21 research outputs found
CLASH: z ~ 6 young galaxy candidate quintuply lensed by the frontier field cluster RXC J2248.7-4431
We present a quintuply lensed z ~ 6 candidate discovered in the field of the
galaxy cluster RXC J2248.7-4431 (z ~ 0.348) targeted within the Cluster Lensing
and Supernova survey with Hubble (CLASH) and selected in the deep HST Frontier
Fields survey. Thanks to the CLASH 16-band HST imaging, we identify the
quintuply lensed z ~ 6 candidate as an optical dropout in the inner region of
the cluster, the brightest image having magAB=24.81+-0.02 in the f105w filter.
We perform a detailed photometric analysis to verify its high-z and lensed
nature. We get as photometric redshift z_phot ~ 5.9, and given the extended
nature and NIR colours of the lensed images, we rule out low-z early type and
galactic star contaminants. We perform a strong lensing analysis of the
cluster, using 13 families of multiple lensed images identified in the HST
images. Our final best model predicts the high-z quintuply lensed system with a
position accuracy of 0.8''. The magnifications of the five images are between
2.2 and 8.3, which leads to a delensed UV luminosity of L_1600 ~ 0.5L*_1600 at
z=6. We also estimate the UV slope from the observed NIR colours, finding a
steep beta=-2.89+-0.38. We use singular and composite stellar population SEDs
to fit the photometry of the hiz candidate, and we conclude that it is a young
(age <300 Myr) galaxy with mass of M ~ 10^8Msol, subsolar metallicity
(Z<0.2Zsol) and low dust content (AV ~ 0.2-0.4).Comment: 21 pages, 13 figures, 6 tables, submitted to MNRAS on 11 Aug 2013,
accepted on 23 Nov 201
Therapeutic photography: enhancing patient communication.
Using photography with patients to help them express concerns, investigate coping strategies and learn from their peers is known as therapeutic photography. The practice has benefits to both professionals and participants, particularly with 'hard to reach' populations who may feel intimidated or disempowered. Neil Gibson explains how this intervention can be structured in the health setting
Multiwavelength observations of 3C 454.3. III. Eighteen months of AGILE monitoring of the "Crazy Diamond"
We report on 18 months of multiwavelength observations of the blazar 3C 454.3
(Crazy Diamond) carried out in July 2007-January 2009. We show the results of
the AGILE campaigns which took place on May-June 2008, July-August 2008, and
October 2008-January 2009. During the May 2008-January 2009 period, the source
average flux was highly variable, from an average gamma-ray flux F(E>100MeV) >
200E-8 ph/cm2/s in May-June 2008, to F(E>100MeV)~80E-8 ph/cm2/s in October
2008-January 2009. The average gamma-ray spectrum between 100 MeV and 1 GeV can
be fit by a simple power law (Gamma_GRID ~ 2.0 to 2.2). Only 3-sigma upper
limits can be derived in the 20-60 keV energy band with Super-AGILE. During
July-August 2007 and May-June 2008, RXTE measured a flux of F(3-20 keV)=
8.4E-11 erg/cm2/s, and F(3-20 keV)=4.5E-11 erg/cm2/s, respectively and a
constant photon index Gamma_PCA=1.65. Swift/XRT observations were carried out
during all AGILE campaigns, obtaining a F(2-10 keV)=(0.9-7.5)E-11 erg/cm2/s and
a photon index Gamma_XRT=1.33-2.04. BAT measured an average flux of ~5 mCrab.
