Mapping dark matter from galactic ripples

Jan 09, 2012

(PhysOrg.com) -- Sukanya Chakrabarti, Ph.D., an assistant professor of physics for the Charles E. Schmidt College of Science at Florida Atlantic University, has developed a way to discover and map dark matter in galaxies. Chakrabarti’s paper, “A New Probe of the Distribution of Dark Matter in Galaxies,” analyzes observed ripples in the outskirts of galaxies to infer the density profile of the dark matter halo. Chakrabarti is presenting her results at this week’s meeting of the American Astronomical Society in Austin, Texas.

“Most of the mass in the universe is dark,” said Chakrabarti, who specializes in the study of galaxies. “We have known for a long time that galaxies have massive dark halos. But there are very few probes that can be used to figure out how the dark matter is distributed in specific spiral galaxies.”

The extended gas disks of galaxies are very fragile and respond easily to gravitational interactions with passing satellites. Chakrabarti discovered that if the density profile of dark matter is varied in the spiral galaxy, it is reflected in the disturbances that form in the outer gas disk when the larger spiral galaxy interacts with a satellite galaxy. The ripples in outer gas disks of spiral galaxies act like a mirror of the potential depth of the dark matter halo in the primary galaxy. Even though the dark matter halo cannot be seen directly, scientists may infer the density profile of dark matter using this method.

Chakrabarti previously developed a mathematical method called “tidal analysis” to find satellite, or dwarf, galaxies by analyzing the ripples in the hydrogen gas distribution in large spiral galaxies in outer space. This method, called “tidal analysis,” allows us to infer the mass and relative position of satellites from analysis of ripples in outer gas disks without requiring knowledge of their optical light. Many dwarf are very dim, so it is useful to have a way of finding them that does not rely on their optical light. Earlier, she applied the method to the nearby Whirlpool Galaxy, which has an optically visible satellite to infer the mass and location of its companion and found these values to be observationally corroborated.

Building on her earlier results where she found that the mass and relative position of the Whirlpool Galaxy’s satellite could be derived using “tidal analysis,” she shows here that we can map the dark matter in Whirlpool Galaxy itself.

“The idea is that the in outer gas disks are like a gravitational mirror that let us to see how the is distributed,” said Chakrabarti.

Explore further: Gravitational waves according to Planck

More information: Meeting paper number 441.13. Preprint: arxiv.org/abs/1112.1416

Provided by Florida Atlantic University

5 /5 (2 votes)
add to favorites email to friend print save as pdf

Related Stories

Forget Planet X! New technique could pinpoint Galaxy X

Jan 13, 2011

(PhysOrg.com) -- Planet X, an often-sought 10th planet, is so far a no-show, but Sukanya Chakrabarti has high hopes for finding what might be called Galaxy X – a dwarf galaxy that she predicts orbits ...

Dark matter mystery deepens

Oct 17, 2011

(PhysOrg.com) -- Like all galaxies, our Milky Way is home to a strange substance called dark matter. Dark matter is invisible, betraying its presence only through its gravitational pull. Without dark matter ...

Dark Matter in a Galaxy

Oct 30, 2009

(PhysOrg.com) -- Stars, the most familiar objects in the night sky, make up only a tiny percentage of the total amount of matter in the universe -- about 2%.

Dark matter does not act as growth factor

Jan 26, 2011

(PhysOrg.com) -- Massive black holes have been found at the centers of almost all galaxies, where the largest galaxies – which are also the ones embedded in the largest halos of Dark Matter – harbor ...

Recommended for you

Image: NGC 6872 in the constellation of Pavo

13 hours ago

This picture, taken by the NASA/ESA Hubble Space Telescope's Wide Field Planetary Camera 2 (WFPC2), shows a galaxy known as NGC 6872 in the constellation of Pavo (The Peacock). Its unusual shape is caused ...

Measuring the proper motion of a galaxy

14 hours ago

The motion of a star relative to us can be determined by measuring two quantities, radial motion and proper motion. Radial motion is the motion of a star along our line of sight. That is, motion directly ...

Gravitational waves according to Planck

Sep 22, 2014

Scientists of the Planck collaboration, and in particular the Trieste team, have conducted a series of in-depth checks on the discovery recently publicized by the Antarctic Observatory, which announced last ...

Infant solar system shows signs of windy weather

Sep 22, 2014

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have observed what may be the first-ever signs of windy weather around a T Tauri star, an infant analog of our own Sun. This may help ...

Finding hints of gravitational waves in the stars

Sep 22, 2014

Scientists have shown how gravitational waves—invisible ripples in the fabric of space and time that propagate through the universe—might be "seen" by looking at the stars. The new model proposes that ...

How gamma ray telescopes work

Sep 22, 2014

Yesterday I talked about the detection of gamma ray bursts, intense blasts of gamma rays that occasionally appear in distant galaxies. Gamma ray bursts were only detected when gamma ray satellites were put ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

vidyunmaya
1 / 5 (1) Jan 17, 2012
sub; Limiting functional Index
Both Dark matter and Dark Energy concepts need revision.
Search Cosmic Pot Univese and cosmology vedas Interlinks
Vidyardhi nanduri