109 research outputs found
Nearby radio loud AGN and the Unified Model
The statistical study of the parsec scale properties of radio sources is
crucial to get information on the nature of the central engine and to provide
the foundations of the current unified theories, suggesting that the appearance
of active galactic nuclei depends strongly on orientation. We started a project
to observe at sub-arcsec resolution a complete sample of 94 nearby (z<0.1)
radio galaxies, the Bologna Complete Sample, which is not affected by any
selection effect on the jet velocity and orientation with respect to the line
of sight. Up to now, we published our parsec scale analysis of 77/94 sources.
Here, we describe the last VLBA observations at 5 GHz and EVN data at 18 cm
obtained for the 17 remaining faintest radio core (<5 mJy at 5 GHz in VLA
images) BCS sources and we report our preliminary results on the whole complete
sample.Comment: 4 pages, 1 figure; accepted for publication in the proceeding of the
"12th European VLBI Network Symposium and Users Meeting - EVN 2014" (7-10
October 2014, Cagliari, Italy); published online in Proceedings of Science,
PoS(EVN 2014)09
Twin SMBH candidates in the BCG of RBS 797
The radio-loud BCG at the center of the cool core cluster RBS 797 is known to
exhibit a misalignment of its 5 GHz radio emission observed at different VLA
resolutions, with the innermost kpc-scale jets being almost orthogonal to the
radio lobes which extends for tens of kpc filling the X-ray cavities seen by
Chandra. The different radio directions may be caused by rapid jet
reorientation due to interaction with a secondary supermassive black hole
(SMBH), or to the presence of two AGN, probably in a merging phase, which are
emitting radio jets in different directions. We present the results of new 5
GHz observations performed with the EVN in May 2013. In particular, we detected
two compact radio components, with a projected separation of 77 pc. We discuss
two possible scenarios for the origin and nature of the EVN double source,
showing that both interpretations are consistent with the presence of a SMBH
binary system in the BCG of RBS 797.Comment: 4 pages, 1 figure; accepted for publication in the proceeding of the
"12th European VLBI Network Symposium and Users Meeting - EVN 2014" (7-10
October 2014, Cagliari, Italy); published online in Proceedings of Science,
PoS(EVN 2014)08
JVLA 1.5GHz continuum observation of CLASH clusters I: radio properties of the BCGs
We present high-resolution (), 1.5 GHz continuum observations of the
brightest cluster galaxies (BCGs) of 13 CLASH (Cluster Lensing And Supernova
survey with Hubble) clusters at with the Karl G. Jansky Very
Large Array (JVLA). Radio emission is clearly detected and characterized for 11
BCGs, while for two of them we obtain only upper limits to their radio flux
( mJy at 5 confidence level). We also consider five additional
clusters whose BCG is detected in FIRST or NVSS. We find radio powers in the
range from to and radio spectral
indices (defined as the slope between 1.5 and 30 GHz)
distributed from to around the central value . The radio emission from the BCGs is resolved in three cases
(Abell 383, MACS J1931, and RX J2129), and unresolved or marginally resolved in
the remaining eight cases observed with JVLA. In all the cases the BCGs are
consistent with being powered by active galactic nuclei (AGN). The radio power
shows a positive correlation with the BCG star formation rate, and a negative
correlation with the central entropy of the surrounding intracluster medium
(ICM) except in two cases (MACS J1206 and CL J1226). Finally, over the
restricted range in radio power sampled by the CLASH BCGs, we observe a
significant scatter between the radio power and the average mechanical power
stored in the ICM cavities.Comment: 19 pages, 11 figures, significantly improved following referee's
comments. Accepted by Ap
Polarized Emission In The Mm Band Of Pks0521-365: Alma Observations
The role of magnetic field in the AGN jet physics is still not fully determined. At pc scale, it is known that it is important in the acceleration and collimation processes while at arcsecond scale it could reveal fundamental pieces of the jet dynamics and energetics and its surrounding environment. At intermediate scales, the scenario is more debated. To contribute in this framework, we need to resolve polarized emission even in the low surface brightness extended structures (e.g. lobes). This absolutely requires high sensitivity observations. With the advent of ALMA, now it is possible also in the millimeter, a band which was unexplored by previous facilities. Here I present the impressive images in polarization obtained using ALMA archival multiband data of an ALMA calibrator PKS 0521-365 which represents a prototype of BL Lac object with extended resolved structures (jet and hotspot) at all frequencies from optical to X-rays
VLBI observations of nearby radio loud Active Galactic Nuclei
We present an update of the parsec scale properties of the Bologna Complete
Sample consisting of 95 radio sources from the B2 Catalog of Radio Sources and
the Third Cambridge Revised Catalog (3CR), with z < 0.1. Thanks to recent new
data we have now parsec scale images for 76 sources of the sample. Most of them
show a one-sided jet structure but we find a higher fraction of two-sided
sources in comparison with previous flux-limited VLBI surveys. A few peculiar
sources are presented and discussed in more detail.Comment: 6 pages, 7 figures, Proceedings for "The Universe under the
Microscope" (AHAR 2008), April 2008, to be published in Journal of Physics:
Conference Series by Institute of Physics Publishing; R. Schoedel, A. Eckart,
S. Pfalzner, and E. Ros ed
The Jet of the BL Lac Object PKS 0521-365 in the mm-Band: ALMA Observations
BL Lac objects are low-power active nuclei exhibiting a variety of peculiar properties caused by the presence of a relativistic jet and orientation effects. Since the jet is closely aligned with the line of sight, it is very difficult to observe unless the angular resolution is high. At millimeter wavelength in particular, until the advent of ALMA, information on the jet emission was lacking from the previous facilities. Here we report our preliminary results on the millimeter emission of PKS 0521-365, one of the most interesting BL Lac objects of the southern sky, using ALMA multifrequency archival data...
