Publications (6)0 Total impact
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T. Treu,
P. J. Marshall,
F. -Y. Cyr-Racine,
C. D. Fassnacht,
C. R. Keeton,
E. V. Linder,
L. A. Moustakas,
M. Bradac,
E. Buckley-Geer,
T. Collett, [......],
E. E. Falco,
A. Fritz,
G. Seidel,
D. A. Howell,
C. Giocoli,
N. Jackson,
S. Lopez,
R. B. Metcalf,
V. Motta,
T. Verdugo
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ABSTRACT: Strong lensing gravitational time delays are a powerful and cost effective
probe of dark energy. Recent studies have shown that a single lens can provide
a distance measurement with 6-7 % accuracy (including random and systematic
uncertainties), provided sufficient data are available to determine the time
delay and reconstruct the gravitational potential of the deflector.
Gravitational-time delays are a low redshift (z~0-2) probe and thus allow one
to break degeneracies in the interpretation of data from higher-redshift probes
like the cosmic microwave background in terms of the dark energy equation of
state. Current studies are limited by the size of the sample of known lensed
quasars, but this situation is about to change. Even in this decade, wide field
imaging surveys are likely to discover thousands of lensed quasars, enabling
the targeted study of ~100 of these systems and resulting in substantial gains
in the dark energy figure of merit. In the next decade, a further order of
magnitude improvement will be possible with the 10000 systems expected to be
detected and measured with LSST and Euclid. To fully exploit these gains, we
identify three priorities. First, support for the development of software
required for the analysis of the data. Second, in this decade, small robotic
telescopes (1-4m in diameter) dedicated to monitoring of lensed quasars will
transform the field by delivering accurate time delays for ~100 systems. Third,
in the 2020's, LSST will deliver 1000's of time delays; the bottleneck will
instead be the aquisition and analysis of high resolution imaging follow-up.
Thus, the top priority for the next decade is to support fast high resolution
imaging capabilities, such as those enabled by the James Webb Space Telescope
and next generation adaptive optics systems on large ground based telescopes.
06/2013;
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N Ota,
N. Inada, M. Oguri,
K. Mitsuda,
G. T. Richards,
Y Suto,
W. N. Brandt,
F. J. Castander,
R. Fujimoto,
P. B. Hall,
C. R. Keeton,
R. C. Nichol,
D. P. Schneider,
D. E. Eisenstein,
J. A. Frieman,
E. L. Turner,
T. Minezaki,
Y Yoshii
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ABSTRACT: We present results from Chandra observations of SDSS J1004+4112, a strongly lensed quasar system with a maximum image separation of 15". All four bright images of the quasar, as well as resolved X-ray emission originating from the lensing cluster, are clearly detected. The emission from the lensing cluster extends out to approximately 1.5 arcmin. We measure the bolometric X-ray luminosity and temperature of the lensing cluster to be 4.7e44 erg s^-1 and 6.4 keV, consistent with the luminosity-temperature relation for distant clusters. The mass estimated from the X-ray observation shows excellent agreement with the mass derived from gravitational lensing. The X-ray flux ratios of the quasar images differ markedly from the optical flux ratios, and the combined X-ray spectrum of the images possesses an unusually strong Fe Kalpha emission line, both of which are indicative of microlensing.
03/2006;
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N. Inada, M. Oguri,
B. Pindor,
J. F. Hennawi,
K. Chiu,
W Zheng,
S. -I. Ichikawa,
M. D. Gregg,
R. H. Becker,
Y Suto, [......],
G. T. Richards,
H. -W. Rix,
E. S. Sheldon,
N. A. Bahcall,
J. Brinkmann,
Z. Ivezic,
D. Q. Lamb,
T. A. McKay,
D. P. Schneider,
D. G. York
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ABSTRACT: Gravitational lensing is a powerful tool for the study of the distribution of dark matter in the Universe. The cold-dark-matter model of the formation of large-scale structures predicts the existence of quasars gravitationally lensed by concentrations of dark matter so massive that the quasar images would be split by over 7 arcsec. Numerous searches for large-separation lensed quasars have, however, been unsuccessful. All of the roughly 70 lensed quasars known, including the first lensed quasar discovered, have smaller separations that can be explained in terms of galaxy-scale concentrations of baryonic matter. Although gravitationally lensed galaxies with large separations are known, quasars are more useful cosmological probes because of the simplicity of the resulting lens systems. Here we report the discovery of a lensed quasar, SDSS J1004+4112, which has a maximum separation between the components of 14.62 arcsec. Such a large separation means that the lensing object must be dominated by dark matter. Our results are fully consistent with theoretical expectations based on the cold-dark-matter model.
