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See detailPolarization of changing-look quasars
Hutsemekers, Damien ULiege; Agis-Gonzalez, Beatriz ULiege; Marin, F. et al

in Astronomy and Astrophysics (2019), 625

If the disappearance of the broad emission lines observed in changing- look quasars originates from the obscuration of the quasar core by dusty clouds moving in the torus, high linear optical polarization ... [more ▼]

If the disappearance of the broad emission lines observed in changing- look quasars originates from the obscuration of the quasar core by dusty clouds moving in the torus, high linear optical polarization would be expected in those objects. We then measured the rest-frame UV-blue linear polarization of a sample of 13 changing-look quasars, 7 of them being in a type 1.9-2 state. For all quasars but one the polarization degree is lower than 1%. This suggests that the disappearance of the broad emission lines cannot be attributed to dust obscuration, and supports the scenario in which changes of look are caused by a change in the rate of accretion onto the supermassive black hole. Such low polarization degrees also indicate that these quasars are seen under inclinations close to the system axis. One type 1.9-2 quasar in our sample shows a high polarization degree of 6.8%. While this polarization could be ascribed to obscuration by a moving dusty cloud, we argue that this is unlikely given the very long time needed for a cloud from the torus to eclipse the broad emission line region of that object. We propose that the high polarization is due to the echo of a past bright phase seen in polar-scattered light. This interpretation raises the possibility that broad emission lines observed in the polarized light of some type 2 active galactic nuclei can be echoes of past type 1 phases and not evidence of hidden broad emission line regions. Based on observations made with the William Herschel telescope operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias and observations made with ESO Very Large Telescope at the Paranal Observatory under program ID 101.B-0209. [less ▲]

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See detailQuasar Microlensing: Revolutionizing our Understanding of Quasar Structure and Dynamics
Moustakas, Leonidas; O'Dowd, Matthew; Anguita, Timo et al

in arXiv e-prints (2019)

Microlensing by stars within distant galaxies acting as strong gravitational lenses of multiply-imaged quasars, provides a unique and direct measurement of the internal structure of the lensed quasar on ... [more ▼]

Microlensing by stars within distant galaxies acting as strong gravitational lenses of multiply-imaged quasars, provides a unique and direct measurement of the internal structure of the lensed quasar on nano-arcsecond scales. The measurement relies on the temporal variation of high-magnification caustic crossings which vary on timescales of days to years. Multiwavelength observations provide information from distinct emission regions in the quasar. Through monitoring of these strong gravitational lenses, a full tomographic view can emerge with Astronomical-Unit scale resolution. Work to date has demonstrated the potential of this technique in about a dozen systems. In the 2020s there will be orders of magnitude more systems to work with. Monitoring of lens systems for caustic-crossing events to enable triggering of multi- platform, multi-wavelength observations in the 2020s will fulfill the potential of quasar microlensing as a unique and comprehensive probe of active black hole structure and dynamics. [less ▲]

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See detailH0LiCOW - IX. Cosmographic analysis of the doubly imaged quasar SDSS 1206+4332 and a new measurement of the Hubble constant
Birrer, S.; Treu, T.; Rusu, C. E. et al

in Monthly Notices of the Royal Astronomical Society (2019), 484

We present a blind time-delay strong lensing (TDSL) cosmographic analysis of the doubly imaged quasar SDSS 1206+4332 . We combine the relative time delay between the quasar images, Hubble Space Telescope ... [more ▼]

