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We present our numerical simulation approach for the End-to-End (E2E) model applied to various astronomical spectrographs, such as SOXS (ESO-NTT), CUBES (ESO-VLT), and ANDES (ESO-ELT), covering multiple wavelength regions. The E2E model aim at simulating the expected astronomical observations starting from the radiation of the scientific sources (or calibration sources) up to the raw-frame data produced by the detectors. The comprehensive description includes E2E architecture, computational models, and tools for rendering the simulated frames. Collaboration with Data Reduction Software (DRS) teams is discussed, along with efforts to meet instrument requirements. The contribution to the cross-correlation algorithm for the Active Flexure Compensation (AFC) system of CUBES is detailed., Comment: 19 pages, 17 figures, SPIE Astronomical Telescopes + Instrumentation, Yokohama 2024. arXiv admin note: text overlap with arXiv:2209.07185, arXiv:2012.12684

The first generation of ELT instruments includes an optical-infrared high-resolution spectrograph, indicated as ELT-HIRES and recently christened ANDES (ArmazoNes high Dispersion Echelle Spectrograph). ANDES consists of three fibre-fed spectrographs ([U]BV, RIZ, YJH) providing a spectral resolution of $\sim$100,000 with a minimum simultaneous wavelength coverage of 0.4-1.8 $\mu$m with the goal of extending it to 0.35-2.4 $\mu$m with the addition of a U arm to the BV spectrograph and a separate K band spectrograph. It operates both in seeing- and diffraction-limited conditions and the fibre feeding allows several, interchangeable observing modes including a single conjugated adaptive optics module and a small diffraction-limited integral field unit in the NIR. Modularity and fibre-feeding allow ANDES to be placed partly on the ELT Nasmyth platform and partly in the Coud\'e room. ANDES has a wide range of groundbreaking science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Among the top science cases, there are the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars, tests on the stability of Nature's fundamental couplings, and the direct detection of the cosmic acceleration. The ANDES project is carried forward by a large international consortium, composed of 35 Institutes from 13 countries, forming a team of almost 300 scientists and engineers which include the majority of the scientific and technical expertise in the field that can be found in ESO member states., Comment: SPIE astronomical telescope and instrumentation 2024, in press

Despite recent progress in the spectroscopic characterization of individual exoplanets, the atmospheres of key ultra-hot Jupiters (UHJs) still lack comprehensive investigations. These include WASP-178b, one of the most irradiated UHJs known to date. We observed the dayside emission signal of this planet with CRIRES$^+$ in the spectral K-band. By applying the cross-correlation technique and a Bayesian retrieval framework to the high-resolution spectra, we identified the emission signature of $^{12}$CO (S/N = 8.9) and H$_2$O (S/N = 4.9), and a strong atmospheric thermal inversion. A joint retrieval with space-based secondary eclipse measurements from TESS and CHEOPS allows us to refine our results on the thermal profile and thus to constrain the atmospheric chemistry, yielding a solar to super-solar metallicity (1.4$\pm$1.6 dex) and a solar C/O ratio (0.6$\pm$0.2). We infer a significant excess of spectral line broadening and identify a slight Doppler-shift between the $^{12}$CO and H$_2$O signals. These findings provide strong evidence for a super-rotating atmospheric flow pattern and suggest the possible existence of chemical inhomogeneities across the planetary dayside hemisphere. In addition, the inclusion of photometric data in our retrieval allows us to account for stellar light reflected by the planetary atmosphere, resulting in an upper limit on the geometric albedo (0.23). The successful characterization of WASP-178b's atmosphere through a joint analysis of CRIRES$^+$, TESS, and CHEOPS observations highlights the potential of combined studies with space- and ground-based instruments and represents a promising avenue for advancing our understanding of exoplanet atmospheres., Comment: Accepted for publication in A&A

