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TOPIC: 2XMM J011028.1-460421


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Posts: 130165
Date:
HLX-1
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Hubble Finds Relic of a Shredded Galaxy

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Astronomers using the NASA/ESA Hubble Space Telescope have found a cluster of young blue stars surrounding a mid-sized black hole called HLX-1.
The discovery suggests that the black hole formed in the core of a now-disintegrated dwarf galaxy. The findings have important implications for understanding the evolution of supermassive black holes and galaxies.
Astronomers know how massive stars collapse to form small black holes a few times the mass of the Sun. However, it is not clear how supermassive black holes, which can have masses of millions or even billions of times the Sun's, form in the cores of galaxies. One idea is that supermassive black holes may build up through the merger of small and mid-sized black holes, a view supported by a new study using Hubble.

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ESO 243-49 HLX-1
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Title: A Young Massive Stellar Population Around the Intermediate Mass Black Hole ESO 243-49 HLX-1
Authors: S. Farrell, M. Servillat, J. Pforr, T. Maccarone, C. Knigge, O. Godet, C. Maraston, N. Webb, D. Barret, A. Gosling, R. Belmont, K. Wiersema

We present Hubble Space Telescope and simultaneous Swift X-ray telescope observations of the strongest candidate intermediate mass black hole ESO 243-49 HLX-1. Fitting the spectral energy distribution from X-ray to near-infrared wavelengths showed that the broadband spectrum is not consistent with simple and irradiated disc models, but is well described by a model comprised of an irradiated accretion disc plus a stellar population with a mass ~1E6 solar masses. The age of the population cannot be uniquely constrained, with both very young and very old stellar populations allowed. However, the very old solution requires excessively high levels of disc reprocessing and an extremely small disc, leading us to favour the young solution with an age of ~13 Myr. In addition, the presence of dust lanes and the lack of any nuclear activity from X-ray observations of the host galaxy lead us to propose that a gas-rich minor merger may have taken place less than ~200 Myr ago. Such a merger event would explain the presence of the intermediate mass black hole and support a young stellar population.

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Posts: 130165
Date:
HLX1
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Title: X-ray study of HLX1: intermediate-mass black hole or foreground neutron star?
Authors: Roberto Soria, Luca Zampieri, Silvia Zane, Kinwah Wu

We re-assess the XMM-Newton and Swift observations of HLX1, to examine the evidence for its identification as an intermediate-mass black hole. We show that the X-ray spectral and timing properties are equally consistent with an intermediate-mass black hole in a high state, or with a foreground neutron star with a luminosity of about a few times 10^{32} erg/s ~ 10^{-6} L_{Edd}, located at a distance of about 1.5 to 3 kpc. Contrary to previously published results, we find that the X-ray spectral change between the two XMM-Newton observations of 2004 and 2008 (going from power-law dominated to thermal dominated) is not associated with a change in the X-ray luminosity. The thermal component becomes more dominant (and hotter) during the 2009 outburst seen by Swift, but in a way that is consistent with either scenario.

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Posts: 130165
Date:
HLX-1
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July 1st 2009
Astronomers using ESAs XMM-Newton X-ray observatory have discovered a black hole they labelled HLX-1 (Hyper-Luminous X-ray source 1), which lies towards the outskirts of the galaxy ESO 243-49, approximately 290 million light-years from Earth and weighs more than 500 solar masses, making it a 'missing link' between lighter stellar-mass and heavier supermassive black holes. This discovery is the best detection to date of a new class that has long been searched for: intermediate mass black holes.


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Posts: 130165
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Hyper-Luminous X-ray Source 1
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Astronomers believe they've found something never before detected in the universe: a black hole of intermediate size. And while that may not sound thrilling to the layman, researchers are thrilled by the discovery of the so-called "Hyper-Luminous X-ray Source 1," which is poised at the edge of galaxy ESO 243-49. Astronomers are excited because they've seen plenty of small black holes and large black holes, but experts had questioned whether a medium-sized variety could exist.