We present a blind time-delay strong lensing (TDSL) cosmographic analysis of the doubly imaged quasar SDSS 1206+4332 . We combine the relative time delay between the quasar images, Hubble Space Telescope imaging, the Keck stellar velocity dispersion of the lensing galaxy, and wide-field photometric and spectroscopic data of the field to constrain two angular diameter distance relations. The combined analysis is performed by forward modelling the individual data sets through a Bayesian hierarchical framework, and it is kept blind until the very end to prevent experimenter bias. After unblinding, the inferred distances imply a Hubble constant H[SUB]0[/SUB] = 68.8^{+5.4}_{-5.1} km s[SUP]-1[/SUP] Mpc[SUP]-1[/SUP], assuming a flat Λ cold dark matter cosmology with uniform prior on Ω[SUB]m[/SUB] in [0.05, 0.5]. The precision of our cosmographic measurement with the doubly imaged quasar SDSS 1206+4332 is comparable with those of quadruply imaged quasars and opens the path to perform on selected doubles the same analysis as anticipated for quads. Our analysis is based on a completely independent lensing code than our previous three H0LiCOW systems and the new measurement is fully consistent with those. We provide the analysis scripts paired with the publicly available software to facilitate independent analysis (footnote with link to www.h0licow.org). The consistency between blind measurements with independent codes provides an important sanity check on lens modelling systematics. By combining the likelihoods of the four systems under the same prior, we obtain H[SUB]0[/SUB] = 72.5^{+2.1}_{-2.3} km s[SUP]-1[/SUP] Mpc[SUP]-1[/SUP]. This measurement is independent of the distance ladder and other cosmological probes. [less ▲]

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See detailThe role of Active Galactic Nuclei in galaxy evolution: insights from space ultraviolet spectropolarimetry
Marin, F.; Charlot, S.; Agis-Gonzalez, Beatriz ULiege et al

in arXiv e-prints (2019)

This Astro2020 white paper summarizes the unknowns of active galactic nuclei (AGN) physics that could be unveiled thanks to a new, space-born, ultraviolet spectropolarimeter. The unique capabilities of ... [more ▼]

This Astro2020 white paper summarizes the unknowns of active galactic nuclei (AGN) physics that could be unveiled thanks to a new, space-born, ultraviolet spectropolarimeter. The unique capabilities of high energy polarimetry would help us to understand the precise mechanisms of matter and energy transfer and supermassive black holes growth, together with the impact of AGN feedback on galaxy evolution. [less ▲]

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See detailLarge-field optical monitoring of gravitationally lensed systems: an opportunity for spin-off projects
Sluse, Dominique ULiege

Scientific conference (2019, February 04)

Invitation to propose spin-off science cases for observations to be carried out with the VST at the Paranal observatory over the next 2 years.

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See detaillnsight on quasar changing-look physics from optical polarimetry
Hutsemekers, Damien ULiege; Agis-Gonzalez, Beatriz ULiege; Sluse, Dominique ULiege et al

Conference (2018, December 11)

A handful of quasars changing from type 1 (strong broad and narrow emission lines) to type 1.9 (strong narrow lines only and dim continuum) on timescales of a few years have been recently uncovered. If ... [more ▼]

A handful of quasars changing from type 1 (strong broad and narrow emission lines) to type 1.9 (strong narrow lines only and dim continuum) on timescales of a few years have been recently uncovered. If the disappearance of the broad emission lines observed in changing-look quasars were caused by the obscuration of the quasar core through moving dust clouds in the torus, high linear polarization typical of type 2 quasars would be expected. We measured the polarization of the changing-look quasar J1011+5442 in which the broad emission lines have disappeared between 2003 and 2015. We found a polarization degree compatible with null polarization. This measurement suggests that the observed change of look is not due to a change of obscuration in a torus hiding the continuum source and the broad line region. Our results thus support the idea that the vanishing of the broad emission lines in J1011+5442 is due to an intrinsic dimming of the ionizing continuum source that is most likely caused by a rapid decrease in the rate of accretion onto the supermassive black hole. New polarization measurements have been secured for a sample of changing-look quasars. They essentially confirm our previous results. [less ▲]

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See detailTRUE2: unveiling the nature of true Seyfert 2 candidates through optical polarimetry
Agis-Gonzalez, Beatriz ULiege; Hutsemekers, Damien ULiege; Acosta Pulido, Jose et al

Poster (2018, December 10)

The so-called true Seyfert 2 candidates [1] are Seyferts galaxies whose optical spectra do not show broad lines. Yet, in the X-ray domain, they exhibit some characteristic behavior of Seyferts 1 such as ... [more ▼]