We aim to characterise the small-scale magnetic fields for a sample of 16 Sun-like stars and investigate the capabilities of the newly upgraded near-infrared (NIR) instrument CRIRES$^+$ at the VLT in the context of small-scale magnetic field studies. Our targets also had their magnetic fields studied in the optical, which allows us to compare magnetic field properties at different spatial scales on the stellar surface and to contrast small-scale magnetic field measurements at different wavelengths. We analyse the Zeeman broadening signature for six magnetically sensitive and insensitive \ion{Fe}{I} lines in the H-band to measure small-scale magnetic fields on the stellar surface. We use polarised radiative transfer modelling and NLTE departure coefficients in combination with MCMC to determine magnetic field characteristics together with non-magnetic stellar parameters. We use two different approaches to describe small-scale magnetic fields. The first is a two-component model with a single magnetic region and a free magnetic field strength. The second model contains multiple magnetic components with fixed magnetic field strengths. We find average magnetic field strengths ranging from $\sim 0.4$ kG down to $<0.1$ kG. The results align closely with other results from high resolution NIR spectrographs such as SPIRou. We find that the small-scale fields correlate with the large-scale fields and that the small-scale fields are at least 10 times stronger than the large-scale fields inferred with Zeeman Doppler imaging. The two- and multi-component models produce systematically different results as the strong fields from the multi-component model increase the obtained mean magnetic field strength. When comparing our results with the optical measurements of small-scale fields we find a systematic offset of 2--3 times stronger fields in the optical., Comment: 28 pages, 23 figures, accepted by A&A

The dayside atmospheres of ultra-hot Jupiters (UHJs) are predicted to possess temperature inversion layers with extremely high temperatures at high altitudes. We observed the dayside thermal emission spectra of WASP-18b and WASP-76b with the new CRIRES+ high-resolution spectrograph at near-infrared wavelengths. Using the cross-correlation technique, we detected strong CO emission lines in both planets, which confirms the existence of temperature inversions on their dayside hemispheres. The two planets are the first UHJs orbiting F-type stars with CO emission lines detected; previous detections were mostly for UHJs orbiting A-type stars. Evidence of weak H2O emission signals is also found for both planets. We further applied forward-model retrievals on the detected CO lines and retrieved the temperature-pressure profiles along with the CO volume mixing ratios. The retrieved logarithmic CO mixing ratio of WASP-18b (-2.2) is slightly higher than the value predicted by the self-consistent model assuming solar abundance. For WASP-76b, the retrieved CO mixing ratio (-3.6) is broadly consistent with the value of solar abundance. In addition, we included the equatorial rotation velocity (Veq ) in the retrieval when analyzing the line profile broadening. The obtained Veq is 7.0 km/s for WASP-18b and 5.2 km/s for WASP-76b, which are consistent with the tidally locked rotational velocities., Comment: 11 pages, 12 figures; accepted for publication in A&A

The CRyogenic InfraRed Echelle Spectrograph (CRIRES) Upgrade project CRIRES$^{+}$ extended the capabilities of CRIRES. It transformed this VLT instrument into a cross-dispersed spectrograph to increase the wavelength range that is covered simultaneously by up to a factor of ten. In addition, a new detector focal plane array of three Hawaii 2RG detectors with a 5.3 $\mu$m cutoff wavelength replaced the existing detectors. Amongst many other improvements, a new spectropolarimetric unit was added and the calibration system has been enhanced. The instrument was installed at the VLT on Unit Telescope 3 at the beginning of 2020 and successfully commissioned and verified for science operations during 2021, partly remotely from Europe due to the COVID-19 pandemic. The instrument was subsequently offered to the community from October 2021 onwards. This article describes the performance and capabilities of the upgraded instrument and presents on sky results., Comment: Accepted for publication in Astronomy and Astrophysics

Simulations of frames from existing and upcoming high-resolution spectrographs, targeted for high accuracy radial velocity measurements, are computationally demanding (both in time and space). We present in this paper an innovative approach based on both parallelization and distribution of the workload. By using NVIDIA CUDA custom-made kernels and state-of-the-art cloud-computing architectures in a Platform as a Service (PaaS) approach, we implemented a modular and scalable end-to-end simulator that is able to render synthetic frames with an accuracy of the order of few cm/sec, while keeping the computational time low. We applied our approach to two spectrographs. For VLT-ESPRESSO we give a sound comparison between the actual data and the simulations showing the obtained spectral formats and the recovered instrumental profile. We also simulate data for the upcoming HIRES at the ELT and investigate the overall performance in terms of computational time and scalability against the size of the problem. In addition we demonstrate the interface with data-reduction systems and we preliminary show that the data can be reduced successfully by existing methods., Comment: Accepted for publication in Experimental Astronomy

