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A fast X-ray timing capability on XEUS [article]

D. Barret, G. Skinner, E. Kendziorra, R. Staubert, M. Van der Klis
2002 arXiv   pre-print
The Rossi X-ray Timing Explorer has demonstrated that fast X-ray timing can be used to probe strong gravity fields around collapsed objects and constrain the equation of state of dense matter in neutron  ...  For this reason, it has been proposed to include a fast X-ray timing capability in the focal plane of the XEUS mirrors.  ...  Acknowledgements We are grateful to the following colleagues who are supporting the proposal for a fast X-ray timing capability for XEUS: The authors are grateful to A.  ... 
arXiv:astro-ph/0202451v1 fatcat:uvighcslb5dxxby65uy3kekdli

A fast X-ray timing capability on XEUS [article]

D. Barret, G. Skinner, E. Kendziorra, R. Staubert, P. Lechner, L. Struder (MPI Halbleiterlator, Germany), M. van der Klis (University of Amsterdam, The Netherlands), L. Stella and C. Miller (University of Maryland, United states)
2002 arXiv   pre-print
Fast X-ray timing can be used to probe strong gravity fields around collapsed objects and constrain the equation of state of dense matter in neutron stars.  ...  For this reason, we propose to include a fast X-ray timing capability in the focal plane of the XEUS mirrors. We briefly outline the scientific motivation for such a capability.  ...  We are grateful to the following colleagues who are supporting the proposal for a fast X-ray timing capability  ... 
arXiv:astro-ph/0206028v1 fatcat:mebcnhig65bjrleaxvxlbgxyvm

MAGIC Highlights [article]

Josep M. Paredes, MAGIC Collaboration
2020 arXiv   pre-print
MAGIC has been exploring the sky at Very High Energy gamma-rays (50 GeV - 50 TeV) since 2004, operating first with a single telescope and from 2009 with two telescopes in stereoscopic mode.  ...  For z ∼ 1 the EBL cut-off is at ∼ 100 GeV, at the border of IACT sensitivity. MAGIC, thanks to its low-energy threshold, has been able to detect the farthest objects ever observed in the TeV sky.  ...  MAGIC GRB program The design of MAGIC was optimized for working at low energy and with a fast repositioning.  ... 
arXiv:2003.03841v1 fatcat:oyckpb4qzzerbjals4t3o73bhe

Recent Results from the MAGIC Telescopes

Dorit Eisenacher Glawion, MAGIC Collaboration
2016 Münster  
Furthermore, the detection of very-high-energy gamma-ray emission from two active galaxies, B0,218$+$357 and PKS,1441$+$25, located at redshift of $\sim$0.94 is presented.  ...  Also, the ultra-fast variability of IC,310, which challenges jet emission models in AGNs, is discussed.  ...  Thus, MAGIC detected the object with a significance of more than 5 σ at ∼ 12 d after the flare seen by Fermi-LAT [16] .  ... 
doi:10.3204/desy-proc-2016-05/24 fatcat:ujplaqgjpzdstjwjexoa5zzidq

FERMILARGE AREA TELESCOPE CONSTRAINTS ON THE GAMMA-RAY OPACITY OF THE UNIVERSE

A. A. Abdo, M. Ackermann, M. Ajello, A. Allafort, W. B. Atwood, L. Baldini, J. Ballet, G. Barbiellini, M. G. Baring, D. Bastieri, B. M. Baughman, K. Bechtol (+181 others)
2010 Astrophysical Journal  
We place upper limits on the gamma-ray opacity of the Universe at various energies and redshifts, and compare this with predictions from well-known EBL models.  ...  The Extragalactic Background Light (EBL) includes photons with wavelengths from ultraviolet to infrared, which are effective at attenuating gamma rays with energy above ~10 GeV during propagation from  ...  L.R.C. acknowledges support by the Kavli Institute for Cosmological Physics at the University of Chicago through grants NSF PHY-0114422 and NSF PHY-0551142 and an endowment from the Kavli Foundation and  ... 
doi:10.1088/0004-637x/723/2/1082 fatcat:nkkstehiunhcppzknj7uxx74ie