The so-called true Seyfert 2 candidates [1] are Seyferts galaxies whose optical spectra do not show broad lines. Yet, in the X-ray domain, they exhibit some characteristic behavior of Seyferts 1 such as lack of X-ray obscuration and/or short timescale variability. A true Seyfert 2 candidate will be confirmed as a true Seyfert 2 galaxy if the lack of the broad line region (BLR) emission is not only observational but physical. Since the BLR is hidden behind the circumnuclear, optically-thick, dusty torus, only polar-scattered light can probe the presence or absence of the BLR. Hence, scattering-induced polarization is the only way to probe the existence of hidden-BLRs (HBLR). [less ▲]

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See detailProbing the structure and evolution of active galactic nuclei with the ultraviolet polarimeter POLLUX aboard LUVOIR
Marin, F.; Charlot, S.; Hutsemekers, Damien ULiege et al

in SF2A-2018: Proceedings of the Annual meeting of the French Society of Astronomy and Astrophysics (2018, December 01)

The ultraviolet (UV) polarization spectrum of nearby active galactic nuclei (AGN) is poorly known. The Wisconsin Ultraviolet Photo-Polarimeter Experiment and a handful of instruments on board the Hubble ... [more ▼]

The ultraviolet (UV) polarization spectrum of nearby active galactic nuclei (AGN) is poorly known. The Wisconsin Ultraviolet Photo-Polarimeter Experiment and a handful of instruments on board the Hubble Space Telescope were able to probe the near- and mid-UV polarization of nearby AGN, but the far-UV band (from 1200 Å down to the Lyman limit at 912 Å) remains completely uncharted. In addition, the linewidth resolution of previous observations was at best 1.89 Å. Such a resolution is not sufficient to probe in detail quantum mechanical effects, synchrotron and cyclotron processes, scattering by electrons and dust grains, and dichroic extinction by asymmetric dust grains. Exploring those physical processes would require a new, high-resolution, broadband polarimeter with full ultraviolet-band coverage. In this context, we discuss the AGN science case for POLLUX, a high-resolution UV spectropolarimeter, proposed for the 15-meter primary mirror option of LUVOIR (a multi-wavelength space observatory concept being developed by the Goddard Space Flight Center and proposed for the 2020 Decadal Survey Concept Study). [less ▲]

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See detailMetrology of solar spectral irradiance at the top of the atmosphere in the near infrared measured at Mauna Loa Observatory: the PYR-ILIOS campaign
Pereira, Nuno; Bolsée, David; Sperfeld, Peter et al

in Atmospheric Measurement Techniques (2018), 11

The near-infrared (NIR) part of the solar spectrum is of prime importance for solar physics and climatology, directly intervening in the Earth's radiation budget. Despite its major role, available solar ... [more ▼]

The near-infrared (NIR) part of the solar spectrum is of prime importance for solar physics and climatology, directly intervening in the Earth's radiation budget. Despite its major role, available solar spectral irradiance (SSI) NIR datasets, space-borne or ground-based, present discrepancies caused by instrumental or methodological reasons. We present new results obtained from the PYR-ILIOS SSI NIR ground-based campaign, which is a replication of the previous IRSPERAD campaign which took place in 2011 at the Izaña Atmospheric Observatory (IZO). We used the same instrument and primary calibration source of spectral irradiance. A new site was chosen for PYR-ILIOS: the Mauna Loa Observatory (MLO) in Hawaii (3397 m a.s.l.), approximately 1000 m higher than IZO. Relatively to IRSPERAD, the methodology of monitoring the traceability to the primary calibration source was improved. The results as well as a detailed error budget are presented. We demonstrate that the most recent results, from PYR-ILIOS and other space-borne and ground-based experiments, show an NIR SSI lower than the previous reference spectrum, ATLAS3, for wavelengths above 1.6 µm. [less ▲]

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See detailConstraining the microlensing effect on time delays with a new time-delay prediction model in H0 measurements
Chen, Geoff C.-F.; Chan, James H. H.; Bonvin, Vivien et al

in Monthly Notices of the Royal Astronomical Society (2018), 481

Time-delay strong lensing provides a unique way to directly measure the Hubble constant (H0). The precision of the H0measurement depends on the uncertainties in the time-delay measurements, the mass ... [more ▼]

