277 research outputs found
MUSE observations of a changing-look AGN I: The re-appearance of the broad emission lines
Optical changing-look Active Galactic Nuclei (AGN) are a class of sources
that change type within a short timescale of years or decades. This change is
characterised by the appearance or disappearance of broad emission lines, often
associated with dramatic AGN continuum flux changes that are orders of
magnitude larger than those expected from typical AGN variability. In this work
we study for the first time the host galaxy of a changing-look AGN, Mrk 590,
using high spatial resolution optical and near-infrared observations. We
discover that after ~ 10 yr absence, the optical broad emission lines of Mrk
590 have reappeared. The AGN optical continuum flux however, is still ~ 10
times lower than that observed during the most luminous state in the 1990s. The
host galaxy shows a 4.5 kpc radius star-forming ring with knots of ionised and
cold molecular gas emission. Extended ionised and warm molecular gas emission
are detected in the nucleus, indicating that there is a reservoir of gas as
close as 60 pc from the black hole. We observe a nuclear gas spiral between
radii r ~ 0.5 - 2 kpc, which has been suggested as a dynamical mechanism able
to drive the necessary gas to fuel AGN. We also discover blue-shifted and high
velocity dispersion [O III] emission out to a radius of 1 kpc, tracing a
nuclear gas outflow. The gas dynamics in Mrk 590 suggest a complex balance
between gas inflow and outflow in the nucleus of the galaxy.Comment: Accepted for publication in MNRA
ALMA reveals the feeding of the Seyfert 1 nucleus in NGC 1566
We report ALMA observations of CO(3-2) emission in the Seyfert 1 galaxy NGC
1566, at a spatial resolution of 25 pc. Our aim is to investigate the
morphology and dynamics of the gas inside the central kpc, and to probe nuclear
fueling and feedback phenomena. NGC 1566 has a nuclear bar of 1.7 kpc radius
and a conspicuous grand design spiral starting from this radius. The ALMA field
of view, of diameter 0.9 kpc, lies well inside the nuclear bar and reveals a
molecular trailing spiral structure from 50 to 300~pc in size, which is
contributing to fuel the nucleus, according to its negative gravity torques.
The spiral starts with a large pitch angle from the center and then winds up
in a pseudo-ring at the inner Lindblad resonance (ILR) of the nuclear bar.
This is the first time that a trailing spiral structure is clearly seen
driving the gas inwards inside the ILR ring of the nuclear bar. This phenomenon
shows that the massive central black hole has a significant dynamical influence
on the gas, triggering its fueling.
The gaseous spiral is well correlated with the dusty spiral seen through
extinction in HST images, and also with a spiral feature emitting 0.87mm
continuum. This continuum emission must come essentially from cold dust heated
by the interstellar radiation field. The HCN(4-3) and HCO+(4-3) lines were
simultaneously mapped and detected in the nuclear spiral. The HCO+(4-3) line is
3 times stronger than the HCN(4-3), as expected when star formation excitation
dominates over active galactic nucleus (AGN) heating. The CO(3-2)/HCO+(4-3)
integrated intensity ratio is \sim 100.
The molecular gas is in remarkably regular rotation, with only slight
non-circular motions at the periphery of the nuclear spiral arms. These
perturbations are quite small, and no outflow nor AGN feedback is detected.Comment: 11 pages, 16 figures, accepted in Astronomy and Astrophysic
ALMA observations of feeding and feedback in nearby Seyfert galaxies: an AGN-driven outflow in NGC 1433
We report ALMA observations of CO(3-2) emission in the Seyfert 2
double-barred galaxy NGC1433, at the unprecedented spatial resolution of
0.5"=24 pc. Our aim is to probe AGN feeding and feedback phenomena through the
morphology and dynamics of the gas inside the central kpc. The CO map, which
covers the whole nuclear region (nuclear bar and ring), reveals a nuclear
gaseous spiral structure, inside the nuclear ring encircling the nuclear
stellar bar.
