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Non-negative matrix factorization (NMF) is widely used as a feature extraction technique for matrices with non-negative entries, such as image data, purchase histories, and other types of count data. In NMF, a non-negative matrix is…

统计计算 · 统计学 2026-01-01 Ryo Ohashi , Hiroyasu Abe , Fumitake Sakaori

The light we receive from distant astrophysical objects carries information about their origins and the physical mechanisms that power them. The study of these signals, however, is complicated by the fact that observations are often a…

We reconstruct the extra-galactic gamma-ray source-count distribution, or $dN/dS$, of resolved and unresolved sources by adopting machine learning techniques. Specifically, we train a convolutional neural network on synthetic 2-dimensional…

宇宙学与河外天体物理 · 物理学 2024-05-16 Aurelio Amerio , Alessandro Cuoco , Nicolao Fornengo

We introduce a distinct method to perform spatially-resolved spectral analysis of astronomical sources with highly structured X-ray emission. The method measures the surface brightness of neighbouring pixels to adaptively size and shape…

高能天体物理现象 · 物理学 2016-05-18 G. J. M. Luna , M. J. S. Smith , G. Dubner , E. Giacani , G. Castelletti

Several classes of astrophysical sources contribute to the approximately isotropic gamma-ray background measured by the Fermi Gamma-Ray Space Telescope. In this paper, we use Fermi's catalog of gamma-ray sources (along with corresponding…

宇宙学与河外天体物理 · 物理学 2015-06-18 Ilias Cholis , Dan Hooper , Samuel D. McDermott

We present an alternative estimate of the unresolved point source contribution to the WMAP temperature power spectrum based on current knowledge of sources from radio surveys in the 1.4-90 GHz range. We implement a stochastic extrapolation…

宇宙学与河外天体物理 · 物理学 2015-05-18 Loris P. L. Colombo , Elena Pierpaoli

We implemented a novel technique to perform the collective spectral analysis of sets of multiple gamma-ray point sources using the data collected by the Large Area Telescope onboard the Fermi satellite. The energy spectra of the sources are…

天体物理仪器与方法 · 物理学 2012-08-02 M. N. Mazziotta , F. Loparco , F. de Palma , N. Giglietto

Approximately one-third of the gamma-ray sources in the third Fermi-LAT catalog are unidentified or unassociated with objects at other wavelengths. Observations with Swift-XRT have yielded possible counterparts in $\sim$30% of these source…

高能天体物理现象 · 物理学 2020-01-08 Amanpreet Kaur , Abraham D Falcone , Michael D Stroh , Jamie A Kennea , Elizabeth C Ferrara

Indirect searches for dark matter using dwarf spheroidal galaxies are limited by systematic uncertainties in modeling diffuse gamma-ray backgrounds. We present a likelihood-based comparison of locally constructed empirical background models…

高能天体物理现象 · 物理学 2026-03-06 Chance Hoskinson , Jason Kumar , Pearl Sandick

We present the strongest robust constraints on primordial non-Gaussianity (PNG) from currently available galaxy surveys, combining large-scale clustering measurements and their cross-correlations with the cosmic microwave background. We…

The Large Area Telescope (LAT) aboard the Fermi satellite allows us to study the high-energy gamma-ray sky with unprecedented sensitivity. However, the origin of 31% of the detected gamma-ray sources remains unknown. This population of…

高能天体物理现象 · 物理学 2015-05-27 Hannes-S. Zechlin , Dieter Horns

The time-frequency map (TFM) is frequently used in condition monitoring, necessitating further processing to select an informative frequency band (IFB) or directly detect damage. However, selecting an IFB is challenging due to the…

信号处理 · 电气工程与系统科学 2026-04-28 Anna Michalak , Justyna Hebda-Sobkowicz , Anil Kumar , Radoslaw Zimroz , Rafal Zdunek , Agnieszka Wylomanska

The Chinese Space Station Survey Telescope (CSST) presents significant potential for high-precision astrometry. In this study, we show that the point spread function (PSF) modeled by the discrete PSF with Multi-Gaussian function can…

天体物理仪器与方法 · 物理学 2025-08-15 Jialu Nie , Peng Wei , Zihuang Cao , Yibo Yan , Chao Liu , Hao Tian , Xin Zhang , Haijun Tian

