Singularity - Black Holes, Gamma Rays, Magnetars, etc

Palomar · 2005-08-04 06:21:17

http://www.spaceref.com/news/viewpr.html?pid=17540]The Glowing X-ray Sky

*Interesting article. Involves Chandra study.

Astronomers have found that the sky glows in very energetic X-rays. They think the X-rays are the last gasp of material being swallowed by massive black holes. These objects hide behind thick walls of gas and dust, walls so thick that only radio waves and very high-energy X-rays can escape. Even moderately energetic X-rays are blocked.
Many galaxies are bright in the infrared because young stars are very efficient at warming interstellar dust, but they are faint in the radio. Some active galactic nuclei, however, are bright in the radio but relatively faint in the infrared. The group surveyed hundreds of radio sources, from which they winnowed 27 that are so bright in the radio and faint in the infrared that they could only be active galactic nuclei. The new method circumvented the dilemma of looking for the hidden sources just at the wavelengths where they are hidden.
All of these 27 objects lie in the region of the deepest X-ray survey ever obtained, a region that the Chandra X-ray Observatory stared at for more than three weeks. Fewer than half of the 27 sources were known sources of X-rays. The group looked for weak hints of X-rays from the rest, but at least five show nothing at all.
It's possible that these five sources differ from other massive black holes and just do not make X-rays, Donley said. However, it's more likely that they are "ordinary" black holes but lie hidden behind walls of gas that are so thick that Chandra cannot see through. "We expect the hidden black holes to behave exactly this way," Donley said.

--Cindy

Palomar · 2005-08-05 08:28:36

http://antwrp.gsfc.nasa.gov/apod/ap010913.html]X-Rays & Circinus Pulsar

*Fabulous image (false color). They refer to it as a bizarre stellar corpse. It's a swiftly spinning neutron star "in" the southern constellation Circinus; 19,000 l/y distant. They're speculating the pulsar might generate in excess of 7,000,000,000,000,000 (quadrillion) volts. Yipes.

Stretching toward the bottom left, x-ray emission traces a jet of particles almost 20 light-years long that seems to arise from the pulsar's south pole, while the arc of bright emission above the central knot is likely a shockwave produced by particles driven from the pulsar's equator.

The "green" gas has been shock-heated to "millions of degrees Celsius."

--Cindy

Palomar · 2005-08-10 07:11:49

http://antwrp.gsfc.nasa.gov/apod/ap970516.html]A black hole's "signature"

*This image was obtained with HST's Imaging Spectrograph (STIS). Is a supermassive BH in M84, which is a galaxy in the Virgo Cluster and aprox 50 million l/y distant. Scientists have estimated that SMBH to contain at least 300 million (geez...) solar masses. It's a whopper.

STIS uses the Doppler effect to measure gas velocity. In this case, it's "rapidly increasing to nearly 240 miles per second within 26 light years" of central M84.

The STIS data show that radiation from approaching gas, shifted to blue wavelengths left of the centerline, is suddenly redshifted to the right of center indicating a rapidly rotating disk of material near the galactic nucleus. The resulting sharp S-shape is effectively the signature of a black hole...

--Cindy

Palomar · 2005-08-11 09:46:42

http://www.spacedaily.com/news/blackhole-05u.html]BH blows bubbles between stars

*The bubble is estimated to be aprox 10 l/y across and expanding at a rate of 225,000 mph. This is in our Milky Way Galaxy.

discovered a vast "jet-powered bubble" formed in the gas around a black hole in the Milky Way....
The discovery means that for decades scientists have been severely underestimating how much power black holes pump back into the universe instead of merely swallowing material across their event horizons.

The jet which has created this bubble is estimated to contain 100,000 times the luminosity of our Sun:

and yet the only evidence for this incredible flow of energy is its impact on the tenuous gas between the stars, resulting in the expanding bubble.

Remarkably, it also means that, after a massive star dies and turns into a black hole, it is still capable of energising its surroundings, by means of completely different mechanisms."

Endlessly fascinating universe. I wonder if black holes are ultimately THE lifegivers/sustainers of the Universe. I have a hunch they are.

