171 research outputs found
Modeling and FPGA-based implementation of an efficient and simple envelope detector using a Hilbert Transform FIR filter for ultrasound imaging applications
Black Hole masses for 14 gravitational lensed quasars
We estimate black hole masses (M) for 14 gravitationally lensed
quasars using the Balmer lines along with estimates based on MgII and CIV
emission lines for four and two of them, respectively. We compare with results
obtained for other lensed quasars.
We use spectroscopic data from the Large Binocular Telescope (LBT), Magellan
and the Very Large Telescope (VLT) to measure the FWHM of the broad emission
lines. Combined with the bolometric luminosity measured from the spectra energy
distribution, we estimate M including uncertainties from
microlensing and variability.
We obtain MBH using the single-epoch method from the H and/or
H broad emission lines for 14 lensed quasars, including the first
estimates for QJ0158-4325, HE0512-3329 and WFI2026-4536. The masses are typical
of non-lensed quasars of similar luminosity, and the implied Eddington ratios
are typical. We have increased the sample of lenses with estimates of MBH by
60%.Comment: 16 pages. Submitted to A&
A hyper luminous starburst at z=4.72 magnified by a lensing galaxy pair at z=1.48
International audienceWe serendipitously discovered in the Herschel Reference Survey an extremely bright infrared source with S500ââŒâ120 mJy in the line of sight of the Virgo cluster which we name Red Virgo 4 (RV4). Based on IRAM/EMIR and IRAM/NOEMA detections of the CO(5â4), CO(4â3), and [CI] lines, RV4 is located at a redshift of 4.724, yielding a total observed infrared luminosity of 1.1 ± 0.6 Ă 1014 Lâ. At the position of the Herschel emission, three blobs are detected with the VLA at 10 cm. The CO(5â4) line detection of each blob confirms that they are at the same redshift with the same line width, indicating that they are multiple images of the same source. In Spitzer and deep optical observations, two sources, High-z Lens 1 (HL1) West and HL1 East, are detected at the center of the three VLA/NOEMA blobs. These two sources are placed at zâ=â1.48 with X-shooter spectra, suggesting that they could be merging and gravitationally lensing the emission of RV4. HL1 is the second most distant lens known to date in strong lensing systems. Constrained by the position of the three VLA/NOEMA blobs, the Einstein radius of the lensing system is 2.2Ⳡ± 0.2 (20 kpc). The high redshift of HL1 and the large Einstein radius are highly unusual for a strong lensing system. In this paper, we present the insterstellar medium properties of the background source RV4. Different estimates of the gas depletion time yield low values suggesting that RV4 is a starburst galaxy. Among all high-z submillimeter galaxies, this source exhibits one of the lowest L[CI] to LIR ratios, 3.2 ± 0.9 Ă 10â6, suggesting an extremely short gas depletion time of only 14 ± 5 Myr. It also shows a relatively high L[CI] to LCO(4â3) ratio (0.7 ± 0.2) and low LCO(5â4) to LIR ratio (only âŒ50% of the value expected for normal galaxies) hinting at low density of gas. Finally, we discuss the short depletion time of RV4. It can be explained by either a very high star formation efficiency, which is difficult to reconcile with major mergers simulations of high-z galaxies, or a rapid decrease of star formation, which would bias the estimate of the depletion time toward an artificially low value
The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-Line Light Curves
In the Spring of 2011 we carried out a 2.5 month reverberation mapping
campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15
low-redshift Seyfert 1 galaxies. This paper describes the observations,
reductions and measurements, and data products from the spectroscopic campaign.
