Serendipitous discovery of quadruply imaged quasars - two diamonds
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2018-02-05 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Authors | J. R. Lucey, Paul L. Schechter, Russell J. Smith, T. Anguita |
| Institutions | Millennium Institute of Astrophysics, Durham University |
| Citations | 22 |
| Analysis | Full AI Review Included |
6CCVD Technical Analysis: Gravitational Lensing and Diamond Optics
Section titled â6CCVD Technical Analysis: Gravitational Lensing and Diamond OpticsâExecutive Summary
Section titled âExecutive SummaryâThis document analyzes the research paper detailing the discovery and modeling of two rare quadruply-imaged quasar systems, poetically dubbed âTwo Diamonds.â The technical resultsâspecifically the derived local convergence (Îș) and shear (Îł) parametersâare critical inputs for advanced astronomical investigations, including microlensing analyses, an application field heavily reliant on high-performance diamond materials.
Core Value Proposition & Technical Achievements
Section titled âCore Value Proposition & Technical Achievementsâ- Rare Quadruple System Discovery: Reported the serendipitous discovery and detailed characterization of two rare, diamond-shaped quadruply-imaged quasar systems (2M1134-2103 and 2M1310-1714).
- Cosmological Constraints: The systems are highly valuable, providing restrictive constraints for gravitational lensing models and furthering progress in several cosmological fields.
- Spectroscopic Confirmation: System 2M1310-1714 was confirmed spectroscopically, yielding a background quasar redshift zQ = 1.975 and a foreground double lensing galaxy redshift zG = 0.293.
- Advanced Lensing Models: The analysis utilized sophisticated Singular Isothermal Ellipsoid (SIE) and Double SIE models, demonstrating high external shear (up to 0.34) and large predicted magnifications (up to ±18.3).
- Input for Microlensing: Critical local parameters (convergence Îș and shear Îł) were calculated for use in microlensing applications, which necessitate extremely stable, high-purity optical components (a key application for 6CCVD SCD).
- Novel Discovery Methodology: The technique successfully complemented conventional searches by prioritizing visually inspected targets initially classified as extended galaxies rather than quasar-colored sources.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the lensing analyses and spectroscopic confirmations described in the paper.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Quasar Redshift (2M1310-1714) | 1.975 | Z | Confirmed by C III] and Mg II emission lines |
| Lensing Galaxy Redshift (2M1310-1714) | 0.293 | Z | Confirmed by Ca II H/K lines, G-band, and Mg I b features |
| Einstein Radius (ΞEin), 2M1310-1714 | 2.9 | arcsec | Exceptionally large for galaxy-scale quad lenses (Range 0.3-1.9 arcsec typical) |
| Einstein Radius (ΞEin), 2M1134-2103 | 1.23 | arcsec | Based on Singular Isothermal Sphere (SIS) model |
| External Shear (γ), 2M1134-2103 | 0.34 | Unitless | Calculated at Position Angle (PA) 43° E of N |
| Predicted Magnification (Ό), 2M1310-1714 | ±17.2 to ±18.3 | Unitless | High values calculated for images A and B |
| Lensing Galaxy Separation (G1/G2) | ~1 | arcsec | Used to model the double lens in 2M1310-1714 |
| VST-ATLAS Seeing Quality | 0.72 | arcsec | Used for high-precision astrometry, superior to PS1 (1.08 arcsec) |
| Predicted Fifth Image (E), 2M1310-1714 | ~5 | magnitude fainter | Result of the double SIE lensing model |
Key Methodologies
Section titled âKey MethodologiesâThe lens systems were identified and characterized using a robust multi-survey approach combining visual inspection, spectroscopy, and advanced modeling.
- Target Selection (Taipan Phase-1 Catalogue): Initial targets were drawn from the 2MASS Extended Source Catalog (XSC) and Point Source Catalog (PSC).
- Visual Inspection Priority: Targets were prioritized based on indicators of confusion or multi-component structure, specifically:
- Objects where the PS1 i-band PSF magnitude and the Kron magnitude difference was < 0.3 magnitude.
- Objects where cross-matched PS1 and 2MASS positions differed by > 1 arcsec.
- Imaging Surveys Utilized:
- Pan-STARRS PS1: Used for initial visual inspection and griz photometry.
- VST-ATLAS (i-band): Used for superior seeing (0.72 arcsec) to derive precise relative astrometry.
- VISTA Hemisphere Survey (VHS): Used for J and Ks band photometry, crucial for identifying the faint lensing galaxy residual.