--Cindy

srmeaney · 2005-08-15 05:23:32

A black hole is not a white hole in negative time. It is a black hole in all vectors of time. If I was traveling in an existance backwards compared to our own time, I would still encounter the black hole.

Does this mean there is no such thing as a "white hole"?

Palomar · 2005-08-19 06:10:03

Newborn black holes

*This study from Swift. Newborn BH's are (not surprisingly) very chaotic; they consume and expel/propel material simultaneously.

Mentions hypernovae and the death throes of stars. A new model is emerging: Instead of 1 stellar blast there are multiple explosions: The initial blast followed by powerful "hiccups." Apparently the energies involved are also much greater than previously thought.

Mentions the difference between hypernovae and supernovae. Also, newborn BH's "immediately get to work."

--Cindy

Palomar · 2005-08-25 10:37:04

You've heard of accretion discs...

*Say hello to advective discs. Includes 10 illustrations. Points out that most BH's are thought to be part of a binary system.

--Cindy

Palomar · 2005-09-01 13:26:10

Escaping pulsar breaks speed records

*It's designated B1508+55, aprox 7700 l/y distant. It's zipping along at a rate of 670 miles per second. Originating "in" the constellation of Cygnus, speculation is it got kicked into its current trajectory (which will ultimately take it completely out of our Milky Way Galaxy) by a nearby supernova.

"We know that supernova explosions can give a kick to the resulting neutron star, but the tremendous speed of this object pushes the limits of our current understanding..."

With the ultrasharp radio "vision" of the continent-wide VLBA, they were able to precisely measure both the distance and the speed of the pulsar, a spinning neutron star emitting powerful beams of radio waves.

--Cindy

Palomar · 2005-09-12 11:37:38

*Here's one for the record books:

Most Powerful Explosion Ever Seen

Involves a gamma-ray burst, which is why I'm posting in this thread. It blew from 12.7 billion l/y away (cannot comprehend that distance). Article says the blast contained 300 times more energy than our Sun will ever produce in its entire 10+ billion year lifetime. :shock:

Kudos to the Italian astronomers who made this discovery.

It is thus seen when the Universe was less than 900 million years old, or less than 7 percent its present age.

--Cindy

Palomar · 2005-09-14 11:17:39

Black hole lurks in invisible galaxy

*A bit lengthy article and I'm currently short on time.

In a strange reversal, astronomers have detected a massive black hole but can find no traces of the surrounding galaxy that should be feeding it.

Hypotheses listed towards the end of the article. Enjoy.

--Cindy

::EDIT:: Want to toss this in here:

when they looked at HE0450-2958, a quasar located some 5 billion light-years away, they didn’t find any sign of a galaxy.
“We must therefore conclude that, contrary to our expectations, this bright quasar is not surrounded by a massive galaxy...”
Quasars are relatively small compared to the galaxies they outshine. They are only about the size of our solar system, but they can emit up to 100 times as much radiation as an entire galaxy.

Rather rad.

Palomar · 2005-09-20 11:26:10

Mystery stars around Andromeda Galaxy's black hole

*That galaxy's central black hole is 140 solar masses. They've discovered 400+ blue stars -- fairly new, only aprox 200 million years old, formed in a burst of activity -- orbiting the BH. This is unexpected. The stars' orbiting speed is akin to traveling from Earth to the Moon in 6 minutes.

This group of 400+ stars are packed into a stellar disc measuring no more than 1 light year across (the distance from Sol to Alpha Centauri is 4.3 light years) -- very tightly compressed. That's just one of the mysteries; the other of course is how the stars came about forming so near to that BH in the first place.

They're wondering about a similar setup in our own Milky Way Galaxy.

--Cindy

::EDIT:: Different article, same story... with a fabulous illustration which can be enlarged.

Palomar · 2005-09-27 09:29:56

Huge quake cracks star (magnetar)

*Fab. This magnetar has been posted about before (scroll back to December 2004 entries, please). Is SGR 1806-20; 50,000 l/y distant towards the constellation Sagittarius. A tremendous explosion from it was detected in 12/04: That explosion temporarily blinded some of our satellites and briefly altered our upper atmosphere.

