3,077 research outputs found
Arp 220 - IC 4553/4: understanding the system and diagnosing the ISM
Arp220 is a nearby system in final stages of galaxy merger with powerful
ongoing star-formation at and surrounding the two nuclei. Arp 220 was detected
in HI absorption and OH Megamaser emission and later recognized as the nearest
ultra-luminous infrared galaxy also showing powerful molecular and X-ray
emissions. In this paper we review the available radio and mm-wave
observational data of Arp 220 in order to obtain an integrated picture of the
dense interstellar medium that forms the location of the powerful
star-formation at the two nuclei.Comment: 9 pages, 4 figures, to appear in: IAU Symposium 242 Astrophysical
Masers and their Environment
C ion-implanted TiO2 thin film for photocatalytic applications
Third-generation TiO2 photocatalysts were prepared by implantation of C+ ions into 110 nm thick TiO2 films. An accurate structural investigation was performed by Rutherford backscattering spectrometry, secondary ion mass spectrometry, X-ray diffraction, Raman-luminescence spectroscopy, and UV/VIS optical characterization. The C doping locally modified the TiO2 pure films, lowering the band-gap energy from 3.3 eV to a value of 1.8 eV, making the material sensitive to visible light. The synthesized materials are photocatalytically active in the degradation of organic compounds in water under both UV and visible light irradiation, without the help of any additional thermal treatment. These results increase the understanding of the C-doped titanium dioxide, helpful for future environmental applications. (C) 2015 AIP Publishing LLC
Detection of 183 GHz water megamaser emission towards NGC 4945
Aim: The aim of this work is to search Seyfert 2 galaxy NGC 4945, a
well-known 22 GHz water megamaser galaxy, for water (mega)maser emission at 183
GHz. Method: We used APEX SEPIA Band 5 to perform the observations. Results: We
detected 183 GHz water maser emission towards NGC 4945 with a peak flux density
of ~3 Jy near the galactic systemic velocity. The emission spans a velocity
range of several hundred km/s. We estimate an isotropic luminosity of > 1000
Lsun, classifying the emission as a megamaser. A comparison of the 183 GHz
spectrum with that observed at 22 GHz suggests that 183 GHz emission also
arises from the active galactic nucleus (AGN) central engine. If the 183 GHz
emission originates from the circumnuclear disk, then we estimate that a
redshifted feature at 1084 km/s in the spectrum should arise from a distance of
0.022 pc from the supermassive black hole (1.6 x 10(5) Schwarzschild radii),
i.e. closer than the water maser emission previously detected at 22 GHz. This
is only the second time 183 GHz maser emission has been detected towards an AGN
central engine (the other galaxy being NGC 3079). It is also the strongest
extragalactic millimetre/submillimetre water maser detected to date.
Conclusions: Strong millimetre 183 GHz water maser emission has now been shown
to occur in an external galaxy. For NGC 4945, we believe that the maser
emission arises, or is dominated by, emission from the AGN central engine.
Emission at higher velocity, i.e. for a Keplerian disk closer to the black
hole, has been detected at 183 GHz compared with that for the 22 GHz megamaser.
This indicates that millimetre/submillimetre water masers can indeed be useful
probes for tracing out more of AGN central engine structures and dynamics than
previously probed. Future observations using ALMA Band 5 should unequivocally
determine the origin of the emission in this and other galaxies.Comment: 4 pages, accepted by A&A Letter
Delayed eruption of permanent dentition and maxillary contraction in patients with cleidocranial dysplasia: review and report of a family
Introduction. Cleidocranial dysplasia (CCD) is an inherited disease caused by mutations in the RUNX2 gene on chromosome 6p21. This pathology, autosomal dominant or caused by a spontaneous genetic mutation, is present in one in one million individuals, with complete penetrance and widely variable expressivity. Aim. To identify the incidence of these clinical findings in the report of the literature by means of PubMed interface from 2002 to 2015, with the related keywords. The report of local patients presents a clinical example, related to the therapeutic approach. Results and Discussions. The PubMed research resulted in 122 articles. All the typical signs were reported in all presented cases. The maxilla was hypoplastic in 94% of the patients. Missing of permanent teeth was found in two cases: one case presented a class II jaw relationship, instead of class III malocclusion. Similar findings were present in our cohort. Conclusion. CCD is challenging for both the dental team and the patient. The treatment requires a multidisciplinary approach. Further studies are required to better understand the cause of this disease. According to this review, a multistep approach enhances the possibilities to achieve the recovery of the most possible number of teeth, as such to obtain a good occlusion and a better aesthetic
Long term Arecibo monitoring of the water megamaser in MG J0414+0534
We monitored the 22 GHz maser line in the lensed quasar MG J0414+0534 at
z=2.64 with the 300-m Arecibo telescope for almost two years to detect possible
additional maser components and to measure a potential velocity drift of the
lines. The main maser line profile is complex and can be resolved into a number
