113 research outputs found
The nuclear and extended mid-infrared emission of Seyfert galaxies
We present subarcsecond resolution mid-infrared (MIR) images obtained with
8-10 m-class ground-based telescopes of a complete volume-limited (DL<40 Mpc)
sample of 24 Seyfert galaxies selected from the Swift/BAT nine month catalog.
We use those MIR images to study the nuclear and circumnuclear emission of the
galaxies. Using different methods to classify the MIR morphologies on scales of
~400 pc, we find that the majority of the galaxies (75-83%) are extended or
possibly extended and 17-25% are point-like. This extended emission is compact
and it has low surface brightness compared with the nuclear emission, and it
represents, on average, ~30% of the total MIR emission of the galaxies in the
sample. We find that the galaxies whose circumnuclear MIR emission is dominated
by star formation show more extended emission (650+-700 pc) than AGN-dominated
systems (300+-100 pc). In general, the galaxies with point-like MIR
morphologies are face-on or moderately inclined (b/a~0.4-1.0), and we do not
find significant differences between the morphologies of Sy1 and Sy2. We used
the nuclear and circumnuclear fluxes to investigate their correlation with
different AGN and SF activity indicators. We find that the nuclear MIR emission
(the inner ~70 pc) is strongly correlated with the X-ray emission (the harder
the X-rays the better the correlation) and with the [O IV] lambda 25.89 micron
emission line, indicating that it is AGN-dominated. We find the same results,
although with more scatter, for the circumnuclear emission, which indicates
that the AGN dominates the MIR emission in the inner ~400 pc of the galaxies,
with some contribution from star formation.Comment: 27 pages, 12 figures, accepted by MNRA
The nuclear and extended infrared emission of the Seyfert galaxy NGC 2992 and the interacting system Arp 245
We present subarcsecond resolution infrared (IR) imaging and mid-IR
spectroscopic observations of the Seyfert 1.9 galaxy NGC 2992, obtained with
the Gemini North Telescope and the Gran Telescopio CANARIAS (GTC). The N-band
image reveals faint extended emission out to ~3 kpc, and the PAH features
detected in the GTC/CanariCam 7.5-13 micron spectrum indicate that the bulk of
this extended emission is dust heated by star formation. We also report
arcsecond resolution MIR and far-IR imaging of the interacting system Arp 245,
taken with the Spitzer Space Telescope and the Herschel Space Observatory.
Using these data, we obtain nuclear fluxes using different methods and find
that we can only recover the nuclear fluxes obtained from the subarcsecond data
at 20-25 micron, where the AGN emission dominates. We fitted the nuclear IR
spectral energy distribution of NGC 2992, including the GTC/CanariCam nuclear
spectrum (~50 pc), with clumpy torus models. We then used the best-fitting
torus model to decompose the Spitzer/IRS 5-30 spectrum (~630 pc) in AGN and
starburst components, using different starburst templates. We find that,
whereas at shorter mid-IR wavelengths the starburst component dominates (64% at
6 micron), the AGN component reaches 90% at 20 micron. We finally obtained dust
masses, temperatures and star formation rates for the different components of
the Arp 245 system and find similar values for NGC 2992 and NGC 2993. These
measurements are within those reported for other interacting systems in the
first stages of the interaction.Comment: 20 pages, 12 figures, accepted by MNRA
A mid-infrared view of the inner parsecs of the Seyfert galaxy Mrk 1066 using CanariCam/GTC
We present mid-infrared (MIR) imaging and spectroscopic data of the Seyfert 2 galaxy Mrk 1066 obtained with CanariCam (CC) on the 10.4-m Gran Telescopio CANARIAS (GTC). The galaxy was observed in imaging mode with an angular resolution of 0.24âarcsec (54 pc) in the Si-2 filter (8.7 ÎŒm). The image reveals a series of star-forming knots within the central âŒ400 pc, after subtracting the dominant active galactic nucleus (AGN) component. We also subtracted this AGN unresolved component from the 8â13 ÎŒm spectra of the knots and the nucleus, and measured equivalent widths (EWs) of the 11.3 ÎŒm polycyclic aromatic hydrocarbon (PAH) feature which are typical of pure starburst galaxies. This EW is larger in the nucleus than in the knots, confirming that, at least in the case of Mrk 1066, the AGN dilutes, rather than destroys, the molecules responsible for the 11.3 ÎŒm PAH emission. By comparing the nuclear GTC/CC spectrum with the Spitzer/Infrared Spectrograph (IRS) spectrum of the galaxy, we find that the AGN component that dominates