The explosion was so powerful that in the mere first 200 milliseconds it unleashed energy equivalent to what Sol produces in 250,000 years. :shock:

The cracks detected on this magnetar are several miles long. One is 3 miles long; which is all the more remarkable as the magnetar itself is only 6 miles in diameter. Radiation spewing from the crack enabled its detection.

Also remarkable is the fact that the outer crust of a magnetar is not pliable; it's mostly made of iron.

Quite a universe out there...

--Cindy

Palomar · 2005-09-27 09:47:07

Cosmic ray-forming remnant

*Is an x-ray image from Chandra; image built during 41-hour observation time. Is the leftover of a supernova shockwave. First observed/recorded by Tycho Brahe in 1572 and is 7,500 l/y distant.

Study focuses on production of cosmic rays. Solar flares from stars, pulsars and black hole accretion disks are also thought to produce CR's.

--Cindy

SpaceNut · 2005-09-27 10:32:20

Fantastic image..
Just think we are looking back in time to an event that happened 7,000 plus years ago. Since first spotted in 1572 and it being 2005 it is a meir 433 years since it blew up. In the progress of time this is small.
Does anyone know how wide this?

Palomar · 2005-09-27 11:04:23

Does anyone know how wide this?

*Nearly 20 light years across:

APOD article

Also includes temperature info.

--Cindy

SpaceNut · 2005-09-27 12:56:19

Thanks Cindy

I would have thought it would have been bigger given how fast light moves and how long ago it happened. ???

Some scientist feel that Supernova Explosion May Have Caused Mammoth Extinction

A distant supernova that exploded 41,000 years ago may have led to the extinction of the mammoth, according to research that will be presented tomorrow (Sept. 24) by nuclear scientist Richard Firestone of the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab).

They think it was only 250 light years away.

Palomar · 2005-09-27 15:27:04

Thanks Cindy
I would have thought it would have been bigger given how fast light moves and how long ago it happened. ???

*Hi SpaceNut. Supernova remnants -- the actual expelled gases -- don't expand indefinitely. This is why the Trifid Nebula, Lagoon Nebula, etc., have distinct forms and will retain those shapes for thousands of years before dispersing or fading. The light from the supernova's initial blast will travel indefinitely, but the remnant's gases will stop expanding eventually.

--Cindy

Yang Liwei Rocket · 2005-09-28 10:22:47

Huge quake cracks star (magnetar)
*Fab. This magnetar has been posted about before (scroll back to December 2004 entries, please). Is SGR 1806-20; 50,000 l/y distant towards the constellation Sagittarius. A tremendous explosion from it was detected in 12/04: That explosion temporarily blinded some of our satellites and briefly altered our upper atmosphere.
The explosion was so powerful that in the mere first 200 milliseconds it unleashed energy equivalent to what Sol produces in 250,000 years. :shock:
The cracks detected on this magnetar are several miles long. One is 3 miles long; which is all the more remarkable as the magnetar itself is only 6 miles in diameter. Radiation spewing from the crack enabled its detection.
Also remarkable is the fact that the outer crust of a magnetar is not pliable; it's mostly made of iron.
Quite a universe out there...
--Cindy

more info on this story
Missing link found by Double Star and Cluster
http://sci.esa.int/science-e/www/object … ctid=37944
Double Star and Cluster observe first evidence of crustal cracking

Palomar · 2005-10-03 21:41:29

"Holy Grail" of black hole astronomy

*...is within our grasp.

This is an awesome article. Astronomers predicting within a few years' time we'll be able to see (via submillimeter telescopy and infrared observations) close to our galaxy's central BH's edge. Our CBH is 25,000 l/y distant and 10 million miles wide.

"We could see the shadow that the black hole casts on surrounding material, and determine the size and spin of the black hole itself."

The shadow of a black hole? I'd never considered it. :shock: Weird concept.

--Cindy

P.S.: Article also refers to Einstein's Theory of Relativity.

Palomar · 2005-10-05 14:01:55

*This'll be ranked as one of the most important of 2005 astronomy discoveries.

Mystery of short gamma ray bursts solved?

