J/A+A/633/A101 SDSS J081830.46+060138.0 spectropolarimetry (Hutsemekers+, 2020)
Spatially separated continuum sources revealed by microlensing in the
gravitationally lensed broad absorption line quasar SDSS J081830.46+060138.0.
Hutsemekers D., Sluse D., Kumar P.
<Astron. Astrophys. 633, A101 (2020)>
=2020A&A...633A.101H 2020A&A...633A.101H (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Polarization ; Gravitational lensing
Keywords: gravitational lensing: micro - quasars: general -
quasars: absorption lines
Abstract:
Gravitational microlensing is a powerful tool for probing the inner
structure of distant quasars. In this context, we have obtained
spectropolarimetric observations of the two images of the broad
absorption line (BAL) quasar SDSS J081830.46+060138.0 (J0818+0601) at
redshift z≈2.35. We first show that J0818+0601 is actually
gravitationally lensed, and not a binary quasar. A strong absorption
system detected at z=1.0065±0.0002 is possibly due to the lensing
galaxy. Microlensing is observed in one image and it magnifies the
emission lines, the continuum, and the BALs differently. By
disentangling the part of the spectrum that is microlensed from the
part that is not microlensed, we unveil two sources of continuum that
must be spatially separated: a compact one, which is microlensed, and
an extended one, which is not microlensed and contributes to two
thirds of the total continuum emission. J0818+0601 is the second BAL
quasar in which an extended source of rest-frame ultraviolet continuum
is found. We also find that the images are differently polarized,
suggesting that the two continua might be differently polarized. Our
analysis provides constraints on the BAL flow. In particular, we find
that the outflow is seen with a nonzero onset velocity, and stratified
according to ionization.
Description:
This Table contains the spectropolarimetric data obtained for images A
and B of the gravitationally lensed quasar SDSS J081830.46+060138 on
December 24 and 25, 2017, with FORS2 at the ESO VLT.
Objects:
----------------------------------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------------------------------
08 18 30.47 +06 01 38.1 SDSS J081830.46+060138.0 = SDSS J081830.46+060138.0
----------------------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
spectra.dat 105 3600 Spectropolarimetric data
--------------------------------------------------------------------------------
See also:
J/A+A/332/410 : Quasar polarization (Hutsemekers 1998)
J/A+A/340/371 : Quasar polarization (Hutsemekers+ 1998)
J/A+AS/142/451 : Optical Polarization of 47 QSOs (Lamy+, 2000)
J/A+A/427/107 : Polarization in BAL QSOs (Lamy+, 2004)
J/A+A/433/757 : Optical polarization of 203 QSOs (Sluse+, 2005)
J/A+A/606/A101 : Polarization of quasars (Hutsemekers+, 2017)
J/A+A/620/A68 : Polarization of quasars (Hutsemekers+, 2018)
Byte-by-byte Description of file: spectra.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 E15.7 0.1nm lambda Wavelength
16- 30 E15.7 --- FA Flux density for image A (1)
31- 45 E15.7 --- QA Normalized Stokes Q for image A
46- 60 E15.7 --- UA Normalized Stokes U for image A
61- 75 E15.7 --- FB Flux density for image B (1)
76- 90 E15.7 --- QB Normalized Stokes Q for image B
91-105 E15.7 --- UB Normalized Stokes U for image B
--------------------------------------------------------------------------------
Note (1): The fluxes FA and FB are not corrected for the instrumental response
and given in arbitrary units
--------------------------------------------------------------------------------
Acknowledgements:
Damien Hutsemekers, D.Hutsemekers(at)uliege.be
(End) Patricia Vannier [CDS] 09-Dec-2019