ALMA FITS header keywords: a study from the archive User perspective
ALMA products are stored in the Science Archive in the form of FITS images.
It is a common idea that the FITS image headers should collect in their
keywords all the information that an archive User might want to search for in
order to quickly select, compare, or discard datasets. With this perspective in
mind, we first present a short description of the current status of the ALMA
FITS archive and images. We realized that at the moment most of the parameters
that could be useful for a general User are still missing in the archived data.
We then provide a CASA task generating the image header keywords that we
suggest to be relevant for the scientific exploitation of the ALMA archival
data. The proposed tool could be also applied to several types of
interferometer data and part of it is implemented in a web interface. An
example of the scientific application of the keywords is also discussed.Comment: 20 pages, 6 figures, ALMA Memo 613
https://library.nrao.edu/public/memos/alma/main/memo613.pd
Synergies between SKA and ALMA: observations of Nearby Galaxies
The past decade has seen amazing advances in radioastronomy, which led to the construction of brand-new instruments such as LOFAR and ALMA, and the updating of existing ones, e. g. JVLA and e-MERLIN. The SKA will be the spearhead of a future technological development and it will change the way astrophysical topics have been studied so far by opening up new frequency windows with unprecedented spatial resolution and sensitivity. The SKA location in the southern hemisphere makes it particularly suitable to complement ALMA, which is already giving exciting results both on the local and the more distant Universe.
Among the possible synergies between SKA and ALMA, we focus on the observations of nearby star forming galaxies. Star formation processes in galaxies involve all the components of the interstellar medium, so the only way to have a complete picture of them is through multifrequency observations.
ALMA observes gas and dust emission, while the SKA will trace both the free-free thermal and the non-thermal synchrotron emission. The spatial comparison between these components gives information about the contribution to star formation processes provided by magnetic fields and
cosmic rays. The high spatial resolution achievable with ALMA and SKA will make it possible to compare these emissions on very small spatial scales, by resolving single molecular clouds in nearby galaxies.
By the time the SKA will start observing, ALMA will have already imaged many nearby galaxies in the southern hemisphere, for which no low frequency data at comparably high spatial resolution will be available. The SKA will fill this gap, and have a profound impact on the studies of nearby galaxies, making valuable contributions to our understanding of star formation processes, and of the role of magnetic fields and cosmic rays in them
Serum miRNAs Expression and SNAP-25 Genotype in Alzheimer’s Disease
MicroRNAs (miRNAs) are small non-coding RNAs that control gene expression by binding their 3′ untranslated region (3′UTR) region; these molecules play a fundamental role in several pathologies, including Alzheimer’s disease (AD). Synaptosomal-associated protein of 25 kDa (SNAP-25) is a vesicular protein of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) involved in neural plasticity and in the exocytosis of neurotransmitters, processes that are altered in AD. Recent results showed that a reduction of SNAP-25 is associated with dementia, and that the rs363050 SNAP-25 polymorphism correlates with cognitive decline and brain atrophy, as well as with the outcome of multistructured rehabilitation in AD patients. We verified the presence of possible correlations between the serum concentration of miRNAs that bind the SNAP-25 3′UTR region and AD. Six different microRNAs (miR-181a-5p, miR-361-3p, miR-23a-3p, miR-15b-3p, 130a-3p and miR-27b-3p) that bind the SNAP-25 3′UTR region were measured by qPCR in serum of AD patients (n = 22), mild cognitive impairment (MCI) subjects (n = 22) and age- and sex-matched controls (n = 22); analysis of results was done stratified for the rs363050 SNAP-25 genotype. Results showed that miR-27b-3p, miR-23a-3p and miR181a-5p serum concentration was significantly reduced in rs363050 SNAP-25 GG homozygous AD patients. Notably, concentration of these miRNAs was comparable in rs363050 AA homozygous AD patients, MCI and healthy controls (HCs). Data herein suggest that miRNAs that bind the SNAP-25 3′UTR region interact with SNAP-25 polymorphisms to influence the neural plasticity typical of AD brains, possibly as a consequence of modulatory activity on SNAP-25 mRNA and/or protein
The ALMA Re-imaging Project Study
In the first 6 years of ALMA operations, data for more than 1700 projects have been calibrated and manually imaged for quality assessment purposes before being delivered to the PI and being added to the ALMA Science Archive. However, imaging is a time-consuming process and therefore the data-reducers have only created image products for a small fraction of the original data for quality control purposes. We study the feasibility and cost of a potential ALMA Re-Imaging project which would use the newly developed ALMA imaging pipeline to create image products for all the existing data. We here report about the concept and the currrent state of this study
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