640 research outputs found
Far-infrared line spectra of active galaxies from the Herschel/PACS Spectrometer: the complete database
We present a coherent database of spectroscopic observations of far-IR
fine-structure lines from the Herschel/PACS archive for a sample of 170 local
AGN, plus a comparison sample of 20 starburst galaxies and 43 dwarf galaxies.
Published Spitzer/IRS and Herschel/SPIRE line fluxes are included to extend our
database to the full 10-600 spectral range. The observations are
compared to a set of CLOUDY photoionisation models to estimate the above
physical quantities through different diagnostic diagrams. We confirm the
presence of a stratification of gas density in the emission regions of the
galaxies, which increases with the ionisation potential of the emission lines.
The new [OIV]25.9/[OIII]88 vs [NeIII]15.6/[NeII]12.8 diagram is proposed as the best diagnostic to separate: AGN activity
from any kind of star formation; and low-metallicity dwarf galaxies from
starburst galaxies. Current stellar atmosphere models fail to reproduce the
observed [OIV]25.9/[OIII]88 ratios, which are much higher when
compared to the predicted values. Finally, the ([NeIII]15.6 +
[NeII]12.8)/([SIV]10.5 + [SIII]18.7) ratio is proposed as
a promising metallicity tracer to be used in obscured objects, where optical
lines fail to accurately measure the metallicity. The diagnostic power of mid-
to far-infrared spectroscopy shown here for local galaxies will be of crucial
importance to study galaxy evolution during the dust-obscured phase at the peak
of the star formation and black-hole accretion activity (). This
study will be addressed by future deep spectroscopic surveys with present and
forthcoming facilities such as JWST, ALMA, and SPICA.Comment: Accepted for publication in the ApJ
Outflows of hot molecular gas in ultra-luminous infra-red galaxies mapped with VLT-SINFONI
We present the detection and morphological characterization of hot molecular
gas outflows in nearby ultra-luminous infrared galaxies, using the near-IR
integral-field spectrograph SINFONI on the VLT. We detect outflows observed in
the 2.12 micron H 1-0 S(1) line for three out of four ULIRGs analyzed;
IRAS 12112+0305, 14348-1447, and 22491-1808. The outflows are mapped on scales
of 0.7-1.6 kpc, show typical outflow velocities of 300-500 km/s, and appear to
originate from the nuclear region. The outflows comprise hot molecular gas
masses of ~6-8x10 M(sun). Assuming a hot-to-cold molecular gas mass ratio
of 6x10, as found in nearby luminous IR galaxies, the total (hot+cold)
molecular gas mass in these outflows is expected to be ~1x10 M(sun). This
translates into molecular mass outflow rates of ~30-85 M(sun)/yr, which is a
factor of a few lower than the star formation rate in these ULIRGs. In
addition, most of the outflowing molecular gas does not reach the escape
velocity of these merger systems, which implies that the bulk of the outflowing
molecular gas is re-distributed within the system and thus remains available
for future star formation. The fastest H outflow is seen in the
Compton-thick AGN of IRAS 14348-1447, reaching a maximum outflow velocity of
~900 km/s. Another ULIRG, IRAS 17208-0014, shows asymmetric H line
profiles different from the outflows seen in the other three ULIRGs. We discuss
several alternative explanations for its line asymmetries, including a very
gentle galactic wind, internal gas dynamics, low-velocity gas outside the disk,
or two superposed gas disks. We do not detect the hot molecular counterpart to
the outflow previously detected in CO(2-1) in IRAS 17208-0014, but we note that
our SINFONI data are not sensitive enough to detect this outflow if it has a
small hot-to-cold molecular gas mass ratio of < 9x10.Comment: Accepted for publication in A&A (11 pages, 10 figures
Mid-J CO Emission in Nearby Seyfert Galaxies
We study for the first time the complete sub-millimeter spectra (450 GHz to
1550 GHz) of a sample of nearby active galaxies observed with the SPIRE Fourier
Transform Spectrometer (SPIRE/FTS) onboard Herschel. The CO ladder (from Jup =
4 to 12) is the most prominent spectral feature in this range. These CO lines
probe warm molecular gas that can be heated by ultraviolet photons, shocks, or
X-rays originated in the active galactic nucleus or in young star-forming
regions. In these proceedings we investigate the physical origin of the CO
emission using the averaged CO spectral line energy distribution (SLED) of six
Seyfert galaxies. We use a radiative transfer model assuming an isothermal
homogeneous medium to estimate the molecular gas conditions. We also compare
this CO SLED with the predictions of photon and X-ray dominated region (PDR and
XDR) models.Comment: Proceedings of the Torus Workshop 2012 held at the University of
Texas at San Antonio, 5-7 December 2012. C. Packham, R. Mason, and A.
