Maria Santos-Lleo

Context. PG 0043+039 has been identified as an extremely X-ray-weak quasar and as a peculiar broad-absorption-line quasar (BALQ) based on UV HST spectra. Aims. This study aims to investigate the spectral properties and their variation in PG 0043+039 in more detail. Methods. We took simultaneous deep X-ray observations of PG 0043+039 with XMM-Newton & NuSTAR, UV spectra with the HST, and optical spectra with the HET telescope in 2022. Results. PG 0043+039 was an extreme low-X-ray-luminosity quasar in 2022. This AGN showed an extreme steep α _ox value of −2.47. These values are similar to those measured in 2005. The X-ray luminosity was a factor of 3.4 higher in the meantime in 2013. The optical and UV continuum only decreased by a factor of 1.3–1.5 from 2013 to 2022. Very strong emission-line intensity variations by factors of eight or more were observed in the O VI λ 1038 and Si IV λ 1403 lines between 2013 and 2022. The other UV emission lines such as Ly α only decreased by a factor of 1.4. The optical emission lines showed only minor intensity variations. We derive black hole masses of M = 6.95 × 10 ⁸ M _⊙ (based on H β ) and M = 3.53 × 10 ⁸ M _⊙ (based on Mg II λ 2800). This corresponds to Eddington ratios of L / L _edd = 0.115 (H β ) and 0.157 (Mg II λ 2800). PG 0043+039 exhibits strong and broad absorption lines in the UV. The highly ionized absorption lines show the largest velocity blueshifts in their broad absorption lines (BALs). Lower ionized BALs have smaller blueshifts. The P V absorption is very strong, with equivalent widths of 7–10 Å. PG 0043+039 shows strong Ly α emission despite strong P V absorption. PG 0043+039 is the only source with strong Ly α in the sample of strong P V absorbers. All the strong absorption-line troughs in the UV varied in unison in velocity space back and forward (−2000. ± 300. km s ⁻¹ , +2740. ± 200. km s ⁻¹ ) without any major changes in absorption strength or in their profiles for the years 1991, 2013, and 2022. We found no general correlations of X-ray/opt/UV continuum variations with the broad absorption line variations. However, based on the simultaneous UV and X-ray observations – taken in 2013 and 2022 – we see higher maximum velocities of the blueshifted broad absorption lines in the UV when the X-ray flux was lower.

XMM‐Newton is an ESA space x‐ray observatory launched on 11 December 1999, and after 25 years, a study is presented demonstrating that the data of the mission are efficiently used by an engaged and productive community. The total number of refereed papers published between 2000 and 2024 is 8486. These papers have a total of 15,627 different authors, including 3292 unique first authors. The total available science time during this period amounts to 556 Ms (16,894 observations) 87% of which (84% of observations) have been used in at least one refereed publication, excluding primary catalogue papers. Accounting for multiple use, the observation time has been over‐used by a factor of up to 15 in dedicated publications and even a factor of up to 30 when including a small fraction of papers classified as survey/catalogue. The speed with which observations are published for the first time peaks around 2 years and is thus longer than the proprietary period for Guest–Observer (GO) observations. A strong secondary peak at 3 years suggests that data not published by the proposing teams are picked up by the community, then also taking about 2 years to be published. The publication rate remains stable at refereed articles per year with a small increase in recent years, owed to an increased use of primary XMM‐Newton catalogues. 95% of articles focus on specific data using observations while 99% of articles use less than 239 observations. Since 2010, the annual number of first‐time authors has remained relatively constant, equalling the number of last‐time authors. This implies that the number of scientists engaged in research utilising XMM‐Newton data has remained constant at 4300, of whom 570 are lead (first) authors. A histogram of the activity period demonstrates that 51% of first authors publish for only 1 year, 24% of first authors are active for up to 6 years, and 25% were active for more than 6 years. We further identify a highly productive core community of approximately 120 scientists publishing an XMM‐Newton article at least every 2 year as first authors. When all authors are considered, the figures are 40%, 25% and 35%, respectively. The considerable number of time‐limited activities may reflect a high level of utilisation during the early stages of a research career, from Master's studies through the PhD and initial postdoctoral years. The trends assessed indicate a vital community with positive perspectives and a continued, active interest in XMM‐Newton for the future.

