Search Publications
Globular cluster scale sizes in giant galaxies: orbital anisotropy and tidally underfilling clusters in M87, NGC 1399 and NGC 5128
Sills, Alison; Puzia, Thomas H.; Paolillo, Maurizio +4 more
We investigate the shallow increase in globular cluster half-light radii with projected galactocentric distance Rgc observed in the giant galaxies M87, NGC 1399, and NGC 5128. To model the trend in each galaxy, we explore the effects of orbital anisotropy and tidally underfilling clusters. While a strong degeneracy exists between the tw…
The XMM Cluster Survey: the halo occupation number of BOSS galaxies in X-ray clusters
Streblyanska, Alina; Schneider, Donald P.; Hilton, Matt +26 more
We present a direct measurement of the mean halo occupation distribution (HOD) of galaxies taken from the eleventh data release (DR11) of the Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey (BOSS). The HOD of BOSS low-redshift (LOWZ: 0.2 < z < 0.4) and Constant-Mass (CMASS: 0.43 < z < 0.7) galaxies is inferred via …
The ionized X-ray outflowing torus in ESO 323-G77: low-ionization clumps confined by homogeneous warm absorbers
Miniutti, G.; Krongold, Y.; Longinotti, A. L. +2 more
We report on the long- and short-term X-ray spectral analysis of the polar-scattered Seyfert 1.2 galaxy ESO 323-G77, observed in three epochs between 2006 and 2013 with Chandra and XMM-Newton. Four high-resolution Chandra observations give us a unique opportunity to study the properties of the absorbers in detail, as well as their short time-scale…
A possible mechanism for the formation of magnetic field dropouts in the coma of 67P/Churyumov-Gerasimenko
Altwegg, K.; Huang, Z.; Jia, X. +10 more
The Rosetta Plasma Consortium MAGnetometer (RPC-MAG) has detected signatures of diamagnetic regions associated with comet 67P/Churyumov-Gerasimenko at distances from 30 to 400 km at different heliocentric distances, which is larger than what has been predicted by numerical simulations of the cometary plasam environment. The physical mechanism behi…
The featureless and non-variable optical spectral energy distribution of AXP 4U 0142+61
Muñoz-Darias, T.; Casares, J.; de Ugarte Postigo, A.
We present GTC-10.4 m spectroscopy and multiband photometry of the faint (r ∼ 26) optical counterpart of the anomalous X-ray pulsar 4U 0142+61. The 5000-9000 Å spectrum - the first obtained for a magnetar - is featureless, allowing us to set an equivalent width upper limit EW < 25 Å to the presence of emission lines in the H α region. Multiband…
Ultraviolet emission lines of Si II in cool star and solar spectra
Ayres, Thomas R.; Laha, Sibasish; Ferland, Gary J. +6 more
Recent atomic physics calculations for Si II are employed within the CLOUDY modelling code to analyse Hubble Space Telescope (HST) STIS ultraviolet spectra of three cool stars, β Geminorum, α Centauri A and B, as well as previously published HST/GHRS observations of α Tau, plus solar quiet Sun data from the High Resolution Telescope and Spectrogra…
Spatially resolved dust emission of extremely metal-poor galaxies*
Li, Aigen; Armus, Lee; Helou, George +4 more
We present infrared (IR) spectral energy distributions (SEDs) of individual star-forming regions in four extremely metal-poor (EMP) galaxies with metallicity Z ≲ Z⊙/10 as observed by the Herschel Space Observatory. With the good wavelength coverage of the SED, it is found that these EMP star-forming regions show distinct SED shapes as c…
H-ATLAS: the far-infrared properties of galaxies in and around the Coma cluster
Ibar, E.; Dunne, L.; Dye, S. +12 more
We describe a far-infrared survey of the Coma cluster and the galaxy filament it resides within. Our survey covers an area of ∼150 deg2 observed by Herschel H-ATLAS (Herschel Astrophysical Terahertz Large Area Survey) in five bands at 100, 160, 250, 350 and 500 µm. The SDSS spectroscopic survey (mr ≤ 17.8) is used to de…
Evidence for variable, correlated X-ray and optical/IR extinction towards the nearby, pre-main-sequence binary TWA 30
Kastner, J. H.; Alcalá, J. M.; Principe, David A. +2 more
We present contemporaneous XMM-Newton X-ray and ground-based optical/near-IR spectroscopic observations of the nearby (D ≈ 42 pc), low-mass (mid-M) binary system TWA 30A and 30B. The components of this wide (separation ∼3400 au) binary are notable for their nearly edge-on disc viewing geometries, high levels of variability, and evidence for collim…
A tale of two tails: exploring stellar populations in the tidal tails of NGC 3256
Gronwall, Caryl; Ciardullo, Robin; Charlton, Jane +7 more
We have developed an observing programme using deep, multiband imaging to probe the chaotic regions of tidal tails in search of an underlying stellar population, using NGC 3256's 400 Myr twin tidal tails as a case study. These tails have different colours of u - g = 1.05 ± 0.07 and r - I = 0.13 ± 0.07 for NGC 3256W, and u - g = 1.26 ± 0.07 and r -…