Search Publications
Running with BICEP2: implications for small-scale problems in CDM
Kaplinghat, Manoj; Bullock, James S.; Garrison-Kimmel, Shea +2 more
The BICEP2 results, when interpreted as a gravitational wave signal and combined with other cosmic microwave background data, suggest a roll-off in power towards small scales in the primordial matter power spectrum. Among the simplest possibilities is a running of the spectral index. Here we show that the preferred level of running alleviates smal…
The puzzling source IGR J17361-4441 in NGC 6388: a possible planetary tidal disruption event
Lodato, G.; Segreto, A.; De Cesare, G. +5 more
On 2011 August 11, INTEGRAL discovered the hard X-ray source IGR J17361-4441 near the centre of the globular cluster NGC 6388. Follow-up observations with Chandra showed the position of the transient was inconsistent with the cluster dynamical centre, and thus not related to its possible intermediate mass black hole. The source showed a peculiar h…
Photometric and Structural Properties of NGC 6544: A Combined VVV-Hubble Space Telescope Study
Cohen, Roger E.; Dotter, Aaron; Geisler, Doug +3 more
We combine archival Hubble Space Telescope imaging with wide-field near-infrared photometry to study the neglected metal-poor Galactic globular cluster NGC 6544. A high spatial resolution map of differential reddening over the inner portion of the cluster is constructed, revealing variations of up to half of the total reddening, and the resulting …
The FUV to Near-IR Morphologies of Luminous Infrared Galaxies in the Goals Sample
Le Floc'h, E.; Surace, J. A.; Inami, H. +9 more
We compare the morphologies of a sample of 20 luminous infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey (GOALS) in the FUV, B, I, and H bands, using the Gini (G) and M20 parameters to quantitatively estimate the distribution and concentration of flux as a function of wavelength. Hubble Space Telescope (HST) ima…
Searching for primordial non-Gaussianity in Planck CMB maps using a combined estimator
Wuensche, C. A.; Novaes, C. P.; Bernui, A. +1 more
The extensive search for deviations from Gaussianity in cosmic microwave background radiation (CMB) data is very important due to the information about the very early moments of the universe encoded there. Recent analyses from Planck CMB data do not exclude the presence of non-Gaussianity of small amplitude, although they are consistent with the G…
PCA of PCA: principal component analysis of partial covering absorption in NGC 1365
Fabian, A. C.; Parker, M. L.; Walton, D. J. +1 more
We analyse 400 ks of XMM-Newton data on the active galactic nucleus NGC 1365 using principal component analysis (PCA) to identify model-independent spectral components. We find two significant components and demonstrate that they are qualitatively different from those found in MCG-6-30-15 using the same method. As the variability in NGC 1365 is kn…
A Chandra-Swift View of Point Sources in Hickson Compact Groups: High AGN Fraction but a Dearth of Strong AGNs
Hornschemeier, A. E.; Brandt, W. N.; Gallagher, S. C. +6 more
We present Chandra X-ray point source catalogs for 9 Hickson Compact Groups (HCGs, 37 galaxies) at distances of 34-89 Mpc. We perform detailed X-ray point source detection and photometry and interpret the point source population by means of simulated hardness ratios. We thus estimate X-ray luminosities (LX ) for all sources, most of whi…
Early-type Galaxies in the Chandra COSMOS Survey
Civano, F.; Elvis, M.; Pellegrini, S. +4 more
We study a sample of 69 X-ray detected early-type galaxies (ETGs), selected from the Chandra COSMOS survey, to explore the relation between the X-ray luminosity of hot gaseous halos (L X, gas) and the integrated stellar luminosity (LK ) of the galaxies, in a range of redshift extending out to z = 1.5. In the local universe, …
A Multi-instrument Analysis of Sunspot Umbrae
Watson, F. T.; Livingston, W.; Penn, M. J.
The recent solar minimum and rise phase of solar cycle 24 have been unlike any period since the early 1900s. This article examines some of the properties of sunspot umbrae over the last 17 yr with three different instruments on the ground and in space: MDI, HMI and BABO. The distribution of magnetic fields and their evolution over time is shown an…
Characterizing the Galactic warp with Gaia - I. The tilted ring model with a twist
Figueras, Francesca; Mateu, Cecilia; Romero-Gómez, Mercè +2 more
We explore the possibility of detecting and characterizing the warp of the stellar disc of our Galaxy using synthetic Gaia data. The availability of proper motions and, for the brightest stars radial velocities, adds a new dimension to this study. A family of Great Circle Cell Counts methods is used. They are ideally suited to find the tilt and tw…