Context.NGC 1566 is a local face-on Seyfert galaxy and is known for exhibiting recurrent outbursts that are accompanied by changes in spectral type. The most recent transient event occurred from 2017 to 2019 and was reported to be accompanied by a change in Seyfert classification from Seyfert 1.8 to Seyfert 1.2.Aims.We aim to study the transient event in detail by analyzing the variations in the optical broad-line profiles. In particular, we intend to determine the structure and kinematics of the broad-line region.Methods.We analyzed data from an optical spectroscopic variability campaign of NGC 1566 taken with the 9.2 m Southern African Large Telescope (SALT) between July 2018 and October 2019 triggered by the detection of hard X-ray emission in June 2018. We supplemented this data set with optical to near-infrared (NIR) spectroscopic archival data taken by VLT/MUSE in September 2015 and October 2017, and investigated the emission from different line species during the event.Results.NGC 1566 exhibits pronounced spectral changes during the transient event. We observe the emergence and fading of a strong power-law-like blue continuum as well as strong variations in the Balmer, He I, and He IIlines and the coronal lines [Fe VII], [Fe X], and [Fe XI]. Moreover, we detect broad double-peaked emission line profiles of O Iλ8446 and the Ca IIλλ8498, 8542, 8662 triplet. This is the first time that genuine double-peaked O Iλ8446 and Ca IIλλ8498, 8542, 8662 emission in AGN is reported in the literature. All broad lines show a clear redward asymmetry with respect to their central wavelength and we find indications for a significant blueward drift of the total line profiles during the transient event. The profiles and the FWHM of the Balmer lines remain largely constant during all observations. We show that the double-peaked emission line profiles are well approximated by emission from a low-inclination, relativistic eccentric accretion disk, and that single-peaked profiles can be obtained by broadening due to scale-height-dependent turbulence. Small-scale features in the O Iand Ca IIlines suggest the presence of inhomogeneities in the broad-line region.Conclusions.We conclude that the broad-line region in NGC 1566 is dominated by the kinematics of a relativistic eccentric accretion disk. The broad-line region can be modeled to be vertically stratified with respect to scale-height turbulence with O Iand Ca IIbeing emitted close to the disk in a region with high (column) density, while the Balmer and helium lines are emitted at greater scale height above the disk. The observed blueward drift might be attributed to a low-optical-depth wind launched during the transient event. Except for this wind, the observed kinematics of the broad-line region remain largely unchanged during the transient event.

The field of artificial intelligence based image enhancement has been rapidly evolving over the last few years and is able to produce impressive results on non-astronomical images. In this work we present the first application of Machine Learning based super-resolution (SR) and de-noising (DN) to enhance X-ray images from the European Space Agency’s XMM-Newton telescope. Using XMM-Newton images in band [0.5,2] keV from the European Photon Imaging Camera pn detector (EPIC-pn), we develop XMM-SuperRes and XMM-DeNoise — deep learning-based models that can generate enhanced SR and DN images from real observations. The models are trained on realistic XMM-Newton simulations such that XMM-SuperRes will output images with two times smaller point-spread function and with improved noise characteristics. The XMM-DeNoise model is trained to produce images with 2.5× the input exposure time from 20 to 50 ks. When tested on real images, DN improves the image quality by |$8.2{{\%}}$|⁠, as quantified by the global peak-signal-to-noise ratio. These enhanced images allow identification of features that are otherwise hard or impossible to perceive in the original or in filtered/smoothed images with traditional methods. We demonstrate the feasibility of using our deep learning models to enhance XMM-Newton X-ray images to increase their scientific value in a way that could benefit the legacy of the XMM-Newton archive.

The Chandra X-ray Observatory (Chandra) and the X-ray Multi-Mirror Mission (XMM-Newton) continue to expand the frontiers of knowledge about high-energy processes in the Universe. These groundbreaking observatories lead an X-ray astronomy revolution: revealing the physical processes and extreme conditions involved in producing cosmic X-rays in objects ranging in size from a few kilometres (comets) to millions of light years (clusters of galaxies), and particle densities ranging over 20 orders of magnitude. In probing matter under conditions far outside those accessible from Earth, they have a central role in the quest to understand our place in the Universe and the fundamental laws that govern our existence. Chandra and XMM-Newton are also part of a larger picture wherein advances in subarcsecond imaging and high-resolution spectroscopy across a wide range of wavelengths combine to provide a more complete picture of the phenomena under investigation. As these missions mature, deeper observations and larger samples further expand our knowledge, and new phenomena and collaborations with new facilities forge exciting, often unexpected discoveries. This Review provides the highlights of a wide range of studies, including auroral activity on Jupiter, cosmic-ray acceleration in supernova remnants, colliding neutron stars, missing baryons in low-density hot plasma, and supermassive black holes formed less than a billion years after the Big Bang.

Star formation accretion on to the super massive black holes (SMBHs) and feedback processes link the evolution of galaxies with their SMBHs. X-ray observations in the imaging and spectral regime have revealed to be an important tool to study the connection between nuclear activity and circumnuclear star formation in nearby active galactic nuclei (AGN). X-ray spectral diagnostics can lead to disentangle, which is the ionization mechanism in the central kiloparsecs of nearby AGN. In this paper, we investigate, by means of XMM-Newton observations, the nuclear X-ray emission of the changing-look AGN NGC 1566 during its quiescent state. European Photon Imaging Camera (EPIC) soft X-ray images show an extended arm-like morphology. A detailed analysis of the high-resolution Reflection Grating Spectrometer (RGS) and medium resolution EPIC spectra shows that the material concentrated in the central kiloparsecs region is not in the photoionization-dominated regime while the presence of collisionally ionized plasma is needed to explain the observed spectral features. In the inner region (∼1.5 kpc), the brightness of the collisionally ionized gas is comparable to the brightness of the photoionized gas: the inner region hosts a luminous starburst whose ionized gas shows up bright in the X-rays when the AGN is in quiescence.

