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Ground based gamma-ray observations with Imaging Atmospheric Cherenkov Telescopes (IACTs) play a significant role in the discovery of very high energy (E > 100 GeV) gamma-ray emitters. The analysis of IACT data demands a highly efficient…

(abridged) We present a new sample of X-ray selected galaxy groups and clusters serendipitously observed with Swift and the X-ray Telescope (XRT). We searched the XRT archive for extended sources among 336 GRB fields with galactic latitude…

宇宙学与河外天体物理 · 物理学 2012-11-15 Elena Tundo , Alberto Moretti , Paolo Tozzi , Liu Teng , Piero Rosati , Gianpiero Tagliaferri , Sergio Campana

The imaging of galaxy clusters through the Sunyaev--Zel'dovich effect is a valuable tool to probe the thermal pressure of the intra-cluster gas, especially in the outermost regions where X-ray observations suffer from photon statistics. For…

宇宙学与河外天体物理 · 物理学 2019-10-09 Anna Silvia Baldi , Hervé Bourdin , Pasquale Mazzotta , Dominique Eckert , Stefano Ettori , Massimo Gaspari , Mauro Roncarelli

We report on optical searches in the error circles of 93 ROSAT survey sources located at low galactic latitudes (|b| < 20 deg). These sources were extracted from the ROSAT Galactic Plane Survey using various selection criteria on hardness…

天体物理学 · 物理学 2016-08-30 C. Motch , P. Guillout , F. Haberl , J. Krautter , M. W. Pakull , W. Pietsch , K. Reinsch , W. Voges , F. -J. Zickgraf

We describe the application of a statistical method to estimate submillimeter galaxy number counts from confusion limited observations by the Balloon-borne Large Aperture Submillimeter Telescope (BLAST). Our method is based on a maximum…

Gamma ray astronomy is now at the leading edge for studies related both to fundamental physics and astrophysics. The sensitivity of gamma detectors is limited by the huge amount of background, constituted by hadronic cosmic rays (typically…

High-contrast imaging (HCI) is one of the most challenging techniques for exoplanet detection. It relies on sophisticated data processing to reach high contrasts at small angular separations. Most data processing techniques of this type are…

天体物理仪器与方法 · 物理学 2021-02-10 Carl-Henrik Dahlqvist , Olivier Absil

An intriguing challenge in observational astronomy is the separation signals in areas where multiple signals intersect. A typical instance of this in very-high-energy (VHE, E$\gtrsim$100 GeV) gamma-ray astronomy is the issue of residual…

高能天体物理现象 · 物理学 2025-01-14 Marion Ullmo , Emmanuel Moulin

Estimating the true background in an astronomical image is fundamental to detecting faint sources. In a typical low-photon count astronomical image, such as in the far and near-ultraviolet wavelength range, conventional methods relying on…

天体物理仪器与方法 · 物理学 2024-11-27 Pushpak Pandey , Kanak Saha

In recent years, Imaging Atmospheric Cherenkov Telescopes (IACTs) have discovered a rich diversity of very high energy (VHE, > 100 GeV) gamma-ray emitters in the sky. These instruments image Cherenkov light emitted by gamma-ray induced…

天体物理仪器与方法 · 物理学 2009-05-27 Stefan Ohm , Christopher van Eldik , Kathrin Egberts

The XMM Cluster Archive Super Survey (X-CLASS) is a serendipitously-detected X-ray-selected sample of 845 galaxy clusters based on 2774 XMM archival observations and covering approximately 90 deg$^2$ spread across the high-Galactic latitude…

宇宙学与河外天体物理 · 物理学 2017-04-12 J. Ridl , N. Clerc , T. Sadibekova , L. Faccioli , F. Pacaud , J. Greiner , T. Krühler , A. Rau , M. Salvato , M. -L. Menzel , H. Steinle , P. Wiseman , K. Nandra , J. Sanders

Extensive measurements of the X-ray background (XRB) yield a reasonably reliable characterisation of its basic properties. Having resolved most of the cosmic XRB into discrete sources, the levels and spectral shapes of its main components…

宇宙学与河外天体物理 · 物理学 2015-05-13 Doron Lemze , Sharon Sadeh , Yoel Rephaeli

In high-energy astrophysics, it is common practice to account for the background overlaid with the counts from the source of interest with the help of auxiliary measurements carried on by pointing off-source. In this "on/off" measurement,…

天体物理仪器与方法 · 物理学 2014-12-12 Diego Casadei

We propose to use a simple observable, the fractional area of "hot spots" in weak gravitational lensing mass maps which are detected with high significance, to determine background cosmological parameters. Because these high-convergence…

天体物理学 · 物理学 2011-02-11 Sheng Wang , Zoltán Haiman , Morgan May

The sensitivity of astronomical X-ray detectors is limited by the instrumental background. The background is especially important when observing low surface brightness sources that are critical for many of the science cases targeted by…

Many sources contribute to the diffuse gamma-ray background (DGRB), including star forming galaxies, active galactic nuclei, and cosmic ray interactions in the Milky Way. Exotic sources, such as dark matter annihilation, may also make some…

高能天体物理现象 · 物理学 2022-09-21 Eric J. Baxter , J. G. Christy , Jason Kumar

The search for faint emission or absorption lines in astronomical spectra has received considerable attention in recent years, especially in the X-ray wavelength range. These features usually appear as a deficit or excess of counts in a…

高能天体物理现象 · 物理学 2018-10-05 Massimiliano Bonamente

In this first paper of a series we develop a new technique to analyze clusters of galaxies observed during the ROSAT All-Sky Survey (RASS). We call this method the Steepness Ratio Technique (SRT). The SRT uses the convolution between the…

天体物理学 · 物理学 2009-10-30 S. De Grandi , S. Molendi , H. Böhringer , G. Chincarini , W. Voges

We present a new method designed for optimal subtraction of two images with different seeing. Using image subtraction appears to be essential for the full analysis of the microlensing survey images, however a perfect subtraction of two…

天体物理学 · 物理学 2016-08-30 C. Alard , R. H. Lupton

Galaxy clusters are one of the most powerful probes to study extensions of General Relativity and the Standard Cosmological Model. Upcoming surveys like the Vera Rubin Observatory's Legacy Survey of Space and Time are expected to…

宇宙学与河外天体物理 · 物理学 2024-06-19 Markus Michael Rau , Florian Kéruzoré , Nesar Ramachandra , Lindsey Bleem