242 research outputs found
Multiphase gas flows in the nearby Seyfert galaxy ESO428-G14
We present ALMA rest-frame 230 GHz continuum and CO(2-1) line observations of
the nearby Compton-thick Seyfert galaxy ESO428-G14, with angular resolution 0.7
arcsec (78 pc). We detect CO(2-1) emission from spiral arms and a
circum-nuclear ring with 200 pc radius, and from a transverse gas lane with
size of pc, which crosses the nucleus and connects the two portions
the circumnuclear ring. The molecular gas in the host galaxy is distributed in
a rotating disk with intrinsic circular velocity km/s,
inclination deg, and dynamical mass within a radius of kpc. In the inner 100 pc region CO is
distributed in a equatorial bar, whose kinematics is highly perturbed and
consistent with an inflow of gas towards the AGN. This inner CO bar overlaps
with the most obscured, Compton-thick region seen in X-rays. We derive a column
density of in this region,
suggesting that molecular gas may contribute significantly to the AGN
obscuration. We detect a molecular outflow with a total outflow rate , distributed along a bi-conical structure with
size of pc on both sides of the AGN. The bi-conical outflow is also
detected in the emission line at 2.12 m, which traces a warmer
nuclear outflow located within 170 pc from the AGN. This suggests that the
outflow cools with increasing distance from the AGN. We find that the hard
X-ray emitting nuclear region mapped with Chandra is CO-deprived, but filled
with warm molecular gas traced by - thus confirming that the hard
(3-6 keV) continuum and Fe K emission are due to scattering from dense
neutral clouds in the ISM.Comment: Submitted to Ap
The rest-frame UV-to-optical spectroscopy of APM 08279+5255 - BAL classification and black hole mass estimates
We present the analysis of the rest-frame optical-to-UV spectrum of APM
08279+5255, a well-known lensed broad absorption line (BAL) quasar at . The spectroscopic data are taken with the optical DOLoRes and near-IR
NICS instruments at TNG, and include the previously unexplored range between C
III] 1910 and [O III] 4959,5007. We investigate the
possible presence of multiple BALs by computing "balnicity" and absorption
indexes (i.e. BI, BI and AI) for the transitions Si IV 1400, C IV
1549, Al III 1860 and Mg II 2800. No clear evidence
for the presence of absorption features is found in addition to the already
known, prominent BAL associated to C IV, which supports a high-ionization BAL
classification for APM 08279+5255. We also study the properties of the [O III],
H and Mg II emission lines. We find that [O III] is intrinsically weak
(), as it is typically found in
luminous quasars with a strongly blueshifted C IV emission line (2500 km
s for APM 08279+5255). We compute the single-epoch black hole mass based
on Mg II and H broad emission lines, finding M, with the magnification factor that can
vary between 4 and 100 according to CO and rest-frame UV-to-mid-IR imaging
respectively. Using a Mg II equivalent width (EW)-to-Eddington ratio relation,
the EW \AA\ measured for APM 08279+5255 translates into an
Eddington ratio of 0.4, which is more consistent with . This
magnification factor also provides a value of that is consistent
with recent reverberation-mapping measurements derived from C IV and Si IV.Comment: 10 pages, 4 figures, 4 tables, accepted for publication in A&
Widespread QSO-driven outflows in the early Universe
We present the stacking analysis of a sample of 48 quasi-stellar objects (QSOs) at 4.5 < z < 7.1 detected by the Atacama Large
Millimetre Array (ALMA) in the [CII] \u3bb158 \ub5m emission line to investigate the presence and the properties of massive, cold outflows
associated with broad wings in the [CII] profile. The high sensitivity reached through this analysis allows us to reveal very broad
[CII] wings tracing the presence of outflows with velocities in excess of 1000 km s 121. We find that the luminosity of the broad [CII]
emission increases with LAGN, while it does not significantly depend on the star formation rate of the host galaxy, indicating that the
central active galactic nucleus (AGN) is the main driving mechanism of the [CII] outflows in these powerful, distant QSOs. From
the stack of the ALMA cubes, we derive an average outflow spatial extent of 3c3.5 kpc. The average atomic neutral mass outflow rate
inferred from the stack of the whole sample is M\u2d9out 3c 100 M yr 121, while for the most luminous systems it increases to 3c200 M yr 121.
