ترغب بنشر مسار تعليمي؟ اضغط هنا

Gravitationally Lensed QSOs: Optical Monitoring with the EOCA and the Liverpool Telescope (LT)

106   0   0.0 ( 0 )
 نشر من قبل Luis Julian Goicoechea
 تاريخ النشر 2006
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

The aim of this contribution is to present the two first phases of the optical monitoring programme of the Gravitational Lenses group at the Universidad de Cantabria (GLUC, http://grupos.unican.es/glendama/). In an initial stage (2003 March-June), the Estacion de Observacion de Calar Alto (EOCA) was used to obtain VR frames of SBS 0909+532 and QSO 0957+561. These observations in 2003 led to accurate fluxes of the two components of both double QSOs, which are being compared and complemented with data from other 1-1.5 m telescopes located in the North Hemisphere: Fred Lawrence Whipple Observatory (USA), Maidanak Observatory (Uzbekistan) and Wise Observatory (Israel). On the other hand, the GLUC started the second phase of its monitoring programme in 2005 January. In this second phase, they are using the 2 m fully robotic Liverpool Telescope (LT). The key idea is the two-band photometric follow-up of four lensed QSOs with different main lensing galaxies: SBS 0909+532 (elliptical), QSO 0957+561 (giant cD), B1600+434 (edge-on spiral) and QSO 2237+0305 (face-on spiral). Thus, the light rays associated with the components of the four gravitational mirages cross different galaxy environments, and the corresponding light curves could unveil the content of these environments. While SBS 0909+532 and QSO 0957+561 are the targets for the two first years with the LT (2005-2006), the rest of targets (B1600+434 and QSO 2237+0305) will be monitored starting from 2007.

قيم البحث

اقرأ أيضاً

Thanks to its sharp view, HST has significantly improved our knowledge of tens of gravitationally lensed quasars in four different respects: (1) confirming their lensed nature; (2) detecting the lensing galaxy responsible for the image splitting; (3) improving the astrometric accuracy on the positions of the unresolved QSO images and of the lens; (4) resolving extended lensed structures from the QSO hosts into faint NIR or optical rings or arcs. These observations have helped to break some degeneracies on the lens potential, to probe the galaxy evolution and to reconstruct the true shape of the QSO host with an increased angular resolution.
We present results of the long term monitoring of the gravitationally lensed quasar HE1104-1805. The photometric data were collected between August 1997 and January 2002 as a subproject of the OGLE survey. We determine the time delay in the light c urves of images A and B of HE1104-1805 to be equal to 157+/-21 days with the variability in the image B light curve leading variability of the image A. The result is in excellent agreement with the earlier determination by Ofek and Maoz. OGLE photometry of HE1104-1805 is available to the astronomical community from the OGLE Internet archive.
Small galaxies consisting entirely of population III (pop III) stars may form at high redshifts, and could constitute one of the best probes of such stars. Here, we explore the prospects of detecting gravitationally lensed pop III galaxies behind the galaxy cluster J0717.5+3745 (J0717) with both the Hubble Space Telescope (HST) and the upcoming James Webb Space Telescope (JWST). By projecting simulated catalogs of pop III galaxies at z~7-15 through the J0717 magnification maps, we estimate the lensed number counts as a function of flux detection threshold. We find that the ongoing HST survey CLASH, targeting a total of 25 galaxy clusters including J0717, potentially could detect a small number of pop III galaxies if ~1% of the baryons in these systems have been converted into pop III stars. Using JWST exposures of J0717, this limit can be pushed to ~0.1% of the baryons. Ultra-deep JWST observations of unlensed fields are predicted to do somewhat worse, but will be able to probe pop III galaxies with luminosities intermediate between those detectable in HST/CLASH and in JWST observations of J0717. We also explain how current measurements of the galaxy luminosity function at z=7-10 can be used to constrain pop III galaxy models with very high star formation efficiencies (~10% of the baryons converted into pop III stars).
We present new spectroscopic and polarimetric observations of the gravitational lens SDSS J1004+4112 taken with the 6m telescope of the Special Astrophysical Observatory (SAO, Russia). In order to explain the variability that is observed only in the blue wing of the C IV emission line, corresponding to image A, we analyze the spectroscopy and polarimetry of the four images of the lensed system. Spectra of the four images were taken in 2007, 2008, and 2018, and polarization was measured in the period 2014-2017. Additionally, we modeled the microlensing effect in the polarized light, assuming that the source of polarization is the equatorial scattering in the inner part of the torus. We find that a blue enhancement in the CIV line wings affects component A in all three epochs. We also find that the UV continuum of component D was amplified in the period 2007-2008, and that the red wings of CIII] and CIV appear brighter in D than in the other three components. We report significant changes in the polarization parameters of image D, which can be explained by microlensing.Our simulations of microlensing of an equatorial scattering region in the dusty torus can qualitatively explain the observed changes in the polarization degree and angle of image D. We do not detect significant variability in the polarization parameters of the other images (A, B, and C), although the averaged values of the polarization degree and angle are different for the different images. Microlensing of a broad line region model including a compact outflowing component can qualitatively explain the CIV blue wing enhancement (and variation) in component A. However, to confirmed this hypothesis, we need additional spectroscopic observation in future.
We present an analysis of polarimetric observations of standard stars performed over the period of more than three years with the RINGO3 polarimeter mounted on the Liverpool Telescope. The main objective was to determine the instrumental polarisation of the RINGO3 polarimeter in three spectral energy ranges: blue (350--640~nm), green (650--760~nm) and red (770--1000~nm). The observations were conducted between 2012 and 2016. The total time span of 1126 days was split into five epochs due to the hardware changes to the observing system. Our results should be applied to calibrate all polarimetric observations performed with the RINGO3 polarimeter.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا