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Title: DETECTION OF SUBSTRUCTURE IN THE GRAVITATIONALLY LENSED QUASAR MG0414+0534 USING MID-INFRARED AND RADIO VLBI OBSERVATIONS

Abstract

We present 11.2 {mu}m observations of the gravitationally lensed, radio-loud z{sub s} = 2.64 quasar MG0414+0534, obtained using the Michelle camera on Gemini North. We find a flux ratio anomaly of A2/A1 = 0.93 {+-} 0.02 for the quasar images A1 and A2. When combined with the 11.7 {mu}m measurements from Minezaki et al., the A2/A1 flux ratio is nearly 5{sigma} from the expected ratio for a model based on the two visible lens galaxies. The mid-IR flux ratio anomaly can be explained by a satellite (substructure), 0.''3 northeast of image A2, as can the detailed very long baseline interferometry (VLBI) structures of the jet produced by the quasar. When we combine the mid-IR flux ratios with high-resolution VLBI measurements, we find a best-fit mass between 10{sup 6.2} and 10{sup 7.5} M{sub Sun} inside the Einstein radius for a satellite substructure modeled as a singular isothermal sphere at the redshift of the main lens (z{sub l} = 0.96). We are unable to set an interesting limit on the mass to light ratio due to its proximity to the quasar image A2. While the observations used here were technically difficult, surveys of flux anomalies in gravitational lenses with the James Webbmore » Space Telescope will be simple, fast, and should well constrain the abundance of substructure in dark matter halos.« less

Authors:
 [1]; ;  [2];  [3]
  1. Physics Department, United States Naval Academy, Annapolis, MD 21403 (United States)
  2. Astronomy Department, University of Washington, Seattle, WA 98195 (United States)
  3. Department of Astronomy and the Center for Cosmology and Astroparticle Physics, Ohio State University, Columbus, OH 43210 (United States)
Publication Date:
OSTI Identifier:
22140269
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 773; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DETECTION; GALAXIES; GRAVITATIONAL LENSES; INTERFEROMETRY; MASS; NONLUMINOUS MATTER; QUASARS; RED SHIFT; RESOLUTION; SPACE; TELESCOPES; VISIBLE RADIATION

