High-resolution observations and mass modelling of the CLASS gravitational lens B1152+199

Rusin, D.; Norbury, M.; Biggs, A. D.; Marlow, D. R.; Jackson, N.; Browne, I. W. A.; Wilkinson, P. N.; Myers, S. T.

doi:10.1046/j.1365-8711.2002.05043.x

Cited by 58 publications

(97 citation statements)

References 31 publications

(38 reference statements)

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“…The FP strongly favors nearly isothermal (n ¼ 2) mass profiles on scales of a few effective radii, with a mean density slope of n ¼ 2:06 AE 0:17 (68% C.L.). These statistical constraints are consistent with the isothermal paradigm favored by modeling (Kochanek 1995;Cohn et al 2001;Muñoz et al 2001;Rusin et al 2002;Winn et al 2003) and dynamical (Treu & Koopmans 2002a, 2002b) studies of individual lens galaxies, the dynamics of local ellipticals (e.g., Rix et al 1997;Romanowsky & Kochanek 2001;Gerhard et al 2001), and their X-ray halos (e.g., Fabbiano 1989;Matsushita et al 1998;Loewenstein & White 1999). Note, however, that Treu & Koopmans (2004) favor models with systematically shallower profiles, while Romanowsky et al (2003) favor significantly more concentrated models.…”

Section: Summary and Discussionsupporting

confidence: 81%

“…However, the geometry of the lensed images allows the velocity dispersion to be estimated very accurately, given a model for the mass distribution. An isothermal ( / r À2 ) model is the common choice, since it is consistent with most constraints on lens galaxies (Kochanek 1995;Cohn et al 2001;Muñoz et al 2001;Treu & Koopmans 2002a, 2004Rusin et al 2002;Winn et al 2003;Rusin et al 2003a [hereafter RKK]; and local ellipticals (Fabbiano 1989;Rix et al 1997;Gerhard et al 2001; see Romanowsky et al 2003 for an alternative conclusion). In the context of evolution studies, the issue is then whether the isothermal assumption is robust and sufficient.…”

Section: Introductionmentioning

confidence: 98%

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The Evolution and Structure of Early‐Type Field Galaxies: A Combined Statistical Analysis of Gravitational Lenses

Rusin¹,

Kochanek²

2005

ApJ

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151

166

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We introduce a framework for simultaneously investigating the structure and luminosity evolution of early-type gravitational lens galaxies. The method is based on the fundamental plane, which we interpret using the aperture mass-radius relations derived from lensed image geometries. We apply this method to our previous sample of 22 lens galaxies with measured redshifts and excellent photometry. Modeling the population with a single mass profile and evolutionary history, we find that early-type galaxies are nearly isothermal (logarithmic density slope n ¼ 2:06 AE 0:17, 68% C.L.) and that their stars evolve at a rate of d log (M =L) B =dz ¼ À0:50 AE 0:19 (68% C.L.) in the rest-frame B band. For a Salpeter initial mass function and a concordance cosmology, this implies a mean star formation redshift of hz f i > 1:5 at 95% confidence. While this model can neatly describe the mean properties of early-type galaxies, it is clear that the scatter of the lens sample is too large to be explained by observational uncertainties alone. We therefore consider statistical models in which the galaxy population is described by a distribution of star formation redshifts. We find that stars must form over a significant range of redshifts (Áz f > 1:7, 68% C.L.), which can extend as low as z f $ 1 for some acceptable models. However, the typical galaxy will still have an old stellar population (hz f i > 1:5). The lens sample therefore favors early star formation in field ellipticals, even if we make no a priori assumption regarding the shape of the mass distribution in lenses and include the range of possible deviations from homology in the uncertainties. Our evolution results call into question several recent claims that early-type galaxies in low-density environments have much younger stars than those in rich clusters.