The associated outflow kinetic power is about 0.1% of LAGN, while the outflow momentum rate is 3cLAGN/c or lower, suggesting that
these outflows are either driven by radiation pressure onto dusty clouds or, alternatively, are driven by the nuclear wind and energy
conserving but with low coupling with the interstellar medium. We discuss the implications of the resulting feedback effect on galaxy
evolution in the early Universe
Widespread {QSO}-driven outflows in the early Universe
We present the stacking analysis of a sample of 48 quasi-stellar objects (QSOs) at 4.5 < z < 7.1 detected by the Atacama Large Millimetre Array (ALMA) in the [CII] lambda 158 mu m emission line to investigate the presence and the properties of massive, cold outflows associated with broad wings in the [CII] profile. The high sensitivity reached through this analysis allows us to reveal very broad [CII] wings tracing the presence of outflows with velocities in excess of 1000 km s(-1). We find that the luminosity of the broad [CII] emission increases with L-AGN, while it does not significantly depend on the star formation rate of the host galaxy, indicating that the central active galactic nucleus (AGN) is the main driving mechanism of the [CII] outflows in these powerful, distant QSOs. From the stack of the ALMA cubes, we derive an average outflow spatial extent of similar to 3.5 kpc. The average atomic neutral mass outflow rate inferred from the stack of the whole sample is (M)over dot(out) similar to 100 M-circle dot yr(-1), while for the most luminous systems it increases to similar to 200 M(circle dot)yr(-1). The associated outflow kinetic power is about 0.1% of LAGN, while the outflow momentum rate is similar to L-AGN/C or lower, suggesting that these outflows are either driven by radiation pressure onto dusty clouds or, alternatively, are driven by the nuclear wind and energy conserving but with low coupling with the interstellar medium. We discuss the implications of the resulting feedback effect on galaxy evolution in the early Universe
The WISSH Quasars Project III. X-ray properties of hyper-luminous quasars
We perform a survey of the X-ray properties of 41 objects from the WISE/SDSS
selected Hyper-luminous (WISSH) quasars sample, composed by 86 broad-line
quasars (QSOs) with bolometric luminosity , at z~2-4. All but 3 QSOs show unabsorbed 2-10 keV luminosities
. Thanks to their extreme radiative output
across the Mid-IR-to-X-ray range, WISSH QSOs offer the opportunity to
significantly extend and validate the existing relations involving .
We study as a function of (i) X-ray-to-Optical (X/O) flux ratio,
(ii) mid-IR luminosity (), (iii) as well as (iv)
vs. the 2500 luminosity. We find that WISSH QSOs
show very low X/O(<0.1) compared to typical AGN values;
ratios significantly smaller than those derived for AGN with lower luminosity;
large X-ray bolometric corrections 100-1000; and steep
. These results lead to a scenario where the X-ray
emission of hyper-luminous quasars is relatively weaker compared to
lower-luminosity AGN. Models predict that such an X-ray weakness can be
relevant for the acceleration of powerful high-ionization emission line-driven
winds, commonly detected in the UV spectra of WISSH QSOs, which can in turn
perturb the X-ray corona and weaken its emission. Accordingly, hyper-luminous
QSOs represent the ideal laboratory to study the link between the AGN energy
output and wind acceleration. Additionally, WISSH QSOs show very large BH
masses (>9.5). This enables a more robust modeling
of the relation by increasing the statistics at high masses. We
derive a flatter dependence than previously found over the broad range
5 < < 11.Comment: 20 pages, 14 Figures. Accepted for publication on A&
The dense molecular gas in the QSO SDSS J231038.88+185519.7 resolved by ALMA
We present ALMA observations of the CO(6-5) and [CII] emission lines and the
sub-millimeter continuum of the quasi-stellar object (QSO) SDSS
J231038.88+185519.7. Compared to previous studies, we have analyzed a synthetic
beam that is ten times smaller in angular size, we have achieved ten times
better sensitivity in the CO(6-5) line, and two and half times better
sensitivity in the [CII] line, enabling us to resolve the molecular gas
emission. We obtain a size of the dense molecular gas of kpc, and
of kpc for the 91.5 GHz dust continuum. By assuming that CO(6-5) is
thermalized, and by adopting a CO--to-- conversion factor , we infer a molecular gas mass of
. Assuming that the
observed CO velocity gradient is due to an inclined rotating disk, we derive a
dynamical mass of , which is a factor of approximately two smaller than the previously
reported estimate based on [CII]. Regarding the central black hole, we provide
a new estimate of the black hole mass based on the C~IV emission line detected
in the X-SHOOTER/VLT spectrum: . We find a molecular gas fraction of ,
where . We derive a ratio
suggesting high gas turbulence, outflows/inflows
and/or complex kinematics due to a merger event. We estimate a global Toomre
parameter , indicating likely cloud fragmentation. We compare,
at the same angular resolution, the CO(6-5) and [CII] distributions, finding
that dense molecular gas is more centrally concentrated with respect to [CII].
