Scientific Thoughts: Galaxy Calling...

Wednesday, March 02, 2005

A mysterious object is sending out powerful radio signals from near the center of our galaxy. As reported by NewScientist, the pulses are coming from a spot just to one side of the galactic centre. Each pulse lasts about 10 minutes, and they repeat regularly every 77 minutes. If the source is near the centre of the Milky Way, it would be one of the most powerful emitters in the galaxy. The shape and timing of the pulses rules out most known sources, such as radio pulsars.

Milky Way Galaxy (Courtesy: NASA)According to the researchers (led by Scott Hyman of Sweet Briar College), who detected the object using the Very Large Array (VLA) radio telescope in New Mexico, the object could be a magnetar (a neutron star with a very powerful magnetic field). A pulse from another powerful magnetar collided our atmosphere in December.
The team is currently studying the phenomenon using the Green Bank radio telescope in West Virginia, and also plan to use the orbiting Chandra X-Ray telescope to see if the object is also spewing X-Rays.

I have to stop here... my friends are calling again from the center of the galaxy...

Galaxy Calling...

sendingNewScientist

Milky Way Galaxy (Courtesy: NASA)Sweet Briar CollegeVery Large Arrayneutron starcollidedGreen BankChandra

14 Comments:

At March 03, 2005 1:09 AM, Sray said...: LOL... but seriously, who knows, perhaps it is a beacon, released by some advanced civilization to monitor the growth of milky way's central black-hole.
At March 03, 2005 2:06 AM, Sray said...: They might be using the Arecibo to check on this new object. Arecibo is often used to 'spy' on emissions from the galactic center :-). They use the Arecibo L-band Feed Array (ALFA) which can pick up really faint objects (see my post on dark galaxies, where they use the ALFA to look at large areas of the sky). Also, Arecibo is a radio-telescope, and should be able to supplement what Chandra sees (in the x-ray range). Optical wont work, because of the huge dust clouds near the galactic center, which obscure our view.
At March 03, 2005 2:11 AM, Sray said...: Also, read this article that appeared an hour ago. It says:
he bursts coming from the new source, dubbed GCRT J1745-3009, each lasted about 10 minutes and repeated on a 77-minute cycle for nearly seven hours. In addition, the source is not stationary. "It [GCRT J1745-3009] has not been detected since 2002," Hyman notes, "nor is it present on earlier images."

Whatever it is, it is unique: the astronomers suggest it is either the first of a new type of object or an example of a known source acting in a novel way. Of interest to the scientists is the fact that no x-rays were detected along with the radio waves, because many astronomical sources emit both. In the future, the team plans to continue monitoring the Milky Way for further evidence of GCRT J1745-3009 using both radio and x-ray telescopes.
So there! Gotta be a beacon of some kind, wont you say?!
At March 03, 2005 2:33 AM, Sray said...: "the source is not stationary"

I think that is not really surprising. If the source is very close to the center, it has to orbit it at a very fast rate. The motion of the source relative to us should then be easily visible.

I would like to know the speed of the object, though. I am still looking for more details.. will let you know once I find anything :-).
At March 03, 2005 2:39 AM, Sray said...: Check this out.. not yet sure what all the columns mean... just keeping it here for the record.
At March 03, 2005 9:22 AM, Sray said...: MJD stands for Modified Julian Date. The Modified Julian Day was introduced by space scientists in the late 1950's. It is defined as MJD = JD - 2400000.5.

An MJD of 52000 corresponds to JD = 2452000.5, which corresponds to March 31, 2001. The plot represents light curve (intensity of the light vs. time), so there was a spike in the apparent brightness of the object around March 31, 2001.