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Section: Summary and Discussionsupporting

confidence: 81%

Section: Introductionmentioning

confidence: 98%

The Evolution and Structure of Early‐Type Field Galaxies: A Combined Statistical Analysis of Gravitational Lenses

Rusin¹,

Kochanek²

2005

ApJ

Self Cite

151

166

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“…External evidence from the dynamics of nearby elliptical galaxies (Romanowsky & Kochanek 1999) and internal evidence from lensed systems with multiple and extended sources (Kochanek 1995;Bernstein & Fischer 1999;Cohn et al 2001;Rusin et al 2002) consistently give potentials with logarithmic slopes very nearly that of an isothermal sphere.…”

Section: Nonisothermality: Is Smoothlymentioning

confidence: 90%

Quasar Microlensing at High Magnification and the Role of Dark Matter: Enhanced Fluctuations and Suppressed Saddle Points

Schechter

Wambsganß

2002

ApJ

242

306

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Contrary to naive expectation, diluting the stellar component of the lensing galaxy in a highly magnified system with smoothly distributed '' dark '' matter increases rather than decreases the microlensing fluctuations caused by the remaining stars. For a bright pair of images straddling a critical curve, the saddle point (of the arrival time surface) is much more strongly affected than the associated minimum. With a mass ratio of smooth matter to microlensing matter of 4 : 1, a saddle point with a macromagnification of l ¼ 9:5 will spend half of its time more than a magnitude fainter than predicted. The anomalous flux ratio observed for the close pair of images in MG 0414+0534 is a factor of 5 more likely than computed by Witt, Mao, & Schechter, if the smooth matter fraction is as high as 93%. The magnification probability histograms for macroimages exhibit a distinctly different structure that varies with the smooth matter content, providing a handle on the smooth matter fraction. Enhanced fluctuations can manifest themselves either in the temporal variations of a light curve or as flux ratio anomalies in a single epoch snapshot of a multiply imaged system. While the millilensing simulations of Metcalf & Madau also give larger anomalies for saddle points than for minima, the effect appears to be less dramatic for extended subhalos than for point masses. Moreover, microlensing is distinguishable from millilensing because it will produce noticeable changes in the magnification on a timescale of a decade or less.

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“…Such systems can be used in a number of astrophysical investigations, including modeling the mass distribution of the lens galaxy (Kochanek 1995;Treu & Koopmans 2002;Rusin et al 2002), studying the interstellar medium in lens galaxies (Falco et al 1999), and constraining the source size through microlensing studies (Wyithe et al 2000;Kochanek 2004). For a comprehensive review of the principles and applications of strong lensing, the reader is referred to Kochanek et al (2004).…”

Section: Introductionmentioning

confidence: 99%

Discovering Gravitational Lenses through Measurements of Their Time Delays

Pindor

2005

ApJ

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We consider the possibility that future wide-field time domain optical imaging surveys may be able to discover gravitationally lensed quasar pairs through serendipitous measurements of their time delays. We discuss the merits such a discovery technique would have relative to conventional lens searches. Using simulated quasar light curves, we demonstrate that in a survey that observes objects several times each lunar cycle over the course of five years it is possible, through the use of time delay selection, to significantly improve the efficiency of a gravitational lens search relative to that of an equivalent search that does not take advantage of time delay information. We show that window function effects associated with the length of the observing season are more important than the total number of data points in determining the effectiveness of this method. We also qualitatively discuss several complications that might be relevant to a real-time delay search.

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High-resolution observations and mass modelling of the CLASS gravitational lens B1152+199

Cited by 58 publications

References 31 publications

The Evolution and Structure of Early‐Type Field Galaxies: A Combined Statistical Analysis of Gravitational Lenses

The Evolution and Structure of Early‐Type Field Galaxies: A Combined Statistical Analysis of Gravitational Lenses

Quasar Microlensing at High Magnification and the Role of Dark Matter: Enhanced Fluctuations and Suppressed Saddle Points

Discovering Gravitational Lenses through Measurements of Their Time Delays

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