Time-delay strong lensing provides a unique way to directly measure the Hubble constant (H0). The precision of the H0measurement depends on the uncertainties in the time-delay measurements, the mass distribution of the main deflector(s), and the mass distribution along the line of sight. Tie & Kochanek have proposed a new microlensing effect on time delays based on differential magnification of the coherent accretion disc variability of the lensed quasar. If real, this effect could significantly broaden the uncertainty on the time-delay measurements by up to 30 per cent for lens systems such as PG 1115+080, which have relatively short time delays and monitoring over several different epochs. In this paper we develop a new technique that uses the cosmological time-delay ratios and simulated microlensing maps within a Bayesian framework in order to limit the allowed combinations of microlensing delays and thus to lessen the uncertainties due to the proposed effect. We show that, under the assumption of Tie & Kochanek, the uncertainty on the time-delay distance (D∆t, which is proportional to 1/H0) of the short time-delay (18 d) lens, PG 1115+080, increases from 7 per cent to ̃10 per cent by simultaneously fitting the three time-delay measurements from the three different data sets across 20 yr, while in the case of the long time-delay (̃90 d) lens, the microlensing effect on time delays is negligible as the uncertainty on D[SUB]∆t[/SUB] of RXJ 1131-1231 only increases from ̃2.5 per cent to 2.6 per cent. [less ▲]

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See detailOptical linear polarization measurements of quasars obtained with the Very Large Telescope at Paranal Observatory⋆
Hutsemekers, Damien ULiege; Borguet, B.; Sluse, Dominique ULiege et al

in Astronomy and Astrophysics (2018), 620

We report 87 previously unpublished optical linear polarization measurements of 86 quasars obtained in May and October 2008, and from April to July 2015 with the FOcal Reducer and low-dispersion ... [more ▼]

We report 87 previously unpublished optical linear polarization measurements of 86 quasars obtained in May and October 2008, and from April to July 2015 with the FOcal Reducer and low-dispersion Spectrographs FORS1 and FORS2 attached to the Very Large Telescope at the Paranal Observatory. Of the 86 quasars, 37 have p ≥ 0.6%, 9 have p ≥ 2%, and 1 has p ≥ 10%. Based on observations made with the ESO VLT at the Paranal Observatory under programme ID 081.A-0023, 082.B-0029, 095.A-0600.Full Table 3 is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A> (<A href="http://ftp://130.79.128.5">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/620/A68">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/620/A68</A> [less ▲]

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See detailVizieR Online Data Catalog: Polarization of quasars (Hutsemekers+, 2018)
Hutsemekers, Damien ULiege; Borguet, B.; Sluse, Dominique ULiege et al

Textual, factual or bibliographical database (2018)

This Table contains optical linear polarization measurements of 86 quasars obtained in May 2008, October 2008, and from April to July 2015 with the Focal Reducer and low dispersion Spectrographs FORS1 and ... [more ▼]

This Table contains optical linear polarization measurements of 86 quasars obtained in May 2008, October 2008, and from April to July 2015 with the Focal Reducer and low dispersion Spectrographs FORS1 and FORS2 attached to the Very Large Telescope at the Paranal Observatory. (1 data file). [less ▲]

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See detailThe New SCIAMACHY Reference Solar Spectral Irradiance and Its Validation
Hilbig, T.; Weber, M.; Bramstedt, K. et al

in Solar Physics (2018), 293

This paper describes a new reference solar spectrum retrieved from measurements of the satellite instrument SCIAMACHY in the wavelength region from 0.24 μm to 2.4 μm and its comparison with several other ... [more ▼]

