Neutron Star

Like Professor Link said, later on, there is no theoretical limit but there are other limiting factors such as the age of the universe and how much could be accreted over that time. Etc.. The prediction for the UMBH is really interesting.
BTW the ~ 1.51 days to fall from r=2M to r=0 was only 1/2 right. It's ~ 3.03 days proper time. I figured it for M not 2M.

 

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Unfortunately, this result has gone away. It seems that there was an error in understanding the instrument calibration.

Science is hard.

There are many other reasons, both theoretical and observational, to conclude that a neutron star consists of over a solar mass of quantum liquid (superfluid).

 

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Welcome to Sciforums, Prof. Link!

 

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Thanks for the update. The science going on now is amazing in my estimation. The experiments in cosmology especially. You folks are doing a great job. I notice you have 26 papers in the arxiv. If you wanted me to read one which would it be. I read a lot of scientific literature. Mainly physics. Apparently not enough since I wasn't aware of the problem with instrument calibration. Nice of you to make the comments for us while it's rather a rarity when an expert posts in a place like this. I'll probably read several papers. LOL. If you felt like impressing us, you surely will, you could tell in what realm your physics passion lies at the present.

 

Brucep,

Though I realize that questions about the scientific process are not the subject of this thread, they have come up, so I see no reason to not post about it here. The Moderator can take appropriate measures if this is out of line.

I just learned about the CHANDRA calibration issues myself a few months ago at a conference in a private conversation. Just like in any other area, when the press reports on some high-profile science, they don't issue a follow-up report if that science turns out to be wrong. Regarding cosmology, the BICEP2 results giving evidence for the inflationary universe have disappeared as well. The BICEP2 people knew all along that galactic dust was a potential problem, and a better dust map killed their results. The media were talking about Nobel Prizes at first, but I don't think they followed up on what happened. The BICEP2 people are trying to do something that is very hard, and there are so many ways to make mistakes or to have promising results invalidated by new data.

I won't be reading or posting very often on this forum - forums are infinite time sinks - but I might chime in on occasion. I became interested in this forum when Tashja contacted me and I saw how much genuine interest there is. I think that in the modern world it is important that everyone understand science; I wish that politicians did.

It would be nice if discussion on this forum could proceed without the personal attacks; they lead nowhere, and are a waste of energy and forum space.

You asked about my work. I've worked on neutron stars, early universe physics, condensed matter physics, and gamma-ray bursts. Lately I'm fascinated with magnetars, neutron stars with ultra-strong magnetic fields. You can read a bit more about them on my website (see link below).

As for my papers, I have about 40 peer-reviewed papers. That is considered a low publication rate nowadays, so I try to make these papers good. A recent paper of mine that I'm fond of that might be fairly readable is arXiv:1312.5144.

Best,

Bennett

 

Echoing tashja, welcome to the fray. Even chiming in on occasion will almost certainly be appreciated.

One of the things that is nice about this forum is that it is not as ridgedly moderated as some others, which allows.., even encourages some lay oriented questions and discussion, you might not often see on a forum adhering more closely to a standardized mainstream dialogue. A little more of the what ifs and lay speculation, to stimulate discussion... It also means that we have to put up with some of the personalized dialogue and attacks, even sometimes get caught up in the trend...

Still as long as you can stand the noise, a voice of reason, with a solid foundation in the science is welcome.

 

Thank you for the response and the abstract number for your latest work. The results for BICEP2 break my heart but I think they have a plan for a BICEP3. As for the 'intellectually dishonest' and 'ignorant by choice' they're driving our race to ruin. The distrust of science seems to be related to personal reasons but if there's 'no money or sex involved' [Eagles] then ignorance serves them well. Thanks Professor Link.

 

Yes, wouldn't that be great!
Hi Professor, I echo the sentiments of brucep and OnlyMe and welcome you to the forum.
I'm an old bastard, and and an old layman to boot, as well as being a retired maintenance Fitter and Machinist. I have always had a great Interest in astronomy and cosmology and have read many books to boost my knowledge above that of the average layman...Books by authors such as Mitch Begalman and Sir Martin Rees, Kip Thorne, Sean Carroll, Michio Kaku, Brian Greene, Paul Davis, Max Tegmark and a few others.
And although a lot of the complicated mathematical derivations and such are beyond me, I'm fairly sure I understand the basic premise and message that those books have presented.
I was also part of another forum more then a decade ago, [that is now defunct] in which we were fortunate enough to have as regular members a professional astronomer [Geraint Lewis] and a young GR theorist.
Both those scientists kept our cosmological conversations above the navel
and kept all participants honest...including myself

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Some have referred to me here as a "science cheer leader" which they could be forgiven for I suppose. It just seems to me that any reputable scientist/physicist, with any reputable alternative hypothesis, would not be coming to a science forum to voice his hypothesis. That coupled with the fact that the scientific method and peer review, although not perfect, is the best we have got, and is self correcting in the end, says a lot for the establishment.
We did also have discussions here re the BICEP2 project, which ignoring the sensationalism and errors of the press, is another great example of science correcting itself and moving on.
Another issue on this forum a while back was the sensationalistic headlines re "Hawking says BHs do not exist"

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And didn't some of our more anti establishment members jump on that comment!!

Totally agree, and although I'm no Angel, let me say without pissing in your pocket, that perhaps the presence of a verified professional cosmologist/physicist such as yourself, may help to subdue some of the personal attacks.

I'll certainly read that and get back to you.

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When you do have time, could you perhaps comment on some of these publishing companies, for scientific papers, how reputable they are, if they have any obvious agendas and other relevant issues.
Again, welcome to our forum!