This gaseous spiral is well correlated with the dusty spiral seen in Hubble
Space Telescope images. The nuclear spiral winds up in a pseudo-ring at 200 pc
radius, which might correspond to the inner ILR. Continuum emission is detected
at 0.87 mm only at the very centre, and its origin is more likely thermal dust
emission than non-thermal emission from the AGN. It might correspond to the
molecular torus expected to exist in this Seyfert 2 galaxy. The HCN(4-3) and
HCO+(4-3) lines were observed simultaneously, but only upper limits are
derived, with a ratio to the CO(3-2) line lower than 1/60 at 3sigma, indicating
a relatively low abundance of very dense gas. The kinematics of the gas over
the nuclear disk reveal rather regular rotation only slightly perturbed by
streaming motions due to the spiral; the primary and secondary bars are too
closely aligned with the galaxy major or minor axis to leave a signature in the
projected velocities. Near the nucleus, there is an intense high-velocity CO
emission feature redshifted to 200 km/s (if located in the plane), with a
blue-shifted counterpart, at 2" (100 pc) from the centre. While the CO spectra
are quite narrow in the centre, this wide component is interpreted as an
outflow involving a molecular mass of 3.6 10^6 Mo and a flow rate 7 Mo/yr. The
flow could be in part driven by the central star formation, but is mainly
boosted by the AGN through its wind or radio jets.Comment: 11 pages, 9 figures, Accepted in Astronomy and Astrophysic
Italian Science Case for ALMA Band 2+3
The Premiale Project "Science and Technology in Italy for the upgraded ALMA
Observatory - iALMA" has the goal of strengthening the scientific,
technological and industrial Italian contribution to the Atacama Large
Millimeter/submillimeter Array (ALMA), the largest ground based international
infrastructure for the study of the Universe in the microwave. One of the main
objectives of the Science Working Group (SWG) inside iALMA, the Work Package 1,
is to develop the Italian contribution to the Science Case for the ALMA Band 2
or Band 2+3 receiver. ALMA Band 2 receiver spans from ~67 GHz (bounded by an
opaque line complex of ozone lines) up to 90 GHz which overlaps with the lower
frequency end of ALMA Band 3. Receiver technology has advanced since the
original definition of the ALMA frequency bands. It is now feasible to produce
a single receiver which could cover the whole frequency range from 67 GHz to
116 GHz, encompassing Band 2 and Band 3 in a single receiver cartridge, a so
called Band 2+3 system. In addition, upgrades of the ALMA system are now
foreseen that should double the bandwidth to 16 GHz. The science drivers
discussed below therefore also discuss the advantages of these two enhancements
over the originally foreseen Band 2 system.Comment: 43 pages, 21 figure
Learning object relationships which determine the outcome of actions
Peer reviewedPublisher PD
ALMA reveals a warm and compact starburst around a heavily obscured supermassive black hole at z=4.75
We report ALMA Cycle 0 observations at 1.3mm of LESS J033229.4-275619
(XID403), an Ultraluminous Infrared Galaxy at in the Chandra Deep
Field South hosting a Compton-thick QSO. The source is not resolved in our data
at a resolution of 0.75 arcsec, placing an upper-limit of 2.5 kpc to the
half-light radius of the continuum emission from heated-dust. After
deconvolving for the beam size, however, we found a indication of
an intrinsic source size of arcsec (Gaussian FWHM), which would
correspond to kpc. We build the far-IR SED of XID403 by
combining datapoints from both ALMA and Herschel and fit it with a modified
blackbody spectrum. For the first time, we measure the dust temperature
K in this system, which is comparable to what has been
observed in other high-z submillimeter galaxies. The measured star formation
rate is SFR= yr, in agreement with previous
estimates at lower S/N. Based on the measured SFR and source size, we constrain
the SFR surface density to be yrkpc
(yrkpc for kpc). The
compactness of this starburst is comparable to what has been observed in other
local and high-z starburst galaxies. If the gas mass measured from previous
