Search Publications
Variation of the X-ray non-thermal emission in the Arches cloud.
Ponti, G.; Decourchelle, A.; Terrier, R. +5 more
The origin of the iron fluorescent line at 6.4 keV from an extended region surrounding the Arches cluster is debated and the non-variability of this emission up to 2009 has favoured the low-energy cosmic ray origin over a possible irradiation by hard X-rays. By probing the variability of the Arches cloud non-thermal emission in the most recent yea…
New insights on the recoiling/binary black hole candidate J0927+2943 via molecular gas observations
Decarli, R.; Montuori, C.; Mazzucchelli, C. +2 more
The peculiar QSO J0927+2943 shows multiple sets of emission lines in its optical spectrum. This signature has been interpreted as the relative motion between a black hole, either recoiling or bound in a binary system, and its host galaxy, or as a superposition of two galaxies along the line of sight. In order to test these scenarios, we have colle…
The Herschel Virgo Cluster Survey - XVI. A cluster inventory
Bianchi, S.; Fritz, J.; De Looze, I. +12 more
Herschel far-infrared (FIR) observations are used to construct Virgo cluster galaxy luminosity functions and to show that the cluster lacks the very bright and the numerous faint sources detected in field galaxy surveys. The FIR spectral energy distributions are fitted to obtain dust masses and temperatures and the dust mass function. The cluster …
Two physical regimes for the giant H II regions and giant molecular clouds in the Antennae galaxies
García-Lorenzo, B.; Gutiérrez, L.; Beckman, J. E. +3 more
We have combined observations of the Antennae galaxies from the radio interferometer ALMA (Atacama Large Millimeter/submillimeter Array) and from the optical interferometer GHαFaS (Galaxy Hα Fabry-Perot System). The two sets of observations have comparable angular and spectral resolutions, enabling us to identify 142 giant molecular clouds (GMCs) …
A multiwavelength view on the dusty Wolf-Rayet star WR 48a★
Zhekov, Svetozar A.; Borissova, Jura; Hajduk, Marcin +5 more
We present results from the first attempts to derive various physical characteristics of the dusty Wolf-Rayet (WR) star WR 48a based on a multiwavelength view of its observational properties. This is done on the basis of new optical and near-infrared spectral observations and on data from various archives in the optical, radio and X-rays. The opti…
The soft X-ray spectrum of the luminous narrow line Seyfert galaxy PG 1211+143 - evidence for a second high-velocity outflow component
Pounds, K. A.
An XMM-Newton observation of the luminous Seyfert galaxy PG 1211+143 in 2001 revealed the first clear evidence for a highly ionized high-speed wind (in a non-broad absorption line active galactic nucleus), with a velocity of v ∼ 0.09c based on the identification of blueshifted absorption lines in both EPIC and Reflection Grating Spectrometer (RGS)…
Ionizing stellar population in the disc of NGC 3310 - I. The impact of a minor merger on galaxy evolution
Pérez-Montero, E.; Sánchez, S. F.; Díaz, A. I. +2 more
Numerical simulations of minor mergers predict little enhancement in the global star formation activity. However, it is still unclear the impact they have on the chemical state of the whole galaxy and on the mass build-up in the galaxy bulge and disc. We present a two-dimensional analysis of NCG 3310, currently undergoing an intense starburst like…
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…
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…