Gas Metallicity in the Narrow-Line Regions of High-Redshift Active Galactic Nuclei

We analyze optical (UV rest-frame) spectra of X-ray selected narrow-line QSOs at redshift 1.5 < z < 3.7 found in the Chandra Deep Field South and of narrow-line radio galaxies at redshift 1.2 < z < 3.8 to investigate the gas metallicity of the narrow-line regions and their evolution in this redshift range. Such spectra are also compared with UV spectra of local Seyfert 2 galaxies. The observational data are inconsistent with the predictions of shock models, suggesting that the narrow-line regions are mainly photoionized. The photoionization models with dust grains predict line flux ratios which are also in disagreement with most of the observed values, suggesting that the high-ionization part of the narrow-line regions (which is sampled by the available spectra) is dust-free. The photoionization dust-free models provide two possible scenarios which are consistent with the observed data: low-density gas clouds (n < 10^3 cm^-3) with a sub-solar metallicity (0.2 < Z/Z_sun < 1.0), or high-density gas clouds (n ~ 10^5 cm^-3) with a wide range of gas metallicity (0.2 < Z/Z_sun < 5.0). Regardless of the specific interpretation, the observational data do not show any evidence for a significant evolution of the gas metallicity in the narrow-line regions within the redshift range 1.2 < z < 3.8. Instead, we find a trend for more luminous active galactic nuclei to have more metal-rich gas clouds (luminosity-metallicity relation), which is in agreement with the same finding in the studies of the broad-line regions. The lack of evolution for the gas metallicity of the narrow-line regions implies that the major epoch of star formation in the host galaxies of these active galactic nuclei is at z > 4.Comment: 16 pages, 12 figures, submitted to Astronomy and Astrophysic

ANDES, the high resolution spectrograph for the European Extremely Large Telescope

I will describe ANDES (ArmazoNes high Dispersion Echelle Spectrograph) the optical-infrared High Resolution Spectrograph of the ELT, formerly known as ELT-HIRES, which has started construction activities in 2022 to arrive at the telescope as early as 2031. The project is carried out by an international consortium composed of 33 institutes from 13 countries. The top science cases will be the detection of life signatures from exoplanet atmospheres, tests on the stability of Nature’s fundamental couplings, the direct detection of the cosmic acceleration, the characterization of astrophysical plasmas from the atmospheres of cool stars to the integalactic medium. Many of these science cases require that the instrument is capable of reaching challenging levels of precision and accuracy. I will present an overview of the project, describing science cases and the baseline design. The baseline design, which allows to fulfil the top science cases, consists of a modular fibre-fed cross-dispersed echelle spectrograph providing a simultaneous range of 0.4-1.8 µm with a goal of 0.35-2.4 µm, at a resolution of 100,000 and with several observing modes. The spectrograph will be equipped with both seeing- and diffraction-limited observing modes, the latter being characterised by a unique high resolution IFU, capable of a simultaneous wavelength coverage of 1-1.8 µm. Finally, I will conclude by discussing the challenges in spectral fidelity that ANDES will have to face

The Relation between Black Hole Mass, Bulge Mass, and Near-Infrared Luminosity

We present new accurate near-infrared (NIR) spheroid (bulge) structural parameters obtained by two-dimensional image analysis for all galaxies with a direct black hole (BH) mass determination. As expected, NIR bulge luminosities Lbul and BH masses are tightly correlated, and if we consider only those galaxies with secure BH mass measurement and accurate Lbul (27 objects), the spread of MBH-Lbul is similar to MBH-sigma, where sigma is the effective stellar velocity dispersion. We find an intrinsic rms scatter of ~0.3 dex in log MBH. By combining the bulge effective radii R_e measured in our analysis with sigma, we find a tight linear correlation (rms ~ 0.25 dex) between MBH and the virial bulge mass (propto R_e sigma^2), with ~ 0.002. A partial correlation analysis shows that MBH depends on both sigma and R_e, and that both variables are necessary to drive the correlations between MBH and other bulge properties.Comment: Astrophysical Journal Letters, in pres

The Distance to NGC 5904 (M 5) via the Subdwarfs Main Sequence Fitting Method

We present a determination of the distance modulus of the globular cluster NGC 5904 (M 5), obtained by means of the subdwarf main-sequence fitting on the (V,V-I) color-magnitude diagram. The subdwarf sample has been selected from the HIPPARCOS catalog in a metallicity range homogeneous with the cluster ([Fe/H] \~= -1.1). Both the cluster and the subdwarfs have been observed with the same telescope+instrument+filters setup (namely, ESO-NTT equipped with the SUSI2 camera), in order to preserve homogeneity and reduce systematic uncertainties. A set of archival HST data has then been used to obtain a deep and precise ridge line. These have been accurately calibrated in the ground photometric system by using the NTT data and used to fit the cluster distance modulus. By adopting the most commonly accepted values for the reddening, E(B-V) = 0.035 and 0.03, we obtain respectively mu_0 = 14.44 +- 0.09 +- 0.07 and mu_0 = 14.41 +- 0.09 +- 0.07, in agreement with recent determinations.Comment: 11 pages, 14 figures, accepted for publication in Astronomy and Astrophysic

How Special Are Brightest Cluster Galaxies? The Impact of Near-Infrared Luminosities on Scaling Relations for BCGs

Using the extended J, H and K magnitudes provided by the 2MASS data archive, we consider the position of brightest cluster galaxies (BCGs) in the observed relations between inferred supermassive black hole (SMBH) mass and the host galaxy properties, as well as their position in the stellar velocity dispersion and luminosity ( ∗ − L) relation, compared to E and S0 galaxies. We find that SMBH masses (M•) derived from near-infrared (NIR) magnitudes do not exceed 3×109M⊙ and that these masses agree well with the predictions made from ∗. In the NIR, there is no evidence that BCGs leave the ∗ − L relation defined by less luminous galaxies. The higher SMBH masses predicted from V-band luminosities (M• . 1010.5M⊙) are attributed to the presence of extended envelopes around the BCGs, however, this will need to be confirmed using deeper multiwavelength imaging

Designing an Evaluation System for Climate Change Mitigation Policies using GPT-4

In the realm of addressing global warming, the development and implementation of effective policies play a pivotal role. Given the vast amount of legislative documents generated annually, it becomes imperative to have a system in place that can efficiently analyze these documents to identify measures aimed at climate change mitigation. This article outlines the design of an innovative system that employs GPT-4, a state-of-the-art language model developed by OpenAI, to evaluate climate change policy. The proposed system is designed to ingest legislative documents as input and utilize GPT-4 to identify, categorize, and evaluate the policies within these documents that are related to climate change mitigation efforts. The system would be capable of processing a wide range of document formats and languages, thanks to GPT-4's multimodal and multilingual capabilities