We find that the current BH growth rate is similar to that of its host galaxy.Comment: A&A in pres
The WISSH quasars Project: II. Giant star nurseries in hyper-luminous quasars
Studying the coupling between the energy output produced by the central
quasar and the host galaxy is fundamental to fully understand galaxy evolution.
Quasar feedback is indeed supposed to dramatically affect the galaxy properties
by depositing large amounts of energy and momentum into the ISM. In order to
gain further insights on this process, we study the SEDs of sources at the
brightest end of the quasar luminosity function, for which the feedback
mechanism is supposed to be at its maximum. We model the rest-frame UV-to-FIR
SEDs of 16 WISE-SDSS Selected Hyper-luminous (WISSH) quasars at 1.8 < z < 4.6
disentangling the different emission components and deriving physical
parameters of both the nuclear component and the host galaxy. We also use a
radiative transfer code to account for the contribution of the quasar-related
emission to the FIR fluxes. Most SEDs are well described by a standard
combination of accretion disk+torus and cold dust emission. However, about 30%
of them require an additional emission component in the NIR, with temperatures
peaking at 750K, which indicates the presence of a hotter dust component in
these powerful quasars. We measure extreme values of both AGN bolometric
luminosity (LBOL > 10^47 erg/s) and SFR (up to 2000 Msun/yr). A new relation
between quasar and star-formation luminosity is derived (LSF propto
LQSO^(0.73)) by combining several Herschel-detected quasar samples from z=0 to
4. Future observations will be crucial to measure the molecular gas content in
these systems, probe the impact between quasar-driven outflows and on-going
star-formation, and reveal the presence of merger signatures in their host
galaxies.Comment: 19 pages, 12 figures; Accepted for publication in Astronomy &
Astrophysics on June 13, 201
Soil and water bioengineering: practice and research needs for reconciling natural hazard control and ecological restoration
Soil and water bioengineering is a technology that encourages scientists and practitioners to combine their knowledge and skills in the management of ecosystems with a common goal to maximize benefits to both man and the natural environment. It involves techniques that use plants as living building materials, for: (i) natural hazard control (e.g., soil erosion, torrential floods and landslides) and (ii) ecological restoration or nature-based re-introduction of species on degraded lands, river embankments, and disturbed environments. For a bioengineering project to be successful, engineers are required to highlight all the potential benefits and ecosystem services by documenting the technical, ecological, economic and social values. The novel approaches used by bioengineers raise questions for researchers and necessitate innovation from practitioners to design bioengineering concepts and techniques. Our objective in this paper, therefore, is to highlight the practice and research needs in soil and water bioengineering for reconciling natural hazard control and ecological restoration. Firstly, we review the definition and development of bioengineering technology, while stressing issues concerning the design, implementation, and monitoring of bioengineering actions. Secondly, we highlight the need to reconcile natural hazard control and ecological restoration by posing novel practice and research questions
Exploring the association of electron-donating corroles with phthalocyanines as electron acceptors
Electron-donating corroles (Cor) were integrated with electron-accepting phthalocyanines (Pc) to afford two different non-covalent Cor ⋅ Pc systems. At the forefront was the coordination between a 10-meso-pyridine Cor and a ZnPc. The complexation was corroborated in a combination of NMR, absorption, and fluorescence assays, and revealed association with binding constants as high as 106 m−1. Steady-state and time-resolved spectroscopies evidenced that regardless of exciting Cor or Pc, the charge-separated state evolved efficiently in both cases, followed by a slow charge-recombination to reinstate the ground state. The introduction of non-covalent linkages between Cor and Pc induces sizeable differences in the context of light harvesting and transfer of charges when compared with covalently linked Cor-Pc conjugates
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