Citation Formats

MacLeod, Chelsea L., Jones, Ramsey, Agol, Eric, and Kochanek, Christopher S., E-mail: macleod@usna.edu. DETECTION OF SUBSTRUCTURE IN THE GRAVITATIONALLY LENSED QUASAR MG0414+0534 USING MID-INFRARED AND RADIO VLBI OBSERVATIONS. United States: N. p., 2013. Web. doi:10.1088/0004-637X/773/1/35.
MacLeod, Chelsea L., Jones, Ramsey, Agol, Eric, & Kochanek, Christopher S., E-mail: macleod@usna.edu. DETECTION OF SUBSTRUCTURE IN THE GRAVITATIONALLY LENSED QUASAR MG0414+0534 USING MID-INFRARED AND RADIO VLBI OBSERVATIONS. United States. doi:10.1088/0004-637X/773/1/35.
MacLeod, Chelsea L., Jones, Ramsey, Agol, Eric, and Kochanek, Christopher S., E-mail: macleod@usna.edu. Sat . "DETECTION OF SUBSTRUCTURE IN THE GRAVITATIONALLY LENSED QUASAR MG0414+0534 USING MID-INFRARED AND RADIO VLBI OBSERVATIONS". United States. doi:10.1088/0004-637X/773/1/35.
@article{osti_22140269,
title = {DETECTION OF SUBSTRUCTURE IN THE GRAVITATIONALLY LENSED QUASAR MG0414+0534 USING MID-INFRARED AND RADIO VLBI OBSERVATIONS},
author = {MacLeod, Chelsea L. and Jones, Ramsey and Agol, Eric and Kochanek, Christopher S., E-mail: macleod@usna.edu},
abstractNote = {We present 11.2 {mu}m observations of the gravitationally lensed, radio-loud z{sub s} = 2.64 quasar MG0414+0534, obtained using the Michelle camera on Gemini North. We find a flux ratio anomaly of A2/A1 = 0.93 {+-} 0.02 for the quasar images A1 and A2. When combined with the 11.7 {mu}m measurements from Minezaki et al., the A2/A1 flux ratio is nearly 5{sigma} from the expected ratio for a model based on the two visible lens galaxies. The mid-IR flux ratio anomaly can be explained by a satellite (substructure), 0.''3 northeast of image A2, as can the detailed very long baseline interferometry (VLBI) structures of the jet produced by the quasar. When we combine the mid-IR flux ratios with high-resolution VLBI measurements, we find a best-fit mass between 10{sup 6.2} and 10{sup 7.5} M{sub Sun} inside the Einstein radius for a satellite substructure modeled as a singular isothermal sphere at the redshift of the main lens (z{sub l} = 0.96). We are unable to set an interesting limit on the mass to light ratio due to its proximity to the quasar image A2. While the observations used here were technically difficult, surveys of flux anomalies in gravitational lenses with the James Webb Space Telescope will be simple, fast, and should well constrain the abundance of substructure in dark matter halos.},
doi = {10.1088/0004-637X/773/1/35},
journal = {Astrophysical Journal},
number = 1,
volume = 773,
place = {United States},
year = {Sat Aug 10 00:00:00 EDT 2013},
month = {Sat Aug 10 00:00:00 EDT 2013}
}
  • We present the first resolved mid-infrared (IR) (11 {mu}m) observations of the four-image quasar lens H1413+117 using the Michelle camera on Gemini North. All previous observations (optical, near-IR, and radio) of this lens show a 'flux anomaly', where the image flux ratios cannot be explained by a simple, central lens galaxy. We attempt to reproduce the mid-IR flux ratios, which are insensitive to extinction and microlensing, by modeling the main lens as a singular isothermal ellipsoid. This model fails to reproduce the flux ratios. However, we can explain the flux ratios simply by adding to the model a nearby galaxymore » detected in the H band by the Hubble Space Telescope. This perturbing galaxy lies 4.''0 from the main lens and it has a critical radius of 0.''63 {+-} 0.''02 which is similar to that of the main lens, as expected from their similar H-band fluxes. More remarkably, this galaxy is not required to obtain a good fit to the system astrometry, so this represents the first clear detection of an object through its effect on the image fluxes of a gravitational lens. This is a parallel to the detections of visible satellites from astrometric anomalies, and provides a proof of the concept of searching for substructure in galaxies using anomalous flux ratios.« less
  • The gravitationally lensed quasar 0957+561 has been studied at wavelengths of 2, 6, 18, and 21 cm, using the VLA. The A and B quasar images have essentially identical radio spectra but polarization rotation measures that differ by 100 rad m/sup -2/. The lambda = 6 cm maps are of especially high quality and show many more features than are visible optically. The giant cD galaxy designated G1 in the optical observations has a radio source at its nucleus, 1'' north of the B image, and designated G in the radio maps. In addition, there is a pronounced jet ofmore » relativistic plasma extending northeast of the A image, with a less pronounced lobe to the southwest. These have no obvious counterpart at the B image. All singularity-free gravitational lenses produce an odd number of images, leading to an interpretation in which most of the jet structures are singly imaged. A number of possible mass models were considered, one of which, by judicious choice of parameters, explains the radio observations acceptably. The cD galaxy is an important component of the lens, but an additional, far more massive component must be invoked. This must be nonluminous, generally associated with the cluster, but not with individual galaxies. The total mass is model-dependent, but the mass-to-luminosity ratio in the inner part of the system must be several thousand to one.« less
