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Title: A Deep Chandra ACIS Survey of M83
Author: Knox S. Long (STScI), Kip D. Kuntz (JHU), William P. Blair (JHU), Leith Godfrey (Curtin Univ., ASTRON), Paul P. Plucinsky (Havard-Smithsonian Center for Astrophysics), Roberto Soria (Curtin Univ.), Christopher Stockdale (Marquette Univ.), P. Frank Winkler (Middlebury College)

We have obtained a series of deep X-ray images of the nearby galaxy M83 using Chandra, with a total exposure of 729 ks. Combining the new data with earlier archival observations totaling 61 ks, we find 378 point sources within the D25 contour of the galaxy. We find 80 more sources, mostly background AGN, outside of the D25 contour. Of the X-ray sources, 47 have been detected in a new radio survey of M83 obtained using the Australia Telescope Compact Array. Of the X-ray sources, at least 87 seem likely to be supernova remnants (SNRs), based on a combination of their properties in X-rays and at other wavelengths. We attempt to classify the point source population of M83 through a combination of spectral and temporal analysis. As part of this effort, we carry out an initial spectral analysis of the 29 brightest X-ray sources. The soft X-ray sources in the disk, many of which are SNRs, are associated with the spiral arms, while the harder X-ray sources, mostly X-ray binaries (XRBs), do not appear to be. After eliminating AGN, foreground stars and identified SNRs from the sample, we construct the cumulative luminosity function (CLF) of XRBs brighter than 8 10^35 ergs/s. Despite M83's relatively high star formation rate, the CLF indicates that most of the XRBs in the disk are low mass XRBs.

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Discovery of Super-Powered Black Hole in Nearby Galaxy M83

In an article featured on the cover of the journal Science this week, a team of astronomers led by Dr. Roberto Soria at Curtin University, and including ASTRON research fellow Dr. Leith Godfrey, presented the exciting discovery of a black hole that has been blasting out an extremely powerful release of energy, at a much faster rate than previously thought possible, for over 10,000 years.
The powerful black hole, classified as a "microquasar" and called MQ1, was discovered in the inner disk of the spiral galaxy M83 (the "Southern Pinwheel"), as part of a detailed study of the various classes of object found in this galaxy. The in-depth study involves data from the Chandra X-ray observatory, Hubble Space Telescope, the Australia Telescope Compact Array, and the Australian Long Baseline Array.

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A galaxy with two hearts

This new Hubble image shows the spiral galaxy Messier 83, otherwise known as the Southern Pinwheel Galaxy. One of the largest and closest barred spirals to us, this galaxy is dramatic and mysterious; it has hosted a large number of supernova explosions, and is thought to have a double nucleus lurking at its core.
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Messier 83
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Title: Star Formation & Dust Heating in the FIR Bright Sources of M83
Authors: K. Foyle, G. Natale, C. D. Wilson, C. C. Popescu, M. Baes, G. J. Bendo, M. Boquien, A. Boselli, A. Cooray, D. Cormier, I. De Looze, J. Fischera, O. . Karczewski, V. Lebouteiller, S. Madden, M. Pereira-Santaella, M. W. L. Smith, L. Spinoglio, R. J. Tuffs

We investigate star formation and dust heating in the compact FIR bright sources detected in the Herschel maps of M83. We use the source extraction code GETSOURCES to detect and extract sources in the FIR, as well as their photometry in the MIR and H{\alpha}. By performing infrared SED fitting and applying an H{\alpha} based star formation rate (SFR) calibration, we derive the dust masses and temperatures, SFRs, gas masses and star formation efficiencies (SFEs). The detected sources lie exclusively on the spiral arms and represent giant molecular associations (GMAs), with gas masses and sizes of 10^6-10^8 solar masses and 200-300 pc, respectively. The inferred parameters show little to no radial dependence and there is only a weak correlation between the SFRs and gas masses, which suggests that more massive clouds are less efficient at forming stars. Dust heating is mainly due to local star formation. However, although the sources are not optically thick, the total intrinsic young stellar population luminosity can almost completely account for the dust luminosity. This suggests that other radiation sources contribute to the dust heating as well and approximately compensate for the unabsorbed fraction of UV light.

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 NASA'S Chandra Sees Remarkable Outburst from Old Black Hole

An extraordinary outburst produced by a black hole in a nearby galaxy has provided direct evidence for a population of old, volatile stellar black holes. The discovery, made by astronomers using NASA's Chandra X-ray Observatory, provides new insight into the nature of a mysterious class of black holes that can produce as much energy in X-rays as a million suns radiate at all wavelengths.
Researchers used Chandra to discover a new ultraluminous X-ray source, or ULX. These objects give off more X-rays than most binary systems, in which a companion star orbits the remains of a collapsed star. These collapsed stars form either a dense core called a neutron star or a black hole. The extra X-ray emission suggests ULXs contain black holes that might be much more massive than the ones found elsewhere in our galaxy.