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Date:
RE: 2XMM J011028.1-460421
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Discovery of New Class of Black Holes Leaves the Future of Galaxy Uncertain
A new class of black hole, more than 500 times the mass of the Sun, has been discovered by an international team of astronomers.
The finding in a distant galaxy approximately 290 million light years from Earth is reported today in the journal Nature.
Until now, identified black holes have been either super-massive (several million to several billion times the mass of the Sun) in the centre of galaxies, or about the size of a typical star (between three and 20 Solar masses).
The new discovery is the first solid evidence of a new class of medium-sized black holes. The team, led by astrophysicists at the Centre d'Etude Spatiale des Rayonnements in France, detected the new black hole with the European Space Agency's XMM-Newton X-ray space telescope.


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Posts: 130165
Date:
Intermediate mass black hole
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XMM-Newton discovers a new class of black holes
Artist's view of intermediate-mass black hole in its host galaxy
Artist's impression of galaxy and HLX-1 (blue star to the left)

Astronomers using ESA's XMM-Newton X-ray observatory have discovered a black hole weighing more than 500 solar masses, a missing link between lighter stellar-mass and heavier supermassive black holes, in a distant galaxy. This discovery is the best detection to date of a new class that has long been searched for: intermediate mass black holes.

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Posts: 130165
Date:
HLX-1
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Title: An intermediate-mass black hole of over 500 solar masses in the galaxy ESO 243-49
Authors: Sean A. Farrell, Natalie A. Webb, Didier Barret, Olivier Godet & Joana M. Rodrigues

Ultraluminous X-ray sources are extragalactic objects located outside the nucleus of the host galaxy with bolometric luminosities1 exceeding 10^39 erg s^-1. These extreme luminosities - if the emission is isotropic and below the theoretical (Eddington) limit, where the radiation pressure is balanced by the gravitational pressure - imply the presence of an accreting black hole with a mass of approx 10^2 - 10^5 solar masses. The existence of such intermediate-mass black holes is in dispute, and though many candidates have been proposed, none are widely accepted as definitive. Here we report the detection of a variable X-ray source with a maximum 0.2 - 10 keV luminosity of up to 1.1 times 10^42 erg s^-1 in the edge-on spiral galaxy ESO 243-49, with an implied conservative lower limit for the mass of the black hole of approx 500 solar masses.

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Posts: 130165
Date:
2XMM J011028.1-460421
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Astronomers sniff intermediate mass black hole
Astronomers from the University of Leicester and the CESR astrophysics lab in Toulouse reckon they've spotted an intermediate mass black hole - one of an elusive group of beasts weighing in between single star black holes and their supermassive cousins.
A team led by Sean Farrell was perusing X-ray sources dating back to 2000 when they spied an object in the galaxy ESO 243-49 emitting fluctuating X-rays "400 times as bright as the maximum value for a stellar black hole", as New Scientist explains.

The newly discovered object, called HLX-1, is the first to show an intermediate weight between stellar-mass and supermassive black holes. Astronomers led by Sean Farrell, formerly at the Centre d'Etude Spatiale des Rayonnements in France, detected HLX-1, hanging just outside a galaxy about 290 million light-years away, during a search for unusual white dwarfs and neutron stars. As the researchers report tomorrow in Nature, they found that HLX-1 is spewing 10 times as much x-radiation as stellar-mass black holes normally do, suggesting that the object is much heavier. Based on its radiation intensity, the team conservatively estimates its mass at 500 times that of the sun, says Farrell, now at the University of Leicester in the United Kingdom.

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Some black holes are too big. Some black holes are too small. A letter appearing in this week's edition of Nature describes how astronomers may have found one that is just right.
The letter, written by a team of British and French astronomers, does not state that they have found an intermediate mass black holeone that could be termed just rightbut that they have found an object where most other explanations fail to explain its behaviour.
The object, 2XMM J011028.1-460421 or (more conveniently) HLX-1, is a source of ultraluminous X-rays near the spiral galaxy ESO 243-49. These X-rays have been postulated to be the product of an intermediate mass black hole, one between 100 and 10,000 solar masses, but to date no candidate object has been widely accepted.

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