1,625 research outputs found
Strange magnification pattern in the large separation lens SDSS J1004+4112 from optical to X-rays
We present simultaneous XMM-Newton UV and X-ray observations of the quadruply
lensed quasar SDSS J1004+4112 (RBS 825). Simultaneously with the XMM-Newton
observations we also performed integral field spectroscopy on the two closest
lens images A and B using the Calar Alto PMAS spectrograph. In X-rays the
widely spaced components C and D are clearly resolved, while the closer pair of
images A and B is marginally resolved in the XMM-EPIC images. The integrated
X-ray flux of the system has decreased by a factor of 6 since it was observed
in the ROSAT All Sky Survey in 1990, while the X-ray spectrum became much
harder with the power law index evolving from Gamma=-2.3 to -1.86. By
deblending the X-ray images of the lensed QSO we find that the X-ray flux
ratios between the lens images A and B are significantly different from the
simultaneously obtained UV ratios and previously measured optical flux ratios.
Our optical spectrum of lens image A shows an enhancement in the blue emission
line wings, which has been observed in previous epochs as a transient feature.
We propose a scenario where intrinsic UV and X-ray variability gives rise to
line variations which are selectively magnified in image A by microlensing. The
extended emission of the lensing cluster of galaxies is clearly detected in the
EPIC images, we measure a 0.5-2.0 keV luminosity of 1.4 E44 erg/s. Based on the
cluster X-ray properties, we estimate a mass of 2-6 E14 solar masses.Comment: 11 pages, 10 figures, accepted for publication in Astronomy &
Astrophysic
Probing the extended non-Fermi liquid regimes of MnSi and Fe
Recent studies show that the non-Fermi liquid (NFL) behavior of MnSi and Fe
spans over an unexpectedly broad pressure range, between the critical pressure
p_c and around 2p_c. In order to determine the extension of their NFL regions,
we analyze the evolution of the resistivity rho(T) A(p)T^n at higher pressures.
We find that in MnSi the n=3/2 exponent holds below 4.8 GPa=3 p_c, but it
increases above that pressure. At 7.2 GPa we observe the low temperature Fermi
liquid exponent n=2 whereas for T>1.5 K, n=5/3. Our measurements in Fe show
that the NFL behavior rho T^{5/3} extends at least up to 30.5 GPa, above the
entire superconducting (SC) region. In the studied pressure range, the onset of
the SC transition reduces by a factor 10 down to T_c^onset(30.5 GPa)=0.23 K,
while the A-coefficient diminishes monotonically by around 50%.Comment: 2 pages, 2 figures, Proceedings SCES 200
The Sloan Digital Sky Survey Quasar Lens Search. V. Final Catalog from the Seventh Data Release
We present the final statistical sample of lensed quasars from the Sloan
Digital Sky Survey (SDSS) Quasar Lens Search (SQLS). The well-defined
statistical lens sample consists of 26 lensed quasars brighter than i=19.1 and
in the redshift range of 0.6<z<2.2 selected from 50,836 spectroscopically
confirmed quasars in the SDSS Data Release 7 (DR7), where we restrict the image
separation range to 1"<\theta<20" and the i-band magnitude differences in two
image lenses to be smaller than 1.25 mag. The SDSS DR7 quasar catalog also
contains 36 additional lenses identified with various techniques. In addition
to these lensed quasars, we have identified 81 pairs of quasars from follow-up
spectroscopy, 26 of which are physically associated binary quasars. The
statistical lens sample covers a wide range of image separations, redshifts,
and magnitudes, and therefore is suitable for systematic studies of
cosmological parameters and surveys of the structure and evolution of galaxies
and quasars.Comment: 42 pages, 2 figures, 6 tables, accepted for publication in AJ; see
http://www-utap.phys.s.u-tokyo.ac.jp/~sdss/sqls/ for supplemental informatio
The Sloan Digital Sky Survey Quasar Lens Search. VI. Constraints on Dark Energy and the Evolution of Massive Galaxies
We present a statistical analysis of the final lens sample from the Sloan
Digital Sky Survey Quasar Lens Search (SQLS). The number distribution of a
complete subsample of 19 lensed quasars selected from 50,836 source quasars is
compared with theoretical expectations, with particular attention to the
selection function. Assuming that the velocity function of galaxies does not
evolve with redshift, the SQLS sample constrains the cosmological constant to
\Omega_\Lambda=0.79^{+0.06}_{-0.07}(stat.)^{+0.06}_{-0.06}(syst.) for a flat
universe. The dark energy equation of state is found to be consistent with w=-1
when the SQLS is combined with constraints from baryon acoustic oscillation
(BAO) measurements or results from the Wilkinson Microwave Anisotropy Probe
(WMAP). We also obtain simultaneous constraints on cosmological parameters and
redshift evolution of the galaxy velocity function, finding no evidence for
redshift evolution at z<1 in any combinations of constraints. For instance,
number density evolution quantified as \nu_n=d\ln\phi_*/d\ln(1+z) and the
velocity dispersion evolution \nu_\sigma=d\ln\sigma_*/d\ln(1+z) are constrained
to \nu_n=1.06^{+1.36}_{-1.39}(stat.)^{+0.33}_{-0.64}(syst.) and
\nu_\sigma=-0.05^{+0.19}_{-0.16}(stat.)^{+0.03}_{-0.03}(syst.) respectively
when the SQLS result is combined with BAO and WMAP for flat models with a
cosmological constant. We find that a significant amount of dark energy is
preferred even after fully marginalizing over the galaxy evolution parameters.
Thus the statistics of lensed quasars robustly confirm the accelerated cosmic
expansion.Comment: 44 pages, 12 figures, 4 tables, accepted for publication in A
The Sloan Digital Sky Survey Quasar Lens Search. IV. Statistical Lens Sample from the Fifth Data Release
We present the second report of our systematic search for strongly lensed
quasars from the data of the Sloan Digital Sky Survey (SDSS). From extensive
follow-up observations of 136 candidate objects, we find 36 lenses in the full
sample of 77,429 spectroscopically confirmed quasars in the SDSS Data Release
5. We then define a complete sample of 19 lenses, including 11 from our
previous search in the SDSS Data Release 3, from the sample of 36,287 quasars
with i<19.1 in the redshift range 0.6<z<2.2, where we require the lenses to
have image separations of 1"<\theta<20" and i-band magnitude differences
between the two images smaller than 1.25 mag. Among the 19 lensed quasars, 3
have quadruple-image configurations, while the remaining 16 show double images.
This lens sample constrains the cosmological constant to be
\Omega_\Lambda=0.84^{+0.06}_{-0.08}(stat.)^{+0.09}_{-0.07}(syst.) assuming a
flat universe, which is in good agreement with other cosmological observations.
We also report the discoveries of 7 binary quasars with separations ranging
from 1.1" to 16.6", which are identified in the course of our lens survey. This
study concludes the construction of our statistical lens sample in the full
SDSS-I data set.Comment: 37 pages, 2 figures and 5 tables, accepted to A
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