Context. We present a deep XMM-Newton observation of the massive edge-on galaxy NGC 5746. The total exposure time of ∼250 ks provides unprecedented sensitivity to study the diffuse hot gas in the halo, significantly surpassing the depth of previous observations. Aims. While the presence of hot, circumgalactic gas has been thoroughly tested in starburst galaxies, detections in normal galaxies remain scarce. By studying the diffuse X-ray emission in NGC 5746, we aim to constrain the extent and physical properties of its halo. Methods. We created X-ray images and surface-brightness profiles to quantify the distribution of extraplanar gas in NGC 5746. In addition, we isolated the diffuse emission from point-source and background contamination and studied its spectral characteristics. Results. We detected diffuse extraplanar emission in the azimuthally averaged surface-brightness profile out to a projected radius of ∼30 kpc with an integrated significance of 3σ. The emission is anisotropic: The western quadrant shows a significant excess at ∼1.5 − 3.5′ (integrated 3.7σ), while the eastern quadrant exhibits a marginal enhancement in a single radial bin. The northern and southern quadrants are consistent with the background within uncertainties. The X-ray luminosity of the hot halo is ∼8.8 ⋅ 1039 erg s−1 in 0.3–2.0 keV. Spectral modeling yielded a plasma temperature of ∼0.6 keV, while the disk emission is dominated by nonthermal emission from unresolved X-ray sources. Conclusions. Our results provide evidence of the presence of diffuse hot gas in the halo of NGC 5746 and suggest that earlier nondetections may be attributed to sensitivity limits. The asymmetric morphology highlights the complexity of the halo emission. Distinguishing between the possible origin scenarios for the extraplanar gas requires future observations with improved sensitivity and spectral resolution.

The X-ray Integral Field Unit is the X-ray imaging spectrometer on-board one of ESA's next large missions, Athena. Athena is set to investigate the theme of the Hot and Energetic Universe, with a launch planned in the late-2030s. Based on a high sensitivity Transition Edge Sensor (TES) detector array operated at very low temperature (50 mK), X-IFU will provide spatially resolved high resolution spectroscopy of the X-ray sky in the 0.2-12 keV energy band, with an energy resolution goal of 4 eV up to 7 keV [3 eV design goal]. This paper presents the current calibration plan of the X-IFU. It provides the requirements applicable to the X-IFU calibration, describes the overall calibration strategy, and details the procedure and sources needed for the ground calibration of each parameter or characteristics of the X-IFU.

Context. Pulse profiles probe the emission geometry of accreting X-ray pulsars, but their observed shapes may depend on instrumental response and observational setup. The pulsed fraction spectrum provides a compact spectro-timing observable that can both trace localized spectral features and serve as a quantitative cross-calibration diagnostic. Aims. We assess the consistency of energy-resolved pulse profiles obtained with simultaneous XMM-Newton/EPIC-pn and NuSTAR/FPM observations of Vela X-1 and investigate the broadband pulsed fraction spectrum as a diagnostic of spectral features from 1 to 70 keV. Methods. We constructed energy–phase matrices for both instruments and derived pulsed fraction spectra after carefully accounting for instrumental and observational effects. We quantified the residual systematics in the overlapping 3–10 keV band. We then modeled the broadband pulsed fraction spectra phenomenologically and searched for timing signatures of spectral features. Results. After correcting for instrumental effects, the pulsed fraction spectra derived strictly over the common exposure intervals of the two instruments agree within 5% in their overlapping 3–10 keV range. Remaining discrepancies larger than 5% are confined to the iron-line region and can be attributed to the different energy resolutions of the two instruments. The broadband pulsed fraction spectrum reveals significant localized features corresponding to known emission lines in the soft band and to the fundamental and harmonic cyclotron resonant scattering features at ∼25 and ∼55 keV. An orbital-phase-resolved modeling of the pulsed fraction spectrum of EPIC-pn shows that the soft band features strongly depend on the value of the equivalent absorption column, with emission line signatures becoming progressively suppressed during highly absorbed intervals. Conclusions. The pulsed fraction spectrum serves both as a quantitative cross-calibration diagnostic and as a powerful spectro-timing diagnostic. Its modeling provides independent constraints on spectral features, complementing traditional phase-averaged spectroscopy.

