Comments on: Astronomers Discover Medium-Sized Class of Black Holes

By: Jon Hanford

Jon Hanford — Sat, 04 Jul 2009 23:57:25 +0000

A recent paper on a proposed 1000 solar mass BH at the heart of the Sagittarius Dwarf Galaxy can be found here: http://arxiv.org/PS_cache/arxiv/pdf/0906/0906.4894v1.pdf . Other candidates have also been proposed.

By: Jon Hanford

Jon Hanford — Thu, 02 Jul 2009 17:02:22 +0000

From the story posted at the PhysOrg site, it would appear that the researchers classify this object as an ULX. from the article: "This new source, dubbed HLX-1 (Hyper-Luminous X-ray source 1), lies towards the edge of the galaxy ESO 243-49. It is ultra-luminous in X-rays, with a maximum X-ray brightness of approximately 260 million times that of the Sun.

The X-ray signature of HLX-1 and the lack of a counterpart in optical images confirm that it is neither a foreground star nor a background galaxy, and its position indicates that it is not the central engine of the host galaxy. " Concerning the XMM x-ray observations, the PhysOrg piece states: "Using XMM-Newton observations carried out on the 23rd November 2004 and the 28th November 2008, the team showed that HLX-1 displayed a variation in its X-ray signature. This indicated that it must be a single object and not a group of many fainter sources. "

By: Jon Hanford

Jon Hanford — Thu, 02 Jul 2009 15:11:11 +0000

mikester brings up a good point as to the immediate enviroment of this purported IMBH. IMBHs have been proposed (and in a few cases, claimed to have been found) in either globular clusters, dwarf galaxies or ultraluminous x-ray sources( ULXs). A 'naked' IMBH, perhaps ejected by a close gravitational encounter with another massive object in the galaxy also seems plausible. I would be interested in reading the original paper to see the authors discussion of this issue. @nimo, thanks for finding that info regarding the illustration. The picture just looked too 'good', even if it was a multiwavelength composite (check out the DSS images. Also note several peculiar or distorted galaxies nearby on the DSS images – possible past interactions with this galaxy?)

By: Lawrence B. Crowell

Lawrence B. Crowell — Thu, 02 Jul 2009 12:43:14 +0000

The blue object is some sort of accretion process. I have found some XMM paper by the author Farrell et al,

http://arxiv.org/PS_cache/arxiv/pdf/0807/0807.1067v2.pdf

but have not found this one referenced above. I am not clear about the source of energy released by the BH. It is most likely the evidence for the BH rests with the X-ray flux.

The image is indeed an artistic representation. It is meant to illustrate the energetic object with respect to the galaxy.

By: nimo

nimo — Thu, 02 Jul 2009 08:48:07 +0000

peace..
(H&H)ly..
..
this photo is said to be an "artist-impression" @ http://www.physorg.com/news165675129.html
~
quote:
"//This is an artist's impression of the new source HLX-1 (represented by the light blue object to the top left of the galactic bulge) in the periphery of the edge-on spiral galaxy ESO 243-49. This is the first strong evidence for the existence of intermediate mass black holes. Credit: Heidi Sagerud.."
..endQuote
~

By: Dave Finton

Dave Finton — Thu, 02 Jul 2009 04:48:45 +0000

Lawrence: I can hear the supermassive BH right now, "GET IN MAH BELLY!"

By: opencluster

opencluster — Thu, 02 Jul 2009 02:50:02 +0000

What is accreting onto the bh to make it shine if it is not in the galaxy? A naked bh would be invisible, except perhaps for gravitational lensing.

By: Lawrence B. Crowell

Lawrence B. Crowell — Thu, 02 Jul 2009 02:29:48 +0000

The 500M_{sol} BH is in orbit around the galaxy. Eventually it will coalesce with the much large BH in the galaxy.

By: mikester

mikester — Thu, 02 Jul 2009 00:26:43 +0000

What is this BH doing there relative to the beautiful edge-on galaxy? Is it the center core of a satellite subgalaxy or part of straggling cluster?

By: IVAN3MAN

IVAN3MAN — Wed, 01 Jul 2009 20:24:43 +0000

@ CinIN,

I think that the difference in the diffraction spikes is probably due to the above image being a composite of two image sources — one from an optical telescope (e.g., Hubble) and the other from the XMM-Newton X-ray space telescope.

By: CinIN

CinIN — Wed, 01 Jul 2009 18:56:01 +0000

Beautiful image, but I'm puzzled by the difference in the diffraction spikes around HLX-1 and the other bright object to its right. Shouldn't the diffraction patterns look more similar (allowing for differences in brightness.) Could the image of the black hole been altered for emphasis?