[CII] and CO(2-1) observations at low resolution is confined within the same
dust region, assuming kpc, this would produce a column
density of cm towards the central SMBH,
similar to the column density of cm measured
from the X-rays. Then, in principle, if both gas and dust were confined on
sub-kpc scales, this would be sufficient to produce the observed X-ray column
density without any need of a pc-scale absorber [abridged].Comment: 11 pages, 5 figures. Accepted for publication in A&
Molecular line emission in NGC1068 imaged with ALMA: II. The chemistry of the dense molecular gas
We present a detailed analysis of ALMA Bands 7 and 9 data of CO, HCO+, HCN
and CS, augmented with Plateau de Bure Interferometer (PdBI) data of the ~ 200
pc circumnuclear disk (CND) and the ~ 1.3 kpc starburst ring (SB ring) of
NGC~1068, a nearby (D = 14 Mpc) Seyfert 2 barred galaxy. We aim at determining
the physical characteristics of the dense gas present in the CND and whether
the different line intensity ratios we find within the CND as well as between
the CND and the SB ring are due to excitation effects (gas density and
temperature differences) or to a different chemistry. We estimate the column
densities of each species in Local Thermodynamic Equilibrium (LTE). We then
compute large one-dimensional non-LTE radiative transfer grids (using RADEX) by
using first only the CO transitions, and then all the available molecules in
order to constrain the densities, temperatures and column densities within the
CND. We finally present a preliminary set of chemical models to determine the
origin of the gas. We find that in general the gas in the CND is very dense (>
10^5 cm^-3) and hot (T> 150K), with differences especially in the temperature
across the CND. The AGN position has the lowest CO/HCO+, CO/HCN and CO/CS
column density ratios. RADEX analyses seem to indicate that there is chemical
differentiation across the CND. We also find differences between the chemistry
of the SB ring and some regions of the CND; the SB ring is also much colder and
less dense than the CND. Chemical modelling does not succeed in reproducing all
the molecular ratios with one model per region, suggesting the presence of
multi-gas phase components. The LTE, RADEX and chemical analyses all indicate
that more than one gas-phase component is necessary to uniquely fit all the
available molecular ratios within the CND.Comment: Accepted by A&A; please contact the author for a better version of
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Programa de rehabilitación cardíaca mediante un entrenamiento de tenis adaptado
The aims of this study were to determine the effect of a cardiac rehabilitation program, based on the adjustment of a sports modality (tennis), on differentes laboratory analysis variables (triglycerides, cholesterol,cholesterol LDL, cholesterol HDL and glucose ) And and on an exercise stress test (metabolics equivalent-METs-, time of effort, systolic pressure, dyastolic pressure, maximum cardiac frecuencia and double product). The study involved 7 patients with low risk myocardial heart attack. The ages was include between 48 and 63 years old. By the end of the program, which has lasted 3 months, triglycerides, cholesterol, exercise capacity and double product had improved significantly (p<.005 for all).Los objetivos de este estudio son evaluar los efectos de nuestro programa de rehabilitación cardiaca, basado en la adaptación de una modalidad deportiva (tenis), sobre diferentes variables del perfil lipídico (triglicéridos, colesterol, cLDL, cHDL, y glucosa) así como en la prueba de esfuerzo (MET, tiempo de esfuerzo, presión sistólica, presión diastólica, frecuencia cardíaca máxima y doble producto). Analizamos a 7 pacientes con infarto agudo de miocardio de bajo riesgo. Las edades estaban comprendidas entre los 48 y 63 años. Tras la realización del programa, que ha tenido 3 meses de duración, se han producido mejoras significativas a nivel de triglicéridos, colesterol, capacidad funcional valorada en equivalentes metabólicos y doble producto (p<.005 para todos)
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