Search Publications
A newly discovered double-double candidate microquasar in NGC 300
Maccarone, T. J.; Motch, C.; Scaringi, S. +7 more
We present the discovery of a powerful candidate microquasar in NGC 300, associated with the S 10 optical nebula (previously classified as a supernova remnant). Chandra images show four discrete X-ray knots aligned in the plane of the sky over a length of ≈150 pc. The X-ray emission from the knots is well fitted with a thermal plasma model at a te…
Broadband spectral analysis of MXB 1659-298 in its soft and hard state
Sanna, A.; Di Salvo, T.; Burderi, L. +7 more
Context. The X-ray transient eclipsing source MXB 1659-298 went into outburst in 1999 and 2015. During these two outbursts the source was observed by XMM-Newton, NuSTAR, and Swift/XRT.
Aims: Using these observations, we studied the broadband spectrum of the source to constrain the continuum components and to verify whether it had a reflection…
Cross-correlation of CMB Polarization Lensing with High-z Submillimeter Herschel-ATLAS Galaxies
Baccigalupi, C.; Borrill, J.; Stompor, R. +46 more
We report a 4.8σ measurement of the cross-correlation signal between the cosmic microwave background (CMB) lensing convergence reconstructed from measurements of the CMB polarization made by the POLARBEAR experiment and the infrared-selected galaxies of the Herschel-ATLAS survey. This is the first measurement of its kind. We infer a best-fit galax…
Ultralow-amplitude RR Lyrae Stars in M4
Wallace, Joshua J.; Hartman, Joel D.; Bakos, Gáspár Á. +1 more
We report evidence for a new class of variable star, which we dub millimagnitude RR Lyrae (mmRR). From K2 observations of the globular cluster M4, we find that out of 24 horizontal branch stars not previously known to be RR Lyrae variables, two show photometric variability with periods and shapes consistent with those of first-overtone RR Lyrae va…
A short and sudden increase of the magnetic field strength and the accompanying spectral variability in the O9.7 V star HD 54879
Hubrig, S.; Schöller, M.; Järvinen, S. P. +4 more
Only 11 O-type stars have been confirmed to possess large-scale organized magnetic fields. The presence of a -600 G longitudinal magnetic field in the O9.7 V star HD 54879 with a lower limit of the dipole strength of ∼2 kG was discovered a few years ago in the framework of the ESO large program `B-fields in OB stars'. Our FORS 2 spectropolarimetri…
Dependence of Galactic Halo Kinematics on the Adopted Galactic Potential
Beers, Timothy C.; Lee, Young Sun; Kim, Young Kwang
We explore differences in Galactic halo kinematic properties derived from two commonly employed Galactic potentials: the Stäckel potential and the default Milky Way-like potential used in the “Galpy” package (MWPotential2014), making use of stars with available metallicities, radial velocities, and proper motions from Sloan Digital Sky Survey Data…
A remarkable change of the spectrum of the magnetic Of?p star HD 148937 reveals evidence of an eccentric, high-mass binary
Howarth, I. D.; Wade, G. A.; Gamen, R. +10 more
We report new spectroscopic observations of the magnetic Of?p star HD 148937 obtained since 2015 that differ qualitatively from its extensive historical record of weak, periodic spectral variations. This remarkable behaviour represents clear evidence for an unprecedented change in the character of variability of the star. In this paper, we describ…
Effect of the non-uniform solar chromospheric Lyα radiation on determining the coronal H I outflow velocity
Sasso, C.; Romoli, M.; Andretta, V. +13 more
We derived maps of the solar wind outflow velocity of coronal neutral hydrogen atoms at solar minimum in the altitude range 1.5-4.0 R⊙. We applied the Doppler dimming technique to coronagraphic observations in the UV H I Lyα line at 121.6 nm. The technique exploits the intensity reduction in the coronal line with increasing velocities o…
A deep X-ray view of the bare AGN Ark 120. VI. Geometry of the hot corona from spectroscopic and polarization signatures
Bianchi, S.; Porquet, D.; Matt, G. +9 more
Context. The spectral shape of the hard X-ray continuum of Active Galactic Nuclei (AGN) can be ascribed to inverse Compton scattering of optical/UV seed photons from the accretion disc by a hot corona of electrons. This physical process produces a polarization signal which is strongly sensitive to the geometry of the scattering medium (i.e. the ho…
The Two Most Recent Thermonuclear Supernovae in the Local Group: Radio Constraints on their Progenitors and Evolution
Chomiuk, Laura; Badenes, Carles; Tremou, Evangelia +3 more
Young supernova remnants (SNRs) provide a unique perspective on supernova (SN) progenitors and connect the late evolution of SNe with the onset of the SNR phase. Here we study SN 1885A and G1.9+0.3, the most recent thermonuclear SNe in the Local Group (with ages ∼100 yr) with radio data, which provide a sensitive probe of the SN environment and en…