POLLUX: a UV spectropolarimeter for the LUVOIR space telescope project

Muslimov, Eduard; Bouret, Jean-Claude; Neiner, C.; Ariste, A. López; Fabert, Marc; Vivès, S.; Hugot, Emmanuel; Grange, Robert; Lombardo, Simona; Lopes, Louise; Costeraste, J.; Brachet, Frank

doi:10.1117/12.2310133

Cited by 11 publications

(8 citation statements)

References 13 publications

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“…Future work using the existing facility will include additional spectropolarimic observations of distant quasars focusing on C III] and C IV emission lines. Current limitations will be largely surpassed with a next-generation instrument POLLUX (Muslimov et al 2018) that will be aboard the mission LUVOIR (Large UV/Optical/IR Surveyor, The LUVOIR Team 2019).…”

Section: Discussionmentioning

confidence: 99%

Estimating supermassive black hole masses in active galactic nuclei using polarization of broad Mg ii, H α, and H β lines

Savić

Shablovinskaya

Afanasiev

2020

Monthly Notices of the Royal Astronomical Society

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For type-1 active galactic nuclei (AGNs) for which the equatorial scattering is the dominant broad line polarization mechanism, it is possible to measure the supermassive black hole mass by tracing the Keplerian motion across the polarization plane position angle ϕ. So far this method has been used for 30 objects but only for Hα emission line. We explore the possibilities this method for determining SMBH masses using polarization in broad emission lines by applying it for the first time to Mg II λ2798 Åspectral line. We use 3D Monte Carlo radiative transfer code stokes for simultaneous modeling of equatorial scattering of Hα, Hβ and Mg II lines. We included vertical inflows and outflows in the Mg II broad line region (BLR). We find that polarization states of Hα and Hβ lines are almost identical and SMBH mass estimates differ by 7%. For Mg II line, we find that ϕ exhibits an additional “plateau” with a constant ϕ, which deviates than the profiles expected for pure Keplerian motion. SMBH mass estimates using Mg II line are higher by up to 35% than those obtained from Hα and Hβ lines. Our model shows that for vertical inflows and outflows in the BLR that is higher or comparable to Keplerian velocity, this method can be applied as a first approximation for obtaining SMBH mass.

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Section: Discussionmentioning

confidence: 99%

Estimating supermassive black hole masses in active galactic nuclei using polarization of broad Mg ii, H α, and H β lines

Savić

Shablovinskaya

Afanasiev

2020

Monthly Notices of the Royal Astronomical Society

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“…This 5 will facilitate the detection of additional weak high order He I absorption lines. The identification of new He I absorbers should be considered a key goal for the future UV space-based observatories 31 that are on the horizon. He I absorbers will be easier to identify along sightlines 32 to quasars in the redshift interval 1.5 z qso 2.0, where the contamination due to unrelated absorption near the high order H I and He I absorption lines is considerably less compared with high redshift quasars.…”

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confidence: 99%

Measurement of the primordial helium abundance from the intergalactic medium

Cooke

Fumagalli

2018

Nat Astron

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Almost every helium atom in the Universe was created just a few minutes after the Big Bang through a process commonly referred to as Big Bang Nucleosynthesis 1, 2 .The amount of helium that was made during Big Bang Nucleosynthesis is determined by the combination of particle physics and cosmology 3 . The current leading measures of the primordial helium abundance (Y P ) are based on the relative strengths of H I and He I emission lines emanating from star-forming regions in local metal-poor galaxies 4-7 . As the statistical errors on these measurements improve, it is essential to test for systematics by developing independent techniques. Here we report the first determination of the primordial helium abundance based on a near-pristine intergalactic gas cloud that is seen in absorption against the light of a background quasar. This gas cloud, observed when the Universe was just one-third of its present age (z abs = 1.724), has a metal content ∼ 100 times less than the Sun, and 30% less metals than the most metal-poor H II region currently known where a determination of the primordial helium abundance is afforded. We conclude that the helium abundance of this intergalactic gas cloud is Y = 0.250 +0.033 −0.025 , which agrees with the Standard Model primordial value 8-10 , Y P = 0.24672 ± 0.00017. Our determination 1 arXiv:1810.06561v1 [astro-ph.CO]

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“…The target spectral resolving power of the instrument is 120 000 in the ex- Figure 6. More details about the design can be found in [25] and [24].…”

Section: Optical Designmentioning

confidence: 99%

“…The initial design version [25] suffered from a low diffraction efficiency, since the recording source coordinates were optimized only accounting for the grating aberrations. It compelled us to re-optimize the entire design including deviation from the Bragg condition as a part of the merit function.…”

Section: Diffraction Efficiency Analysismentioning

confidence: 99%

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Design and modeling of spectrographs with holographic gratings on freeform surfaces

et al. 2018

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In the present paper we demonstrate the approach of using a holographic grating on a freeform surface for advanced spectrographs design. We discuss the surface and groove pattern description used for ray-tracing. Moreover, we present a general procedure of diffraction efficiency calculation, which accounts for the change of hologram recording and operation conditions across the surface. The primary application of this approach is the optical design of the POLLUX spectropolarimeter for the LUVOR mission project where a freeform holographic grating operates simultaneously as a cross-disperser and a camera with high resolution and high dispersion. The medium ultraviolet channel design of POLLUX is considered in detail as an example. Its resolving power reaches [126,000] in the region of 118.5-195 nm. Also, we show a possibility to use a similar element working in transmission to build an unobscured double-Schmidt spectrograph. The spectral resolving power reaches 4000 in the region 350-550 nm and remains stable along the slit.

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POLLUX: a UV spectropolarimeter for the LUVOIR space telescope project

Cited by 11 publications

References 13 publications

Estimating supermassive black hole masses in active galactic nuclei using polarization of broad Mg ii, H α, and H β lines

Estimating supermassive black hole masses in active galactic nuclei using polarization of broad Mg ii, H α, and H β lines

Measurement of the primordial helium abundance from the intergalactic medium

Design and modeling of spectrographs with holographic gratings on freeform surfaces

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