This paper describes a new reference solar spectrum retrieved from measurements of the satellite instrument SCIAMACHY in the wavelength region from 0.24 μm to 2.4 μm and its comparison with several other established solar reference spectra. The SCIAMACHY reference spectrum was recorded early in the mission before substantial optical degradation due to the harsh space environment sets in. The radiometric calibration of SCIAMACHY, applied in this study, includes a physical model of the scanner unit. Furthermore, SCIAMACHY's internal white light source (WLS) is used to correct for on-ground to in-flight changes. The resultant calibrated solar spectrum from SCIAMACHY is in good agreement with several available solar spectral irradiance (SSI) references in the visible spectral range. Strong throughput losses due to detector icing in the near infrared (NIR) are now adequately accounted for. Nevertheless, a deficit with respect to the ATLAS-3 composite and SORCE/SIM SSI is observed in the NIR. However, the SCIAMACHY solar reference spectrum agrees well with the recently re-evaluated SOLAR/SOLSPEC-ISS and recent ground measurements taken at Mauna Loa in the NIR. [less ▲]

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See detailH0LiCOW VIII. A weak-lensing measurement of the external convergence in the field of the lensed quasar HE 0435-1223
Tihhonova, O.; Courbin, F.; Harvey, D. et al

in Monthly Notices of the Royal Astronomical Society (2018), 477

We present a weak gravitational lensing measurement of the external convergence along the line of sight to the quadruply lensed quasar HE 0435-1223. Using deep r-band images from Subaru Suprime Cam, we ... [more ▼]

We present a weak gravitational lensing measurement of the external convergence along the line of sight to the quadruply lensed quasar HE 0435-1223. Using deep r-band images from Subaru Suprime Cam, we observe galaxies down to a 3σ limiting magnitude of ˜26 mag resulting in a source galaxy density of 14 galaxies per square arcminute after redshift-based cuts. Using an inpainting technique and multiscale entropy filtering algorithm, we find that the region in close proximity to the lens has an estimated external convergence of κ =-0.012^{+0.020}_{-0.013} and is hence marginally underdense. We also rule out the presence of any halo with a mass greater than M[SUB]vir[/SUB] = 1.6 × 10[SUP]14[/SUP]h[SUP]-1[/SUP]M[SUB]⊙[/SUB] (68 per cent confidence limit). Our results, consistent with previous studies of this lens, confirm that the intervening mass along the line of sight to HE 0435-1223 does not affect significantly the cosmological results inferred from the time-delay measurements of that specific object. [less ▲]

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See detailALMA view of RX J1131-1231: Sub-kpc CO (2-1) mapping of a molecular disk in a lensed star-forming quasar host galaxy
Paraficz, D.; Rybak, M.; McKean, J. P. et al

in Astronomy and Astrophysics (2018), 613

We present ALMA 2-mm continuum and CO (2-1) spectral line imaging of the gravitationally lensed z = 0.654 star-forming/quasar composite RX J1131-1231 at 240-400 mas angular resolution. The continuum ... [more ▼]

We present ALMA 2-mm continuum and CO (2-1) spectral line imaging of the gravitationally lensed z = 0.654 star-forming/quasar composite RX J1131-1231 at 240-400 mas angular resolution. The continuum emission is found to be compact and coincident with the optical emission, whereas the molecular gas forms a complete Einstein ring, which shows strong differential magnification. The de-lensed source structure is determined on 400-parsec-scales resolution using a Bayesian pixelated visibility-fitting lens modelling technique. The reconstructed molecular gas velocity-field is consistent with a large rotating disk with a major-axis FWHM 9.4 kpc at an inclination angle of i = 54° and with a maximum rotational velocity of 280 km s[SUP]-1[/SUP]. From dynamical model fitting we find an enclosed mass within 5 kpc of M(r < 5 kpc) = (1.46 ± 0.31) × 10[SUP]11[/SUP] M[SUB]⊙[/SUB]. The molecular gas distribution is highly structured, with clumps that are co-incident with higher gas velocity dispersion regions (40-50 km s[SUP]-1[/SUP]) and with the intensity peaks in the optical emission, which are associated with sites of on-going turbulent star-formation. The peak in the CO (2-1) distribution is not co-incident with the AGN, where there is a paucity of molecular gas emission, possibly due to radiative feedback from the central engine. The intrinsic molecular gas luminosity is L'[SUB]CO[/SUB] = 1.2 ± 0.3 × 10[SUP]10[/SUP] K km s[SUP]-1[/SUP] pc[SUP]2[/SUP] and the inferred gas mass is M[SUB]H[SUB]2[/SUB][/SUB] = 8.3 ± 3.0 × 10[SUP]10[/SUP] M[SUB]⊙[/SUB], which given the dynamical mass of the system is consistent with a CO-H[SUB]2[/SUB] conversion factor of α = 5.5 ± 2.0 M[SUB]⊙[/SUB] (K km s[SUP]-1[/SUP] pc[SUP]2[/SUP])[SUP]-1[/SUP]. This suggests that the star-formation efficiency is dependent on the host galaxy morphology as opposed to the nature of the AGN. The far-infrared continuum spectral energy distribution shows evidence for heated dust, equivalent to an obscured star-formation rate of SFR = 69[SUB]-25[/SUB][SUP]+41[/SUP] × (7.3/μ[SUB]IR[/SUB]) M[SUB]⊙[/SUB] yr[SUP]-1[/SUP], which demonstrates the composite star-forming and AGN nature of this system. [less ▲]

