Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Black hole, star collisions may illuminate universe's dark side

20.09.2011
Scientists looking to capture evidence of dark matter -- the invisible substance thought to constitute much of the universe -- may find a helpful tool in the recent work of researchers from Princeton University and New York University.

The team unveiled in a report in the journal Physical Review Letters this month a ready-made method for detecting the collision of stars with an elusive type of black hole that is on the short list of objects believed to make up dark matter. Such a discovery could serve as observable proof of dark matter and provide a much deeper understanding of the universe's inner workings.

Postdoctoral researchers Shravan Hanasoge of Princeton's Department of Geosciences and Michael Kesden of NYU's Center for Cosmology and Particle Physics simulated the visible result of a primordial black hole passing through a star. Theoretical remnants of the Big Bang, primordial black holes possess the properties of dark matter and are one of various cosmic objects thought to be the source of the mysterious substance, but they have yet to be observed.

If primordial black holes are the source of dark matter, the sheer number of stars in the Milky Way galaxy -- roughly 100 billion -- makes an encounter inevitable, the authors report. Unlike larger black holes, a primordial black hole would not "swallow" the star, but cause noticeable vibrations on the star's surface as it passes through.

Thus, as the number of telescopes and satellites probing distant stars in the Milky Way increases, so do the chances to observe a primordial black hole as it slides harmlessly through one of the galaxy's billions of stars, Hanasoge said. The computer model developed by Hanasoge and Kesden can be used with these current solar-observation techniques to offer a more precise method for detecting primordial black holes than existing tools.

"If astronomers were just looking at the sun, the chances of observing a primordial black hole are not likely, but people are now looking at thousands of stars," Hanasoge said.

"There's a larger question of what constitutes dark matter, and if a primordial black hole were found it would fit all the parameters -- they have mass and force so they directly influence other objects in the universe, and they don't interact with light. Identifying one would have profound implications for our understanding of the early universe and dark matter."

Although dark matter has not been observed directly, galaxies are thought to reside in extended dark-matter halos based on documented gravitational effects of these halos on galaxies' visible stars and gas. Like other proposed dark-matter candidates, primordial black holes are difficult to detect because they neither emit nor absorb light, stealthily traversing the universe with only subtle gravitational effects on nearby objects.

Because primordial black holes are heavier than other dark-matter candidates, however, their interaction with stars would be detectable by existing and future stellar observatories, Kesden said. When crossing paths with a star, a primordial black hole's gravity would squeeze the star, and then, once the black hole passed through, cause the star's surface to ripple as it snaps back into place.

"If you imagine poking a water balloon and watching the water ripple inside, that's similar to how a star's surface appears," Kesden said. "By looking at how a star's surface moves, you can figure out what's going on inside. If a black hole goes through, you can see the surface vibrate."

Eyeing the sun's surface for hints of dark matter
Kesden and Hanasoge used the sun as a model to calculate the effect of a primordial black hole on a star's surface. Kesden, whose research includes black holes and dark matter, calculated the masses of a primordial black hole, as well as the likely trajectory of the object through the sun. Hanasoge, who studies seismology in the sun, Earth and stars, worked out the black hole's vibrational effect on the sun's surface.

Video simulations of the researchers' calculations were created by NASA's Tim Sandstrom using the Pleiades supercomputer at the agency's Ames Research Center in California. One clip shows the vibrations of the sun's surface as a primordial black hole -- represented by a white trail -- passes through its interior. A second movie portrays the result of a black hole grazing the Sun's surface.

Marc Kamionkowski, a professor of physics and astronomy at Johns Hopkins University, said that the work serves as a toolkit for detecting primordial black holes, as Hanasoge and Kesden have provided a thorough and accurate method that takes advantage of existing solar observations. A theoretical physicist well known for his work with large-scale structures and the universe's early history, Kamionkowski had no role in the project, but is familiar with it.

"It's been known that as a primordial black hole went by a star, it would have an effect, but this is the first time we have calculations that are numerically precise," Kamionkowski said.

"This is a clever idea that takes advantage of observations and measurements already made by solar physics. It's like someone calling you to say there might be a million dollars under your front doormat. If it turns out to not be true, it cost you nothing to look. In this case, there might be dark matter in the data sets astronomers already have, so why not look?"

One significant aspect of Kesden and Hanasoge's technique, Kamionkowski said, is that it narrows a significant gap in the mass that can be detected by existing methods of trolling for primordial black holes .

The search for primordial black holes has thus far been limited to masses too small to include a black hole, or so large that "those black holes would have disrupted galaxies in heinous ways we would have noticed," Kamionkowski said. "Primordial black holes have been somewhat neglected and I think that's because there has not been a single, well-motivated idea of how to find them within the range in which they could likely exist."

The current mass range in which primordial black holes could be observed was set based on previous direct observations of Hawking radiation -- the emissions from black holes as they evaporate into gamma rays -- as well as of the bending of light around large stellar objects, Kesden said. The difference in mass between those phenomena, however, is enormous, even in astronomical terms. Hawking radiation can only be observed if the evaporating black hole's mass is less than 100 quadrillion grams. On the other end, an object must be larger than 100 septillion (24 zeroes) grams for light to visibly bend around it. The search for primordial black holes covered a swath of mass that spans a factor of 1 billion, Kesden explained -- similar to searching for an unknown object with a weight somewhere between that of a penny and a mining dump truck.

He and Hanasoge suggest a technique to give that range a much-needed trim and established more specific parameters for spotting a primordial black hole. The pair found through their simulations that a primordial black hole larger than 1 sextillion (21 zeroes) grams -- roughly the mass of an asteroid -- would produce a noticeable effect on a star's surface.

"Now that we know primordial black holes can produce detectable vibrations in stars, we could try to look at a larger sample of stars than just our own sun," Kesden said.

"The Milky Way has 100 billion stars, so about 10,000 detectable events should be happening every year in our galaxy if we just knew where to look."

This research was funded by grants from NASA and by the James Arthur Postdoctoral Fellowship at New York University.

Morgan Kelly | EurekAlert!
Further information:
http://www.princeton.edu

More articles from Physics and Astronomy:

nachricht Hope to discover sure signs of life on Mars? New research says look for the element vanadium
22.09.2017 | University of Kansas

nachricht Calculating quietness
22.09.2017 | Forschungszentrum MATHEON ECMath

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

Hope to discover sure signs of life on Mars? New research says look for the element vanadium

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>