BL LAC POPULATION STUDY AT HIGH ENERGIES

LUCIE GÉRARD, GILLES HENRI, SANTIAGO PITA, MICHAEL PUNCH
2014 International Journal of Modern Physics, Conference Series  
The population of BL Lacs emitting at High Energy (> 100 MeV) is used in order to constrain the jet characteristics of the objects: its intrinsic luminosity, Lorentz factor and geometrical opening angle  ...  The density of the AGN population associated with BL Lacs and the Doppler factor of the objects detectable at HE are estimated as a function of the jet parameters.  ...  In this study, the population of BL Lacs emitting at HE is considered to constrain the intrinsic properties of these objects.  ... 
doi:10.1142/s201019451460177x fatcat:ihf66s2hbvcflieyfpxuooq57a

XTRA: The fast X-ray timing detector on XEUS

Didier Barret
2004 AIP Conference Proceedings  
By combining fast X-ray timing and spectroscopy, XTRA will thus provide the first real opportunity to test general relativity in the strong gravity field regime and to constrain with unprecedented accuracy  ...  the equation of state of matter at supranuclear density.  ...  This again offers independent opportunities to constrain the compact object mass and spin, as well as the radius at which the line is produced.  ... 
doi:10.1063/1.1781063 fatcat:6xe4cafnyzfjtjdzwqmealydha

Black Hole Lightning from the Peculiar Gamma-Ray Loud Active Galactic Nucleus IC 310 [article]

Dorit Eisenacher Glawion, Julian Sitarek, Karl Mannheim, Pierre Colin, for the MAGIC Collaboration, Matthias Kadler, Robert Schulz, Eduardo Ros, Uwe Bach, Felicia Krauß, Jörn Wilms
2015 arXiv   pre-print
The fast variability constrains the size of the gamma-ray emission regime to be smaller than 20% of the gravitational radius of its central black hole.  ...  spectrum over two decades in energy.  ...  This object has been detected at high energies above 30 GeV with Fermi/LAT [6] as well as at very high energies above 260 GeV by MAGIC [7, 8] .  ... 
arXiv:1508.05031v1 fatcat:2wqaworvdrgrjofcjkxcm55hyi

AGILE Observations of Two Repeating Fast Radio Bursts with Small Intrinsic Dispersion Measure [article]

C. Casentini, F. Verrecchia, M. Tavani, A. Ursi, L.A. Antonelli, A. Argan, G. Barbiellini, A. Bulgarelli, P. Caraveo, M. Cardillo, P.W. Cattaneo, A. Chen, E. Costa (+20 others)
2019 arXiv   pre-print
Fast radio bursts (FRBs) are transient radio sources of unknown origin.  ...  The sources are constrained to emit an MeV-fluence in the millisecond range below F'_MeV = 10^-8 erg cm^-2 corresponding to an isotropic energy near E_MeV,UL≃ 10^ 40 erg for an assumed distance of 100  ...  CONCLUSIONS Fast radio bursts continue to be puzzling with features that are not satisfactorily explained in current modelling of compact objects.  ... 
arXiv:1911.10189v1 fatcat:rjdf2an3zvhkhe5va42vdnezou

Learning Pixel-Wise Signal Energy for Understanding Semantics

J Ng, S Gong
2001 Procedings of the British Machine Vision Conference 2001  
Gaussian mixture models are used to model slow long-term changes in pixel distributions while pixel energy histories are used to extract fast-change signatures from short-term events and modelled by CONDENSATION  ...  We propose a new pixel-level approach for learning the temporal characteristics of change at individual pixels.  ...  However, object segmentation and trajectory extraction relies on spatial proximity (region-growing) and temporally constrained correlations.  ... 
doi:10.5244/c.15.71 dblp:conf/bmvc/NgG01 fatcat:3z7pigfkevhhrkmunicbod5q7a