CRIRES, the ESO high resolution infrared spectrometer, is a unique instrument which allows astronomers to access a parameter space which up to now was largely uncharted. In its current setup, it consists of a single-order spectrograph providing long-slit, single-order spectroscopy with resolving power up to R=100,000 over a quite narrow spectral range. This has resulted in sub-optimal efficiency and use of telescope time for all the scientific programs requiring broad spectral coverage of compact objects (e.g. chemical abundances of stars and intergalactic medium, search and characterization of extra-solar planets). To overcome these limitations, a consortium was set-up for upgrading CRIRES to a cross-dispersed spectrometer, called CRIRES+. This paper presents the updated optical design of the crossdispersion module for CRIRES+. This new module can be mounted in place of the current pre-disperser unit. The new system yields a factor of >10 increase in simultaneous spectral coverage and maintains a quite long slit (10"), ideal for observations of extended sources and for precise sky-background subtraction., Comment: 14 pages, 9 figures, 22 tables. Presented at SPIE Astronomical Telescope + Instrumentation 2014 (Ground-based and Airbone Instrumentation for Astronomy 5, 9147-289). To be published in Proceeding of SPIE Volume 9147

In this article we present the integral field spectroscopy (IFS) wiki site, http://ifs.wikidot.com; what the wiki is, our motivation for creating it, and a short introduction to IFS. The IFS wiki is designed to be a central repository of information, tips, codes, tools, references, etc., regarding the whole subject of IFS, which is accessible and editable by the whole community. Currently the wiki contains a broad base of information covering topics from current and future integral field spectrographs, to observing, to data reduction and analysis techniques. We encourage everyone who wants to know more about IFS to look at this web-site, and any question you may have you can post from there. And if you have had any experience with IFS yourself, we encourage you to contribute your knowledge and help the site develop its full potential. Before re-inventing the wheel, consult the wiki..., Comment: This article accompanies the opening of the IFS wiki site http://ifs.wikidot.com

We study the two-dimensional distribution and kinematics of the stellar and gaseous components in the centre of the blue compact dwarf galaxy, He 2-10. The aim is to compare the kinematics of gas and stars in order to determine whether they are consistent with one another, or if stars and gas can be decoupled due to gravitational perturbations and feedback from star formation. We have used the integral field unit ARGUS, part of FLAMES on the European Southern Observatory's Very Large Telescope, to target the near-infrared Ca-triplet in the central 300 times 480 parsecs of He 2-10. The selected wavelength regime includes several prominent spectral features, including the Paschen series and an [SIII] emission-line, which we have used to derive the kinematics of the ionised interstellar medium. We find no systematic trend in the velocities of the stars over the observed field of view and conclude that the stellar kinematics is governed by random motions. This is in contrast to the motions the ionised interstellar medium, where we find spatial velocity variations up to 60 km/s. Our gas velocity field is consistent with previous studies of both the molecular gas and the feedback-driven outflow in He 2-10. We interpret the kinematic decoupling between the stars and the gas as He 2-10 being in the process of transformation to a dwarf elliptical galaxy., Comment: 4 pages, 3 figures, accepted for publication in A&A Letters, resubmitted with minor revisions

Luminous Compact Galaxies are enigmatic sources by many aspects. They can reach the luminosity of the Milky Way within a radius of only a few kpc. They also represent one of the most rapidly evolving populations of galaxies since they represent up to 1/5 of the luminous galaxies at redshift z= 0.7 while being almost absent in the local Universe. The measurement of their dynamics is crucial to our understanding of LCGs since this has the potential of telling us which physical process(es) that drives them, and ultimately to link them to the existing present-day galaxies. Here we derive the 3 dimensional velocity fields and velocity dispersion (sigma) maps of 17 Luminous Compact Galaxies selected from the Canada France Redshift Survey and the Hubble Deep Field South with redshifts ranging from z=0.4 to z=0.75. We find that only 18% of them show rotational velocity fields typical of rotating disks, the others showing more complex kinematics. Assuming that LCGs are not too far from equilibrium, about half of LCGs then appear to be either non-relaxed objects, or objects that are not supported by velocity dispersion alone. This supports the view that an important fraction of LCGs are probably mergers. It brings additional support to the ``spiral rebuilding scenario'' in which LCGs correspond to a previous or post-merger phase before the disk re-building., Comment: (1) GEPI, Obs. Meudon, France (2) Stockholm Observatory, Sweden (3)Dept. of Astronomy and Space Physics, Sweden. ;. See also the ESO press release http://www.eso.org/outreach/press-rel/pr-2006/pr-10-06.html. To appear in A&A