We present a detailed analysis of XMM-Newton X-ray spectra of the Narrow-Line Seyfert 1 galaxy Mrk 1044. We find robust evidence for a multiphase, ultrafast outflow, traced by four separate components in the grating spectrum. One component has high column density and ionization state, and is outflowing at ∼0.15c. The other three wind components have lower temperature, lower column density, and have outflow velocities ∼0.08c. This wind structure is strikingly similar to that found in IRAS 17020+4544, suggesting that stratified winds may be a common feature of ultrafast outflows. Such structure is likely produced by fluid instabilities that form when the nuclear wind shocks the ambient medium. We show that, in an energy-driven wind scenario, the wind in Mrk 1044 might carry enough energy to produce significant feedback on its host galaxy. We further discuss the implications of the presence of a fast wind in yet another NLS1 galaxy with high Eddington ratio.

We present joint NuSTAR and XMM–Newton observations of the bright, variable quasar IRAS 13349+2438. This combined data set shows two clear iron absorption lines at 8 and 9 keV, which are most likely associated with two layers of mildly relativistic blueshifted absorption, with velocities of ∼0.14c and ∼0.27c. We also find strong evidence for a series of Ly α absorption lines at intermediate energies in a stacked XMM–Newton EPIC-pn spectrum, at the same blueshift as the lower velocity iron feature. This is consistent with a scenario where an outflowing wind is radially stratified, so faster, higher ionization material is observed closer to the black hole, and cooler, slower material is seen from streamlines at larger radii.

We present joint XMM-Newton and NuSTAR observations of the ‘bare’ narrow line Seyfert 1 Ton S180 (z = 0.062), carried out in 2016 and providing the first hard X-ray view of this luminous galaxy. We find that the 0.4–30 keV band cannot be self-consistently reproduced by relativistic reflection models, which fail to account simultaneously for the soft and hard X-ray emission. The smooth soft excess prefers extreme blurring parameters, confirmed by the nearly featureless nature of the RGS spectrum, while the moderately broad Fe K line and the modest hard excess above 10 keV appear to arise in a milder gravity regime. By allowing a different origin of the soft excess, the broadband X-ray spectrum and overall spectral energy distribution (SED) are well explained by a combination of: (a) direct thermal emission from the accretion disc, dominating from the optical to the far/extreme UV; (b) Comptonization of seed disc photons by a warm (kT_e ∼ 0.3 keV) and optically thick (τ ∼ 10) corona, mostly contributing to the soft X-rays; (c) Comptonization by a standard hot (⁠|$kT_{\rm e}\gtrsim 100$| keV) and optically thin (τ < 0.5) corona, responsible for the primary X-ray continuum; and (d) reflection from the mid/outer part of the disc. The two coronae are suggested to be rather compact, with |$R_{\rm hot}\lesssim R_{\rm warm}\lesssim 10\, r_{\rm g}$|⁠. Our SED analysis implies that Ton S180 accretes at super-Eddington rates. This is a key condition for the launch of a wind, marginal (i.e., 3.1σ significance) evidence of which is indeed found in the RGS spectrum.

Aims.We detected a very strong X-ray decline in the galaxy IRAS 23226-3843 within theXMM-Newtonslew survey in 2017. Subsequently, we carried out multi-band follow-up studies to investigate this fading galaxy in more detail.Methods.We took deep follow-upSwift,XMM-Newton, andNuSTARobservations in combination with optical SALT spectra of IRAS 23226-3843 in 2017. In addition, we reinspected optical, UV, and X-ray data that were taken in the past.Results.IRAS 23226-3843 decreased in X-rays by a factor of more than 30 with respect to ROSAT andSwiftdata taken 10 to 27 years before. The broadbandXMM-Newton/NuSTARspectrum is power-law dominated, with a contribution from photoionized emission from cold gas, likely the outer accretion disk or torus. The optical continuum decreased by 60% and the Balmer line intensities decreased by 50% between 1999 and 2017. The optical Seyfert spectral type changed simultaneously with the X-ray flux from a clear broad-line Seyfert 1 type in 1999 to a Seyfert 1.9 type in 2017. The Balmer line profiles in IRAS 23226-3843 are extremely broad. The profiles during the minimum state indicate that they originate in an accretion disk. The unusual flat Balmer decrement Hα/ Hβwith a value of 2 indicates a very high hydrogen density ofn_H > 10¹¹cm⁻³at the center of the accretion disk. IRAS 23226-3843 shows unusually strong FeII blends with respect to the broad line widths, in contrast to what is known from Eigenvector 1 studies.