The interesting thing in the plot is the oscillations towards the end of the graph (which corresponds to a period of 100 days before Feb 28, 2005). That shows there is something new afoot in that object.
At March 03, 2005 9:44 AM, Tupinambah said...: great news: We are not alone...
Nice picture
At March 03, 2005 1:05 PM, Sray said...: "amazing amount of stories about space discoveries and inventions this year."...

this year? It has only been two months! But I know what you mean :-D. Space is the last frontier, and discoveries are only going to get more frequent!
At March 04, 2005 1:00 PM, Wayne Smallman said...: Isn't this thing thought to be a magnetar?

Which is a neutron star with massive amounts of electromagnetic energy...
At March 04, 2005 1:21 PM, Sray said...: "Isn't this thing thought to be a magnetar?"

Thats what I wrote!:
"the object could be a magnetar (a neutron star with a very powerful magnetic field)"

But magnetars emit strong x-rays, and little or no x-ray was detected here. Also, it seems the light curves do not match any other magnetars. perhaps a future chandra observation will clear the doubts.
At March 05, 2005 9:46 AM, Wayne Smallman said...: I understand that by using magnetic energy, it has been proposed that it may well be possible to visualize the surface of a black hole, or what are technically called quantum singularities.

The pattern of magnetic energy is influenced by the surface properties of the black hole -- which is a star, only one one which is unimaginably dense.

Black holes are known not to emit X-ray themselves, but the swirling storm of matter around them gets so furiously hot and moves so quickly -- typically a 3rd the speed of light -- that X-ray emissions are observed.

It has also been proposed that black holes do in fact emit radiation, which has since been called Hawkins Radiation, after Professor Stephen Hawking, who first proposed the idea.

So over time, a black hole would ultimately 'bleed' away into nothingness. However, this process would take a very long time.

So, maybe what they're looking at is a fading, dyeing black hole?

I'm sure Sray will fill out / pick holes with that idea...
At March 05, 2005 10:56 AM, Sray said...: Wayne: Interesting idea. But the Hawking radiation is very very faint for large black holes. It takes eons for such a black hole to evaporate. According to quantum uncertainity principle, pairs of matter/anti-matter particles are always created and destroyed. If and when such a pair is created near the black hole surface (event horizon), the black hole might capture one of them, and then the other can escape, thus carrying a small amount of momentum (i.e. energy from E=mc^2, and thus the black hole slowly bleeds to nothingness.

The Hawking temperature of a 30 solar mass black hole is a tiny 2×10^(-9) Kelvin, and its Hawking luminosity a miserable 10^(-31) Watts. The black hole has to be really small to generate the amount of power seen with the object in this post... and then it would radiate so fast that it would vanish in a couple of years, and also follow a certain decay pattern. This object has been going steady for the last few years, and with no apparent pattern.
At March 05, 2005 11:07 AM, Wayne Smallman said...: Here's where I just pluck an idea out of thin air, throw it at the wall of reason and hope that it sticks:

What if this was still a black hole, quite a small one -- as you've said -- but it's being fed dark matter?

Might we not see any radiation at all from the vortex of dark matter surrounding the black hole and then think the little devil was sat there all on its lonesome?
At March 05, 2005 11:28 AM, Sray said...: Suppose it is dark matter. The nature of dark matter is not yet well understood, but it is generally accepted to be of three kinds:
1. Inert matter, which are cold, and do not emit radiation and hence are invisible. Most extremely diffuse gas clouds (and brown dwarfs) fall in this category
2. Non-baryonic matter, like leptons etc.
3. Some new form of matter.

The first two kinds should get accelerated when drawn into the black hole, and should produce x-rays. It could be that some nearby star/mass is feeding this object, and so it is flaring up from time to time.

But if that is the case, it cannot be a evaporating black hole. If the radiation that is observed is mostly due to evaporation, it should blast out any matter stream that is coming from a disintegrating star nearby.

Now, it could be some new form of matter. That can only be said for certain once the chandra and other x-ray observatories produce their results on this object. Perhaps this form of matter does not produce x-rays while falling into the horizon.. only time will tell :-).

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Wednesday, March 02, 2005

Galaxy Calling...

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