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CTQ 327
Gravitationally-lensed quasar in constellation Hydra From Wikipedia, the free encyclopedia
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CTQ 327 also known as Q 1355-2257, is a gravitationally-lensed quasar located in the constellation of Hydra. It was discovered in 1992 from the Calan-Tololo Survey,[1] with its redshift of the object calculated as (z) 1.37 by N.D. Morgan during the Hubble Space Telescope Imaging Spectrograph snapshot survey in August 2003.[2]
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CTQ 327 is a double imaged quasar.[3][4] When imaged by Morgan, the object is found to separate into two bright images or components, with an estimated separation gap of 1.22 arcseconds and a g-band flux ratio roughly 5 to 1. The components are found to display continuum and emission line features in their spectra, mainly doubly ionized carbon and magnesium, despite not similar to one another, with component A having much weaker emission lines compared to component B.[2][5][6]
The lensing galaxy of CTQ 327 is resolved and classified an early-type elliptical galaxy with a redshift of (z) 0.70, located from component B by 0.29 milliarcseconds.[2][7] An absorption feature is found to be associated with it at (z) 0.48.[8] A stellar mass of 11.56 Mʘ, and an effective radius of 1.24 ± 0.29 arcseconds has been found for the lens galaxy with the total Einstein radius of 0.62 arcseconds.[9]
The quasar displays time-delays. Based on observations by P. Saha using a lens model, the predicted time-delay is -89+28-39 days long.[6] A more recent study in August 2020, estimated a new time-delay of -81.5+10.8-12.0 days based on a measurement pipeline.[10] It is shown the flux ratios of both components have temporal variations based on g-band Magellan observations of 0.14 magnitude during a period of over three months. Comparison of second-epoch data obtained in March and June, have also found component A of CTQ 327 underwent a significant decrease in brightness by 0.125 ± 0.001 magnitude while component B showed no observed changes.[2]
CTQ 327 has evidence of chromatic microlensing with wavelengths greater than ʎ > 6180Å. Astronomers also noted, the core of emission lines and continuum also displayed a discrepancy in magnitude results of -0.06 and +0.08 respectively. They also noted the accretion disk of CTQ 327 is larger with a size of 3.6+3.0-1.6 x 1.3 ± 0.6 M/Mʘ and has a temperature profile of 2.0 ± 0.7. The black hole mass is estimated as 1.1 x 109 Mʘ.[11]
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