GASP-WEBT monitored 3C 454.3 during the whole 2007-2008 period from the radio
to the optical. A correlation analysis between the optical and the gamma-ray
fluxes shows a time lag of tau=-0.4 days. An analysis of 15 GHz and 43 GHz VLBI
core radio flux observations shows an increasing trend of the core radio flux,
anti- correlated with the higher frequency data. The modeling SEDs, and the
behavior of the long-term light curves in different energy bands, allow us to
compare the jet properties during different emission states, and to study the
geometrical properties of the jet on a time-span longer than one year.Comment: Accepted for publication in ApJ. Adapted Abstract. 17 pages, 19
Figures, 5 Table
Cluster Lenses
Clusters of galaxies are the most recently assembled, massive, bound
structures in the Universe. As predicted by General Relativity, given their
masses, clusters strongly deform space-time in their vicinity. Clusters act as
some of the most powerful gravitational lenses in the Universe. Light rays
traversing through clusters from distant sources are hence deflected, and the
resulting images of these distant objects therefore appear distorted and
magnified. Lensing by clusters occurs in two regimes, each with unique
observational signatures. The strong lensing regime is characterized by effects
readily seen by eye, namely, the production of giant arcs, multiple-images, and
arclets. The weak lensing regime is characterized by small deformations in the
shapes of background galaxies only detectable statistically. Cluster lenses
have been exploited successfully to address several important current questions
in cosmology: (i) the study of the lens(es) - understanding cluster mass
distributions and issues pertaining to cluster formation and evolution, as well
as constraining the nature of dark matter; (ii) the study of the lensed objects
- probing the properties of the background lensed galaxy population - which is
statistically at higher redshifts and of lower intrinsic luminosity thus
enabling the probing of galaxy formation at the earliest times right up to the
Dark Ages; and (iii) the study of the geometry of the Universe - as the
strength of lensing depends on the ratios of angular diameter distances between
the lens, source and observer, lens deflections are sensitive to the value of
cosmological parameters and offer a powerful geometric tool to probe Dark
Energy. In this review, we present the basics of cluster lensing and provide a
current status report of the field.Comment: About 120 pages - Published in Open Access at:
http://www.springerlink.com/content/j183018170485723/ . arXiv admin note:
text overlap with arXiv:astro-ph/0504478 and arXiv:1003.3674 by other author
The GASP-WEBT monitoring of 3C 454.3 during the 2008 optical-to-radio and gamma-ray outburst
Since 2001, the radio quasar 3C 454.3 has undergone a period of high optical
activity, culminating in the brightest optical state ever observed, during the
2004-2005 outburst. The Whole Earth Blazar Telescope (WEBT) consortium has
carried out several multifrequency campaigns to follow the source behaviour.
The GLAST-AGILE Support Program (GASP) was born from the WEBT to provide
long-term continuous optical-to-radio monitoring of a sample of gamma-loud
blazars, during the operation of the AGILE and GLAST (now known as Fermi GST)
gamma-ray satellites. The main aim is to shed light on the mechanisms producing
the high-energy radiation, through correlation analysis with the low-energy
emission. Thus, since 2008 the monitoring task on 3C 454.3 passed from the WEBT
to the GASP, while both AGILE and Fermi detected strong gamma-ray emission from
the source. We present the main results obtained by the GASP at optical, mm,
and radio frequencies in the 2008-2009 season, and compare them with the WEBT
results from previous years. An optical outburst was observed to peak in mid
July 2008, when Fermi detected the brightest gamma-ray levels. A
contemporaneous mm outburst maintained its brightness for a longer time, until
the cm emission also reached the maximum levels. The behaviour compared in the
three bands suggests that the variable relative brightness of the
different-frequency outbursts may be due to the changing orientation of a
curved inhomogeneous jet. The optical light curve is very well sampled during
the entire season, which is also well covered by the various AGILE and Fermi
observing periods. The relevant cross-correlation studies will be very
important in constraining high-energy emission models.Comment: 5 pages, 5 figures, to be published in A&A (Letters
The GASP-WEBT monitoring of 3C 454.3 during the 2008 optical-to-radio and Îł-ray outburst
Since 2001, the radio quasar 3C 454.3 has undergone a period of high optical
activity, culminating in the brightest optical state ever observed, during the
2004-2005 outburst. The Whole Earth Blazar Telescope (WEBT) consortium has
carried out several multifrequency campaigns to follow the source behaviour.
The GLAST-AGILE Support Program (GASP) was born from the WEBT to provide
long-term continuous optical-to-radio monitoring of a sample of gamma-loud
blazars, during the operation of the AGILE and GLAST (now known as Fermi GST)
gamma-ray satellites. The main aim is to shed light on the mechanisms producing
the high-energy radiation, through correlation analysis with the low-energy
emission. Thus, since 2008 the monitoring task on 3C 454.3 passed from the WEBT
to the GASP, while both AGILE and Fermi detected strong gamma-ray emission from
the source. We present the main results obtained by the GASP at optical, mm,
and radio frequencies in the 2008-2009 season, and compare them with the WEBT
results from previous years. An optical outburst was observed to peak in mid
July 2008, when Fermi detected the brightest gamma-ray levels. A
