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Related papers: Application of a Bayesian Method to Absorption Spe…

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HI 21~cm absorption spectroscopy provides an excellent probe of the neutral gas content of absorbing galaxies, yielding information on their kinematics, mass, physical size and ISM conditions. The high sensitivity, unrivaled frequency…

Astrophysics · Physics 2009-11-10 N. Kanekar , F. H. Briggs

We describe the scientific goals and survey design of the First Large Absorption Survey in HI (FLASH), a wide field survey for 21-cm line absorption in neutral atomic hydrogen (HI) at intermediate cosmological redshifts. FLASH will be…

Bayesian data analysis techniques, together with suitable statistical models, can be used to obtain much more information from noisy data than the traditional frequentist methods. For instance, when searching for periodic signals in noisy…

Earth and Planetary Astrophysics · Physics 2015-06-12 Mikko Tuomi

We present an analysis of the HI absorption in a sample of 101 flux-selected radio AGN (S_1.4 GHz > 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). HI absorption is detected in 32 galaxies, showing a broad variety of…

Astrophysics of Galaxies · Physics 2015-06-23 K. Gereb , F. M. Maccagni , R. Morganti , T. A. Oosterloo

Recent targeted studies of associated HI absorption in radio galaxies are starting to map out the location, and potential cosmological evolution, of the cold gas in the host galaxies of Active Galactic Nuclei (AGN). The observed 21 cm…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 J. R. Allison , E. M. Sadler , S. J. Curran , S. N. Reeves

Using archival data from the HI Parkes All Sky Survey (HIPASS) we have searched for 21 cm line absorption in 204 nearby radio and star-forming galaxies with continuum flux densities greater than $S_{1.4} \approx 250$ mJy within the redshift…

Astrophysics of Galaxies · Physics 2015-06-18 J. R. Allison , E. M. Sadler , A. M. Meekin

Methods currently in use for locating and characterising sources in radio interferometry maps are designed for processing images, and require interferometric maps to be preprocessed so as to resemble conventional images. We demonstrate a…

Instrumentation and Methods for Astrophysics · Physics 2018-12-26 Peter Hague , Haoyang Ye , Bojan Nikolic , Steve Gull

One of the greatest data analysis challenges for the Laser Interferometer Space Antenna (LISA) is the need to account for a large number of gravitational wave signals from compact binary systems expected to be present in the data. We…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Richard Umstätter , Nelson Christensen , Martin Hendry , Renate Meyer , Vimal Simha , John Veitch , Sarah Vigeland , Graham Woan

A survey of the Milky Way disk and the Magellanic System at the wavelengths of the 21-cm atomic hydrogen (HI) line and three 18-cm lines of the OH molecule will be carried out with the Australian Square Kilometre Array Pathfinder telescope.…

Spectrum sensing in a large-scale heterogeneous network is very challenging as it usually requires a large number of static secondary users (SUs) to obtain the global spectrum states. To tackle this problem, in this paper, we propose a new…

Information Theory · Computer Science 2018-11-26 Yizhen Xu , Peng Cheng , Zhuo Chen , Yonghui Li , Branka Vucetic

We present a pilot study of extragalactic HI 21-cm absorption lines using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). We observed 5 continuum sources with HI absorption features firstly identified in the 40% data…

Astrophysics of Galaxies · Physics 2021-03-31 Bo Zhang , Ming Zhu , Zhong-Zu Wu , Qing-Zheng Yu , Peng Jiang , You-Ling Yue , Meng-Lin Huang , Qiao-Li Hao

Radio weak lensing, while a highly promising complementary probe to optical weak lensing, will require incredible precision in the measurement of galaxy shape parameters. In this paper, we extend the Bayesian Inference for Radio…

Instrumentation and Methods for Astrophysics · Physics 2018-11-05 M. Rivi , M. Lochner , S. T. Balan , I. Harrison , F. B. Abdalla

Recent studies have shown that both 21cm HI absorption and soft X-ray absorption serve as excellent tracers of the dense and dusty gas near the active nucleus of young radio galaxies, offering new insight into the physical nature of the…

Astrophysics of Galaxies · Physics 2022-01-05 Emily F. Kerrison , Vanessa A. Moss , Elaine M. Sadler , James R. Allison

We explore the multiphase structure of the circumgalactic medium (CGM) probed by synthetic spectra through a cosmological zoom-in galaxy formation simulation. We employ a Bayesian method for modelling a combination of absorption lines to…

Astrophysics of Galaxies · Physics 2018-07-11 Cameron Liang , Andrey Kravtsov , Oscar Agertz

Automated source extraction and parameterization represents a crucial challenge for the next-generation radio interferometer surveys, such as those performed with the Square Kilometre Array (SKA) and its precursors. In this paper we present…

Instrumentation and Methods for Astrophysics · Physics 2016-05-09 S. Riggi , A. Ingallinera , P. Leto , F. Cavallaro , F. Bufano , F. Schillirò , C. Trigilio , G. Umana , C. S. Buemi , R. P. Norris

A theoretical model of the influence of detection bandwidth properties on observed line shapes in laser absorption spectroscopy is described. The model predicts artificial frequency shifts, extra broadenings and line asymmetries which must…

The use of continuum emission radio galaxies as cosmological tracers of the large-scale structure will soon move into a new phase. Upcoming surveys from the Australian Square Kilometre Array Pathfinder (ASKAP), MeerKAT, and the Square…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-28 Jacobo Asorey , David Parkinson

We present results from a search for the HI 21-cm line in absorption towards 16 bright radio sources with the 6-antenna commissioning array of the Australian Square Kilometre Array Pathfinder (ASKAP). Our targets were selected from the 2-Jy…

Strong evidence has recently emerged for a variation in the fine structure constant, $\alpha\equiv e^2/\hbar c$, over the history of the Universe. This was concluded from a detailed study of the relative positions of redshifted optical…

Astrophysics · Physics 2009-11-10 S. J. Curran , N. Kanekar , J. K. Darling

Spectroscopy is an important tool for probing the properties of materials, chemicals and biological samples. We design a practical transmitter-receiver system that exploits entanglement to achieve a provable quantum advantage over all…

Quantum Physics · Physics 2020-11-03 Haowei Shi , Zheshen Zhang , Stefano Pirandola , Quntao Zhuang