Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userUncovering the deeply embedded AGN activity in the nuclear regions of the interacting galaxy Arp299
122
0
0.0
(
0
)
Added by
Almudena Alonso-Herrero
Publication date
2013
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
We present mid-infrared (MIR) 8-13micron spectroscopy of the nuclear regions of the interacting galaxy Arp299 (IC694+NGC3690) obtained with CanariCam (CC) on the 10.4m Gran Telescopio Canarias (GTC). The high angular resolution (~0.3-0.6arcsec) of the data allows us to probe nuclear physical scales between 60 and 120pc, which is a factor of 10 improvement over previous MIR spectroscopic observations of this system. The GTC/CC spectroscopy displays evidence of deeply embedded Active Galactic Nucleus (AGN) activity in both nuclei. The GTC/CC nuclear spectrum of NGC3690/Arp299-B1 can be explained as emission from AGN-heated dust in a clumpy torus with both a high covering factor and high extinction along the line of sight. The estimated bolometric luminosity of the AGN in NGC3690 is 3.2(+/-0.6)x10^44 erg/s. The nuclear GTC/CC spectrum of IC694/Arp299-A shows 11.3micron polycyclic aromatic hydrocarbon (PAH) emission stemming from a deeply embedded (A_V~24mag) region of less than 120pc in size. There is also a continuum-emitting dust component. If associated with th putative AGN in IC694, we estimate that it would be approximately 5 times less luminous than the AGN in NGC3690. The presence of dual AGN activity makes Arp299 a good example to study such phenomenon in the early coalescence phase of interacting galaxies.
rate research
Read More
We present an optical spectroscopic study of a 90% complete sample of 17 nearby ULIRGs with optical Seyfert nuclei, with the aim of investigating the nature of the nuclear warm gas outflows. A high proportion (94%) of our sample show disturbed emission line kinematics in the form of broad (FWHM > 500 km s-1) and/or strongly blueshifted (Delta V < -150 km s-1) emission line components. This proportion is significantly higher than found in a comparison sample of non-Sy ULIRGs (19%). We also find evidence that the [OII]5007,4959 emission lines in Sy-ULIRGs are broader and more asymmetric that in samples of non-ULIRG Seyferts. The Sy-ULIRG sample encompasses a wide diversity of emission line profiles. In most individual objects we are able to fit the profiles of all the emission lines with a kinematic model derived from the strong [OIII]4959,5007 lines, using between 2 and 5 Gaussian components. From these fits we derive diagnostic line ratios that are used to investigate the ionization mechanisms for the different kinematic components. We show that, in general, the line ratios are consistent with gas of super-solar abundance photoionized by a combination of AGN and starburst activity, with an increasing contribution from the AGN with increasing FWHM of the individual kinematic components, and the AGN contribution dominating for the broadest components. However, shock ionization cannot be ruled out in some cases. Our derived upper limits on the mass outflows rates and kinetic powers of the emission line outflows show that they can be as energetically significant as the neutral and molecular outflows in ULIRGs-consistent with the requirements of the hydrodynamic simulations that include AGN feedback. However, the uncertainties are large, and more accurate estimates of the radii, densities and reddening of the outflows are required to put these results on a firmer footing.
We present high- and intermediate resolution radio observations of the central region in the spiral galaxy IC 2497, performed using the European VLBI Network (EVN) at 18 cm, and the Multi-Element Radio Linked Interferometer Network (MERLIN) at 18 cm and 6 cm. We detect two compact radio sources, with brightness temperatures above 10e5 K, suggesting that they are related to AGN activity. We show that the total 18 cm radio emission from the galaxy is dominated neither by these compact sources nor large-scale emission, but extended emission confined within a sub-kpc central region. IC 2497 therefore appears as a typical luminous infrared galaxy that exhibits a nuclear starburst with a massive star formation rate (M > 5M_solar) of 12.4 M_solar/yr. These results are in line with the hypothesis that the ionisation nebula Hannys Voorwerp at a distance of approx. 15-25 kpc from the galaxy is ionised by the radiation cone of the AGN.
