A Treasure Trove of Black Holes:

Discussion in 'Astronomy, Exobiology, & Cosmology' started by paddoboy, Jan 22, 2017.

  1. paddoboy Valued Senior Member

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    21,494
    The following article is an example of how BH's, hence gravity helped shape our Universe;
    An improvement of the famous Hubble deep field and ultra deep field photographs a while back........
    https://www.nasa.gov/mission_pages/...e-ever-reveals-black-hole-treasure-trove.html

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    Made with over 7 million seconds of Chandra observing time, this image is part of the Chandra Deep Field-South and is the deepest X-ray image ever obtained. With its unprecedented look at the early Universe in X-rays, the CDF-S gives astronomers the best look yet at the growth of black holes over billions of years starting soon after the Big Bang. In this image, low, medium, and high-energy X-rays that Chandra detects are shown as red, green, and blue respectively.
    https://www.nasa.gov/mission_pages/...e-ever-reveals-black-hole-treasure-trove.html
     
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  3. paddoboy Valued Senior Member

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    Some interesting facts......at
    http://chandra.harvard.edu/photo/2017/cdfs/
    • This image contains the highest concentration of black holes ever seen, equivalent to 5,000 over the area on the sky covered by the full Moon.
    • Made with over 7 million seconds of Chandra observing time, this is the deepest X-ray image ever obtained.
    • These data give astronomers the best look yet at the growth of black holes over billions of years soon after the Big Bang.
    This is the deepest X-ray image ever obtained, made with over 7 million seconds of observing time with NASA's Chandra X-ray Observatory. These data give astronomers the best look yet at the growth of black holes over billions of years beginning soon after the Big Bang, as described in our latest press release.

    The image is from the Chandra Deep Field-South, or CDF-S. The full CDF-S field covers an approximately circular region on the sky with an area about two-thirds that of the full Moon. However, the outer regions of the image, where the sensitivity to X-ray emission is lower, are not shown here. The colors in this image represent different levels of X-ray energy detected by Chandra. Here the lowest-energy X-rays are red, the medium band is green, and the highest-energy X-rays observed by Chandra are blue.

    The central region of this image contains the highest concentration of supermassive black holes ever seen, equivalent to about 5,000 objects that would fit into the area on the sky covered by the full Moon and about a billion over the entire sky.
    more at.......
    http://chandra.harvard.edu/photo/2017/cdfs/
     
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  5. paddoboy Valued Senior Member

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    Here is a paper on BH growth in the early Universe.......
    https://arxiv.org/pdf/1608.02614v1.pdf

    The deepest X-ray view of high-redshift galaxies: constraints on low-rate black-hole accretion:

    ABSTRACT

    We exploit the 7 Ms Chandra observations in the Chandra Deep Field-South (CDF-S), the deepest X-ray survey to date, coupled with CANDELS/GOODS-S data, to measure the total X-ray emission arising from 2076 galaxies at 3.5 6 z < 6.5. This aim is achieved by stacking the Chandra data at the positions of optically selected galaxies, reaching effective exposure times of > 109 s. We detect significant (> 3.7σ) X-ray emission from massive galaxies at z ≈ 4. We also report the detection of massive galaxies at z ≈ 5 at a 99.7% confidence level (2.7σ), the highest significance ever obtained for X-ray emission from galaxies at such high redshifts. No significant signal is detected from galaxies at even higher redshifts. The stacking results place constraints on the BHAD associated with the known high-redshift galaxy samples, as well as on the SFRD at high redshift, assuming a range of prescriptions for X-ray emission due to X- ray binaries. We find that the X-ray emission from our sample is likely dominated by processes related to star formation. Our results show that low-rate mass accretion onto SMBHs in individually X-ray-undetected galaxies is negligible, compared with the BHAD measured for samples of X-ray detected AGN, for cosmic SMBH mass assembly at high redshift. We also place, for the first time, constraints on the faint-end of the AGN X-ray luminosity function (logLX ∼ 42) at z > 4, with evidence for fairly flat slopes. The implications of all of these findings are discussed in the context of the evolution of the AGN population at high redshift.
     
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  7. paddoboy Valued Senior Member

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    And here is another informative paper on the same subject...................
    https://arxiv.org/pdf/1611.03501v2.pdf

    THE CHANDRA DEEP FIELD-SOUTH SURVEY: 7 MS SOURCE CATALOGS:

    ABSTRACT

    We present X-ray source catalogs for the ≈ 7 Ms exposure of the Chandra Deep Field-South (CDF-S), which covers a total area of 484.2 arcmin2 . Utilizing WAVDETECT for initial source detection and ACIS Extract for photometric extraction and significance assessment, we create a main source catalog containing 1008 sources that are detected in up to three X-ray bands: 0.5–7.0 keV, 0.5–2.0 keV, and 2–7 keV. A supplementary source catalog is also provided including 47 lower-significance sources that have bright (Ks ≤ 23) near-infrared counterparts. We identify multiwavelength counterparts for 992 (98.4%) of the main-catalog sources, and we collect redshifts for 986 of these sources, including 653 spectroscopic redshifts and 333 photometric redshifts. Based on the X-ray and multiwavelength properties, we identify 711 active galactic nuclei (AGNs) from the main-catalog sources. Compared to the previous ≈ 4 Ms CDF-S catalogs, 291 of the main-catalog sources are new detections. We have achieved unprecedented X-ray sensitivity with average flux limits over the central ≈ 1 arcmin2 region of ≈ 1.9×10−17, 6.4×10−18, and 2.7×10−17 erg cm−2 s −1 in the three X-ray bands, respectively. We provide cumulative number-count measurements observing, for the first time, that normal galaxies start to dominate the X-ray source population at the faintest 0.5–2.0 keV flux levels. The highest X-ray source density reaches ≈ 50500 deg−2 , and 47% ±4% of these sources are AGNs (≈ 23900 deg−2 ).
     

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