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TOPIC: QSO J1148+5251


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RE: QSO J1148+5251
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Quasar May Be Embedded in Unusually Dusty Galaxy

Hubble astronomers have looked at one of the most distant and brightest quasars in the universe and are surprised by what they did not see: the underlying host galaxy of stars feeding the quasar. The best explanation is that the galaxy is shrouded in so much dust that the stars are completely hidden everywhere. Astronomers believe that the James Webb Space Telescope will reveal the galaxy.
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Title: Near-Infrared Imaging of a z=6.42 Quasar Host Galaxy With the Hubble Space Telescope Wide Field Camera 3
Authors: Matt Mechtley, Rogier A. Windhorst, Russell E. Ryan, Glenn Schneider, Seth H. Cohen, Rolf A. Jansen, Xiaohui Fan, Nimish P. Hathi, William C. Keel, Anton M. Koekemoer, Huub Röttgering, Evan Scannapieco, Donald P. Schneider, Michael A. Strauss, Haojing Yan

We report on deep near-infrared F125W (J) and F160W (H) Hubble Space Telescope Wide Field Camera 3 images of the z=6.42 quasar J1148+5251 to attempt to detect rest-frame near-ultraviolet emission from the host galaxy. These observations included contemporaneous observations of a nearby star of similar near-infrared colours to measure temporal variations in the telescope and instrument point spread function (PSF). We subtract the quasar point source using both this direct PSF and a model PSF.
Using direct subtraction, we measure an upper limit for the quasar host galaxy of m_J>22.8, m_H>23.0 AB mag (2 sigma). After subtracting our best model PSF, we measure a limiting surface brightness from 0.3"-0.5" radius of mu_J > 23.5, mu_H > 23.7 AB magarc (2 sigma). We test the ability of the model subtraction method to recover the host galaxy flux by simulating host galaxies with varying integrated magnitude, effective radius, and Sersic index, and conducting the same analysis. These models indicate that the surface brightness limit (mu_J > 23.5 AB magarc) corresponds to an integrated upper limit of m_J > 22 - 23 AB mag, consistent with the direct subtraction method. Combined with existing far-infrared observations, this gives an infrared excess log(IRX) > 1.0 and corresponding ultraviolet spectral slope beta > -1.2±0.2. These values match those of most local luminous infrared galaxies, but are redder than those of almost all local star-forming galaxies and z~6 Lyman break galaxies.

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SDSS J114816.64+525150.3
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Title: Evidence of strong quasar feedback in the early Universe
Authors: R. Maiolino, S. Gallerani, R. Neri, C. Cicone, A. Ferrara, R. Genzel, D. Lutz, E. Sturm, L.J. Tacconi, F. Walter, C. Feruglio, F. Fiore, E. Piconcelli

Most theoretical models invoke quasar driven outflows to quench star formation in massive galaxies, this feedback mechanism is required to account for the population of old and passive galaxies observed in the local universe. The discovery of massive, old and passive galaxies at z=2, implies that such quasar feedback onto the host galaxy must have been at work very early on, close to the reionisation epoch. We have observed the [CII]158um transition in SDSSJ114816.64+525150.3 that, at z=6.4189, is one of the most distant quasars known. We detect broad wings of the line tracing a quasar-driven massive outflow. This is the most distant massive outflow ever detected and is likely tracing the long sought quasar feedback, already at work in the early Universe. The outflow is marginally resolved on scales of about 16 kpc, implying that the outflow can really affect the whole galaxy, as required by quasar feedback models. The inferred outflow rate, dM/dt > 3500 Msun/yr, is the highest ever found. At this rate the outflow can clean the gas in the host galaxy, and therefore quench star formation, in a few million years.