They seem certain of it, thanks to Swift. 30% of all gamma ray bursts are "short" -- lasting mere milliseconds. The burst initially shines the equivalent of a billion suns, then quickly fades.

The SGRB's are believed to occur when either a black hole consumes a neutron star or when two neutron stars collide.

The article also mentions how a black hole consumes a neutron star, based on recent studies: The star is stretched into a crescent shape. "Crumbs" of the broken star are then consumed over a period of minutes to hours.

Thanks to Swift, a 35-year-old mystery seems to have found an answer.

--Cindy

SpaceNut · 2005-10-12 09:23:06

Pretty much a blackhole consumes everything but its shadow.
[url=http://www.msnbc.msn.com/id/9666793/]Scientists strain to spot black hole’s shadow
Radio telescope array could see silhouette of invisible monster[/url]

At the core of the Milky Way is a supermassive black hole that sucks in light, rendering it virtually invisible. But astronomers say they will be able to see the black hole's overall shadow within a few years.
"The Holy Grail of black hole astronomy is within our grasp," says Avery Broderick of the Harvard-Smithsonian Center for Astrophysics. "We could see the shadow that the black hole casts on surrounding material, and determine the size and spin of the black hole itself."

Palomar · 2005-10-13 15:59:25

Live fast, die young

*Massive stars, perhaps 50 to 100 of them, detected close to our galaxy's SMBH. A similar report came out -- more speculative -- which I posted a month or so ago; this article seems more conclusive.

Anywho: The stars are less than 1 light year from the black hole. They're not drawn in, however, and maintain an orbit around the BH like our solar system does around Sol.

It's speculated their life spans are, for stars, incredibly short: A mere 5 million years. It's likely they lose up to 80% of their mass and then go supernova.

--Cindy

Palomar · 2005-10-18 07:53:02

NGC 1097's super-massive black hole

*This galaxy resides "in" Fornax (a southern constellation, "The Furnace"), 45 million l/y distant. Near-infrared studies of it have been done, focusing especially on its SMBH (feeding, etc.).

"This is possibly the first time that a detailed view of the channelling process of matter, from the main part of the galaxy down to the very end in the nucleus is released"

...This unveils a bright nucleus at the centre, but mostly a complex central network of filamentary structures spiralling down to the centre...
The astronomers also note that the curling of the spiral pattern in the innermost 300 light-years seem indeed to confirm the presence of a super-massive black hole in the centre of NGC 1097. Such a black hole in the centre of a galaxy causes the nuclear spiral to wind up as it approaches the centre, while in its absence the spiral would be unwinding as it moves closer to the centre.

The resolution which was achieved in this study was 0.15 arcseconds or the equivalent of a mere 30 light years. Wow. (They offer a comparison: That's only 8 times greater than the distance of Sol to its nearest stellar companion, Proxima Centauri).

Nice photo of NGC 1097, too.

--Cindy

Palomar · 2005-10-20 05:19:20

The short and long of it

*Neat little article from Astropix with illustration regarding long- and short-duration gamma ray bursts, theories, etc.

--Cindy

Palomar · 2005-10-25 05:40:45

Live fast, die young
*Massive stars, perhaps 50 to 100 of them, detected close to our galaxy's SMBH. A similar report came out -- more speculative -- which I posted a month or so ago; this article seems more conclusive.
Anywho: The stars are less than 1 light year from the black hole. They're not drawn in, however, and maintain an orbit around the BH like our solar system does around Sol.
It's speculated their life spans are, for stars, incredibly short: A mere 5 million years. It's likely they lose up to 80% of their mass and then go supernova.

*One of these stars was recently tracked in near-infrared by the Paranal Observatory, using a very large 'scope and camera. One of the stars, named S2, was observed coming to within approximately 17 light hours of the Milky Way Center (17 light hours is roughly comparable to 3 times the radius of Pluto's orbit). S2 appears to move under the influence of enormous gravity, consistent with the MW's central supermassive black hole.

The image reveals the inner 2 light years of the Milky Way's Center, the exact position of which is indicated by the arrows. <low whistle> Resolution to within 2 light years of the Galactic Center? That's amazing.

Astropix article & image

--Cindy

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