Alonso-Herrero (eds.); 6 pages, 3 figure
First detection of the 448 GHz H2O transition in space
We present the first detection of the ortho-H2O 4_23-3_30 transition at 448
GHz in space. We observed this transition in the local (z = 0.010) luminous
infrared (IR) galaxy ESO 320-G030 (IRAS F11506-3851) using the Atacama Large
Millimeter/submillimeter Array (ALMA). The water 4_23-3_30 emission, which
originates in the highly obscured nucleus of this galaxy, is spatially resolved
over a region of ~65 pc in diameter and shows a regular rotation pattern
compatible with the global molecular and ionized gas kinematics. The line
profile is symmetric and well fitted by a Gaussian with an integrated flux of
37.0 +- 0.7 Jy km s-1 . Models predict this water transition as a potential
collisionally excited maser transition. On the contrary, in this galaxy, we
find that the 4_23-3_30 emission is primarily excited by the intense far-IR
radiation field present in its nucleus. According to our modeling, this
transition is a probe of deeply buried galaxy nuclei thanks to the high dust
optical depths (tau_100{\mu}m > 1, N_H > 1e24 cm-2) required to efficiently
excite it.Comment: Accepted for publication in A&A Letters; 4 pages, 5 figure
The starburst-AGN connection in the merger galaxy Mrk 938: an infrared and X-ray view
Mrk938 is a luminous infrared galaxy in the local Universe believed to be the
remnant of a galaxy merger. It shows a Seyfert 2 nucleus and intense star
formation according to optical spectroscopic observations. We have studied this
galaxy using new Herschel far-IR imaging data in addition to archival X-ray,
UV, optical, near-IR and mid-IR data. Mid- and far-IR data are crucial to
characterise the starburst contribution, allowing us to shed new light on its
nature and to study the coexistence of AGN and starburst activity in the local
Universe. The decomposition of the mid-IR Spitzer spectrum shows that the AGN
bolometric contribution to the mid-IR and total infrared luminosity is small
(Lbol(AGN)/LIR~0.02), which agrees with previous estimations. We have
characterised the physical nature of its strong infrared emission and
constrained it to a relatively compact emitting region of <2kpc. It is in this
obscured region where most of the current star formation activity is taking
place as expected for LIRGs. We have used Herschel imaging data for the first
time to constrain the cold dust emission with unprecedented accuracy. We have
fitted the integrated far-IR spectral energy distribution and derived the
properties of the dust, obtaining a dust mass of 3x10^7Msun. The far-IR is
dominated by emission at 35K, consistent with dust heated by the on-going star
formation activity.Comment: 12 pages, 6 figures, 4 tables, accepted for publication in MNRA
Optical integral field spectroscopy of intermediate redshift infrared bright galaxies
The extreme infrared (IR) luminosity of local luminous and ultra-luminous IR
galaxies (U/LIRGs; 11 12,
respectively) is mainly powered by star-formation processes triggered by
mergers or interactions. While U/LIRGs are rare locally, at z > 1, they become
more common, they dominate the star-formation rate (SFR) density, and a
fraction of them are found to be normal disk galaxies. Therefore, there must be
an evolution of the mechanism triggering these intense starbursts with
redshift. To investigate this evolution, we present new optical SWIFT integral
field spectroscopic H{\alpha}+[NII] observations of a sample of 9
intermediate-z (0.2 < z < 0.4) U/LIRG systems selected from Herschel 250{\mu}m
observations. The main results are the following: (a) the ratios between the
velocity dispersion and the rotation curve amplitude indicate that 10-25% (1-2
out of 8) might be compatible with being isolated disks while the remaining
objects are interacting/merging systems; (b) the ratio between un-obscured and
obscured SFR traced by H{\alpha} and LIR, respectively, is similar in both
local and these intermediate-z U/LIRGs; and (c) the ratio between 250{\mu}m and
the total IR luminosities of these intermediate-z U/LIRGs is higher than that
of local U/LIRGs with the same LIR . This indicates a reduced dust temperature
in these intermediate-z U/LIRGs. This, together with their already measured
enhanced molecular gas content, suggests that the interstellar medium
conditions are different in our sample of intermediate-z galaxies when compared
to local U/LIRGs.Comment: Accepted for publication in MNRA
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
Sensorimotor tongue evaluation and rehabilitation in patients with sleep-disordered breathing: a novel approach
We acknowledge the work of Professor O’Connor-Reina
who designed
and produced the Airway Gym® app for his patients and
whose work was central to this research.Study objectives: To evaluate tone, apraxia and stereognosis dysfunctions in patients
with SDB compared with healthy controls, and to monitor the effectiveness of
Airway Gym® as an easy-to-
use
myofunctional therapy (MT) modality in terms of the
tongue's motor and sensory responses, comparing results before and after therapy.
Methods: This was a prospective, non-randomised
pilot study of 25 patients with
moderate to severe obstructive sleep apnoea-hypopnoea
syndrome (OSAHS), 25 patients
with primary snoring (PS) and 20 healthy controls. Qualitative and quantitative
instruments—Iowa
Oral Performance Instrument (IOPI), lingual apraxia and stereognosis
tests were used to assess tongue sensorimotor function.
Results: 22 patients with PS, 21 with OSAHS and all 20 controls ended the therapy.
In OSAHS, the Epworth Sleepiness Scale score decreased from 16 ± 7.3 to 12 ± 4.5
after therapy (p = 0.53). In PS and OSAHS groups, the IOPI scores increased significantly.
These measures did not change significantly in the controls. Lingual apraxia
testing showed that controls performed all the manoeuvres, whereas PS 5.6 ± 1.4
and OSAHS 4.5 ± 1.9 (p = 0.14). In the stereognosis test, the mean number of figures
recognised was 2.6 ± 2.2 in OSAHS, 3.3±1.2 in PS and 5.7±0.9 in control group
(p < 0.05). Patients with OSAHS recognised circles and ovals less often.
Conclusion: Using the Airway Gym®app produced improvements in sensorimotor
tongue function in patients with SDB, due to continuous stimulation of the brain
based on proprioceptive training required to localise responses when doing the
exercises
- …