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With a decade of gamma-ray data from the Fermi-LAT telescope, we can now hope to answer how well we know the local Universe at gamma-ray frequencies. On the other hand, with gamma-ray data alone it is not possible to directly access the…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-27 Simone Ammazzalorso , Nicolao Fornengo , Shunsaku Horiuchi , Marco Regis

We study whether hierarchical galaxy formation in a concordance $\Lambda$CDM universe can produce enough massive and red galaxies compared to the observations. We implement a semi-analytical model in which the central black holes gain their…

Astrophysics · Physics 2008-11-26 X. Kang , Y. P. Jing , J. Silk

The AGN-galaxy cross-correlation function of radio-quiet AGN and radio galaxies has been measured with the Panoramic Deep Fields. Colour selection criteria and photometric redshifts have been used to significantly increase the…

Astrophysics · Physics 2007-05-23 M. J. I. Brown

Active galactic nuclei (AGN) with jets seen at small viewing angles are the most luminous and abundant objects in the $\gamma$-ray sky. AGN with jets misaligned along the line-of-sight appear fainter in the sky, but are more numerous than…

High Energy Astrophysical Phenomena · Physics 2015-06-15 M. Di Mauro , F. Calore , F. Donato , M. Ajello , L. Latronico

Overdense regions at high redshift ($z \gtrsim 2$) are perfect laboratories to study the relations between environment and SMBH growth, and the AGN feedback processes on the surrounding galaxies and diffuse gas. In this white paper, we…

Instrumentation and Methods for Astrophysics · Physics 2023-11-16 Fabio Vito , Paolo Tozzi , Roberto Gilli , Stefano Marchesi , Nico Cappelluti , Adi Foord

We explore the potential of an artificial neural network (ANN) based method intelligence to probe the propagation of cosmic $\gamma$-ray photons in the extragalactic Universe. The journey of $\gamma$-rays emitted from a distant source like…

High Energy Astrophysical Phenomena · Physics 2021-09-29 K K Singh , V K Dhar , P J Meintjes

The artificial neural network (ANN) is a well-established mathematical technique for data prediction, based on the identification of correlations and pattern recognition in input training sets. We present the application of ANNs to predict…

Astrophysics of Galaxies · Physics 2014-05-05 Hossein Teimoorinia , Sara L. Ellison

We present the analysis and results of a spectroscopic follow-up program of a mass-selected sample of six galaxies at 3 < z < 4 using data from Keck-NIRSPEC and VLT-Xshooter. We confirm the z > 3 redshifts for half of the sample through the…

We propose a new method to estimate the photometric redshift of galaxies by using the full galaxy image in each measured band. This method draws from the latest techniques and advances in machine learning, in particular Deep Neural…

Instrumentation and Methods for Astrophysics · Physics 2016-06-16 Ben Hoyle

The unrivalled, extreme luminosities of gamma-ray bursts (GRBs) make them the favored beacons for sampling the high redshift Universe. To employ GRBs to study the cosmic terrain -- e.g., star and galaxy formation history -- GRB luminosities…

Astrophysics · Physics 2007-05-23 J. P. Norris

We use the optical--infrared imaging in the UKIDSS Ultra Deep Survey field, in combination with the new deep radio map of Arumugam et al., to calculate the distribution of radio luminosities among galaxies as a function of stellar mass in…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Chris Simpson , Paul Westoby , Vinod Arumugam , Rob Ivison , Will Hartley , Omar Almaini

Asteroseismology is used to infer the interior physics of stars. The \textit{Kepler} and TESS space missions have provided a vast data set of red-giant light curves, which may be used for asteroseismic analysis. These data sets are expected…

Solar and Stellar Astrophysics · Physics 2022-07-22 Siddharth Dhanpal , Othman Benomar , Shravan Hanasoge , Abhisek Kundu , Dattaraj Dhuri , Dipankar Das , Bharat Kaul

We present new observational determinations of the evolution of the 2-10keV X-ray luminosity function (XLF) of AGN. We utilise data from a number of surveys including both the 2Ms Chandra Deep Fields and the AEGIS-X 200ks survey, enabling…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 J. Aird , K. Nandra , E. S. Laird , A. Georgakakis , M. L. N. Ashby , P. Barmby , A. L. Coil , J. -S. Huang , A. M. Koekemoer , C. C. Steidel , C. N. A. Willmer

Analysis of the frequency and physical properties of galaxies with star-formation and AGN activity in different environments in the local universe is a cornerstone for understanding structure formation and galaxy evolution. We have built a…

Astrophysics · Physics 2008-11-26 Pietro Reviglio , David J. Helfand

The kinematic disturbances associated with major galaxy mergers are known to produce gas inflows, which in turn may trigger accretion onto the supermassive black holes (SMBH) of the participant galaxies. While this effect has been studied…

Astrophysics of Galaxies · Physics 2023-01-25 Robert W. Bickley , Sara L. Ellison , David R. Patton , Scott Wilkinson

We use 80922 galaxies in the Galaxy And Mass Assembly (GAMA) survey to measure the galaxy luminosity function (LF) in different environments over the redshift range 0.04<z<0.26. The depth and size of GAMA allows us to define samples split…

Sensitive Herschel far-infrared observations can break degeneracies that were inherent to previous studies of star formation in high-z AGN hosts. Combining PACS 100 and 160um observations of the GOODS-N field with 2Msec Chandra data, we…

We calculate photometric redshifts from the Sloan Digital Sky Survey Data Release 2 Galaxy Sample using artificial neural networks (ANNs). Different input patterns based on various parameters (e.g. magnitude, color index, flux information)…

Astrophysics · Physics 2007-05-23 Lili Li , Yanxia Zhang , Yongheng Zhao , Dawei Yang

Gamma-ray bursts (GRBs) can be probes of the early universe, but currently, only 26% of GRBs observed by the Neil Gehrels Swift Observatory GRBs have known redshifts ($z$) due to observational limitations. To address this, we estimated the…

Gamma-ray bursts (GRBs) detected at high redshift can be used to trace the Hubble diagram of the Universe. However, the distance calibration of GRBs is not as easily as that of type Ia supernovae (SNe Ia). For the calibrating method based…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-23 Li Tang , Xin Li , Hai-Nan Lin , Liang Liu