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RE: M83 Ultra-Luminous X-ray Source
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Title: The Birth of an Ultra-Luminous X-ray Source in M83
Authors: Roberto Soria, K. D. Kuntz, P. Frank Winkler, William P. Blair, Knox S. Long, Paul P. Plucinsky, Bradley C. Whitmore

A previously undetected X-ray source (L_X<10**36 erg/s) in the strongly star-forming galaxy M83 entered an ultraluminous state between August 2009 and December 2010. It was first seen with Chandra on 23 December 2010 at L_X ~ 4 10**39 ergs/s, and has remained ultraluminous through our most recent observations in December 2011, with typical flux variation of a factor of two. The spectrum is well fitted by a combination of absorbed power-law and disk black-body models. While the relative contributions of the models varies with time, we have seen no evidence for a canonical state transition. The luminosity and spectral properties are consistent with accretion powered by a black hole with M_BH ~ 40-100 solar masses. In July 2011 we found a luminous, blue optical counterpart which had not been seen in deep HST observations obtained in August 2009. These optical observations suggest that the donor star is a low-mass star undergoing Roche-lobe overflow, and that the blue optical emission seen during the outburst is coming from an irradiated accretion disk. This source shows that ultraluminous X-ray sources (ULXs) with low-mass companions are an important component of the ULX population in star-forming galaxies, and provides further evidence that the blue optical counterparts of some ULXs need not indicate a young, high-mass companion, but rather that they may indicate X-ray reprocessing.

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NGC 5236
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Title: The relation between surface star formation rate density and spiral arms in NGC 5236 (M83)
Authors: Esteban Silva-Villa, Soeren Larsen

For a long time the consensus has been that star formation rates are higher in the interior of spiral arms in galaxies, compared to inter-arm regions. However, recent studies have found that the star formation inside the arms is not more efficient than elsewhere in the galaxy. Previous studies have based their conclusion mainly on integrated light. We use resolved stellar populations to investigate the star formation rates throughout the nearby spiral galaxy NGC 5236. We aim to investigate how the star formation rate varies in the spiral arms compared to the inter-arm regions, using optical space-based observations of NGC 5236. Using ground-based H\alpha images we traced regions of recent star formation, and reconstructed the arms of the galaxy. Using HST/ACS images we estimate star formation histories by means of the synthetic CMD method. Arms based on H\alpha images showed to follow the regions where stellar crowding is higher. Star formation rates for individual arms over the fields covered were estimated between 10 to 100 Myr, where the stellar photometry is less affected by incompleteness. Comparison between arms and inter-arm surface star formation rate densities (Sigma_{SFR}) suggested higher values in the arms (~0.6 dex). Over a small fraction of one arm we checked how the Sigma_{SFR} changes for the trailing and leading part. The leading part of the arm showed to have a higher Sigma_{SFR} in the age range 10-100 Myr. Predictions from the density wave theory of a rapid increase in the star formation at the edge where the stars and the gas enter the density wave are confirmed. The Sigma_{SFR} presents a steep decrease with distance from the center of the arms through the inter-arm regions.

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Messier 83
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Nasa has released images of the spiral galaxy, Messier 83, taken by its Wide-field Infrared Survey Explorer (WISE) telescope.

Messier 83, or M83 for short, is a spiral galaxy approximately 15 million light-years away in the constellation Hydra.
It is sometimes referred to as the southern Pinwheel galaxy. M101 is called the Pinwheel galaxy and M83 has a similar appearance, but it is located in the southern sky. At about 55,500 light-years across it is a bit more than half the size of the Milky Way Galaxy, but it has a similar overall structure.

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Clear New View of a Classic Spiral

ESO is releasing a beautiful image of the nearby galaxy Messier 83 taken by the HAWK-I instrument on ESO's Very Large Telescope (VLT) at the Paranal Observatory in Chile. The picture shows the galaxy in infrared light and demonstrates the impressive power of the camera to create one of the sharpest and most detailed pictures of Messier 83 ever taken from the ground.
The galaxy Messier 83 is located about 15 million light-years away in the constellation of Hydra (the Sea Serpent). It spans over 40 000 light-years, only 40 percent the size of the Milky Way, but in many ways is quite similar to our home galaxy, both in its spiral shape and the presence of a bar of stars across its centre. Messier 83 is famous among astronomers for its many supernovae: vast explosions that end the lives of some stars. Over the last century, six supernovae have been observed in Messier 83 - a record number that is matched by only one other galaxy. Even without supernovae, Messier 83 is one of the brightest nearby galaxies, visible using just binoculars.

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