SDSS J024634.11-082536.2: A New Gravitationally Lensed Quasar from the Sloan Digital Sky Survey (original) (raw)
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SDSS J0246-0825: A New Gravitationally Lensed Quasar from the Sloan Digital Sky Survey
2005
We report the discovery of a new two-image gravitationally lensed quasar, SDSS J024634.11-082536.2 (SDSS J0246-0825). This object was selected as a lensed quasar candidate from the Sloan Digital Sky Survey (SDSS) by the same algorithm that was used to discover other SDSS lensed quasars (e.g., SDSS J0924+0219). Multicolor imaging with the Magellan Consortium's Walter Baade 6.5-m telescope and the spectroscopic observations using the W. M. Keck Observatory's Keck II telescope confirm that SDSS J0246-0825 consists of two lensed images ($\Delta{\theta}=$1\farcs04) of a source quasar at z=1.68. Imaging observations with the Keck telescope and the Hubble Space Telescope reveal an extended object between the two quasar components, which is likely to be a lensing galaxy of this system. From the absorption lines in the spectra of quasar components and the apparent magnitude of the galaxy, combined with the expected absolute magnitude from the Faber-Jackson relation, we estimate the redshift of the lensing galaxy to be z=0.724. A highly distorted ring is visible in the Hubble Space Telescope images, which is likely to be the lensed host galaxy of the source quasar. Simple mass modeling predicts the possibility that there is a small (faint) lensing object near the primary lensing galaxy.
The Astronomical Journal, 2003
We report the discovery of a new gravitationally lensed quasar from the Sloan Digital Sky Survey, SDSS J092455.87+021924.9 (SDSS J0924+0219). This object was selected from among known SDSS quasars by an algorithm that was designed to select another known SDSS lensed quasar (SDSS 1226−0006A,B). Five separate components, three of which are unresolved, are identified in photometric follow-up observations obtained with the Magellan Consortium's 6.5m Walter Baade telescope at Las Campanas Observatory. Two of the unresolved components (designated A and B) are confirmed to be quasars with z = 1.524; the velocity difference is less than 100 km sec −1 according to spectra taken with the W. M. Keck Observatory's Keck II telescope on Mauna Kea. A third stellar component, designated C, has the colors of a quasar with redshift similar to components A and B. The maximum separation of the point sources is 1. ′′ 78. The other two sources, designated G and D, are resolved. Component G appears to be the best candidate for the lensing galaxy. Although component D is near the expected position of the fourth lensed component in a four image lens system, its properties are not consistent with being the image of a quasar at z ∼ 1.5. Nevertheless, the identical redshifts of components A and B and the presence of component C strongly suggest that this object is a gravitational lens. Our observations support the idea that a foreground object reddens the fourth lensed component and that another unmodeled effect (such as micro-or milli-lensing) demagnificates it, but we cannot rule out the possibility that SDSS0924+0219 is an example of the relatively rare class of "three component" lens systems.
0 O ct 2 00 1 PMN J 1632 – 0033 : A new gravitationally lensed quasar
2008
We report the discovery of a gravitationally lensed quasar resulting from our survey for lenses in the southern sky. Radio images of J1632–0033 with the VLA and ATCA exhibit two compact, flat-spectrum components with separation 1. ′′47 and flux density ratio 13.2. Images with the HST reveal the optical counterparts to the radio components and also the lens galaxy. An optical spectrum of the bright component, obtained with the first Magellan telescope, reveals quasar emission lines at redshift 3.42. Deeper radio images with MERLIN and the VLBA reveal a faint third radio component located near the center of the lens galaxy, which is either a third image of the background quasar or faint emission from the lens galaxy. Subject headings: gravitational lensing, quasars: individual (J1632–0033)
DISCOVERY OF FOUR GRAVITATIONALLY LENSED QUASARS FROM THE SLOAN DIGITAL SKY SURVEY
The Astronomical Journal, 2008
We present the discovery of four gravitationally lensed quasars selected from the spectroscopic quasar catalog of the Sloan Digital Sky Survey. We describe imaging and spectroscopic follow-up observations that support the lensing interpretation of the following four quasars: SDSS J0832+0404 (image separation θ = 1. 98, source redshift z s = 1.115, lens redshift z l = 0.659); SDSS J1216+3529 (θ = 1. 49, z s = 2.012); SDSS J1322+1052 (θ = 2. 00, z s = 1.716); and SDSS J1524+4409 (θ = 1. 67, z s = 1.210, z l = 0.320). Each system has two lensed images. We find that the fainter image component of SDSS J0832+0404
SDSS J102111.02+491330.4: A Newly Discovered Gravitationally Lensed Quasar
The Astronomical Journal, 2006
We report follow-up observations of two gravitational lens candidates identified in the Sloan Digital Sky Survey (SDSS) dataset. We have confirmed that SDSS J102111.02+491330.4 is a previously unknown gravitationally lensed quasar. This lens system exhibits two images of a z = 1.72 quasar, with an image
The Astrophysical Journal, 2005
We report the discovery of two doubly-imaged quasars, SDSS J100128.61+502756.9 and SDSS J120629.65+433217.6, at redshifts of 1.838 and 1.789 and with image separations of 2. ′′ 86 and 2. ′′ 90, respectively. The objects were selected as lens candidates from the Sloan Digital Sky Survey (SDSS). Based on the identical nature of the spectra of the two quasars in each pair and the identification of the lens galaxies, we conclude -2that the objects are gravitational lenses. The lenses are complicated; in both systems there are several galaxies in the fields very close to the quasars, in addition to the lens galaxies themselves. The lens modeling implies that these nearby galaxies contribute significantly to the lens potentials. On larger scales, we have detected an enhancement in the galaxy density near SDSS J100128.61+502756.9. The number of lenses with image separation of ∼ 3 ′′ in the SDSS already exceeds the prediction of simple theoretical models based on the standard Lambda-dominated cosmology and observed velocity function of galaxies.