Learning pixel-wise signal energy for understanding semantics

Jeffrey Ng, Shaogang Gong
2003 Image and Vision Computing  
Gaussian mixture models are used to model slow long-term changes in pixel distributions while pixel energy histories are used to extract fast-change signatures from short-term events and modelled by CONDENSATION  ...  We propose a new pixel-level approach for learning the temporal characteristics of change at individual pixels.  ...  However, object segmentation and trajectory extraction relies on spatial proximity (region-growing) and temporally constrained correlations.  ... 
doi:10.1016/j.imavis.2003.09.001 fatcat:ib3zf2f4w5ajzppkcewrbdatze

Fourier Locally Linear Soft Constrained MACE for facial landmark localization

Wenming Yang, Xiang Sun, Weihong Deng, Chi Zhang, Qingmin Liao
2016 CAAI Transactions on Intelligence Technology  
Then, soft constrained Minimum Average Correlation Energy filter (soft constrained MACE) is proposed, which is more resistent to overfittings to training set than other variants of correlation filter.  ...  The merits of our method include accurate localization performance, desiring generalization capability to the variance of objects, fast testing speed and insensitivity to parameter settings.  ...  Soft constrained MACE which minimizes the average correlation energy is written as: miñ hh H Sh þ C X i  1 À y i Àh Hx i þ b Áà þ ð6Þ In order to minimize the objective function, if a diagonal entry of  ... 
doi:10.1016/j.trit.2016.10.006 fatcat:nlldrhgld5cmjgxevtmxvu67iq

A FAST FLARE AND DIRECT REDSHIFT CONSTRAINT IN FAR-ULTRAVIOLET SPECTRA OF THE BLAZAR S5 0716+714

Charles W. Danforth, Krzysztof Nalewajko, Kevin France, Brian A. Keeney
2013 Astrophysical Journal  
A system at z=0.2315 is detected in Lya, Lyb, OVI, and NV and defines the lower bound on the source redshift.  ...  This is the first direct redshift limit for this object and is consistent with literature estimates of z=0.31+-0.08 based on the detection of a host galaxy.  ...  This work was supported by NASA grants NNX08AC146 and NAS5-98043 to the University of Colorado at Boulder. The authors made extensive use of the MAST, ADS, and IGwAD Archives during this work.  ... 
doi:10.1088/0004-637x/764/1/57 fatcat:uvulnvddyvcrpak4dibiywr27u

A fast and stable snake algorithm for medical images

Dong Joong Kang
1999 Pattern Recognition Letters  
The algorithm is able to rapidly detect convex and concave objects even when the image quality is poor. Ó  ...  An active contour in this objective is optimized by a dynamic programming algorithm, for which a new constraint that has fast and stable properties is introduced.  ...  It allows for a fast and stable detection of object boundaries in MRI sequences with low contrast and noisy edge peaks.  ... 
doi:10.1016/s0167-8655(99)00019-7 fatcat:ewlc3x4b2besfdqmxi3vmc7c3u

Hunting the gamma-ray emission from Fast Radio Burst with Fermi-LAT [article]

Giacomo Principe, Nicola Omodei, Niccolò Di Lalla, Leonardo Di Venere, Francesco Longo
2021 arXiv   pre-print
In addition, we perform the first stacking analysis at GeV energies of this class of sources in order to constrain the gamma-ray properties of the FRBs that are undetected at high energies.  ...  The recent detection of a MGF at GeV energies by the Fermi Large Area Telescope (LAT) motivated the search for GeV counterparts to the >100 currently known FRBs.  ...  ACKNOWLEDGMENTS We acknowledge use of the CHIME/FRB Public Database, provided at https://www.chimefrb.ca/ by the CHIME/FRB Collaboration. The  ... 
arXiv:2109.03548v2 fatcat:zb7megzuyfe5xmnvolxlve53ka
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