the continuum emission at λ < 15 ÎŒm on scales of âŒ60 pc (90â100 per cent) decreases to 35â50 per cent when the emission of the central âŒ830 pc is considered. On the other hand, the AGN contribution dominates the 15â25 ÎŒm emission (75 per cent) on the scales probed by Spitzer/IRS. We reproduced the nuclear infrared emission of the galaxy with clumpy torus models, and derived a torus gas mass of 2 Ă 10^5 âM_â, contained in a clumpy structure of âŒ2 pc radius and with a column density compatible with Mrk 1066 being a Compton-thick candidate, in agreement with X-ray observations. We find a good match between the MIR morphology of Mrk 1066 and the extended PaÎČ, BrÎł and [O iii] λ5007 emission. This coincidence implies that the 8.7 ÎŒm emission is probing star formation, dust in the narrow-line region and the oval structure previously detected in the near-infrared. On the other hand, the Chandra soft X-ray morphology does not match any of the previous, contrary to what it is generally assumed for Seyfert galaxies. A thermal origin for the soft X-ray emission, rather than AGN photoionization, is suggested by the different data analysed here
Multi-phase feedback processes in the Sy2 galaxy NGC 5643
We study the multi-phase feedback processes in the central ~3 kpc of the
barred Sy 2 galaxy NGC 5643. We use observations of the cold molecular gas
(ALMA CO(2-1)) and ionized gas (MUSE IFU). We study different regions along the
outflow zone which extends out to ~2.3 kpc in the same direction (east-west) as
the radio jet, as well as nuclear/circumnuclear regions in the host galaxy
disk. The deprojected outflowing velocities of the cold molecular gas (median
Vcentral~189 km s^-1) are generally lower than those of the outflowing ionized
gas, which reach deprojected velocities of up to 750 km s^-1 close to the AGN,
and their spatial profiles follow those of the ionized phase. This suggests
that the outflowing molecular gas in the galaxy disk is being entrained by the
AGN wind. We derive molecular and ionized outflow masses of ~5.2x10^7 Msun and
8.5x10^4 Msun and molecular and ionized outflow mass rates of ~51 Msun yr^-1
and 0.14 Msun yr^-1. Therefore, the molecular phase dominates the outflow mass
and outflow mass rate, while the outflow kinetic power and momentum are similar
in both phases. However, the wind momentum load for the molecular and ionized
outflow phases are ~27-5 and <1, which suggests that the molecular phase is not
momentum conserving while the ionized one most certainly is. The molecular gas
content (~1.5x10^7 Msun) of the eastern spiral arm is approximately 50-70% of
the content of the western one. We interpret this as destruction/clearing of
the molecular gas produced by the AGN wind impacting in the host galaxy. The
increase of the molecular phase momentum implies that part of the kinetic
energy from the AGN wind is transmitted to the molecular outflow. This suggest
that in Sy-like AGN such as NGC 5643, the radiative/quasar and the
kinetic/radio AGN feedback modes coexist and may shape the host galaxies even
at kpc-scales via both positive and (mild) negative feedback.Comment: 26 pages, 21 figures, 5 tables. Astronomy and Astrophysics, Accepted
2020 September 11, in pres
A deep look at the nuclear region of UGC 5101 through high angular resolution mid-IR data with GTC/CanariCam
We present an analysis of the nuclear infrared (IR, 1.6â18 ÎŒm) emission of the ultraluminous IR galaxy UGC 5101 to derive the properties of its active galactic nucleus (AGN) and its obscuring material. We use new mid-IR high angular resolution (0.3â0.5 arcsec) imaging using the Si-2 filter (λ_C = 8.7âÎŒm) and 7.5â13 ÎŒm spectroscopy taken with CanariCam (CC) on the 10.4 m Gran Telescopio CANARIAS. We also use archival Hubble Space Telescope/NICMOS and Subaru/COMICS imaging and Spitzer/IRS spectroscopy. We estimate the near- and mid-IR unresolved nuclear emission by modelling the imaging data with GALFIT. We decompose the Spitzer/IRS and CC spectra using a power-law component, which represents the emission due to dust heated by the AGN, and a starburst component, both affected by foreground extinction. We model the resulting unresolved near- and mid-IR, and the starburst subtracted CC spectrum with the CLUMPY torus models of Nenkova et al. The derived geometrical properties of the torus, including the large covering factor and the high foreground extinction needed to reproduce the deep 9.7âÎŒm silicate feature, are consistent with the lack of strong AGN signatures in the optical. We derive an AGN bolometric luminosity L_(bo)l ⌠1.9 Ă 10^(45)âerg s^(â1) that is in good agreement with other estimates in the literature