The reduced spectra were fitted with a multicomponent model in order to isolate
the contributions of various continuum and emission-line components. We present
light curves of broad emission lines and the AGN continuum, and measurements of
the broad H-beta line widths in mean and root-mean square (rms) spectra. For
the most highly variable AGNs we also measured broad H-beta line widths and
velocity centroids from the nightly spectra. In four AGNs exhibiting the
highest variability amplitudes, we detect anticorrelations between broad H-beta
width and luminosity, demonstrating that the broad-line region "breathes" on
short timescales of days to weeks in response to continuum variations. We also
find that broad H-beta velocity centroids can undergo substantial changes in
response to continuum variations; in NGC 4593 the broad H-beta velocity shifted
by ~250 km/s over a one-month duration. This reverberation-induced velocity
shift effect is likely to contribute a significant source of confusion noise to
binary black hole searches that use multi-epoch quasar spectroscopy to detect
binary orbital motion. We also present results from simulations that examine
biases that can occur in measurement of broad-line widths from rms spectra due
to the contributions of continuum variations and photon-counting noise.Comment: 33 pages, 28 figures, accepted for publication in ApJ Supplement
Serie
Black Hole Mass Estimates Based on CIV are Consistent with Those Based on the Balmer Lines
Using a sample of high-redshift lensed quasars from the CASTLES project with
observed-frame ultraviolet or optical and near-infrared spectra, we have
searched for possible biases between supermassive black hole (BH) mass
estimates based on the CIV, Halpha and Hbeta broad emission lines. Our sample
is based upon that of Greene, Peng & Ludwig, expanded with new near-IR
spectroscopic observations, consistently analyzed high S/N optical spectra, and
consistent continuum luminosity estimates at 5100A. We find that BH mass
estimates based on the FWHM of CIV show a systematic offset with respect to
those obtained from the line dispersion, sigma_l, of the same emission line,
but not with those obtained from the FWHM of Halpha and Hbeta. The magnitude of
the offset depends on the treatment of the HeII and FeII emission blended with
CIV, but there is little scatter for any fixed measurement prescription. While
we otherwise find no systematic offsets between CIV and Balmer line mass
estimates, we do find that the residuals between them are strongly correlated
with the ratio of the UV and optical continuum luminosities. Removing this
dependency reduces the scatter between the UV- and optical-based BH mass
estimates by a factor of approximately 2, from roughly 0.35 to 0.18 dex. The
dispersion is smallest when comparing the CIV sigma_l mass estimate, after
removing the offset from the FWHM estimates, and either Balmer line mass
estimate. The correlation with the continuum slope is likely due to a
combination of reddening, host contamination and object-dependent SED shapes.
When we add additional heterogeneous measurements from the literature, the
results are unchanged.Comment: Accepted for publication in The Astrophysical Journal. 37 text pages
+ 8 tables + 23 figures. Updated with comments by the referee and with a
expanded discussion on literature data including new observation
The OGLE View of Microlensing towards the Magellanic Clouds. II. OGLE-II SMC data
The primary goal of this paper is to provide the evidence that can either
prove or falsify the hypothesis that dark matter in the Galactic halo can clump
into stellar-mass compact objects. If such objects existed, they would act as
lenses to external sources in the Magellanic Clouds, giving rise to an
observable effect of microlensing. We present the results of our search for
such events, based on the data from the second phase of the OGLE survey
(1996-2000) towards the SMC. The data set we used is comprised of 2.1 million
monitored sources distributed over an area of 2.4 square degrees. We found only
one microlensing event candidate, however its poor quality light curve limited
our discussion on the exact distance to the lensing object.
Given a single event, taking the blending (crowding of stars) into account
for the detection efficiency simulations, and deriving the HST-corrected number
of monitored stars, the microlensing optical depth is tau=(1.55+-1.55)10e-7.
This result is consistent with the expected SMC self-lensing signal, with no
need of introducing dark matter microlenses. Rejecting the unconvincing event
leads to the upper limit on the fraction of dark matter in the form of MACHOs
to f<20 per cent for deflectors' masses around 0.4 Msun and f<11 per cent for
masses between 0.003 and 0.2 Msun (95 per cent confidence limit). Our result
indicates that the Milky Way's dark matter is unlikely to be clumpy and form
compact objects in the sub-solar-mass range.Comment: Accepted for publication in MNRAS. Data in electronic form are
available on the OGLE's website: http://ogle.astrouw.edu.pl
Preliminary molecular studies of the first report of Burkholderia pseudomallei isolation from soil collected in the AmapĂĄ State, in Northern Brazil.