The 2023/2024 NICER monitoring campaign of the 7 Crab bright black hole X-ray binary Swift J1727.8-1613 covered the outburst in almost all accretion states. High-quality data are available in the high-Eddington-fraction hard-intermediate state, the hard-to-soft transition, the soft state, and the poorly studied back transition to the dim hard state, making it an ideal dataset for comparing the accretion flow at vastly different accretion rates. We apply disk continuum fitting techniques to investigate the evolution of the inner-disk radius throughout the outburst. Taking a temperature-dependent color-correction factor into account, we see an evolution of the disk inner radius by a factor of a few comparing the hard states to the thermal/soft state. We tentatively detect an onset of disk truncation in the soft-to-hard transition, right after the source leaves the soft state. After accounting for model systematics, we find the disk to be more truncated in the high-luminosity bright hard state compared to the low-luminosity dim hard state.

Context. The X-ray spectra of neutron stars with moderate magnetic fields (B ∼ 1012 G) in high-mass X-ray binaries (HMXBs) at low X-ray luminosities (LX ≲ 1035 erg s−1) are characterized by a double humped shape. This shape has been explained either as the radiation from a two-temperature magnetized atmosphere, where thermal radiation dominates at soft X-rays below about 10 keV, and cyclotron radiation with an imprinted cyclotron line dominates at high energies, or by the complex redistribution of primary X-rays in a structured atmosphere. Aims. The theoretical explanations of the double humped structure predict the spectra to depend on the magnetic field. We aim to connect the model predictions with observations. Methods. We analyzed archival NuSTAR observations of four HMXBs consisting of a neutron star and a Be star (BeXRBs), with known magnetic fields at luminosities low enough to show the characteristic double-hump spectrum. We modeled these spectra empirically and derived a relation between the energy of the intersection of the two humps and the magnetic field strength. In a second step, we tested whether this correlation is supported by fitting synthetic spectra simulated with the physically self-consistent polcap model. Results. We find a linear correlation between the magnetic field strength and the intersection energy for the real BeXRB NuSTAR spectra and polcap-based simulated NuSTAR spectra alike. Conclusions. The effect of the magnetic field on spectral formation results in an observable correlation between the field strength and spectral shape. This derived positive correlation between intersection energy and magnetic field strength also allowed us to roughly estimate the magnetic field strength via our proposed 2-B-12 rule. Additional observations of XRBs and dedicated modeling efforts will be necessary to determine whether this approach is valid beyond the B-field range of a few 1012–1013 G that was tested in this work.

Position calibration in the deep sea is typically done by means of acoustic multilateration using three or more acoustic emitters installed at known positions. Rather than using hydrophones as receivers that are exposed to the ambient pressure, the sound signals can be coupled to piezo ceramics glued to the inside of existing containers for electronics or measuring instruments of a deep sea infrastructure. The ANTARES neutrino telescope operated from 2006 until 2022 in the Mediterranean Sea at a depth exceeding 2000 m. It comprised nearly 900 glass spheres with 432 mm diameter and 15 mm thickness, equipped with photomultiplier tubes to detect Cherenkov light from tracks of charged elementary particles. In an experimental setup within ANTARES, piezo sensors have been glued to the inside of such – otherwise empty – glass spheres. These sensors recorded signals from acoustic emitters with frequencies from 46545 to 60235 Hz. Two waves propagating through the glass sphere are found as a result of the excitation by the waves in the water. These can be qualitatively associated with symmetric and asymmetric Lamb-like waves of zeroth order: a fast (early) one with v_e ≈ 5 mm/μs and a slow (late) one with v_ℓ≈ 2 mm/μs . Taking these findings into account improves the accuracy of the position calibration. The results can be transferred to the KM3NeT neutrino telescope, currently under construction at multiple sites in the Mediterranean Sea, for which the concept of piezo sensors glued to the inside of glass spheres has been adapted for monitoring the positions of the photomultiplier tubes.

Cygnus X-1 is a high-mass black hole binary extensively studied since its discovery in 1964. Its rapid X-ray variability provides insights into accretion physics. Unlike other black hole X-ray binaries, its power spectra are generally featureless and modeled with two broad Lorentzians, without requiring narrow quasi-periodic oscillations. We investigate the possibility that some undetected variability components in power spectra may appear in the imaginary part of the cross spectra and the coherence function. Using NICER observations up to Cycle 6, we study the power, cross, and lag spectra, along with the coherence function, searching for these "imaginary" components. We simultaneously fit the power spectra in two energy bands, 0.3-2 keV and 2-12 keV, and the real and imaginary parts of the cross-spectrum with a multi-Lorentzian model. Assuming each Lorentzian is coherent between the two bands but incoherent with others, we predict intrinsic coherence and phase lags. he intrinsic coherence shows a narrow dip at a frequency increasing from 1 Hz to 6 Hz as the power-law index of the Comptonized component increases from 1.8 to 2.4. Simultaneously, the phase lags exhibit a steep increase (the "cliff") at the same frequencies. These features vanish when using energy bands similar to RXTE (e.g., 3-5 keV and 5-12 keV). A narrow Lorentzian component with low fractional rms and large phase lag is required to reproduce the coherence drop. Its rms and phase-lag spectra evolve systematically in the hardness-intensity diagram. This "imaginary" QPO behaves like a type-C QPO despite being undetectable in power spectra alone. Similar features in MAXI J1348-630 and MAXI J1820+070 support this interpretation, suggesting this may be the first detection of a type-C QPO in Cygnus X-1.