- Spectroscopic Confirmation: Long-slit spectra were obtained using the IMACS instrument on the 6.5m Magellan Baade telescope (spatial direction: 0.2 arcsec pixels; spectral sampling: 1.9 Ă per pixel; slit width: 0.9 arcsec).
- Data Processing and Astrometry: The DOPHOT program was used for fitting multiple PSFs and quasi-Gaussians to resolve the closely-spaced quasar components and the underlying lensing galaxies (G1, G2, H).
- Lensing Modeling: Keetonâs lensmodel program was used to constrain physical parameters:
- 2M1134-2103 was modeled using a Singular Isothermal Sphere with External Shear (SIS+XS).
- 2M1310-1714 was modeled using a restricted Double Singular Isothermal Ellipsoid (SIE) plus external shear.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful identification and modeling of these rare âdiamondâ quad systems provide crucial input parameters (Îș and Îł) necessary for subsequent microlensing analyses. Such analyses often require specialized optics, high-stability sensor windows, or high-purity substrates for detector arraysâall areas where 6CCVDâs MPCVD diamond excels.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend the precision required for microlensing and high-resolution astronomical observations, 6CCVD recommends the following materials:
- Optical Grade Single Crystal Diamond (SCD): Required for high-transparency optical windows, beam splitters, or substrate protection in sensitive detectors (such as those used in near-infrared and Ks band astronomy).
- Specification: SCD with thickness 0.1”m - 500”m, polished to Ra < 1nm for minimized scatter loss at optical/IR wavelengths.
- Polycrystalline Diamond (PCD) Substrates: Ideal for large-format (up to 125mm) thermal management layers behind large detector arrays in instruments like IMACS or VISTA, ensuring thermal stability even under varying vacuum and cryogenic conditions.
- Specification: Custom dimensions up to 125mm; Thickness up to 500”m.
Customization Potential
Section titled âCustomization PotentialâThe high-precision astrometry and photometry required for this research (resolving components separated by < 1 arcsec) necessitate highly customized, stable components for instrumentation:
- Custom Dimensions and Etching: 6CCVD offers laser cutting and etching services for creating complex geometries (e.g., custom optical masks or aperture slits) crucial for multi-object spectroscopy instruments.
- Precision Polishing: Achieving the optical quality needed for high-resolution imaging (0.72 arcsec seeing) requires ultra-smooth surfaces. 6CCVD guarantees surface roughness of Ra < 1nm for SCD and Ra < 5nm for inch-size PCD substrates.
- Integrated Metalization Services: Many astronomical detectors and advanced diamond components require custom contact pads or bonding layers. 6CCVD provides in-house metalization capabilities using standard metals including Au, Pt, Pd, Ti, W, and Cu, suitable for integrating diamond substrates into high-vacuum or cryogenic sensor packages.
Engineering Support
Section titled âEngineering SupportâGravitational lensing research, particularly in the realm of microlensing, demands stringent material specifications to minimize thermal drift, optimize light transmission, and ensure component longevity. 6CCVDâs in-house PhD team provides expert engineering consultation to assist researchers in selecting, designing, and manufacturing diamond components tailored for complex astronomical projects. We support integration challenges related to:
- Thermal management in large-format detector arrays.
- Designing stable optical components capable of handling high flux densities without degradation.
- Material selection for high-energy physics and observational astronomy instrumentation.
For custom specifications or material consultation related to microlensing or high-resolution astronomical optics, visit 6ccvd.com or contact our engineering team directly. We ship globally (DDU default, DDP available).
View Original Abstract
Gravitationally lensed quasars are powerful and versatile astrophysical\ntools, but they are challengingly rare. In particular, only ~25\nwell-characterized quadruple systems are known to date. To refine the target\ncatalogue for the forthcoming Taipan Galaxy Survey, the images of a large\nnumber of sources are being visually inspected in order to identify objects\nthat are confused by a foreground star or galaxies that have a distinct\nmulti-component structure. An unexpected by-product of this work has been the\nserendipitous discovery of about a dozen galaxies that appear to be lensing\nquasars, i.e. pairs or quartets of foreground stellar objects in close\nproximity to the target source. Here we report two diamond-shaped systems.\nFollow-up spectroscopy with the IMACS instrument on the 6.5m Magellan Baade\ntelescope confirms one of these as a z = 1.975 quasar quadruply lensed by a\ndouble galaxy at z = 0.293. Photometry from publicly available survey images\nsupports the conclusion that the other system is a highly sheared\nquadruply-imaged quasar. In starting with objects thought to be galaxies, our\nlens finding technique complements the conventional approach of first\nidentifying sources with quasar-like colours and subsequently finding evidence\nof lensing.\n
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 2003 - CDS/ADC Collection of Electronic Catalogues