that younger, more distant galaxy clusters contained far more active galactic nuclei (AGN) than older, nearby ones. It was found that the clusters at 58% of the Universe's current age contained about 20 times more AGN than those at 82% of Universe's age. The galaxies in the earlier Universe contained much more gas that allowed for more star formation and black hole growth. In the Chandra X-ray images, red, green, and blue represent low, medium, and high-energy X-rays.
These galaxy clusters show that younger, more distant galaxy clusters contained far more active galactic nuclei (AGN) than older, nearby ones. It was found that the clusters at 58% of the Universe’s current age contained about 20 times more AGN than those at 82% of Universe’s age. The galaxies in the earlier Universe contained much more gas that allowed for more star formation and black hole growth. In the Chandra X-ray images, red, green, and blue represent low, medium, and high-energy X-rays. Credits: NASA/Chandra

“A lot of what happens in an entire galaxy depends on what’s going on in the minuscule central region where the black hole lies,” said theoretical astrophysicist David Garofalo of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. Garofalo is the lead author of a new paper that appeared online May 27 in the Monthly Notices of the Royal Astronomical Society. Other authors are Daniel A. Evans of the Massachusetts Institute of Technology, Cambridge, Mass., and Rita M. Sambruna of NASA Goddard Space Flight Center, Greenbelt, Md. 

These galaxy clusters show that younger, more distant galaxy clusters contained far more active galactic nuclei (AGN) than older, nearby ones. It was found that the clusters at 58% of the Universe's current age contained about 20 times more AGN than those at 82% of Universe's age. The galaxies in the earlier Universe contained much more gas that allowed for more star formation and black hole growth. In the Chandra X-ray images, red, green, and blue represent low, medium, and high-energy X-rays.
These galaxy clusters show that younger, more distant galaxy clusters contained far more active galactic nuclei (AGN) than older, nearby ones. It was found that the clusters at 58% of the Universe’s current age contained about 20 times more AGN than those at 82% of Universe’s age. The galaxies in the earlier Universe contained much more gas that allowed for more star formation and black hole growth. In the Chandra X-ray images, red, green, and blue represent low, medium, and high-energy X-rays. Credits: NASA/Chandra

Astronomers studying powerful particle jets streaming from supermassive black holes use to think these monsters spin either in the same direction as their accretion disks, called prograde black holes, or against the flow, retrograde black holes. For the past few decades, Garofalo and team have worked with a theory that the faster the spin of a black hole, the more powerful the particle jets streaming from it. Unfortunately, anomalies in the form of some prograde black holes with no jets have been discovered. This has scientists turning their ideas upside down and sideways, to see if flipping their “spin paradigm” model on its head explains recent anomalies in the theory. 

This composite image shows a vast cloud of hot gas (X-ray/red), surrounding high-energy bubbles (radio/blue) on either side of the bright white area around the supermassive black hole. By studying the inner regions of the galaxy with Chandra, scientists estimated the rate at which gas is falling toward the galaxy's supermassive black hole. These data also allowed an estimate of the power required to produce the bubbles, which are each about 10,000 light years in diameter. Surprisingly, the analysis indicates that most of the energy released by the infalling gas goes into producing jets of high-energy particles that create the huge bubbles, rather than into an outpouring of light as observed in many active galactic nuclei.
This composite image shows a vast cloud of hot gas (X-ray/red), surrounding high-energy bubbles (radio/blue) on either side of the bright white area around the supermassive black hole. By studying the inner regions of the galaxy with Chandra, scientists estimated the rate at which gas is falling toward the galaxy’s supermassive black hole. These data also allowed an estimate of the power required to produce the bubbles, which are each about 10,000 light years in diameter. Surprisingly, the analysis indicates that most of the energy released by the infalling gas goes into producing jets of high-energy particles that create the huge bubbles, rather than into an outpouring of light as observed in many active galactic nuclei. X-ray: NASA/CXC/KIPAC/S.Allen et al; Radio: NRAO/VLA/G.Taylor; Infrared: NASA/ESA/McMaster Univ./W.Harris

Using data collected during a more recent study that links their previous theory with observations of galaxies at varying distances from Earth across the observable universe. Astronomers found more distant radio-loud galaxies with jets are powered by retrograde black holes, while closer radio-quiet black holes have prograde black holes. The study showed supermassive black holes found at the core of galaxies evolve over time from a retrograde to prograde state.  

This illustration shows the different features of an active galactic nucleus (AGN), and how our viewing angle determines what type of AGN we observe. The extreme luminosity of an AGN is powered by a supermassive black hole at the center. Some AGN have jets, while others do not. Click on image for unlabeled, high-res version. Image credit: Aurore Simonnet, Sonoma State University.
This illustration shows the different features of an active galactic nucleus (AGN), and how our viewing angle determines what type of AGN we observe. The extreme luminosity of an AGN is powered by a supermassive black hole at the center. Some AGN have jets, while others do not. Click on image for unlabeled, high-res version. Image credit: Aurore Simonnet, Sonoma State University.

“This new model also solves a paradox in the old spin paradigm,” said David Meier, a theoretical astrophysicist at JPL not involved in the study. “Everything now fits nicely into place.” 