of broad features with line widths of 30-160 km/s. A new maser component was
tentatively detected in October 2008 at a velocity of +470 km/s. After
correcting for the estimated lens magnification, we find that the H2O isotropic
luminosity of the maser in MG J0414+0534 is about 26,000 solar luminosities,
making this source the most luminous ever discovered. Both the main line peak
and continuum flux densities are surprisingly stable throughout the period of
the observations. An upper limit on the velocity drift of the main peak of the
line has been estimated from our observations and is of the order of 2 km/s per
year. We discuss the results of the monitoring in terms of the possible nature
of the maser emission, associated with an accretion disk or a radio jet. This
is the first time that such a study is performed in a water maser source at
high redshift, potentially allowing us to study the parsec-scale environment
around a powerful radio source at cosmological distances.Comment: 5 pages, 2 figures, to appear in the Proceedings of the IAU Symposium
287, 2012, "Cosmic masers: from OH to H0
Refining the M_BH-V_c scaling relation with HI rotation curves of water megamaser galaxies
Black hole - galaxy scaling relations provide information about the
coevolution of supermassive black holes and their host galaxies. We compare the
black hole mass - circular velocity (MBH - Vc) relation with the black hole
mass - bulge stellar velocity dispersion (MBH - sigma) relation, to see whether
the scaling relations can passively emerge from a large number of mergers, or
require a physical mechanism, such as feedback from an active nucleus. We
present VLA H I observations of five galaxies, including three water megamaser
galaxies, to measure the circular velocity. Using twenty-two galaxies with
dynamical MBH measurements and Vc measurements extending to large radius, our
best-fit MBH - Vc relation, log MBH = alpha + beta log(Vc /200 km s^-1), yields
alpha = 7.43+/-0.13, beta = 3.68+1.23/-1.20, and intrinsic scatter epsilon_int
= 0.51+0.11/-0.09. The intrinsic scatter may well be higher than 0.51, as we
take great care to ascribe conservatively large observational errors. We find
comparable scatter in the MBH - sigma relations, epsilon_int = 0.48+0.10/-0.08,
while pure merging scenarios would likely result in a tighter scaling with the
dark halo (as traced by Vc) than baryonic (sigma) properties. Instead, feedback
from the active nucleus may act on bulge scales to tighten the MBH - sigma
relation with respect to the MBH - Vc relation, as observed.Comment: 27 pages, 15 figures, ApJ accepte
A search for gravitationally lensed water masers in dusty quasars and star-forming galaxies
Luminous extragalactic water masers are known to be associated with AGN and
have provided accurate estimates for the mass of the central supermassive black
hole and the size and structure of the accretion disk in nearby galaxies. To
find water masers at much higher redshifts, we have begun a survey of known
gravitationally lensed quasars and star-forming galaxies. In this paper, we
present a search for 22 GHz (rest frame) water masers toward five dusty,
gravitationally lensed quasars and star-forming galaxies at redshifts 2.3--2.9
with the Effelsberg telescope and the EVLA. Our observations do not find any
new definite examples of high redshift water maser galaxies, suggesting that
large reservoirs of dust and gas are not a sufficient condition for powerful
water maser emission. However, we do find the tentative detection of a water
maser system in the active galaxy IRAS 10214+4724 at redshift 2.285. Our survey
has now doubled the number of lensed galaxies and quasars that have been
searched for high redshift water masers. We present an analysis of the high
redshift water maser luminosity function that is based on the results presented
here and from the only cosmologically distant (z > 1) water maser galaxy found
thus far, MG J0414+0534 at redshift 2.64. By comparing with the luminosity
function locally and at moderate redshifts, we find that there must be some
evolution in the luminosity function of water maser galaxies at high redshifts.
By assuming a moderate evolution [(1 + z )^4] in the luminosity function, we
find that blind surveys for water maser galaxies are only worthwhile with
extremely high sensitivity like that of the planned Square Kilometre Array.
However, instruments like the EVLA and MeerKAT will be capable of detecting
water maser systems similar to the one found from MG J0414+0534 through
targeted observations.Comment: 10 pages, 4 figures, 4 tables, accepted for publication in MNRA
Magneto-optical characterization of MnxGe1-x alloys obtained by ion implantation
Magneto-optical Kerr effect hysteresis loops at various wavelengths in the
visible/near-infrared range have been used to characterize the magnetic
properties of alloys obtained by implanting Mn ions at fixed energy in a Ge
matrix. The details of the hysteresis loops reveal the presence of multiple
magnetic contributions. They may be attributed to the inhomogeneous
distribution of the magnetic atoms and, in particular, to the known coexistence
of diluted Mn in the Ge matrix and metallic Mn-rich nanoparticles embedded in
it [Phys. Rev. B 73, 195207(2006)].Comment: 2 pages, 2 figures. Proceeding of the International Conference on
Magnetism. Kyoto, August 20-25 200
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