01/2004;
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M. Oguri,
N. Inada,
C. R. Keeton,
B. Pindor,
J. F. Hennawi,
M. D. Gregg,
R. H. Becker,
K. Chiu,
W Zheng,
S. -I. Ichikawa, [......],
T. Goto,
J. E. Gunn,
D. E. Johnston,
S. M. Kent,
R. C. Nichol,
G. T. Richards,
H. -W. Rix,
D. P. Schneider,
E. S. Sheldon,
A. S. Szalay
[show abstract]
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ABSTRACT: We study the recently discovered gravitational lens SDSS J1004+4112, the first quasar lensed by a cluster of galaxies. It consists of four images with a maximum separation of 14.62''. The system has been confirmed as a lensed quasar at z=1.734 on the basis of deep imaging and spectroscopic follow-up observations. We present color-magnitude relations for galaxies near the lens plus spectroscopy of three central cluster members, which unambiguously confirm that a cluster at z=0.68 is responsible for the large image separation. We find a wide range of lens models consistent with the data, but they suggest four general conclusions: (1) the brightest cluster galaxy and the center of the cluster potential well appear to be offset by several kpc; (2) the cluster mass distribution must be elongated in the North--South direction, which is consistent with the observed distribution of cluster galaxies; (3) the inference of a large tidal shear (~0.2) suggests significant substructure in the cluster; and (4) enormous uncertainty in the predicted time delays between the images means that measuring the delays would greatly improve constraints on the models. We also compute the probability of such large separation lensing in the SDSS quasar sample, on the basis of the CDM model. The lack of large separation lenses in previous surveys and the discovery of one in SDSS together imply a mass fluctuation normalization \sigma_8=1.0^{+0.4}_{-0.2} (95% CL), if cluster dark matter halos have an inner slope -1.5. Shallower profiles would require higher values of \sigma_8. Although the statistical conclusion might be somewhat dependent on the degree of the complexity of the lens potential, the discovery is consistent with the predictions of the abundance of cluster-scale halos in the CDM scenario. (Abridged) Comment: 21 pages, 24 figures, 5 tables, accepted for publication in ApJ
12/2003;
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-1:333.
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N. Inada, M. Oguri,
B. Pindor,
JF Hennawi,
KL Chiu,
W Zheng,
SI Ichikawa,
MD Gregg,
RH Becker,
Y Suto, [......],
GT Richards,
HW Rix,
ES Sheldon,
NA Bahcall,
J. Brinkmann,
Z. Ivezic,
DQ Lamb,
TA McKay,
DP Schneider,
DG York
[show abstract]
[hide abstract]
ABSTRACT: Gravitational lensing is a powerful tool for the study of the distribution of dark matter in the Universe. The cold-dark-matter model of the formation of large-scale structures ( that is, clusters of galaxies and even larger assemblies) predicts(1-6) the existence of quasars gravitationally lensed by concentrations of dark matter(7) so massive that the quasar images would be split by over 7 arcsec. Numerous searches(8-11) for large-separation lensed quasars have, however, been unsuccessful. All of the roughly 70 lensed quasars known(12), including the first lensed quasar discovered(13), have smaller separations that can be explained in terms of galaxy-scale concentrations of baryonic matter. Although gravitationally lensed galaxies(14) with large separations are known, quasars are more useful cosmological probes because of the simplicity of the resulting lens systems. Here we report the discovery of a lensed quasar, SDSS J1004+4112, which has a maximum separation between the components of 14.62 arcsec. Such a large separation means that the lensing object must be dominated by dark matter. Our results are fully consistent with theoretical expectations(3-5) based on the cold-dark-matter model. Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/62919/1/nature02153.pdf
Nature.