A mere 11 million light-years away, Centaurus A is a giant elliptical galaxy - the closest active galaxy to Earth. This remarkable composite view of the galaxy combines image data from the x-ray ( Chandra), optical(ESO), and radio(VLA) regimes. Centaurus A's central region is a jumble of gas, dust, and stars in optical light, but both radio and x-ray telescopes trace a remarkable jet of high-energy particles streaming from the galaxy's core. The cosmic particle accelerator's power source is a black hole with about 10 million times the mass of the Sun coincident with the x-ray bright spot at the galaxy's center. Blasting out from the active galactic nucleus toward the upper left, the energetic jet extends about 13,000 light-years. A shorter jet extends from the nucleus in the opposite direction. Other x-ray bright spots in the field are binary star systems with neutron stars or stellar mass black holes. Active galaxy Centaurus A is likely the result of a merger with a spiral galaxy some 100 million years ago.
A mere 11 million light-years away, Centaurus A is a giant elliptical galaxy – the closest active galaxy to Earth. This remarkable composite view of the galaxy combines image data from the x-ray ( Chandra), optical(ESO), and radio(VLA) regimes. Centaurus A’s central region is a jumble of gas, dust, and stars in optical light, but both radio and x-ray telescopes trace a remarkable jet of high-energy particles streaming from the galaxy’s core. The cosmic particle accelerator’s power source is a black hole with about 10 million times the mass of the Sun coincident with the x-ray bright spot at the galaxy’s center. Blasting out from the active galactic nucleus toward the upper left, the energetic jet extends about 13,000 light-years. A shorter jet extends from the nucleus in the opposite direction. Other x-ray bright spots in the field are binary star systems with neutron stars or stellar mass black holes. Active galaxy Centaurus A is likely the result of a merger with a spiral galaxy some 100 million years ago. Credits: X-ray – NASA, CXC, R.Kraft (CfA), et al.; Radio – NSF, VLA, M.Hardcastle (U Hertfordshire) et al.; Optical – ESO, M.Rejkuba (ESO-Garching) et al.

Astrophysicists studying backward spinning black holes believe more powerful particle jets stream from these supermassive black holes because additional space exists between the monster and the inner edge of the accretion disk. This additional space between the monster and accretion disk provides more room for magnetic fields to build-up, which fuels the particle jet and increases its power. This idea is known as Reynold’s Conjecture, after the theoretical astrophysicist Chris Reynolds of the University of Maryland, College Park. 

The optical counterparts of many active galactic nuclei (circled) detected by the Swift BAT Hard X-ray Survey clearly show galaxies in the process of merging. These images, taken with the 2.1-meter telescope at Kitt Peak National Observatory in Arizona, show galaxy shapes that are either physically intertwined or distorted by the gravity of nearby neighbors. These AGN were known prior to the Swift survey, but Swift has found dozens of new ones in more distant galaxies. Credit: NASA/Swift/NOAO/Michael Koss and Richard Mushotzky (Univ. of Maryland)
The optical counterparts of many active galactic nuclei (circled) detected by the Swift BAT Hard X-ray Survey clearly show galaxies in the process of merging. These images, taken with the 2.1-meter telescope at Kitt Peak National Observatory in Arizona, show galaxy shapes that are either physically intertwined or distorted by the gravity of nearby neighbors. These AGN were known prior to the Swift survey, but Swift has found dozens of new ones in more distant galaxies. Credit: NASA/Swift/NOAO/Michael Koss and Richard Mushotzky (Univ. of Maryland)

“If you picture yourself trying to get closer to a fan, you can imagine that moving in the same rotational direction as the fan would make things easier,” said Garofalo. “The same principle applies to these black holes. The material orbiting around them in a disk will get closer to the ones that are spinning in the same direction versus the ones spinning the opposite way.”  

Swift's Hard X-ray Survey offers the first unbiased census of active galactic nuclei in decades. Dense clouds of dust and gas, illustrated here, can obscure less energetic radiation from an active galaxy's central black hole. High-energy X-rays, however, easily pass through. Credit: ESA/NASA/AVO/Paolo Padovani
Swift’s Hard X-ray Survey offers the first unbiased census of active galactic nuclei in decades. Dense clouds of dust and gas, illustrated here, can obscure less energetic radiation from an active galaxy’s central black hole. High-energy X-rays, however, easily pass through. Credit: ESA/NASA/AVO/Paolo Padovani

Scientists believe the powerful particle jets and winds emanating from supermassive black holes found at the center of galaxies also play a key role in shaping their evolution and eventual fate. Often even slowing the formation rate of new stars in a host galaxy and nearby island universes as well.  

“Jets transport huge amounts of energy to the outskirts of galaxies, displace large volumes of the intergalactic gas, and act as feedback agents between the galaxy’s very center and the large-scale environment,” said Sambruna. “Understanding their origin is of paramount interest in modern astrophysics.” 

What lies just beyond the reach of our senses and technology, beneath the exterior of these supermassive black holes? Scientists presently study these enigmatic stellar objects looking for keys to the doors of understanding beyond the veil of gas and dust surrounding these titanic beasts. Keys they hope one day to use to unlock even greater secrets of reality just beyond hidden doors of understanding.  

Watch this video on active galactic nuclei.

Read and learn more about the supermassive black holes astronomers detect in a region called the COSMOS field.

Read about the recent detection by astronomers of read-end collisions between knots in the particle jets of supermassive black holes.

Learn what astronomers have discovered about feedback mechanisms in the feeding processes of active supermassive black holes.

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