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After decades of searching, the true nature of dark matter still eludes us. One potential probe of the form of dark matter in galaxy clusters is to search for microlensing variability in the giant arcs and arclets. In this paper, a simple…

Astrophysics · Physics 2007-05-23 Artem Tuntsov , Geraint Lewis , Rodrigo Ibata , Jean-Paul Kneib

NGC 4631 is an interacting galaxy which exhibits one of the largest gaseous halos observed among edge-on galaxies. We aim to examine the synchrotron and polarization properties of its disk and halo emission with new radio continuum data.…

PKS 2155-304 is the only BL Lac object for which well-sampled multiwavelength light curves resolve the intraday variability at UV and X-ray wavelengths. In particular we focus on the multifrequency campaign of November 1991, which showed a…

Astrophysics · Physics 2007-05-23 A. Treves , F. Rovetti , Ph. Jetzer , C. M. Urry

We report a significant detection of weak, tangential distortion of the images of cosmologically distant, faint galaxies due to gravitational lensing by foreground galaxies. A mean image polarisation of $<p>=0.011\pm 0.006$ is measured for…

Astrophysics · Physics 2016-08-30 Tereasa Brainerd , Roger Blandford , Ian Smail

Multi-frequency (4.6, 5, 5.5, 8, 8.8, 13, 15, 22 & 43 GHz) polarization observations of 6 "blazars" were obtained on the American Very Long Baseline Array (VLBA) over a 24-hr period on 2 July 2006. Observing at several frequencies,…

Astrophysics · Physics 2009-11-13 Shane P. O'Sullivan , Denise C. Gabuzda

Fast Radio Bursts (FRBs) are extragalactic millisecond-duration radio transients whose nature remains unknown. The advent of numerous facilities conducting dedicated FRB searches has dramatically revolutionised the field: hundreds of new…

High Energy Astrophysical Phenomena · Physics 2024-12-03 Inés Pastor-Marazuela

One possibility for detecting low-amplitude pulsational variations is through gravitational microlensing. During a microlensing event, the temporary brightness increase leads to improvement in the signal-to-noise ratio, and thereby better…

Solar and Stellar Astrophysics · Physics 2021-09-01 Sedighe Sajadian , Richard Ignace , Hilding Neilson

(abridged) Using the particularly long gravitational microlensing event OGLE-2014-BLG-1186 with a time-scale $t_\mathrm{E}$ ~ 300 d, we present a methodology for identifying the nature of localised deviations from single-lens point-source…

The intensity of the cosmic microwave background radiation in the fields of clusters of galaxies is modified by inverse Compton scattering in the hot intracluster gas - the Sunyaev-Zel'dovich (SZ) effect. The effect is expected to be most…

Astrophysics · Physics 2009-10-30 Andrew W. Blain

Several macrolensed systems exhibit photometric variability consistent with microlensing due to objects of stellar mass located in the lens. The degree of microlensing amplification is dependent upon the size of the source, with smaller…

Astrophysics · Physics 2016-08-30 G. F. Lewis , M. J. Irwin , P. C. Hewett

We present results from a mini-survey of relatively high redshift (1.7 < z < 4) gravitationally lensed radio-quiet quasars observed with the Chandra X-ray Observatory and with XMM-Newton. The lensing magnification effect allows us to search…

Astrophysics · Physics 2009-11-10 Xinyu Dai , George Chartas , Michael Eracleous , Gordon P. Garmire

We study the BELs in a sample of 11 gravitationally lensed quasars with at least two epochs of observation to identify intrinsic variability and to disentangle it from microlensing. To improve our statistical significance we also include 15…

Astrophysics of Galaxies · Physics 2018-06-06 C. Fian , Eduardo Guerras , E. Mediavilla , J. Jiménez-Vicente , J. A. Muñoz , E. E. Falco , V. Motta , A. Hanslmeier

We investigate the relationship between 5 GHz interstellar scintillation (ISS) and 15 GHz intrinsic variability of compact, radio-selected AGNs drawn from the Microarcsecond Scintillation-Induced Variability (MASIV) Survey and the Owens…

We have used the VLA to study radio variability among a sample of 18 low luminosity active galactic nuclei (LLAGNs), on time scales of a few hours to 10 days. The goal was to measure or limit the sizes of the LLAGN radio-emitting regions,…

Astrophysics · Physics 2009-11-10 James M. Anderson , James S. Ulvestad

Radio observations over the last two decades have provided evidence that diffuse synchrotron emission in the form of megaparsec-scale radio halos in galaxy clusters is likely tracing regions of the intracluster medium where relativistic…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-25 G. Bernardi , T. Venturi , R. Cassano , D. Dallacasa , G. Brunetti , V. Cuciti , M. Johnston-Hollitt , N. Oozeer , O. M. Smirnov

Ultra-steep spectrum (USS) radio sources are good tracers of powerful radio galaxies at $z > 2$. Identification of even a single bright radio galaxy at $z > 6$ can be used to detect redshifted 21cm absorption due to neutral hydrogen in the…

Astrophysics of Galaxies · Physics 2018-01-31 A. Saxena , P. Jagannathan , H. J. A. Röttgering , P. N. Best , H. T. Intema , M. Zhang , K. J. Duncan , C. L. Carilli , G. K. Miley

Ultralight bosonic wave dark matter (DM) is preponderantly contesting the conventional cold DM paradigm in predicting diverse and rich phenomena on small scales. For a DM halo made of ultralight bosons, the wave interference naturally…

Astrophysics of Galaxies · Physics 2025-04-30 Ran Gao , Shuxun Tian , Zhengxiang Li , He Gao , Kai Liao , Bing Zhang , Zong-Hong Zhu

Gravitational waves from inspiraling compact binaries provide direct measurements of luminosity distances and serve as a powerful probe of the high-redshift Universe. In addition to their role as standard sirens, they offer an opportunity…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-12 Fumihiro Chuman , Masamune Oguri

We consider the influence of (milli/micro)lensing on the spectra of lensed QSOs. We propose a method for the observational detection of microlensing in the spectra of lensed QSOs and apply it to the spectra of the three lensed QSOs (PG…

Astrophysics · Physics 2009-11-10 L. C. Popovic , G. Chartas

Central gravitational image detection is very important for the study of the mass distribution of the inner parts ($\sim 100$ pc) of lens galaxies. However, the detection of such images is extremely rare and difficult. We present a 1.7-GHz…

Astrophysics · Physics 2008-11-26 M. Zhang , N. Jackson , R. W. Porcas , I. W. A. Browne
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