Extremely Large Telescope

Abstract:

ABSTRACT We present uniformly reprocessed and re-calibrated data from the RoboPol programme of optopolarimetric monitoring of active galactic nuclei (AGNs), covering observations between 2013, when the instrument was commissioned, and 2017. In total, the data set presented in this paper includes 5068 observations of 222 AGN with Dec. > −25○. We describe the current version of the RoboPol pipeline that was used to process and calibrate the entire data set, and we make the data publicly available for use by the astronomical community. Average quantities summarizing optopolarimetric behaviour (average degree of polarization, polarization variability index) are also provided for each source we have observed and for the time interval we have followed it.

Abstract:

Population III (Pop. III) stars, as of yet, have not been detected, however as we move into the era of extremely large telescopes this is likely to change. One likely tracer for Pop. III stars is the He IIλ1640 emission line, which will be detectable by the HARMONI spectrograph on the European Extremely Large Telescope (ELT) over a broad range of redshifts (2 ≤ z ≤ 14). By post-processing galaxies from the cosmological, AMR-hydrodynamical simulation NEWHORIZON with theoretical spectral energy distributions (SED) for Pop. III stars and radiative transfer (i.e. the Yggdrasil Models and CLOUDY look-up tables, respectively) we are able to compute the flux of He IIλ1640 for individual galaxies. From mock 10 h observations of these galaxies we show that HARMONI will be able to detect Pop. III stars in galaxies up to z ∼ 10 provided Pop. III stars have a top heavy initial mass function (IMF). Furthermore, we find that should Pop. III stars instead have an IMF similar to those of the Pop. I stars, the He IIλ1640 line would only be observable for galaxies with Pop. III stellar masses in excess of 107M⊙⁠, average stellar age <1Myr at z = 4. Finally, we are able to determine the minimal intrinsic flux required for HARMONI to detect Pop. III stars in a galaxy up to z = 10.

Abstract:

The Sloan Digital Sky Survey IV Mapping Nearby Galaxies at APO (MaNGA) program has been operating from 2014 to 2020, and has now observed a sample of 9269 galaxies in the low redshift universe (z ∼ 0.05) with integral-field spectroscopy. With rest-optical (λλ0.36–1.0 μm) spectral resolution R ∼ 2000 the instrumental spectral line-spread function (LSF) typically has 1σ width of about 70 km s⁻¹, which poses a challenge for the study of the typically 20–30 km s⁻¹ velocity dispersion of the ionized gas in present-day disk galaxies. In this contribution, we present a major revision of the MaNGA data pipeline architecture, focusing particularly on a variety of factors impacting the effective LSF (e.g., under-sampling, spectral rectification, and data cube construction). Through comparison with external assessments of the MaNGA data provided by substantially higher-resolution R ∼ 10,000 instruments, we demonstrate that the revised MPL-10 pipeline measures the instrumental LSF sufficiently accurately (≤0.6% systematic, 2% random around the wavelength of Hα) that it enables reliable measurements of astrophysical velocity dispersions σ_Hα ∼ 20 km s⁻¹ for spaxels with emission lines detected at signal-to-noise ratio > 50. Velocity dispersions derived from [O II], Hβ, [O III], [N II], and [S II] are consistent with those derived from Hα to within about 2% at σ_Hα > 30 km s⁻¹. Although the impact of these changes to the estimated LSF will be minimal at velocity dispersions greater than about 100 km s⁻¹, scientific results from previous data releases that are based on dispersions far below the instrumental resolution should be reevaluated.