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GeV-TeV γ-rays produced by electrons in the kpc-scale jet as a result of Comptonization of the inner jet emission
Bednarek, W.
A few radio galaxies have been discovered to emit GeV-TeV γ-ray emission in spite of the relatively large viewing angles of their jets. We consider a scenario in which such large-angle γ-ray emission is preferentially produced by isotropically distributed relativistic electrons in the kpc-scale jet. These electrons Comptonize soft non-thermal radi…
The Possible Astrometric Signature of a Planetary-mass Companion to the Nearby Young Star TW Piscis Austrini (Fomalhaut B): Constraints from Astrometry, Radial Velocities, and Direct Imaging
Esposito, Thomas M.; Kalas, Paul; De Rosa, Robert J. +5 more
We present constraints on the presence of substellar companions to the nearby (d ∼ 7.6 pc) young (440 ± 40 Myr) K4Ve star TW Piscis Austrini, the wide (∼0.3 pc) companion to the A4V star Fomalhaut. We combined absolute astrometry from Hipparcos and Gaia with literature radial velocity measurements and dedicated high-contrast imaging observations o…
New CCD astrometric observations of the five major uranian satellites using Gaia DR1 in 2014-2016
Vienne, A.; Wang, N.; Peng, Q. Y. +4 more
710 CCD frames, observed by 1-m telescope at Yunnan Observatory over 15 nights, have been reduced to derive new precise positions of the five Uranian major satellites (Ariel, Umbriel, Titania, Oberon and Miranda). In the pixel positional measurement of the faint satellites near Uranus, a halo removal procedure similar to that of Veiga et al. (Veig…
Classical T-Tauri stars with VPHAS+: II: NGC 6383 in Sh 2-012
Kalari, V. M.
This paper presents optical (ugriHα)-infrared (JHKs, 3.6-8.0 µm) photometry and Gaia astrometry of 55 Classical T-Tauri stars (CTTS) in the star-forming region Sh 2-012 and its central cluster NGC 6383. The sample was identified based on photometric Hα emission linewidths, and has a median age of 2.8 ± 1.6 Myr, with a mass range between 0.3 …
X-ray properties of two transient ULX candidates in galaxy NGC 7090
O'Brien, P. T.; Osborne, J. P.; Page, K. L. +2 more
We report the X-ray data analysis of two transient ultraluminous X-ray sources (ULXs; hereafter X1 and X2) located in the nearby galaxy NGC 7090. While they were not detected in the 2004 XMM-Newton and 2005 Chandra observations, their 0.3-10 keV X-ray luminosities reached >3 × 1039 erg s-1in later XMM-Newton or Swift obser…
Nuclear spallation in active galaxies
Reynolds, C. S.; Gallo, L. C.; García, J. A. +3 more
A number of works point to the presence of narrow emission features at unusual energies in the X-ray spectra of active galactic nuclei or to potentially low iron abundances as possible evidence for the spallation of iron. With the imminence of high-resolution calorimeter spectroscopy, the potential to test spallation models in astrophysical source…
Unveiling the 100 pc scale nuclear radio structure of NGC 6217 with e-MERLIN and the VLA
Muxlow, T. W. B.; Argo, M. K.; Knapen, J. H. +13 more
We present high-sensitivity 1.51 GHz e-MERLIN (e-Multi-Element Radio-Linked Interferometer Network) radio images of the nearby galaxy NGC 6217. We resolve the compact radio source at the centre of NGC 6217 for the first time, finding a twin-lobed structure with a total linear size of ∼4 arcsec (∼400 pc). The radio source does not have a compact ce…
The Laboratory Millimeter and Submillimeter Rotational Spectrum of Lactaldehyde and an Astronomical Search in Sgr B2(N), Orion-KL, and NGC 6334I
McGuire, Brett A.; Brogan, Crystal L.; Guillemin, Jean-Claude +6 more
We present a laboratory rotational study of, and astronomical search for, lactaldehyde (CH3CH(OH)CH(O)), one of the simplest chiral molecules that could reasonably be seen in the interstellar medium (ISM), in the millimeter and submillimeter wave regions from 80 to 460 GHz. More than 5000 transitions were assigned to the most stable con…
The optical and NIR spectrum of the Crab pulsar with X-shooter
Sollerman, J.; Lundqvist, P.; Vreeswijk, P. M. +2 more
Context. Pulsars are well studied all over the electromagnetic spectrum, and the Crab pulsar may be the most studied object in the sky. Nevertheless, a high-quality optical to near-infrared (NIR) spectrum of the Crab or any other pulsar has not been published to date.
Aims: Obtaining a properly flux-calibrated spectrum enables us to measure t…
X-ray studies of the gamma-ray pulsar J1826-1256 and its pulsar wind nebula with Chandra and XMM-Newton
Karpova, Anna V.; Zyuzin, Dmitry A.; Shibanov, Yuriy A.
We have analysed archival XMM-Newton and Chandra observations of the γ-ray radio-quiet pulsar J1826-1256 and its pulsar wind nebula. The pulsar spectrum can be described by a power-law model with photon index Γ ≈ 1. We find that the nebular spectrum softens with increasing distance from the pulsar, implying synchrotron cooling. The empirical inter…