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See detailOptical polarimetry within the changing-look AGN scenario
Agis-Gonzalez, Beatriz ULiege; Hutsemekers, Damien ULiege; Sluse, Dominique ULiege et al

Conference (2018, April 03)

Changing-look AGN are a extraordinary type of AGN which represents a violation of the AGN unified model. Studying this class of objects in polarized light helps us to shade light on the sub-parsec AGN ... [more ▼]

Changing-look AGN are a extraordinary type of AGN which represents a violation of the AGN unified model. Studying this class of objects in polarized light helps us to shade light on the sub-parsec AGN structure and find out which additional ingredients are needed so that the unified model can describe the complex AGN taxonomy. We carried out a detailed analysis of multi-epoch observations of the Seyfert galaxy ESO 362-G18 in X- ray, UV and optical ranges. In total, 45 X-ray observations and 4 optical data sets, 2 of them in polarized light, ranging from January 2003 till March 2016. The four optical analyzed spectra reveal ESO362-G18 as a changing-look Seyfert galaxy, since two spectra are of type 1.5 and the remaining two show ESO362-G18 as a type 1.9 AGN. We have polarized measurements of one of the type 1.5 data sets and also one of the type 1.9, allowing us to compare the polarization properties in both states of a changing-look Seyfert galaxy by first time. From the X-ray data set, we found ESO362-G18 to exhibit relativistic reflection, including a detected soft time lag between continuum and reflection components, whose results support the compact nature of the X-ray emitting regions. We proved a very rapidly spinning Kerr back hole and a very high inclination of ~53o(in two ways, dependent and independent model; see Agís-González et al 2014). Thanks to this derived model, we have also detected two absorption events driven by clouds situated at torus scales. The relatively high inclination we derived is consistent with the idea that our LOS is grazing the obscuring torus (which has a typical half-opening angle of the order of 45o). If the torus is not homogeneous but clumpy, such high inclination may intercept from time to time some of the clumps of the obscuring torus, explaining the detected X-ray absorption events and possibly why ESO362-G18 exhibits changes of look from type 1 to type 2 in its optical spectra. Moreover, the X-ray luminosity keeps roughly constant along the available observation, which discard a change in the accretion rate. Therefore, we will discuss the polarized properties of this intriguing changing-look Seyfert galaxy whose change of look is probably due to absorption in our LOS. At the same time, we will also expose optical polarimetry as a diagnostic tool to disentangle the cause of changes of look. [less ▲]

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See detailSOLAR-ISS: A new reference spectrum based on SOLAR/SOLSPEC observations
Meftah, M.; Damé, L.; Bolsée, D. et al

in Astronomy and Astrophysics (2018), 611

Context. Since April 5, 2008 and up to February 15, 2017, the SOLar SPECtrometer (SOLSPEC) instrument of the SOLAR payload on board the International Space Station (ISS) has performed accurate ... [more ▼]