The wide spectra of colonizing microorganism, likewise Burkholderia pseudomallei, has been found in different habitats, and presenting distinct activity, as exerting physiological functions among plants, or as a pathogen for man, animals and also as a phytopathogen. A common disease of men and animals caused by B. pseudomallei, melioidosis, is a severe morbidity that usually culminates in the host death. Soil samples from different areas in the AmapĂĄ state, in northern Brazil, were screened for environmental microorganisms to assess potential antimicrobial activity aiming at biotechnological applications. Among the prospected microorganisms, B. pseudomallei was isolated from high humidity soils, mangrove, which is rich in organic materials, produced by the diversified local flora and fauna. The isolated B. pseudomallei was identified by its biochemical profile and growth characteristics. Molecular confirmation of B. pseudomallei phenotypic identification was achieved by PCR amplification of the 16 S ribosomal DNA. The sequencing of amplified products confirmed that the AmapĂĄ sample, and two other isolates from human infections in CearĂĄ state, northeast Brazil, were B. pseudomallei, and sequence alignement to the same specie, MSHR146 strain from Australia, and clone YN01 from uncultured Burkholderia sp., deposited in the GenBank, exhibited close phylogenetic relationship among them. Until now, there is no report of B. pseudomallei related disease among human and animal populations in the AmapĂĄ state, despite the finding of B. pseudomallei in it, in an area of water buffalo ranching and flowing small rivers utilized by human populations
The Lick AGN Monitoring Project 2011: Reverberation Mapping of Markarian 50
The Lick AGN Monitoring Project 2011 observing campaign was carried out over
the course of 11 weeks in Spring 2011. Here we present the first results from
this program, a measurement of the broad-line reverberation lag in the Seyfert
1 galaxy Mrk 50. Combining our data with supplemental observations obtained
prior to the start of the main observing campaign, our dataset covers a total
duration of 4.5 months. During this time, Mrk 50 was highly variable,
exhibiting a maximum variability amplitude of a factor of 4 in the U-band
continuum and a factor of 2 in the H-beta line. Using standard
cross-correlation techniques, we find that H-beta and H-gamma lag the V-band
continuum by tau_cen = 10.64(-0.93,+0.82) and 8.43(-1.28,+1.30) days,
respectively, while the lag of He II 4686 is unresolved. The H-beta line
exhibits a symmetric velocity-resolved reverberation signature with shorter
lags in the high-velocity wings than in the line core, consistent with an
origin in a broad-line region dominated by orbital motion rather than infall or
outflow. Assuming a virial normalization factor of f=5.25, the virial estimate
of the black hole mass is (3.2+-0.5)*10^7 solar masses. These observations
demonstrate that Mrk 50 is among the most promising nearby active galaxies for
detailed investigations of broad-line region structure and dynamics.Comment: Accepted for publication in ApJ Letters. 6 pages, 4 figure
HerMES: The Contribution to the Cosmic Infrared Background from Galaxies Selected by Mass and Redshift
We quantify the fraction of the cosmic infrared background (CIB) that originates from galaxies identified in the UV/optical/near-infrared by stacking 81,250 (~35.7 arcmin^(â2)) K-selected sources (K_(AB) 350 ÎŒm. The contribution from galaxies in the log(M/M_â) = 9.0-9.5 (lowest) and log(M/M_â) = 11.0-12.0 (highest) stellar-mass bins contribute the leastâboth of order 5%âalthough the highest stellar-mass bin is a significant contributor to the luminosity density at z âł 2. The luminosities of the galaxies responsible for the CIB shifts from combinations of "normal" and luminous infrared galaxies (LIRGs) at λ ⟠160 ÎŒm, to LIRGs at 160 ⟠λ ⟠500 ÎŒm, to finally LIRGs and ultra-luminous infrared galaxies at λ âł 500 ÎŒm. Stacking analyses were performed using SIMSTACK, a novel algorithm designed to account for possible biases in the stacked flux density due to clustering. It is made available to the public at www.astro.caltech.edu/~viero/viero_homepage/toolbox.html
UV-to-FIR analysis of Spitzer/IRAC sources in the Extended Groth Strip II: Photometric redshifts, Stellar masses and Star formation rates
Based on the ultraviolet to far-infrared photometry already compiled and
presented in a companion paper (Barro et al. 2011a, Paper I), we present a
detailed SED analysis of nearly 80,000 IRAC 3.6+4.5 micron selected galaxies in
the Extended Groth Strip. We estimate photometric redshifts, stellar masses,
and star formation rates separately for each galaxy in this large sample. The
catalog includes 76,936 sources with [3.6] < 23.75 (85% completeness level of
the IRAC survey) over 0.48 square degrees. The typical photometric redshift
accuracy is Delta z/(1+z)=0.034, with a catastrophic outlier fraction of just
2%. We quantify the systematics introduced by the use of different stellar
population synthesis libraries and IMFs in the calculation of stellar masses.
We find systematic offsets ranging from 0.1 to 0.4 dex, with a typical scatter
of 0.3 dex. We also provide UV- and IR-based SFRs for all sample galaxies,
based on several sets of dust emission templates and SFR indicators. We
evaluate the systematic differences and goodness of the different SFR
estimations using the deep FIDEL 70 micron data available in the EGS. Typical
random uncertainties of the IR-bases SFRs are a factor of two, with
non-negligible systematic effects at z1.5 observed when only MIPS 24
micron data is available. All data products (SEDs, postage stamps from imaging
data, and different estimations of the photometric redshifts, stellar masses,
and SFRs of each galaxy) described in this and the companion paper are publicly
available, and they can be accessed through our the web-interface utility
Rainbow-navigatorComment: 39 pages, 22 figures, Accepted for publication in ApJ. Access the
Rainbow Database at: http://rainbowx.fis.ucm.e
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