Thermal photons from the photosphere may be the primary source of the observed prompt emission of gamma-ray bursts (GRBs). In order to produce the observed non-thermal spectra, some kind of dissipation mechanism near the photosphere is…

高能天体物理现象 · 物理学 2015-06-16 K. Asano , P. Mészáros

We present the first Fermi Large Area Telescope (LAT) catalog of long-term $\gamma$-ray transient sources (1FLT). This comprises sources that were detected on monthly time intervals during the first decade of Fermi-LAT operations. The…

高能天体物理现象 · 物理学 2021-09-29 L. Baldini , J. Ballet , D. Bastieri , J. Becerra Gonzalez , R. Bellazzini , A. Berretta , E. Bissaldi , R. D. Blandford , E. D. Bloom , R. Bonino , E. Bottacini , P. Bruel , S. Buson , R. A. Cameron , P. A. Caraveo , E. Cavazzuti , S. Chen , G. Chiaro , D. Ciangottini , S. Ciprini , P. Cristarella Orestano , M. Crnogorcevic , S. Cutini , F. D'Ammando , P. de la Torre Luque , F. de Palma , S. W. Digel , N. Di Lalla , F. Dirirsa , L. Di Venere , A. Domínguez , A. Fiori , H. Fleischhack , A. Franckowiak , Y. Fukazawa , S. Funk , P. Fusco , F. Gargano , D. Gasparrini , S. Germani , N. Giglietto , F. Giordano , M. Giroletti , D. Green , I. A. Grenier , S. Griffin , S. Guiriec , M. Gustafsson , J. W. Hewitt , D. Horan , R. Imazawa , G. Jóhannesson , M. Kerr , D. Kocevski , M. Kuss , S. Larsson , L. Latronico , J. Li , I. Liodakis , F. Longo , F. Loparco , M. N. Lovellette , P. Lubrano , S. Maldera , A. Manfreda , G. Martí-Devesa , H. Matake , M. N. Mazziotta , I. Mereu , M. Meyer , N. Mirabal , W. Mitthumsiri , T. Mizuno , M. E. Monzani , A. Morselli , I. V. Moskalenko , S. Nagasawa , M. Negro , R. Ojha , M. Orienti , E. Orlando , M. Palatiello , V. Paliya , D. Paneque , Z. Pei , M. Persic , M. Pesce-Rollins , V. Petrosian , H. Poon , T. A. Porter , G. Principe , J. L. Racusin , S. Rainò , R. Rando , B. Rani , M. Razzano , S. Razzaque , A. Reimer , O. Reimer , P. M. Saz Parkinson , L. Scotton , D. Serini , C. Sgrò , E. J. Siskind , G. Spandre , P. Spinelli , D. J. Suson , H. Tajima , D. Tak , D. F. Torres , G. Tosti , E. Troja , K. Wood , M. Yassine , G. Zaharijas

The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to detect photons with energies from 20 MeV to > 300 GeV. The pre-launch response functions of the LAT were determined through…

高能天体物理现象 · 物理学 2016-03-23 LAT Collaboration

The point-spread function (PSF) of an imaging system describes the response of the system to a point source. Accurately determining the PSF enables one to correct for the combined effects of focussing and scattering within the imaging…

天体物理仪器与方法 · 物理学 2022-11-01 Stefan Johann Hofmeister , Michael Hahn , Daniel Wolf Savin

Estimating accurate bolometric fluxes for stars requires reliable photometry to absolutely flux calibrate the spectra. This is a significant problem for studies of very bright stars, which are generally saturated in modern photometric…

太阳与恒星天体物理 · 物理学 2015-06-23 Andrew W. Mann , Kaspar von Braun

In observations of diffuse emissions like, e.g., the Lyman-$\alpha$ heliospheric glow, contributions to the observed signal from point sources (e.g., stars) are considered as a contamination. There are relatively few brightest point sources…

太阳与恒星天体物理 · 物理学 2020-08-19 Marek Strumik , Maciej Bzowski , Izabela Kowalska-Leszczynska , Marzena A. Kubiak

The profile of Navarro, Frenk, and White (the NFW profile), which was derived from the {\it N}-body simulations of cold dark-matter halos, is a strong candidate for a galaxy or cluster profile. In order to check the usability of the NFW…

天体物理学 · 物理学 2015-06-24 K. Asano