Context. The reflection of X-rays at the inner accretion disk around black holes imprints relativistically broadened features in the observed spectrum. Aside from the black hole properties and the ionization and density of the accretion disk, these features also depend on the location and geometry of the primary source of X-rays, often referred to as the corona. Aims. We present a fast general relativistic model for spectral fitting of a radially extended, ring-like corona above the accretion disk. Methods. A common approach used to explain observed X-ray reflection spectra is the lamp post geometry, which assumes a point-like source on the rotational axis of the black hole. While it is typically able to explain the observations, this geometric model does not allow for any constraint to be placed on the radial size of the corona. We therefore extended the publicly available relativistic reflection model RELXILL by implementing a radially extended, ring-like primary source. Results. With the new RELXILL model allowing us to vary the position of the primary source in two dimensions, we present simulated line profiles and spectra and discuss the implications of carrying out a data fitting, in comparison to the lamp post model. We applied this extended RELXILL model to XMM-Newton and NuSTAR data of the radio-quiet Seyfert-2 active galactic nucleus (AGN) ESO 033-G002. The new model describes the data well and we are able to constrain the distance of the source to the black hole to be less than three gravitational radii, while the angular position of the source is poorly constrained. Conclusions. We show that a compact, radially extended corona close to the innermost stable circular orbit is able to explain the observed relativistic reflection as well as the lamp post corona does. This model has been made freely available to the community.

The dynamic range of imaging detectors flown on-board X-ray observatories often only covers a limited flux range of extrasolar X-ray sources. The analysis of bright X-ray sources is complicated by so-called pile-up, which results from high incident photon flux. This nonlinear effect distorts the measured spectrum, resulting in biases in the inferred physical parameters, and can even lead to a complete signal loss in extreme cases. Piled-up data are commonly discarded due to resulting intractability of the likelihood. As a result, a large number of archival observations remain underexplored. We present a machine learning solution to this problem, using a simulation-based inference framework that allows us to estimate posterior distributions of physical source parameters from piled-up eROSITA data. We show that a normalizing flow produces better-constrained posterior densities than traditional mitigation techniques, as more data can be leveraged. We consider model- and calibration-dependent uncertainties and the applicability of such an algorithm to real data in the eROSITA archive.

In 2023 November, the Fermi Large Area Telescope detected a γ -ray flare from the high-redshift blazar GB6 B1428+4217 ( z = 4.715). We initiated a multiwavelength follow-up campaign involving Swift, NuSTAR, the Sierra Nevada and Perkins Observatories, and the Effelsberg 100 m radio telescope. This source, also known as 5BZQ J1430+4204, has shown an anomalous soft X-ray spectrum in previous observations, including possible ionized absorption features or signatures of bulk Comptonization of thermal electrons, which are also detected during the flaring episode. Simultaneous optical data revealed a polarization fraction of ∼8% in the R band, confirming that synchrotron emission dominated over thermal emission from the accretion disk. The hard X-ray flux was enhanced during the flare. Modeling of the broadband spectral energy distribution suggests that the high-energy component is dominated by Compton scattering by external seed photons from the accretion disk. The origin of the flare is consistent with the injection of a hard-spectrum electron population in the emission region. With a γ -ray luminosity among the top 5% of flaring events, GB6 B1428+4217 exemplifies a prototypical MeV blazar. Its Compton-dominated spectral energy distribution and extreme luminosity are in line with expectations from the blazar sequence. High-redshift flares like this are critical for understanding jet physics in the early Universe and may improve detection prospects with future missions such as the Compton Spectrometer and Imager.