Context. Since April 5, 2008 and up to February 15, 2017, the SOLar SPECtrometer (SOLSPEC) instrument of the SOLAR payload on board the International Space Station (ISS) has performed accurate measurements of solar spectral irradiance (SSI) from the middle ultraviolet to the infrared (165 to 3088 nm). These measurements are of primary importance for a better understanding of solar physics and the impact of solar variability on climate. In particular, a new reference solar spectrum (SOLAR-ISS) is established in April 2008 during the solar minima of cycles 23-24 thanks to revised engineering corrections, improved calibrations, and advanced procedures to account for thermal and aging corrections of the SOLAR/SOLSPEC instrument. <BR /> Aims: The main objective of this article is to present a new high-resolution solar spectrum with a mean absolute uncertainty of 1.26% at 1σ from 165 to 3000 nm. This solar spectrum is based on solar observations of the SOLAR/SOLSPEC space-based instrument. <BR /> Methods: The SOLAR/SOLSPEC instrument consists of three separate double monochromators that use concave holographic gratings to cover the middle ultraviolet (UV), visible (VIS), and infrared (IR) domains. Our best ultraviolet, visible, and infrared spectra are merged into a single absolute solar spectrum covering the 165-3000 nm domain. The resulting solar spectrum has a spectral resolution varying between 0.6 and 9.5 nm in the 165-3000 nm wavelength range. We build a new solar reference spectrum (SOLAR-ISS) by constraining existing high-resolution spectra to SOLAR/SOLSPEC observed spectrum. For that purpose, we account for the difference of resolution between the two spectra using the SOLAR/SOLSPEC instrumental slit functions. <BR /> Results: Using SOLAR/SOLSPEC data, a new solar spectrum covering the 165-3000 nm wavelength range is built and is representative of the 2008 solar minimum. It has a resolution better than 0.1 nm below 1000 nm and 1 nm in the 1000-3000 nm wavelength range. The new solar spectrum (SOLAR-ISS) highlights significant differences with previous solar reference spectra and with solar spectra based on models. The integral of the SOLAR-ISS solar spectrum yields a total solar irradiance of 1372.3 ± 16.9 Wm[SUP]-2[/SUP] at 1σ, that is yet 11 Wm[SUP]-2[/SUP] over the value recommended by the International Astronomical Union in 2015. The spectrum shown in Fig. B.1 is available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://cdsarc.u-strasbg.fr">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/611/A1">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/611/A1</A> [less ▲]

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See detailH0LiCOW VII: cosmic evolution of the correlation between black hole mass and host galaxy luminosity
Ding, Xuheng; Treu, Tommaso; Suyu, Sherry H. et al

in Monthly Notices of the Royal Astronomical Society (2017), 472

Strongly lensed active galactic nuclei (AGN) provide a unique opportunity to make progress in the study of the evolution of the correlation between the mass of supermassive black holes (M_BH) and their ... [more ▼]

Strongly lensed active galactic nuclei (AGN) provide a unique opportunity to make progress in the study of the evolution of the correlation between the mass of supermassive black holes (M_BH) and their host galaxy luminosity (L[SUB]host[/SUB]). We demonstrate the power of lensing by analysing two systems for which state-of-the-art lens modelling techniques have been applied to deep Hubble Space Telescope imaging data. We use (i) the reconstructed images to infer the total and bulge luminosity of the host and (ii) published broad-line spectroscopy to estimate M_BH using the so-called virial method. We then enlarge our sample with new calibration of previously published measurements to study the evolution of the correlation out to z ˜ 4.5. Consistent with previous work, we find that without taking into account passive luminosity evolution, the data points lie on the local relation. Once the passive luminosity evolution is taken into account, we find that black holes in the more distant Universe reside in less luminous galaxies than today. Fitting this offset as M_BH/L[SUB]host[/SUB] ∝ (1 + z)[SUP]γ[/SUP], and taking into account selection effects, we obtain γ = 0.6 ± 0.1 and 0.8 ± 0.1 for the case of M_BH-L[SUB]bulge[/SUB] and M_BH-L[SUB]total[/SUB], respectively. To test for systematic uncertainties and selection effects we also consider a reduced sample that is homogeneous in data quality. We find consistent results but with considerably larger uncertainty due to the more limited sample size and redshift coverage (γ = 0.7 ± 0.4 and 0.2 ± 0.5 for M_BH-L[SUB]bulge[/SUB] and M_BH-L[SUB]total[/SUB], respectively), highlighting the need to gather more high-quality data for high-redshift lensed quasar hosts. Our result is consistent with a scenario where the growth of the black hole predates that of the host galaxy. [less ▲]