  • In this paper, we present the discovery and preliminary characterization of a gravitationally lensed quasar with a source redshift z s = 2.74 and image separation of 2.9 arcsec lensed by a foreground z l = 0.40 elliptical galaxy. Since optical observations of gravitationally lensed quasars show the lens system as a superposition of multiple point sources and a foreground lensing galaxy, we have developed a morphology-independent multi-wavelength approach to the photometric selection of lensed quasar candidates based on Gaussian Mixture Models (GMM) supervised machine learning. Using this technique and gi multicolour photometric observations from the Dark Energy Survey (DES),more » near-IR JK photometry from the VISTA Hemisphere Survey (VHS) and WISE mid-IR photometry, we have identified a candidate system with two catalogue components with i AB = 18.61 and i AB = 20.44 comprising an elliptical galaxy and two blue point sources. Spectroscopic follow-up with NTT and the use of an archival AAT spectrum show that the point sources can be identified as a lensed quasar with an emission line redshift of z = 2.739 ± 0.003 and a foreground early-type galaxy with z = 0.400 ± 0.002. We model the system as a single isothermal ellipsoid and find the Einstein radius θ E ~ 1.47 arcsec, enclosed mass M enc ~ 4 × 10 11 M and a time delay of ~52 d. Finally, the relatively wide separation, month scale time delay duration and high redshift make this an ideal system for constraining the expansion rate beyond a redshift of 1.« less
  • We present the discovery and preliminary characterization of a gravitationally lensed quasar with a source redshift zs = 2.74 and image separation of 2.9 arcsec lensed by a foreground zl = 0.40 elliptical galaxy. Since optical observations of gravitationally lensed quasars show the lens system as a superposition of multiple point sources and a foreground lensing galaxy, we have developed a morphology-independent multi-wavelength approach to the photometric selection of lensed quasar candidates based on Gaussian Mixture Models (GMM) supervised machine learning. Using this technique and gi multicolour photometric observations from the Dark Energy Survey (DES), near-IR JK photometry from themore » VISTA Hemisphere Survey (VHS) and WISE mid-IR photometry, we have identified a candidate system with two catalogue components with iAB = 18.61 and iAB = 20.44 comprising an elliptical galaxy and two blue point sources. Spectroscopic follow-up with NTT and the use of an archival AAT spectrum show that the point sources can be identified as a lensed quasar with an emission line redshift of z = 2.739 ± 0.003 and a foreground early-type galaxy with z = 0.400 ± 0.002. We model the system as a single isothermal ellipsoid and find the Einstein radius θE ~ 1.47 arcsec, enclosed mass Menc ~ 4 × 10 11 M⊙ and a time delay of ~52 d. The relatively wide separation, month scale time delay duration and high redshift make this an ideal system for constraining the expansion rate beyond a redshift of 1.« less
  • We present the discovery and preliminary characterization of a gravitationally lensed quasar with a source redshiftmore » $$z_{s}=2.74$$ and image separation of $2.9"$ lensed by a foreground $$z_{l}=0.40$$ elliptical galaxy. Since the images of gravitationally lensed quasars are the superposition of multiple point sources and a foreground lensing galaxy, we have developed a morphology independent multi-wavelength approach to the photometric selection of lensed quasar candidates based on Gaussian Mixture Models (GMM) supervised machine learning. Using this technique and $gi$ multicolour photometric observations from the Dark Energy Survey (DES), near IR $JK$ photometry from the VISTA Hemisphere Survey (VHS) and WISE mid IR photometry, we have identified a candidate system with two catalogue components with $$i_{AB}=18.61$$ and $$i_{AB}=20.44$$ comprised of an elliptical galaxy and two blue point sources. Spectroscopic follow-up with NTT and the use of an archival AAT spectrum show that the point sources can be identified as a lensed quasar with an emission line redshift of $$z=2.739\pm0.003$$ and a foreground early type galaxy with $$z=0.400\pm0.002$$. We model the system as a single isothermal ellipsoid and find the Einstein radius $$\theta_E \sim 1.47"$$, enclosed mass $$M_{enc} \sim 4 \times 10^{11}$$M$$_{\odot}$$ and a time delay of $$\sim$$52 days. The relatively wide separation, month scale time delay duration and high redshift make this an ideal system for constraining the expansion rate beyond a redshift of 1.« less