The far-infrared spectroscopic surveyor (FIRSS)
We are standing at the crossroads of powerful new facilities emerging in the next decade on the ground and in space like ELT, SKA, JWST, and Athena. Turning the narrative of the star formation potential of galaxies into a quantitative theory will provide answers to many outstanding questions in astrophysics, from the formation of planets to the evolution of galaxies and the origin of heavy elements. To achieve this goal, there is an urgent need for a dedicated space-borne, far-infrared spectroscopic facility capable of delivering, for the first time, large scale, high spectral resolution (velocity resolved) multiwavelength studies of the chemistry and dynamics of the ISM of our own Milky Way and nearby galaxies. The Far Infrared Spectroscopic Surveyor (FIRSS) fulfills these requirements and by exploiting the legacy of recent photometric surveys it seizes the opportunity to shed light on the fundamental building processes of our Universe
The Galaxy Activity, Torus, and Outflow Survey (GATOS). III: Revealing the inner icy structure in local AGN
We use JWST/MIRI MRS spectroscopy of a sample of six local obscured type
1.9/2 active galactic nuclei (AGN) to compare their nuclear mid-IR absorption
bands with the level of nuclear obscuration traced by X-rays. This study is the
first to use sub-arcsecond angular resolution data of local obscured AGN to
investigate the nuclear mid-IR absorption bands with a wide wavelength coverage
(4.9-28.1 m). All the nuclei show the 9.7 m silicate band in
absorption. We compare the strength of the 9.7 and 18 m silicate features
with torus model predictions. The observed silicate features are generally well
explained by clumpy and smooth torus models. We report the detection of the 6
m dirty water ice band (i.e., a mix of water and other molecules such as
CO and CO) at sub-arcsecond scales (0.26 arcsec at 6 m; inner
50 pc) in a sample of local AGN with different levels of nuclear
obscuration in the range log N(cm). We
find a good correlation between the 6 m water ice optical depths and
N. This result indicates that the water ice absorption
might be a reliable tracer of the nuclear intrinsic obscuration in AGN. The
weak water ice absorption in less obscured AGN (log N
(cm)23.0 cm) might be related to the hotter dust
temperature (T110 K) expected to be reached in the outer
layers of the torus due to their more inhomogeneous medium. Our results suggest
it might be necessary to include the molecular content, such as, HO,
aliphatic hydrocarbons (CH-) and more complex PAH molecules in torus models to
better constrain key parameters such as the torus covering factor (i.e. nuclear
obscuration).Comment: Accepted for publication in A&A. 13 pages, 12 Figure
The Galaxy Activity, Torus, and Outflow Survey (GATOS): III. Revealing the inner icy structure in local active galactic nuclei
We use JWST/MIRI MRS spectroscopy of a sample of six local obscured type 1.9/2 active galactic nuclei (AGN) to compare their nuclear mid-IR absorption bands with the level of nuclear obscuration traced by X-rays. This study is the first to use subarcsecond angular resolution data of local obscured AGN to investigate the nuclear mid-IR absorption bands with a wide wavelength coverage (4.9â28.1 ÎŒm). All the nuclei show the 9.7 ÎŒm silicate band in absorption. We compare the strength of the 9.7 and 18 ÎŒm silicate features with torus model predictions. The observed silicate features are generally well explained by clumpy and smooth torus models. We report the detection of the 6 ÎŒm dirty water ice band (i.e., a mix of water and other molecules such as CO and CO2) at subarcsecond scales (âŒ0.26âł at 6 ÎŒm; inner âŒ50 pc) in a sample of local AGN with different levels of nuclear obscuration in the range log NHX-Ray (cmâ2)âŒ22â
ââ
25. We find good correlation between the 6 ÎŒm water ice optical depths and NHX-Ray. This result indicates that the water ice absorption might be a reliable tracer of the nuclear intrinsic obscuration in AGN. The weak water ice absorption in less obscured AGN (log NHX-ray (cmâ2)âČ23.0 cmâ2) might be related to the hotter dust temperature (>â
TsubH2Oâ
âŒâ
110 K) expected to be reached in the outer layers of the torus due to their more inhomogeneous medium. Our results suggest it might be necessary to include the molecular content, such as H2O, aliphatic hydrocarbons (CHâ), and more complex polycyclic aromatic hydrocarbon (PAH) molecules, in torus models to better constrain key parameters such as the torus covering factor (i.e., nuclear obscuration)
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