 

Would the extreme magnetic field and field lines of a Magnetar, inhibit it from accretting matter of a companion star?
And would the same magnetic field produce the familiar polar jets we see so often associated with BHs?

 

Supplementary questions:
How long does it take for these intense magnetic fields to decay or dissipate?
Are these intense magnetic fields associated with the angular momentum of the Magnetar?

 

Read about Blandford Znajek process, believe that Kip Thorne touched upon it in his book "Black Holes and Timewarps" ...

 

Yep, he sure did. It's a method of extracting energy from the ergosphere, via a utilisation of the magnetic field of a "Kerr-Newman" BH from memory.
A Kerr-Newman BH is of course a BH with angular momentum and an electric charge.

 

from : http://physics.stackexchange.com/qu...polar-jets-emitted-along-the-axis-of-rotation

begin Quote : " Perhaps the most common mechanism proposed for powering a jet is called the Blandford-Znajek Process---in which the twisting of magnetic fields from a rapidly rotating black-hole (or similarly for a neutron star) transfer rotational energy to outflow energy. The twisted magnetic field lines tend to push outwards.

In some situations it's possible that the immense magnetic field from a magnetar, forced to radiate due to a high spin (called 'dipole emission' also seen in pulsars), could also power a jet. Some people even think that there is enough heat and electromagnetic radiation near the poles of the central object that they would provide enough energy for a strong outflow (this is likely the case in many protostellar jets)." end Quote
above quoted from : http://physics.stackexchange.com/qu...polar-jets-emitted-along-the-axis-of-rotation

 

Yep, that aligns with the extraction of energy from the ergosphere via natural means, while it also infers the theoretical extraction via possible other means.....
http://en.wikipedia.org/wiki/Blandford–Znajek_process
The Blandford–Znajek process is a mechanism for the extraction of energy from a rotating black hole,[1] introduced by Roger Blandford and Roman Znajek in 1977.[2] It is one of the best explanations for the way quasars are powered.[3] As in the Penrose process, the ergosphere plays an important role in the Blandford–Znajek process. In order to extract energy and angular momentum from the black hole, the electromagnetic field around the hole must be modified by magnetospheric currents. In order to drive such currents, the electric field needs to not be screened, and consequently the vacuum field created within the ergosphere by distant sources must have an unscreened component. The most favoured way to provide this is an e+/- pair cascade in a strong electric and radiation field. [4] As the ergosphere causes the magnetosphere inside it to rotate, the outgoing flux of angular momentum results in extraction of energy from the black hole.

Yep thanks dmoe...actually answers one of my questions of Professor Link.....
"And would the same magnetic field produce the familiar polar jets we see so often associated with BHs?"
Which confirms my suspicions that polar jets are emmitted from entities [such as Magnetars] as well as Kerr-Newman BHs.
Noting of course that generally speaking they are associated with BHs.
Thanks again...nice link.

 

I really enjoyed reading the paper you linked. It will be interesting to hear from the model your analysis eliminates. Where the relaxation of the core magnetic field is the source of the flares. Thanks. Looks like some interesting reading coming up. Years ago I read a book by Simon Mitton called The Crab Nebula. I also read Isaac Asimov book on stellar evolution ending in a discussion about condensed stars and black holes. It led to my interest in learning GR. The scientific literature is awesome. Not many take advantage from my perspective. Amateur perspective. Wow, you can even learn about what goes on inside a neutron star.

 

Kip Thornes book is a favorite of mine. I especially like all the historical references on gravitational physics. I feel the same way about Alan Guths book on a great idea called inflation for all the historical reference on modern cosmology.

 

Agreed...I also found it quite interesting towards the end of the book, when he speculates on wormholes etc, and what is allowed by GR, and how some advanced civilisations could theoretically use them as portals to other Universes, or regions of spacetime.

Might line that one up for my next read.

 

Bingo!

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Thank you for the welcome to the forum!

On the subject of publishing companies, it might be easiest to first mention the main, reputable journals in astrophysics. They are:

Astrophysical Journal, Letters, Supplements
Monthly Notices of the Royal Astronomical Society
Astronomy and Astrophysics
Astronomical Journal
Physical Review (Letters and D)

and others.

As for disreputable publishers and associated journals, one should be wary of the hundreds, if not thousands of "open access" journals that have appeared in recent years. "Open access" means no subscription fee. One notorious publisher is Scientific Research Publishing (SCIRP) that has created hundreds of open access journals with highly questionable peer-review standards. It seems that many SCIRP journals are not peer reviewed at all, though SCIRP claims otherwise. They make their money by charging the authors to publish, so there is an economic incentive to not have a peer review process.

An important exception is the Astrophysical Journal. They charge authors by the page but their publisher, the American Astronomical Society, is non-profit. They also charge a subscription fee.

One of the SCIRP journals is the International Journal of Astronomy and Astrophysics, the journal in which Rajesh published. It is clear that his paper was not properly peer reviewed or not reviewed at all. If the paper had been sent to any competent reviewer, that reviewer would have been quick to point out that GR does not allow a material object to be smaller than its Schwarzchild radius, and would have summarily rejected the paper. To their credit, many of the amateur scientists who contribute to this forum already knew this fact. I would not bother reading the International Journal of Astronomy and Astrophysics; it is a disreputable journal with a disreputable publisher.

For more on SCIRP, take a look at:

http://scienceblogs.com/aardvarchaeology/2012/04/12/scam-publisher-fools-swedish-c/

Best,

Bennett

 

These are isolated objects, so there is no accretion. But if there were, the magnetic field would channel the accretion flow.