Search Publications
The properties of polycyclic aromatic hydrocarbons in galaxies: constraints on PAH sizes, charge and radiation fields
Rigopoulou, D.; Pereira-Santaella, M.; Alonso-Herrero, A. +7 more
Based on theoretical spectra computed using Density Functional Theory we study the properties of polycyclic aromatic hydrocarbons (PAH). In particular using bin-average spectra of PAH molecules with varying number of carbons we investigate how the intensity of the mid-infrared emission bands, 3.3, 6.2, 7.7, and 11.3 $\mu$m, respond to changes in t…
X-ray binary accretion states in active galactic nuclei? Sensing the accretion disc of supermassive black holes with mid-infrared nebular lines
Fernández-Ontiveros, Juan A.; Muñoz-Darias, Teo
Accretion states, which are universally observed in stellar mass black holes in X-ray binaries, might be expected in active galactic nuclei (AGN). This is the case at low luminosities, when the jet-corona coupling dominates the energy output in both populations. Previous attempts to extend this framework to a wider AGN population have been extreme…
The dust mass in Cassiopeia A from infrared and optical line flux differences
De Looze, I.; Barlow, M. J.; Milisavljevic, D. +2 more
The large quantities of dust that have been found in a number of high-redshift galaxies have led to suggestions that core-collapse supernovae (CCSNe) are the main sources of their dust and have motivated the measurement of the dust masses formed by local CCSNe. For Cassiopeia A (Cas A), an oxygen-rich remnant of a Type IIb CCSN, a dust mass of 0.6…
The nearby extreme accretion and feedback system PDS 456: finding a complex radio-emitting nucleus
Nardini, Emanuele; Paragi, Zsolt; Varenius, Eskil +5 more
When a black hole accretes close to the Eddington limit, the astrophysical jet is often accompanied by radiatively driven, wide-aperture and mildly relativistic winds. Powerful winds can produce significant non-thermal radio emission via shocks. Among the nearby critical accretion quasars, PDS 456 has a very massive black hole (about 1 billion sol…
Chemical abundances in Seyfert galaxies - VII. Direct abundance determination of neon based on optical and infrared emission lines
Feltre, Anna; Dors, O. L.; Hägele, G. F. +6 more
For the first time, neon abundance has been derived in the narrow line region from a sample of Seyfert 2 nuclei. In view of this, we compiled from the literature fluxes of optical and infrared (IR) narrow emission lines for 35 Seyfert 2 nuclei in the local universe ($z \:\lesssim \:0.06$). The relative intensities of emission lines were used to de…
Hot graphite dust in the inner regime of NGC 4151
Shalima, P.; Swain, Subhashree; Latha, K. V. P. +1 more
We model the near-infrared (NIR) spectral energy distribution (SED) of NGC 4151 with a 3D radiative transfer SKIRT code, using which torus only (TO) and ring and torus (RAT) scenarios are studied. In the RAT models, a graphite ring-like structure (clumpy or smooth) is incorporated between the torus and the accretion disc. We vary the inclination a…
The cold dust content of the nearby galaxies IC 5325, NGC 7496, NGC 7590, and NGC 7599
Crawford, T. M.; Vieira, J. D.; Ashby, M. L. N. +6 more
Star-forming galaxies are rich reservoirs of dust, both warm and cold. But the cold dust emission is faint alongside the relatively bright and ubiquitous warm dust emission. Recently, evidence for a very cold dust (VCD) component has also been revealed via millimetre/submillimetre (mm/sub-mm) photometry of some galaxies. This component, despite be…
The effect of continuum elimination in identifying circumstellar dust around Mira
Speck, Angela K.; Shepard, Lisa M.
Asymptotic giant branch (AGB) stars are major contributors of cosmic dust to the universe. Typically, dust around AGB stars is investigated via radiative transfer (RT) modelling, or via simple deconstruction of observed spectra. However, methodologies applied vary. Using archival spectroscopic, photometric, and temporal data for the archetypal dus…