Search Publications
The detection of variable radio emission from the fast rotating magnetic hot B-star HR\xA07355 and evidence for its X-ray aurorae
Umana, G.; Leone, F.; Ignace, R. +6 more
In this paper, we investigate the multiwavelength properties of the magnetic early B-type star HR 7355. We present its radio light curves at several frequencies, taken with the Jansky Very Large Array, and X-ray spectra, taken with the XMM-Newton X-ray telescope. Modelling of the radio light curves for the Stokes I and V provides a quantitative an…
Determining the torus covering factors for a sample of type 1 AGN in the local Universe
Done, Chris; Gandhi, Poshak; Dewangan, Gulab C. +4 more
In the unified scheme of active galactic nuclei, a dusty torus absorbs and then reprocesses a fraction of the intrinsic luminosity which is emitted at longer wavelengths. Thus, subject to radiative transfer corrections, the fraction of the sky covered by the torus as seen from the central source (known as the covering factor fc) can be …
Galactoseismology and the local density of dark matter
Widrow, Lawrence M.; Banik, Nilanjan; Dodelson, Scott
We model vertical breathing mode perturbations in the Milky Way's stellar disc and study their effects on estimates of the local dark matter density, surface density, and vertical force. Evidence for these perturbations, which involve compression and expansion of the Galactic disc perpendicular to the mid-plane, comes from three different surveys …
X-ray constraints on the fraction of obscured active galactic nuclei at high accretion luminosities
Georgakakis, A.; Salvato, M.; Liu, Z. +9 more
The wide-area XMM-XXL X-ray survey is used to explore the fraction of obscured active galactic nuclei (AGNs) at high accretion luminosities, LX(2-10 keV) ≳ 1044 erg s - 1, and out to redshift z ≈ 1.5. The sample covers an area of about 14 deg2 and provides constraints on the space density of powerful AGN…
Red but not dead: unveiling the star-forming far-infrared spectral energy distribution of SpARCS brightest cluster galaxies at 0 < z < 1.8
Lidman, C.; Surace, J.; Muzzin, A. +8 more
We present the results of a Spitzer/Herschel infrared photometric analysis of the largest (716) and the highest-redshift (z = 1.8) sample of brightest cluster galaxies (BCGs), those from the Spitzer Adaptation of the Red-Sequence Cluster Survey Given the tension that exists between model predictions and recent observations of BCGs at z < 2, we …
Constraints on cometary surface evolution derived from a statistical analysis of 67P's topography
Jorda, L.; Lamy, P. L.; Lara, L. M. +51 more
We present a statistical analysis of the distribution of large-scale topographic features on comet 67P/Churyumov-Gerasimenko. We observe that the cumulative cliff height distribution across the surface follows a power law with a slope equal to -1.69 ± 0.02. When this distribution is studied independently for each region, we find a good correlation…
Narrow phase-dependent features in X-ray dim isolated neutron stars: a new detection and upper limits
Tiengo, A.; Rea, N.; Zane, S. +3 more
We report on the results of a detailed phase-resolved spectroscopy of archival XMM-Newton observations of X-ray dim isolated neutron stars (XDINSs). Our analysis revealed a narrow and phase-variable absorption feature in the X-ray spectrum of RX J1308.6+2127. The feature has an energy of ∼740 eV and an equivalent width of ∼15 eV. It is detected on…
Gaia's view of the λ Boo star puzzle
Murphy, Simon J.; Paunzen, Ernst
The evolutionary status of the chemically peculiar class of λ Boo stars has been intensely debated. It is now agreed that the λ Boo phenomenon affects A stars of all ages, from star formation to the terminal age main sequence, but the cause of the chemical peculiarity is still a puzzle. We revisit the debate of their ages and temperatures in order…
Investigating the X-ray time lags in PG 1244+026 using an extended corona model
Chainakun, P.; Young, A. J.
We present an extended corona model based on ray-tracing simulations to investigate X-ray time lags in active galactic nuclei (AGNs). This model consists of two axial point sources illuminating an accretion disc that produce the reverberation lags. These lags are due to the time delays between the directly observed and reflection photons and are a…
The Magellanic Inter-Cloud Project (MAGIC) III: first spectroscopic evidence of a dwarf stripping a dwarf
Conn, Blair C.; Carrera, Ricardo; Noël, Noelia E. D. +2 more
The Magellanic Bridge (MB) is a gaseous stream that links the Large (LMC) and Small (SMC) Magellanic Clouds. Current simulations suggest that the MB forms from a recent interaction between the Clouds. In this scenario, the MB should also have an associated stellar bridge formed by stars tidally stripped from the SMC by the LMC. There are several o…