Radio-loud ROSAT sources near the North Ecliptic Pole

Brinkmann, W.; Chester, M.; Kollgaard, R. I.; Feigelson, E. D.; Voges, W.; Hertz, P.

doi:10.1051/aas:1999136

Cited by 14 publications

(22 citation statements)

References 44 publications

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“…The redshifts of the four other extended X-ray sources are still unknown and may possibly coincide with known overdensities. If the coincidence of X-ray groups and clusters with known '' filaments '' in the CDF-N region is anything like that in the ROSAT North Ecliptic Pole Survey, we should expect at least 25% (or $2) of the extended X-ray sources to lie within such large-scale structures (e.g., Burg et al 1992;Brinkmann et al 1999;Mullis et al 2001). Alternatively, we find no evidence for X-ray emission associated with the optically detected cluster ClG 1236+6215.…”

Section: Coincidence Of X-ray Emission Withmentioning

confidence: 99%

The Chandra Deep Field North Survey. IX. Extended X-Ray Sources

Bauer¹,

Alexander²,

Brandt³

et al. 2002

The Astronomical Journal

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The %1 Ms Chandra Deep Field North observation is used to study the extended X-ray sources in the region surrounding the Hubble Deep Field North (HDF-N), yielding the most sensitive probe of extended X-ray emission at cosmological distances to date. A total of six such sources are detected, the majority of which align with small numbers of optically bright galaxies. Their angular sizes, band ratios, and X-ray luminosities-assuming they lie at the same distances as the galaxies coincident with the X-ray emission-are generally consistent with the properties found for nearby groups of galaxies. One source is notably different and is likely to be a poor-to-moderate X-ray cluster at high redshift (i.e., z & 0.7). This source has a large angular extent, a double-peaked X-ray morphology, and an overdensity of unusual objects [very red objects, optically faint (I ! 24) radio and X-ray sources]. Another of the six sources is coincident with several z % 1.01 galaxies located within the HDF-N itself, including the FR I radio galaxy VLA J123644+621133, and is likely to be a group or poor cluster of galaxies at that redshift. We are also able to place strong constraints on the optically detected cluster of galaxies ClG 1236+6215 at z = 0.85 and the wide-angle-tailed radio galaxy VLA J123725+621128 at z $ 1-2; both sources are expected to have considerable associated diffuse X-ray emission, and yet they have rest-frame 0.5-2.0 keV X-ray luminosities of .3 Â 10 42 and .(3-15) Â 10 42 ergs s À1 , respectively. The environments of both sources are either likely to have a significant deficit of hot intracluster gas compared with local clusters of galaxies, or they are X-ray groups. We find the surface density of extended X-ray sources in this observation to be 167 þ97 À67 deg À2 at a limiting soft-band flux of %3 Â 10 À16 ergs cm À2 s À1 . No evolution in the X-ray luminosity function of clusters is needed to explain this value.

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Section: Coincidence Of X-ray Emission Withmentioning

confidence: 99%

The Chandra Deep Field North Survey. IX. Extended X-Ray Sources

Bauer¹,

Alexander²,

Brandt³

et al. 2002

The Astronomical Journal

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“…Our deep counts shall be used to identify sources in deep X-ray and far-infrared surveys (Brinkmann et al 1999;Hacking & Houck 1987) and study their broad band energy distribution.…”

Section: Modelsmentioning

confidence: 99%

A wide field survey at the Northern Ecliptic Pole

Kümmel

Wagner²

2001

A&A

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Abstract. We present a medium deep survey carried out in the three filters Bj, R and K. The survey covers homogeneously the central square degree around the Northern Ecliptic Pole (NEP) down to a completeness limit (95%) of 24.25, 23.0 and 17.5 mag in Bj, R and K, respectively. While the near infrared data have been presented in the first paper of this series, here we concentrate on the optical data and the results based on the combined BjRK-data. The unique combination of area and depth in our survey allows to perform a variety of investigations based on homogeneous material covering more than ten magnitudes in apparent brightness. We analyze the number counts for point-like and extended sources in Bj and R to determine the slopes in d log N/dm and to test for possible breaks therein. While we can confirm the slopes found in previous works with a higher statistical significance, the largest uncertainty remaining for the amplitudes is galactic extinction. We determine the colour distributions of galaxies in Bj − R and R − K down to Bj = 24.0 and K = 18.0 mag, respectively. The distributions in both colours are modeled using galaxy spectral evolution synthesis. We demonstrate that the standard models of galaxy evolution are unable to reproduce the steady reddening trend in R − K despite flawless fits to the colour distributions in the optical (Bj −R). The BjRK data collected over a large area provides the opportunity to select rare objects like candidates for high-redshift galaxies and extremely red objects (EROs, R − K > 5.0) and to determine their surface density. Our EROs are selected at an intermediate magnitude range and contain contribution from both galactic as well as extragalactic sources. At K < 16.5 mag, where a morphological classification is possible, the stellar component dominates the sample.

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“…The relativistic generalization of the Bondi type accretion has been used for analysing accretion around a black hole [57,58]. It has been demonstrated that radiative processes can have interesting effects for accretion around a black hole [59,60,61] or other spherically symmetric space-times [62]. The accretion also gets effected from rotation of a black hole [63].…”

Section: Resultsmentioning

confidence: 99%

The effect of modified dispersion relation on dumb holes

Dutta

Gangopadhyay

Bahamonde

et al. 2018

Int. J. Mod. Phys. D

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In this paper, we will deform the usual energy-momentum dispersion relation of a photon gas at an intermediate scale between the Planck and electroweak scales. We will demonstrate that such a deformation can have non-trivial effects on the physics of dumb holes. So, motivated by the physics of dumb holes, we will first analyse the effect of such a deformation on thermodynamics. Then we observe that the velocity of sound also gets modified due to such a modification of the thermodynamics. This changes the position of the horizon of a dumb holes, and the analogous Hawking radiation from a dumb hole. Therefore, dumb holes can be used to measure the deformation of the usual energy-momentum dispersion relation. *

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Radio-loud ROSAT sources near the North Ecliptic Pole

Cited by 14 publications

References 44 publications

The Chandra Deep Field North Survey. IX. Extended X-Ray Sources

The Chandra Deep Field North Survey. IX. Extended X-Ray Sources

A wide field survey at the Northern Ecliptic Pole

The effect of modified dispersion relation on dumb holes

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