PMN J2004-1349: A new gravitationally lensed quasar
2000
We report the discovery of a new double-image quasar resulting from our search for gravitational lenses in the southern sky. Radio source PMN J2004-1349 is composed of two flat-spectrum components of approximately equal brightness separated by 1. ′′ 13 in VLA, MERLIN and VLBA images. The I-band optical counterpart is also double, with roughly the same separation, position angle, and flux ratio as the radio double. Upon subtraction of the quasars from the I-band image, we identify a dim pattern of residuals as the lens galaxy. While the present observations are sufficient to establish that PMN J2004-1349 is a gravitational lens, additional information (such as the redshifts of the quasar and lens galaxy) will be needed before many interesting astrophysical quantities (such as the mass of the galaxy, or the predicted time delay between lensed images) can be inferred.
The Host Galaxy of the Lensed Quasar Q0957+561
The Astrophysical Journal, 2000
Infrared images of the Q 0957+561 gravitational lens obtained with the Hubble Space Telescope show two large (∼5 ′′ ) lensed images of the z s = 1.41 quasar host galaxy. Parts of the host galaxy are doubly-imaged like the quasar, while other parts are quadruply-imaged. The distortions of the host galaxy offer the best probe yet of the global structure of the lensing potential, which is essential for determining the Hubble constant from the measured time delay. The distortions are inconsistent with the predictions of previously published lens models, which invalidates those models and their implications for H 0 . New models show that the distortions finally break the long-standing degeneracy between the shape of the lens galaxy and the tidal shear contributed by the cluster containing the lens galaxy. The shape of the lens galaxy's mass distribution must be remarkably similar to the shape of its luminosity distribution, and most models that produce reasonable values for the Hubble constant roughly match the observed ellipticity gradient and isophote twist of the lens galaxy. Also, the cluster must be non-spherical and produce a relatively small tidal shear. Although there are still degeneracies in the lens models that lead to a 25% uncertainty in the derived value of the Hubble constant, there are also strong prospects for new observations to further improve the constraints and reduce the uncertainties.
PMN J2004–1349: A new gravitationally lensed quasar 1
2013
We report the discovery of a new double-image quasar resulting from our search for gravitational lenses in the southern sky. Radio source PMN J2004-1349 is composed of two flat-spectrum components of approximately equal brightness separated by 1. ′′ 13 in VLA, MERLIN and VLBA images. The I-band optical counterpart is also double, with roughly the same separation, position angle, and flux ratio as the radio double. Upon subtraction of the quasars from the I-band image, we identify a dim pattern of residuals as the lens galaxy. While the present observations are sufficient to establish that PMN J2004-1349 is a gravitational lens, additional information (such as the redshifts of the quasar and lens galaxy) will be needed before many interesting astrophysical quantities (such as the mass of the galaxy, or the predicted time delay between lensed images) can be inferred.
SDSS J090334. 92+ 502819 2: A New Gravitational Lens
We report the discovery of a new gravitationally lensed quasar from the Sloan Digital Sky Survey, SDSS J090334.92+502819.2. This object was targeted for SDSS spectroscopy as a Luminous Red Galaxy (LRG), but manual examination of the spectrum showed the presence of a quasar at z ≃ 3.6 in addition to a red galaxy at z = 0.388, and -2the SDSS image showed a second possible QSO image nearby. Follow-up imaging and spectroscopy confirmed the lensing hypothesis. In images taken at the ARC 3.5-meter telescope, two quasars are separated by 2. ′′ 8; the lensing galaxy is clearly seen and is blended with one of the quasar images. Spectroscopy taken at the Keck II telescope shows that the quasars have identical redshifts of z ≃ 3.6 and both show the presence of the same broad absorption line-like troughs. We present simple lens models which account for the geometry and magnifications. The lens galaxy lies near two groups of galaxies and may be a part of them. The models suggest that the groups may contribute considerable shear and may have a strong effect on the lens configuration. Subject headings: gravitational lensing-quasars: individual (SDSS J090334.92+502819.2) 19 see