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Title: A Kiloparsec-Scale Hyper-Starburst in a Quasar Host Less than 1 Gigayear after the Big Bang
Authors: F. Walter, D. Riechers, P. Cox, R. Neri, C. Carilli, F. Bertoldi, A. Weiss, R. Maiolino

The host galaxy of the quasar SDSS J114816.64+525150.3 (at redshift z=6.42, when the Universe was <1 billion years old) has an infrared luminosity of 2.2x10¹³ L_sun, presumably significantly powered by a massive burst of star formation. In local examples of extremely luminous galaxies such as Arp220, the burst of star formation is concentrated in the relatively small central region of <100pc radius. It is unknown on which scales stars are forming in active galaxies in the early Universe, which are likely undergoing their initial burst of star formation. We do know that at some early point structures comparable to the spheroidal bulge of the Milky Way must have formed. Here we report a spatially resolved image of [CII] emission of the host galaxy of J114816.64+525150.3 that demonstrates that its star forming gas is distributed over a radius of ~750pc around the centre. The surface density of the star formation rate averaged over this region is ~1000 M_sun/yr/kpc². This surface density is comparable to the peak in Arp220, though ~2 orders of magnitudes larger in area. This vigorous star forming event will likely give rise to a massive spheroidal component in this system.

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QSO J114816.64+525150.3
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When galaxies are born, do their stars form everywhere at once, or only within a small core region? Recent measurements of an international team led by scientists from the Max Planck Institute for Astronomy provide the first concrete evidence that star-forming regions in infant galaxies are indeed small - but also hyperactive, producing stars at astonishingly high rates.
Galaxies, including our own Milky Way, consist of hundreds of billions of stars. How did such gigantic galactic systems come into being? Did a central region with stars first form then with time grow? Or did the stars form at the same time throughout the entire galaxy? An international team led by researchers from the Max Planck Institute for Astronomy is now much closer to being able to answer these questions.
The researchers studied one of the most distant known galaxies, a so-called quasar with the designation J1148+5251. Light from this galaxy takes 12.8 billion years to reach Earth; in turn, astronomical observations show the galaxy as it appeared 12.8 billion years ago, providing a glimpse of the very early stages of galactic evolution, less than a billion years after the Big Bang.
With the IRAM Interferometer, a German-French-Spanish radio telescope, the researchers were able to obtain images of a very special kind: they recorded the infrared radiation emitted by J1148+5251 at a specific frequency associated with ionised carbon atoms, which is a reliable indicator of ongoing star formation.
The resulting images show sufficient detail to allow, for the first time, the measurement of the size of a very early star-forming region. With this information, the researchers were able to conclude that, at that time, stars were forming in the core region of J1148+5251 at record rates - any faster and star formation would have been in conflict with the laws of physics.

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A stellar factory millions of times larger than anything comparable in the Milky Way has been identified in a galaxy in the very early universe. The work bolsters the case that massive galaxies formed very quickly - in spectacular bursts of star formation - soon after the big bang.
Regions of intense star formation, called starbursts, span a few light years at most in the Milky Way, and less than a few hundred light years in nearby, bright galaxies such as Arp 220 (pictured). But it has not been clear how large the stellar nurseries were in the early universe.
To find out, researchers led by Fabian Walter of the Max Planck Institute for Astronomy in Heidelberg, Germany, carefully scrutinised a distant galaxy whose light has taken so long to reach Earth that it appears as it was just 870 million years after the big bang.

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QSO J1148+5251
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An intense star-forming region that produces a combined mass of more than one thousand solar masses a year has been found 12.8 billion light-years from Earth.
The so-called 'hyper-starburst' is part of a young, quasar-containing galaxy. Because it is so far away, we can only see how the galaxy appeared far into the past, when the universe was less than a billion years old.
This fledgling galaxy produces 1,000 times more star matter than our galaxy, and within a diameter of just 4,000 light-years, compared with the Milky Way's 100,000 light-years.
It helps confirm a theory that young galaxies can grow massive very rapidly.

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Position(2000): RA 11 48 16.64, Dec +52 51 50.3
z = 6.43

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