# A COMPARISON OF COSMOLOGICAL MODELS USING STRONG GRAVITATIONAL LENSING GALAXIES

http://hdl.handle.net/10150/614768
Title:
A COMPARISON OF COSMOLOGICAL MODELS USING STRONG GRAVITATIONAL LENSING GALAXIES
Author:
Melia, Fulvio ( 0000-0002-8014-0593 ) ; Wei, Jun-Jie ( 0000-0003-0162-2488 ) ; Wu, Xue-Feng ( 0000-0002-6299-1263 )
Affiliation:
The University of Arizona
Issue Date:
2014-11-25
Publisher:
IOP PUBLISHING LTD
Citation:
A COMPARISON OF COSMOLOGICAL MODELS USING STRONG GRAVITATIONAL LENSING GALAXIES 2014, 149 (1):2 The Astronomical Journal
Journal:
The Astronomical Journal
Rights:
Collection Information:
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.
Abstract:
Strongly gravitationally lensed quasar-galaxy systems allow us to compare competing cosmologies as long as one can be reasonably sure of the mass distribution within the intervening lens. In this paper, we assemble a catalog of 69 such systems from the Sloan Lens ACS and Lens Structure and Dynamics surveys suitable for this analysis, and carry out a one-on-one comparison between the standard model, $\Lambda$CDM, and the $R_{\rm h}=ct$ Universe, which has thus far been favored by the application of model selection tools to other kinds of data. We find that both models account for the lens observations quite well, though the precision of these measurements does not appear to be good enough to favor one model over the other. Part of the reason is the so-called bulge-halo conspiracy that, on average, results in a baryonic velocity dispersion within a fraction of the optical effective radius virtually identical to that expected for the whole luminous-dark matter distribution modeled as a singular isothermal ellipsoid, though with some scatter among individual sources. Future work can greatly improve the precision of these measurements by focusing on lensing systems with galaxies as close as possible to the background sources. Given the limitations of doing precision cosmological testing using the current sample, we also carry out Monte Carlo simulations based on the current lens measurements to estimate how large the source catalog would have to be in order to rule out either model at a $\sim 99.7\%$ confidence level. We find that if the real cosmology is $\Lambda$CDM, a sample of $\sim 200$ strong gravitational lenses would be sufficient to rule out $R_{\rm h}=ct$ at this level of accuracy, while $\sim 300$ strong gravitational lenses would be required to rule out $\Lambda$CDM if the real Universe were instead $R_{\rm h}=ct$. The difference in required sample size reflects the greater number of free parameters available to fit the data with $\Lambda$CDM. We point out that, should the $R_{\rm h}=ct$ Universe eventually emerge as the correct cosmology, its lack of any free parameters for this kind of work will provide a remarkably powerful probe of the mass structure in lensing galaxies, and a means of better understanding the origin of the bulge-halo conspiracy.
ISSN:
1538-3881
DOI:
10.1088/0004-6256/149/1/2
Version:
Final accepted manuscript
http://stacks.iop.org/1538-3881/149/i=1/a=2?key=crossref.ebd59126da1a1b0ab5b71a96e4877745

# Full metadata record

DC FieldValue Language
dc.contributor.authorMelia, Fulvioen
dc.contributor.authorWei, Jun-Jieen
dc.contributor.authorWu, Xue-Fengen
dc.date.accessioned2016-06-25T00:43:45Z-
dc.date.available2016-06-25T00:43:45Z-
dc.date.issued2014-11-25-
dc.identifier.citationA COMPARISON OF COSMOLOGICAL MODELS USING STRONG GRAVITATIONAL LENSING GALAXIES 2014, 149 (1):2 The Astronomical Journalen
dc.identifier.issn1538-3881-
dc.identifier.doi10.1088/0004-6256/149/1/2-
dc.identifier.urihttp://hdl.handle.net/10150/614768-
dc.description.abstractStrongly gravitationally lensed quasar-galaxy systems allow us to compare competing cosmologies as long as one can be reasonably sure of the mass distribution within the intervening lens. In this paper, we assemble a catalog of 69 such systems from the Sloan Lens ACS and Lens Structure and Dynamics surveys suitable for this analysis, and carry out a one-on-one comparison between the standard model, $\Lambda$CDM, and the $R_{\rm h}=ct$ Universe, which has thus far been favored by the application of model selection tools to other kinds of data. We find that both models account for the lens observations quite well, though the precision of these measurements does not appear to be good enough to favor one model over the other. Part of the reason is the so-called bulge-halo conspiracy that, on average, results in a baryonic velocity dispersion within a fraction of the optical effective radius virtually identical to that expected for the whole luminous-dark matter distribution modeled as a singular isothermal ellipsoid, though with some scatter among individual sources. Future work can greatly improve the precision of these measurements by focusing on lensing systems with galaxies as close as possible to the background sources. Given the limitations of doing precision cosmological testing using the current sample, we also carry out Monte Carlo simulations based on the current lens measurements to estimate how large the source catalog would have to be in order to rule out either model at a $\sim 99.7\%$ confidence level. We find that if the real cosmology is $\Lambda$CDM, a sample of $\sim 200$ strong gravitational lenses would be sufficient to rule out $R_{\rm h}=ct$ at this level of accuracy, while $\sim 300$ strong gravitational lenses would be required to rule out $\Lambda$CDM if the real Universe were instead $R_{\rm h}=ct$. The difference in required sample size reflects the greater number of free parameters available to fit the data with $\Lambda$CDM. We point out that, should the $R_{\rm h}=ct$ Universe eventually emerge as the correct cosmology, its lack of any free parameters for this kind of work will provide a remarkably powerful probe of the mass structure in lensing galaxies, and a means of better understanding the origin of the bulge-halo conspiracy.en
dc.language.isoenen
dc.publisherIOP PUBLISHING LTDen
dc.relation.urlhttp://stacks.iop.org/1538-3881/149/i=1/a=2?key=crossref.ebd59126da1a1b0ab5b71a96e4877745en
dc.titleA COMPARISON OF COSMOLOGICAL MODELS USING STRONG GRAVITATIONAL LENSING GALAXIESen
dc.typeArticleen
dc.contributor.departmentThe University of Arizonaen
dc.identifier.journalThe Astronomical Journalen
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en
dc.eprint.versionFinal accepted manuscripten
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Final Accepted Manuscript