Results 41 to 50 of about 282 (177)

Optical Spectroscopic Observations of Gamma-Ray Blazar Candidates. XII. Follow-up Observations from SOAR, Blanco, NTT, and OAN-SPM

The Astronomical Journal, 2023
Roughly one third of the sources in the Fermi-LAT catalogs are listed as unidentified/unassociated γ -ray sources (UGS), i.e., they lack a low-energy counterpart.
Abigail García-Pérez, Harold A. Peña-Herazo, Francesco Massaro, Vahram Chavushyan, Raffaele D’abrusco, Nicola Masetti, Marco Landoni, Fabio La Franca, Víctor M. Patiño-Álvarez, Raúl A. Amaya-Almazán, Dan Milisavljevic, Alessandro Paggi, Federica Ricci, Elena Jiménez-Bailón, Howard A. Smith   +14 more
doaj   +1 more source

Multifrequency variability study of flat-spectrum radio quasar PKS 0346-27

Monthly Notices of the Royal Astronomical Society, 2023
ABSTRACT We have presented a multiwavelength temporal and spectral study of the blazar PKS 0346-27 for the period 2019 January–2021 December (MJD 58484–59575) using data from Fermi-LAT (γ-rays), Swift-XRT (X-rays), and Swift-UVOT (ultraviolet and optical).
Sushanth Reddy Kamaram, Raj Prince, Suman Pramanick, Debanjan Bose   +3 more
openaire   +2 more sources

Machine Learning–Driven Near‐ and Mid‐Infrared Chemometrics for Rapid, Cost‐Effective COVID‐19 Screening in Dried Plasma

Journal of Chemometrics, Volume 39, Issue 12, December 2025.
ABSTRACT The COVID‐19 pandemic has highlighted the urgent need for rapid, accurate, and cost‐effective diagnostic alternatives to conventional methods such as RT‐qPCR and immunoassays. In this study, we explored the potential of vibrational spectroscopy, specifically near‐infrared (NIR) and mid‐infrared (MID) spectroscopy, for detecting SARS‐CoV‐2 ...
Fernanda F. S. Oliveira, Wilson J. Cardoso, Luiz F. P. Ramos, Túlio R. Freitas, Priscilla S. Filgueiras, Rafaella F. Q. Grenfell, Reinaldo F. Teófilo, Adriano de Paula Sabino   +7 more
wiley   +1 more source

The relationship between the emission line, continuum luminosity, and Baldwin effect in blazars

Astronomy & Astrophysics
Aims. This study investigates the relationship between the Mg II λ2798 Å emission line and the 3000 Å continuum luminosity, as well as the Baldwin effect, in a sample of 40’,685 radio-quiet (RQ) quasars and 441 flat spectrum radio quasars (FSRQs ...
Patiño-Álvarez Víctor M., Guerrero-González Jonhatan U., Chavushyan Vahram, Monjardin-Ward Douglas E., Arshakian Tigran G., Cruz-González Irene   +5 more
doaj   +1 more source

Multiwavelength Temporal Variability of the Blazar PKS 1510–089

The Astrophysical Journal, 2023
We perform correlation and periodicity search analyses on long-term multiband light curves of the flat-spectrum radio quasar PKS 1510−089 observed by the space-based Fermi-Large Area Telescope in γ -rays, the SMARTS and Steward Observatory telescopes in ...
Q. Yuan, Pankaj Kushwaha, Alok C. Gupta, Ashutosh Tripathi, Paul J. Wiita, M. Zhang, X. Liu, Anne Lähteenmäki, Merja Tornikoski, Joni Tammi, Venkatessh Ramakrishnan, L. Cui, X. Wang, M. F. Gu, Cosimo Bambi, A. E. Volvach   +15 more
doaj   +1 more source

Localized Energy Absorption through LaB6 Surface Modification of PA12 Enables Enhanced Tensile Performance in Diode Laser PBF‐LB

Chemistry–Methods, Volume 5, Issue 12, November 2025.
LaB6 surface modification of PA12 enables efficient NIR diode laser PBF‐LB processing, with enhanced tensile strength and tailored microstructures achieved at minimal additionaly energy. By reducing the need for high filler content, this approach expands the options and performance levels of advanced industrial‐grade polymer additive manufacturing. The
Nadine Stratmann, Michael Willeke, Simon Leupold, Kateryna Loza, Arne Lüddecke, Arno Kwade, Michael Schmidt, Stephan Barcikowski, Anna Rosa Ziefuss   +8 more
wiley   +1 more source

Modeling the Multiwavelength Spectral Energy Distributions of the Fermi-4LAC Bright Flat-spectrum Radio Quasars

The Astrophysical Journal
In this paper, we present a long-term multiwavelength investigation focusing on 12 distinct samples of Fermi-4LAC bright flat-spectrum radio quasars (FSRQs).
R. X. Zhou, Y. G. Zheng, K. R. Zhu, S. J. Kang, X. P. Li   +4 more
doaj   +1 more source

Multiwavelength Variability Analysis of the Blazar PKS 0727-11: An ~ 168 day Quasiperiodic Oscillation in the γ-Ray

The Astrophysical Journal
We performed variability analysis of the multiwavelength light curves (LCs) for the flat-spectrum radio quasar PKS 0727-11. Using the generalized Lomb–Scargle periodogram, we identified a possible quasiperiodic oscillation (QPO) of ~168.6 days (persisted
Yuncai Shen, Tingfeng Yi, Vinit Dhiman, Lisheng Mao, Liang Dong   +4 more
doaj   +1 more source

Jet Physics of Accreting Super-Massive Black Holes in the Era of the Fermi Gamma-ray Space Telescope

Frontiers in Astronomy and Space Sciences, 2017
The Fermi Gamma-ray Space Telescope with its main instrument on-board, the Large Area Telescope (LAT), opened a new era in the study of high-energy emission from Active Galactic Nuclei (AGN).
Filippo D'Ammando, Filippo D'Ammando
doaj   +1 more source

Flat-spectrum radio quasars as high-energy neutrino sources

Astronomy & Astrophysics
The astrophysical sources responsible for the production of high-energy neutrinos remain largely uncertain. The strongest associations suggest a correlation between neutrinos and active galactic nuclei. However, it is still unclear which specific regions and mechanisms of the accreting supermassive black hole are responsible for ...
A. Moretti, A. Caccianiga
openaire   +2 more sources