Results 21 to 30 of about 17,981 (269)
An Optical View of Extragalactic γ-Ray Emitters
Frontiers in Astronomy and Space Sciences, 2017 The Fermi Gamma-ray Observatory discovered about a thousand extragalactic sources emitting energy from 100 MeV to 100 GeV. The majority of these sources belong to the class of blazars characterized by a quasi-featureless optical spectrum (BL Lac Objects).
Simona Paiano +6 more
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Sakarya University Journal of Education, 2018 Bu çalışmanın amacı, Hubble’ın “Kırmızıya KaymaYasası” çerçevesinde test oluşturularak fen bilgisi öğretmen adaylarının bilgive bilişsel süreç yeterliklerinin incelenmesidir. Araştırmada nitel durumçalışması deseni kullanılmıştır.
Nilgün Aydın, Abdullah Aydın
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Redshifting rings of power [PDF]
Physical Review D, 2003 The cosmic microwave background (CMB) has provided a precise template for features in the linear power spectrum: the matter-radiation turnover, sound horizon drop, and acoustic oscillations. In a two dimensional power spectrum in redshift and angular space, the features appear as distorted rings, and yield simultaneous, purely geometric, measures of ...
Hu, Wayne, Haiman, Zoltan
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Metals at High Redshifts [PDF]
Proceedings of the International Astronomical Union, 2001 The amount of metals present in the Universe and its cosmological evolution is a key issue for our understanding of how star formation proceeds from the collapse of the first objects to the formation of present day galaxies. We discuss here recent results at the two extremes of the density scale.1.
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Variable G versus the Accelerated Expansion of the Universe
Open Astronomy, 2017 It is shown that the hypothesis of permitting variability of the Newtonian constant G, increasing with the local density of dark matter, implies that there is no need for the introduction of a cosmological constant or accelerated expansion of the ...
Colenbrander Bernard G. +1 more
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Reproductive Biology and Endocrinology, 2020 Background Numerous studies have demonstrated substantial differences in assisted reproductive technology outcomes between black non-Hispanic and white non-Hispanic women. We sought to determine if disparities in assisted reproductive technology outcomes
D. B. Seifer +3 more
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Redshift Survey of 12 Moderate-redshift Clusters
Research Notes of the AAS, 2022 Abstract We conducted a redshift survey of 12 X-ray selected clusters in the redshift range z = 0.35–0.50 with MMT/Hectospec. The redshift surveys confirm that these clusters are massive systems. There are no massive groups or clusters projected along the line of sight that might contaminate the observed cluster X-ray properties ...
Kenneth J. Rines, Margaret J. Geller
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High-redshift cosmography [PDF]
Journal of Cosmology and Astroparticle Physics, 2010 We constrain the parameters describing the kinematical state of the universe using a cosmographic approach, which is fundamental in that it requires a very minimal set of assumptions (namely to specify a metric) and does not rely on the dynamical equations for gravity.
Vitagliano, V. +3 more
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Peering into the Cosmic Dawn: JWST Cycle 1 Data Reveals Early Galaxy Candidates at Redshifts z > 9.5
Edinburgh Student Journal of ScienceObserving high-redshift objects provides a window into the past, enabling insight into galaxy formation, matter distribution, and the nature of dark matter and energy.
Sev Zielinska
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On the Observation of Distant Objects in General Relativity and Its Implications in Cosmology
UniverseWe carry out a careful analysis of the notion of observation of distant events in a curved Universe. This leads us to hypothesise that all measurements of our physical environment are performed with respect to a representation referential that obeys the ...
Théophile Caby
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