contemporaneous mm outburst maintained its brightness for a longer time, until
the cm emission also reached the maximum levels. The behaviour compared in the
three bands suggests that the variable relative brightness of the
different-frequency outbursts may be due to the changing orientation of a
curved inhomogeneous jet. The optical light curve is very well sampled during
the entire season, which is also well covered by the various AGILE and Fermi
observing periods. The relevant cross-correlation studies will be very
important in constraining high-energy emission models
Multiwavelength observations of 3C 454.3. III. Eighteen months of agile monitoring of the "crazy diamond"
We report on 18 months of multiwavelength observations of the blazar 3C 454.3 (Crazy Diamond) carried out in the period 2007 July-2009 January. In particular, we show the results of the AGILE campaigns which took place on 2008 May-June, 2008 July-August, and 2008 October-2009 January. During the 2008 May-2009 January period, the source average flux was highly variable, with a clear fading trend toward the end of the period, from an average Îł-ray flux F E>100 MeV âł 200 Ă 10-8photonscm -2s-1 in 2008 May-June, to F E>100 MeV 80 Ă 10-8photonscm-2s-1 in 2008 October-2009 January. The average Îł-ray spectrum between 100 MeV and 1 GeV can be fit by a simple power law, showing a moderate softening (from ÎGRID ⌠2.0 to ÎGRID ⌠2.2) toward the end of the observing campaign. Only 3Ï upper limits can be derived in the 20-60 keV energy band with Super-AGILE, because the source was considerably off-axis during the whole time period. In 2007 July-August and 2008 May-June, 3C 454.3 was monitored by Rossi X-ray Timing Explorer (RXTE). The RXTE/Proportional Counter Array (PCA) light curve in the 3-20 keV energy band shows variability correlated with the Îł-ray one. The RXTE/PCA average flux during the two time periods is F 3-20 keV = 8.4 Ă 10-11ergcm-2s -1, and F 3-20 keV = 4.5 Ă 10 -11ergcm-2s-1, respectively, while the spectrum (a power law with photon index ÎPCA = 1.65 0.02) does not show any significant variability. Consistent results are obtained with the analysis of the RXTE/High-Energy X-Ray Timing Experiment quasi-simultaneous data. We also carried out simultaneous Swift observations during all AGILE campaigns. Swift/XRT detected 3C 454.3 with an observed flux in the 2-10 keV energy band in the range (0.9-7.5) Ă 10-11ergcm-2s-1 and a photon index in the range ÎXRT = 1.33-2.04. In the 15-150 keV energy band, when detected, the source has an average flux of about 5mCrab. GASP-WEBT monitored 3C 454.3 during the whole 2007-2008 period in the radio, millimeter, near-IR, and optical bands. The observations show an extremely variable behavior at all frequencies, with flux peaks almost simultaneous with those at higher energies. A correlation analysis between the optical and the Îł-ray fluxes shows that the Îł-optical correlation occurs with a time lag of Ï = -0.4+0.6-0.8 days, consistent with previous findings for this source. An analysis of 15 GHz and 43 GHz VLBI core radio flux observations in the period 2007 July-2009 February shows an increasing trend of the core radio flux, anti-correlated with the higher frequency data, allowing us to derive the value of the source magnetic field. Finally, the modeling of the broadband spectral energy distributions for the still unpublished data, and the behavior of the long-term light curves in different energy bands, allow us to compare the jet properties during different emission states, and to study the geometrical properties of the jet on a time-span longer than one year. © 2010. The American Astronomical Society. All rights reserved
Blood cell responses following heavy alcohol consumption coincide with changes in acute phase reactants of inflammation, indices of hemolysis and immune responses to ethanol metabolites
Abstract
Aberrations in blood cells are common among heavy alcohol drinkers. In order to shed further light on such responses, we compared blood cell status with markers of hemolysis, mediators of inflammation and immune responses to ethanol metabolites in alcohol-dependent patients at the time of admission for detoxification and after abstinence. Blood cell counts, indices of hemolysis (LDH, haptoglobin, bilirubin), calprotectin (a marker of neutrophil activation), suPAR, CD163, pro- and anti-inflammatory cytokines and autoantibodies against protein adducts with acetaldehyde, the first metabolite of ethanol, were measured from alcohol-dependent patients (73 men, 26 women, mean age 43.8 ± 10.4 years) at baseline and after 8 ± 1 days of abstinence. The assessments also included information on the quantities of alcohol drinking and assays for biomarkers of alcohol consumption (CDT), liver function (AST, ALT, ALP, GGT) and acute phase reactants of inflammation. At baseline, the patients showed elevated values of CDT and biomarkers of liver status, which decreased significantly during abstinence. A significant decrease also occurred in LDH, bilirubin, CD163 and IgA and IgM antibodies against acetaldehyde adducts, whereas a significant increase was noted in blood leukocytes, platelets, MCV and suPAR levels. The changes in blood leukocytes correlated with those in serum calprotectin (p < 0.001), haptoglobin (p < 0.001), IL-6 (p < 0.02) and suPAR (p < 0.02). The changes in MCV correlated with those in LDH (p < 0.02), MCH (p < 0.01), bilirubin (p < 0.001) and anti-adduct IgG (p < 0.01). The data indicates that ethanol-induced changes in blood leukocytes are related with acute phase reactants of inflammation and release of neutrophil calprotectin. The studies also highlight the role of hemolysis and immune responses to ethanol metabolites underlying erythrocyte abnormalities in alcohol abusers