Lockman Hole

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The Lockman Hole ( English for "Lockman Hole") is an area of ​​the sky in the constellation Great Bear . As there are hardly any HI regions in our own galaxy in this direction of observation, observations of distant objects that are not particularly disturbed are possible. Accordingly, it is one of the most precisely surveyed regions of the sky. From observations of such clearly defined regions of the sky - the Lockman Hole, but also, for example, the Hubble Deep Field - in as many different areas of the spectrum as possible, conclusions can be drawn about the relative and absolute frequencies of the various types of astronomical objects on galactic distance scales.

Radio and infrared observations

In terms of radio , the Lockman Hole contains around 150 strong sources. Some of them are also sources of strong X-rays , and most of the objects that can be detected in both radio and X-rays are also detectable in visible light . The majority of them (around 60 percent) are apparently quasars , the rest mostly normal galaxies . Infrared observations with the ISO satellite telescope indicate the existence of many galaxies in a phase of active star formation .

X-ray observations

In the X-ray area, the Lockman Hole was the target area for a survey using the ROSAT satellite telescope back in the 1990s . Almost 1200 distinguishable sources were proven. In subsequent X-ray observations with the XMM-Newtonian satellite telescope , these and other objects were examined more closely; For example, this resulted in data series that show how the X-ray brightnesses of various active galactic nuclei change on time scales from months to years.

The analysis of observations in Lockman Hole with the Chandra X-ray satellite provided information about the various types of supermassive black holes , the energy source of active galaxies, and suggests an association between the incidence of material into the central black hole of a galaxy and the phases of star formation .

Individual evidence

  1. ^ HR de Ruiter et al .: Deep radio observations of the "Lockman Hole". In: Astronomy and Astrophysics , Vol. 319, 1997, pp. 7-17. bibcode : 1997A & A ... 319 .... 7D
  2. ↑ H. Matsuhara et al .: ISO deep far-infrared survey in the "Lockman Hole". II. Power spectrum analysis: evidence of a strong evolution in number counts . In: Astronomy and Astrophysics , Vol. 361, 2000, pp. 407-414. bibcode : 2000A & A ... 361..407M
  3. ^ G. Hasinger et al .: A Deep X-Ray Survey in the Lockman-Hole and the Soft X-Ray N-Log . In: Astronomy and Astrophysics , Vol. 275, 1993, p. 1. bibcode : 1993A & A ... 275 .... 1H ;
    G. Hasinger et al .: The ROSAT Deep Survey. I. X-ray sources in the Lockman Field . In: Astronomy and Astrophysics , Vol. 329, 1998, pp. 482-494. bibcode : 1998A & A ... 329..482H
  4. ^ H. Brunner et al .: XMM observations of the Lockman Hole . In: Astronomy and Astrophysics , Vol. 479, 2008, p. 283B, bibcode : 2008yCat..34790283B ;
    IE Papadakis et al .: The long-term X-ray variability properties of AGNs in the Lockman Hole region . In: Astronomy and Astrophysics , Vol. 487, 2008, pp. 475-483. bibcode : 2008A & A ... 487..475P
  5. ^ A. Barger et al .: The Cosmic Evolution of Hard X-Ray-selected Active Galactic Nuclei . In: Astronomical Journal , Vol. 129, No. 2, pp. 578-609. bibcode : 2005AJ .... 129..578B

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