We aim to investigate the chemistry of internal photon-dominated regions surrounding deeply embedded hypercompact and ultracompact HII regions. We search for specific tracers of this evolutionary stage of massive star formation that can be detected with current astronomical facilities. We modeled hot cores with embedded HC/UCHII regions, by coupling the astrochemical code Saptarsy to a radiative transfer framework obtaining the spatio-temporal evolution of abundances as well as time-dependent synthetic spectra. In these models where we focused on the internal PDR surrounding the HI region, the gas temperature is set to the dust temperature and we do not include dynamics thus the density structure is fixed. We compared this to hot molecular core models and studied the effect on the chemistry of the radiation field which is included in the HII region models only during the computation of abundances. In addition, we investigated the chemical evolution of the gas surrounding HII regions with models of different densities at the ionization front, different sizes of the ionized cavity and different initial abundances. We obtain the time evolution of synthetic spectra for a dozen of selected species as well as ratios of their integrated intensities. We find that some molecules such as C, N2H+, CN, and HCO do not trace the inner core and so are not good tracers to distinguish the HII/PDR regions to the HMCs phase. On the contrary, C+ and O trace the internal PDRs, in the two models starting with different initial abundances, but are unfortunately currently unobservable with the current achievable spatial resolution because of the very thin internal PDR (r < 100 AU). In addition, we find that the abundance profiles are highly affected by the choice of the initial abundances, hence the importance to properly define them.
We present a follow-up study of a series of papers concerning the role of close interactions as a possible triggering mechanism of the activity of AGN and starburst (SB) galaxies. We have already studied the close (<100 kpc) and the large scale (<1 Mpc) environment of Sy1, Sy2 and Bright IRAS galaxies and their respective control samples (Koulouridis et al.). The results led us to the conclusion that a close encounter appears capable of activating a sequence where a normal galaxy becomes first a starburst, then a Sy2 and finally a Sy1 galaxy. However since both galaxies of an interacting pair should be affected, we present here optical spectroscopy and X-ray imaging of the neighbouring galaxies around our Seyfert and BIRG galaxy samples. We find that more than 70% of all neighbouring galaxies exhibit thermal or/and nuclear activity (namely enhanced star formation, starbursting and/or AGN) and furthermore we discovered various trends regarding the type and strength of the neighbours activity with respect to the activity of the central galaxy, the most important of which is that the neighbours of Sy2 are systematically more ionized, and their straburst is younger, than the neighbours of Sy1s. Our results not only strengthen the link between close galaxy interactions and activity but also provide more clues regarding the evolutionary sequence inferred by previous results.
We report on C-band (5 - 7 GHz) observations of the galaxy, NGC~2992, from the CHANG-ES sample. This galaxy displays an embedded nuclear double-lobed radio morphology within its spiral disk, as revealed in linearly polarized emission but {it not} in total intensity emission. The radio lobes are kpc-sized, similar to what has been observed in the past for other Seyfert galaxies, and show ordered magnetic fields. NGC~2992 has shown previous evidence for AGN-related activity, but not the linearly polarized radio features that we present here. We draw attention to this galaxy as the first clear example (and prototype) of bipolar radio outflow that is revealed in linearly polarized emission only. Such polarization observations, which are unobscured by dust, provide a new tool for uncovering hidden weak AGN activity which may otherwise be masked by brighter unpolarized emission within which it is embedded. The radio lobes observed in NGC~2992 are interacting with the surrounding interstellar medium and offer new opportunities to investigate the interactions between nuclear outflows and the ISM in nearby galaxies. We also compare the radio emission with a new CHANDRA X-ray image of this galaxy. A new CHANG-ES image of NGC~3079 is also briefly shown as another example as to how much more obvious radio lobes appear in linear polarization as opposed to total intensity.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