Context. Multiwavelength studies of transients in actively accreting supermassive black holes have revealed that large-amplitude variability is frequently linked to significant changes in the optical spectra. This phenomenon is known as a changing-look active galactic nucleus (CLAGN). Aims. In 2020, the Zwicky Transient Facility detected a transient flaring event in the type 1.9 AGN LEDA 1154204, wherein the brightness sharply increased by 0.55 mag in one month and then began to decay. Spectrum Roentgen Gamma (SRG)/eROSITA also observed the object as part of its all-sky X-ray surveys after the flare had started to decay. Methods. We performed a three-year multiwavelength follow-up campaign to track the spectral and temporal characteristics of the source during the post-flare fading. This campaign included optical spectroscopy, X-ray spectroscopy and photometry, and ultraviolet, optical, and infrared continuum photometry. Results. Optical spectra taken near the flare peak revealed a broad double-peaked H beta emission and a blue continuum, neither of which were detected in a 2005 archival spectrum. The broad H beta had increased by a factor of > 5-6. From late 2020 through 2023, the broad Balmer-line flux faded as the continuum faded, and the Balmer decrement increased by similar to 2.2. This is consistent with the expected ionization response. The X-ray spectrum exhibits no significant spectral variability despite dramatic flux variation of a factor of 17. There is no evidence of a soft X-ray excess, which indicates an energetically unimportant warm corona. Conclusions. The transient event was likely triggered by a disk instability in a preexisting AGN-like accretion flow that culminated in the observed multiwavelength variability (X-rays via thermal Comptonization, illumination of the broad-line region, and infrared dust echo) and in the CLAGN event.

The Athena mission entered a redefinition phase in July 2022, driven by the imperative to reduce the mission cost at completion for the European Space Agency below an acceptable target, while maintaining the flagship nature of its science return. This notably called for a complete redesign of the X-ray Integral Field Unit (X-IFU) cryogenic architecture towards a simpler active cooling chain. Passive cooling via successive radiative panels at spacecraft level is now used to provide a 50 K thermal environment to an X-IFU owned cryostat. 4.5 K cooling is achieved via a single remote active cryocooler unit, while a multi-stage Adiabatic Demagnetization Refrigerator ensures heat lift down to the 50 mK required by the detectors. Amidst these changes, the core concept of the readout chain remains robust, employing Transition Edge Sensor microcalorimeters and a SQUID-based Time-Division Multiplexing scheme. Noteworthy is the introduction of a slower pixel. This enables an increase in the multiplexing factor (from 34 to 48) without compromising the instrument energy resolution, hence keeping significant system margins to the new 4 eV resolution requirement. This allows reducing the number of channels by more than a factor two, and thus the resource demands on the system, while keeping a 4' field of view (compared to 5' before). In this article, we will give an overview of this new architecture, before detailing its anticipated performances. Finally, we will present the new X-IFU schedule, with its short term focus on demonstration activities towards a mission adoption in early 2027.

We present a study of X-ray normal galaxies using data from the first all-sky scan of the eROSITA X-ray survey. eRASS1 provides the first unbiased X-ray census of normal galaxies allowing us to study the X-ray emission from XRBs and the hot ISM in the full range of stellar population parameters present in the local Universe. By combining the HECATE value-added galaxy catalogue with the eRASS1, we study the X-ray emission from normal galaxies as a function of their SFR, M$_{*}$, Metallicity, and stellar population age. After applying optical and mid-IR activity classification criteria, we constructed a sample of 18790 star-forming galaxies with measurements of their L$_{X}$. By stacking the X-ray data in SFR-M$_{*}$-distance bins we study the correlation between the average L$_{X}$ and stellar population parameters. We also present updated L$_{\rm{X}}$-SFR and L$_{\rm{X}}$/SFR-Metallicity scaling relations accounting for the scatter dependence on the SFR. We find that the integrated L$_{X}$ of the HEC-eR1 star-forming galaxies is significantly elevated with respect to that expected from the current scaling relations. The observed scatter is also significantly larger. This excess persists even when we measure the average L$_{X}$ of galaxies in SFR-M$_{*}$-distance and metallicity bins and it is stronger in lower SFRs. The excess is not the result of hot gas, LMXBs, background AGN, LLAGN (including TDEs), or stochastic sampling of the XRB XLF. We find that while the excess correlates with lower metallicity, its primary driver is the age of the stellar populations. Our analysis reveals a sub-population of X-ray luminous starbursts with high sSFRs, low metallicities, and young stellar populations. This population drives upwards the X-ray scaling relations for star-forming galaxies, and has important implications for understanding the population of XRBs in the local and high-z Universe.

