32 research outputs found
Adaptive optics near infrared integral field spectroscopy of NGC 2992
NGC 2992 is an intermediate Seyfert 1 galaxy showing outflows on kilo parsec
scales which might be due either to AGN or starburst activity. We therefore aim
at investigating its central region for a putative starburst in the past and
its connection to the AGN and the outflows. Observations were performed with
the adaptive optics near infrared integral field spectrograph SINFONI on the
VLT, complemented by longslit observations with ISAAC on the VLT, as well as N-
and Q-band data from the Spitzer archive. The spatial and spectral resolutions
of the SINFONI data are 50 pc and 83 km/s, respectively. The field of view of
3" x 3" corresponds to 450 pc x 450 pc. Br_gamma equivalent width and line
fluxes from PAHs were compared to stellar population models to constrain the
age of the putative recent star formation. A simple geometric model of two
mutually inclined disks and an additional cone to describe an outflow was
developed to explain the observed complex velocity field in H_2 1-0S(1). The
morphologies of the Br_gamma and the stellar continuum are different suggesting
that at least part of the Br_gamma emission comes from the AGN. This is
confirmed by PAH emission lines at 6.2 micron and 11.2 micron and the strength
of the silicon absorption feature at 9.7 micron, which point to dominant AGN
activity with a relatively minor starburst contribution. We find a starburst
age of 40 Myr - 50 Myr from Br_gamma line diagnostics and the radio continuum;
ongoing star formation can be excluded. Both the energetics and the timescales
indicate that the outflows are driven by the AGN rather than the starburst. The
complex velocity field observed in H_2 1-0S(1) in the central 450 pc can be
explained by the superposition of the galaxy rotation and an outflow.Comment: 10 pages, 8 figures, accepted for publication in A&
OTELO Survey: Deep BVRI broadband photometry of the Groth strip. II Properties of X-ray Emitters
The Groth field is one of the sky regions that will be targeted by the OTELO
(OSIRIS Tunable Filter Emission Line Object) survey in the optical 820 nm and
920 nm atmospheric windows. This field has been observed by AEGIS
(All-wavelength Extended Groth strip International Survey) covering the full
spectral range, from X-rays to radio waves. Chandra X-ray data with total
exposure time of 200ksec are analyzed and combined with optical broadband data
of the Groth field in order to study a set of structural parameters of the
X-ray emitters and its relation with X-ray properties. We processed the raw,
public X-ray data using the Chandra Interactive Analysis of Observations and
determined and analyzed different structural parameters in order to produce a
morphological classification of X-ray sources. Finally, we analyzed the angular
clustering of these sources using 2-point correlation functions. We present a
catalog of 340 X-ray emitters with optical counterpart. We obtained the number
counts and compared them with AEGIS data. Objects have been classified by
nuclear type using a diagnostic diagram relating X-ray-to-optical ratio (X/O)
to hardness ratio (HR). Also, we combined structural parameters with other
X-ray and optical properties, and found for the first time an anticorrelation
between the X/O ratio and the Abraham concentration index which might suggest
that early type galaxies have lower Eddington rates than those of late type
galaxies. A significant positive angular clustering was obtained from a
preliminary analysis of 4 subsamples of the X-ray sources catalog. The
clustering signal of the opticaly extended counterparts is similar to that of
strongly clustered populations like red and very red galaxies, suggesting that
the environment plays an important role in AGN phenomena.Comment: 23 pages, 19 Postscript figure
Enabling planetary science across light-years. Ariel Definition Study Report
Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution
Calibrating an Ionosonde for Ionospheric Attenuation Measurements
Vertical ionospheric soundings have been performed at almost all ionospheric observatories with little attention to measuring the attenuation of the signal between transmission and reception. When the absorption has been determined, this has been achieved by comparing the received power after the first and second reflections, but this method has some limitations due to the unknown reflection coefficient of the ground and the non-continuous presence of the second reflection. This paper deals with a different method based on precise calibration of the sounding system, allowing determination of absolute signal attenuation after a single reflection. This approach is affected by a systematic error due to imperfect calibration of the antennas, but when the focus of interest is to measure a trend over a specified period, it is very accurate. The article describes how calibration was implemented, the measurement output formats, and finally it presents some results from a meaningful set of measurements in order to demonstrate what this method can accomplish
Calibrating an Ionosonde for Ionospheric Attenuation Measurements
Vertical ionospheric soundings have been performed at almost all ionospheric observatories with little attention to measuring the attenuation of the signal between transmission and reception. When the absorption has been determined, this has been achieved by comparing the received power after the first and second reflections, but this method has some limitations due to the unknown reflection coefficient of the ground and the non-continuous presence of the second reflection. This paper deals with a different method based on precise calibration of the sounding system, allowing determination of absolute signal attenuation after a single reflection. This approach is affected by a systematic error due to imperfect calibration of the antennas, but when the focus of interest is to measure a trend over a specified period, it is very accurate. The article describes how calibration was implemented, the measurement output formats, and finally it presents some results from a meaningful set of measurements in order to demonstrate what this method can accomplish.Published15642A. Fisica dell'alta atmosfera2IT. Laboratori analitici e sperimentali6IT. Osservatori non satellitariJCR Journa
BIOCONTROL OF THE BACTERIAL BLIGHT OF WALNUT: IS THERE A CHANCE TO REDUCE COPPER INPUTS INTO WALNUT GROVES?
The bacterial blight is a re-emerging disease, severely affecting
the productivity of walnut groves. Disease symptoms are observed
on all aerial parts of the host plant, but the most damaging are the
necrotic spots developing on fruits, leading to massive fruit drops,
mainly before endocarp hardening. The causal agent is Xanthomonas
arboricola pv. juglandis (Xaj), a gram-negative rod with a worldwide
distribution. The population structure of Xaj includes several morphotypes,
at least five sequence types, and other features confirming
its genomic heterogeneity. Copper resistance is widespread and very
effective among Xaj populations: therefore, disease management
based on copper sprays is not particularly effective, even in cases
of 10-14 treatments during the growing season. The recent, severe
outbreaks reported in Italy are due to two concomitant events: i) the
rapid increase of walnut acreage, especially in the northern part of
the Country and ii) the development of Xaj populations showing
high resistance to copper. Since most of the cultivated walnut varieties
are either highly susceptible or susceptible to the disease, we
tried to implement control strategies based on the use of a single antagonist
or the field application of microbial consortia. Additionally,
innovative agrochemicals, with a reduced copper content, have also
been used. Results showed that: i) microbial biocontrol agents were
able to significantly reduce the disease in the field; ii) innovative
agrochemicals may reduce the bacterial blight, but might enhance
phytotoxicity; iii) a significant reduction of copper inputs is possible,
coupled with an effective disease control in walnut groves