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See detailConstraining the geometry and kinematics of the quasar broad emission line region using gravitational microlensing. I. Models and simulations
Braibant, Lorraine ULiege; Hutsemekers, Damien ULiege; Sluse, Dominique ULiege et al

in Astronomy and Astrophysics (2017), 607

Recent studies have shown that line profile distortions are commonly observed in gravitationally lensed quasar spectra. Often attributed to microlensing differential magnification, line profile ... [more ▼]

Recent studies have shown that line profile distortions are commonly observed in gravitationally lensed quasar spectra. Often attributed to microlensing differential magnification, line profile distortions can provide information on the geometry and kinematics of the broad emission line region (BLR) in quasars. We investigate the effect of gravitational microlensing on quasar broad emission line profiles and their underlying continuum, combining the emission from simple representative BLR models with generic microlensing magnification maps. Specifically, we considered Keplerian disk, polar, and equatorial wind BLR models of various sizes. The effect of microlensing has been quantified with four observables: μ[SUP]BLR[/SUP], the total magnification of the broad emission line; μ[SUP]cont[/SUP], the magnification of the underlying continuum; as well as red/blue, RBI and wings/core, WCI, indices that characterize the line profile distortions. The simulations showed that distortions of line profiles, such as those recently observed in lensed quasars, can indeed be reproduced and attributed to the differential effect of microlensing on spatially separated regions of the BLR. While the magnification of the emission line μ[SUP]BLR[/SUP] sets an upper limit on the BLR size and, similarly, the magnification of the continuum μ[SUP]cont[/SUP] sets an upper limit on the size of the continuum source, the line profile distortions mainly depend on the BLR geometry and kinematics. We thus built (WCI,RBI) diagrams that can serve as diagnostic diagrams to discriminate between the various BLR models on the basis of quantitative measurements. It appears that a strong microlensing effect puts important constraints on the size of the BLR and on its distance to the high-magnification caustic. In that case, BLR models with different geometries and kinematics are more prone to produce distinctive line profile distortions for a limited number of caustic configurations, which facilitates their discrimination. When the microlensing effect is weak, there is a larger overlap between the characteristics of the line profile distortions produced by the different models, and constraints can only be derived on a statistical basis. [less ▲]

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See detailH0LiCOW - II. Spectroscopic survey and galaxy-group identification of the strong gravitational lens system HE 0435-1223
Sluse, Dominique ULiege; Sonnenfeld, A.; Rumbaugh, N. et al

in Monthly Notices of the Royal Astronomical Society (2017), 470

Galaxies located in the environment or along the line of sight towards gravitational lenses can significantly affect lensing observables, and can lead to systematic errors on the measurement of H[SUB]0 ... [more ▼]

Galaxies located in the environment or along the line of sight towards gravitational lenses can significantly affect lensing observables, and can lead to systematic errors on the measurement of H[SUB]0[/SUB] from the time-delay technique. We present the results of a systematic spectroscopic identification of the galaxies in the field of view of the lensed quasar HE 0435-1223 using the W. M. Keck, Gemini and ESO-Very Large telescopes. Our new catalogue triples the number of known galaxy redshifts in the direct vicinity of the lens, expanding to 102 the number of measured redshifts for galaxies separated by less than 3 arcmin from the lens. We complement our catalogue with literature data to gather redshifts up to 15 arcmin from the lens, and search for galaxy groups or clusters projected towards HE 0435-1223. We confirm that the lens is a member of a small group that includes at least 12 galaxies, and find 8 other group candidates near the line of sight of the lens. The flexion shift, namely the shift of lensed images produced by high-order perturbation of the lens potential, is calculated for each galaxy/group and used to identify which objects produce the largest perturbation of the lens potential. This analysis demonstrates that (i) at most three of the five brightest galaxies projected within 12 arcsec of the lens need to be explicitly used in the lens models, and (ii) the groups can be treated in the lens model as an external tidal field (shear) contribution. [less ▲]

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