We present BVI photometry and long-slit Halpha rotation curve data obtained with ESO VLT/FORS2 for six low surface brightness galaxies with extremely blue colours and very faint central regions. We find no evidence for a steep central density cusp of the type predicted by many N-body simulations of cold dark matter (CDM) halos. Our observations are instead consistent with dark matter halos characterized by cores of roughly constant density, in agreement with previous investigations. While unremarkable in terms of the central density slope, these galaxies appear very challenging for existing CDM halo models in terms of average central halo density, as measured by the Delta_(V/2) parameter. Since most of our target galaxies are bulgeless disks, our observations also disfavour a recently suggested mechanism for lowering the central mass concentration of the halo by means of a fast collapse phase, as this scenario predicts that the original CDM profile should still be detectable in bulgeless galaxies. Other potential ways of reconciling the CDM predictions with these observations are discussed., Comment: 14 pages, 9 figures, accepted for publication in Astronomy & Astrophysics

We have studied the afterglow of the gamma-ray burst (GRB) of February 18, 2006. This is a nearby long GRB, with a very low peak energy, and is therefore classified as an X-ray Flash (XRF). XRF 060218 is clearly associated with a supernova -- dubbed SN 2006aj. We present early spectra for SN 2006aj as well as optical lightcurves reaching out to 50 days past explosion. Our optical lightcurves define the rise times, the lightcurve shapes and the absolute magnitudes in the U, V and R bands, and we compare these data with data for other relevant supernovae. SN 2006aj evolved quite fast, somewhat similarly to SN 2002ap, but not as fast as SN 1994I. Our spectra show the evolution of the supernova over the peak, when the U-band portion of the spectrum rapidly fades due to extensive line blanketing. We compare to similar spectra of very energetic Type Ic supernovae. Our first spectra are earlier than spectra for any other GRB-SN. The spectrum taken 12 days after burst in the rest frame is similar to somewhat later spectra of both SN 1998bw and SN 2003dh, implying a rapid early evolution. This is consistent with the fast lightcurve. From the narrow emission lines from the host galaxy we derive a redshift of z=0.0331+-0.0007. This makes XRF 060218 the second closest gamma-ray burst detected. The flux of these emission lines indicate a high-excitation state, and a modest metallicity and star formation rate of the host galaxy., Comment: Accepted by A&A. Replaced with revised version. More observations added

Optical/near-IR broadband photometry of the halos of blue compact galaxies (BCGs) have revealed a very red spectral energy distribution, which cannot easily be reconciled with any normal, metal-poor stellar population. Here, three possible explanations for the red excess are explored: nebular emission, metal-rich stars and a stellar population with a very bottom-heavy initial mass function (IMF). We find, that nebular emission in BCG halos would produce very blue near-IR colours, and hence fails to explain the observed red excess. Although metal-rich stars may in principle explain the colours observed, the required stellar metallicity is very high (solar or higher), which would be a curious halo property given the low gas metallicity (~10% solar) of the central starburst in these objects. A stellar population with a low to intermediate metallicity and a very bottom-heavy IMF does however adequately reproduce the observed BCG halo colours. A bottom-heavy IMF also proves successful in explaining a similar red excess observed in the halos of stacked edge-on disk galaxies from the Sloan Digital Sky Survey. This may indicate that halos dominated by low-mass stars is a phenomenon common to galaxies of very different Hubble types., Comment: 6 pages, 4 figures, proceedings of the conference "Starbursts: From 30 Doradus to Lyman Break Galaxies", held in Cambridge, UK, September 6-10, 2004