Inner-shell transitions are ubiquitous in nonequilibrium collisionally ionized plasmas, such as supernova remnants, and in photoionized plasmas, such as outflows from active galactic nuclei and X-ray binaries. Inner-shell X-ray emission can help determine key parameters of these systems, such as ionization time, τ , and ionization parameter, ξ . Despite their importance, only theoretical inner-shell transition energies are available for many ions. To provide experimental benchmarks, we have measured the dominant n → 1 K-shell transitions of sulfur ions where n ≥ 3 from Li-like S xiv to F-like S viii using LLNL’s SuperEBIT electron beam ion trap and the NASA/GSFC EBIT Calorimeter Spectrometer (ECS). We identify over 30 spectral features and measure their energies with uncertainties in the ∼0.1–1 eV range. We compare these results to Flexible Atomic Code (FAC) and multireference Møller–Plesset (MR-MP) calculations and find differences between theory and experiment of ∼1 eV for FAC and <0.5 eV for most MR-MP calculations. We also compare these results to two widely used atomic databases, AtomDB and CHIANTI, and find discrepancies as high as 7 eV. Furthermore, many transitions are missing from these databases despite being prominent in our data.

X-ray observations are essential for understanding the multimessenger emission mechanisms of active galactic nuclei (AGN). Blazars, a subset of AGN whose X-ray emission predominantly originates from relativistic jets, have been proposed as promising high-energy neutrino sources. In this work, we study the candidate neutrino-emitting blazar 5BZB J0630-2406, which has been observed over multiple epochs with the XMM-Newton, NuSTAR, Neil Gehrels Swift-XRT, and eROSITA observatories. Analysis of the X-ray spectra in the 2.0–10.0 keV band shows significant variability, with high-flux states adhering to a power-law model indicative of jet emission. However, during low-flux states, the spectrum reveals an additional component in hard X-rays, indicating a transition from jet-dominated to multicomponent X-ray emission, possibly associated with hadronic processes. To investigate this spectral evolution, we tested various models and found it to be consistent with coronal emission or photoionized absorption processes typically observed in obscured AGN. The identification of the X-ray spectral variability in 5BZB J0630-2406, combined with its potential for neutrino production, opens new perspectives in multimessenger astrophysics of blazars, highlighting the synergies between the mechanisms of the jet and the nuclear environment.

Context. We present a deep XMM-Newton observation of the massive, edge-on galaxy NGC 5746. The total exposure time of 250 ks provides unprecedented sensitivity to study the diffuse hot gas in the halo, significantly surpassing the depth of previous observations. Aims. While the presence of hot, circumgalactic gas is well tested for starburst galaxies, detections in normal galaxies remain scarce. By studying the diffuse X-ray emission in NGC 5746, we aim to provide new insights into the evolution of star-forming galaxies and their surroundings. Methods. We create X-ray images and surface brightness profiles to quantify the distribution of extraplanar gas in the halo of NGC 5746. In addition, we isolate the diffuse emission component from point source- and background-contamination and study the spectral characteristics of the hot plasma. Results. We detect soft X-ray emission out to 40 kpc from the galactic disc. The gas distribution is reminiscent of a stellar outflow, with two bubbles extending perpendicular to the disc in a biconical shape. The spectral analysis of the halo emission yields a plasma temperature of 0.56 keV, higher than the typical values observed in spiral galaxies (0.2 keV). The disc has an even higher plasma temperature of 0.7 keV, and is dominated by non-thermal emission from unresolved X-ray binaries. The signs of a stellar outflow, bright X-ray emission, and high plasma temperatures indicate that the star-forming activity in NGC 5746 might be higher than previously thought. Conclusions. Our results demonstrate that massive spiral galaxies can host luminous X-ray halos, and support theoretical models that predict their existence. Earlier claims of a lack of hot gas around quiescent spirals might be attributed to the detection thresholds in shallower observations, stressing the need for more, deeper observations of non-starburst galaxies.

The eROSITA instrument on board Spectrum-Roentgen-Gamma (SRG) has completed four scans of the X-ray sky, leading to the detection of almost one million X-ray sources in eRASS1 alone, including multiple new X-ray binary candidates. We report on analysis of the X-ray binary 1eRASS J085039.9−421151, using a ∼55 ks long NuSTAR observation, following its detection in each eROSITA scan. An analysis of the eROSITA and NuSTAR X-ray spectra in combination with X-shooter data of the optical counterpart provide evidence of an X-ray binary with a red supergiant (RSG) companion, confirming previous results. However, we did determine a cooler spectral type for M2–3, owing to the presence of TiO bands in the optical and near-infrared spectra. The X-ray spectrum is well-described by an absorbed power law with a high-energy cutoff typically applied for accreting high mass X-ray binaries. In addition, we detected a strong fluorescent neutral iron line with an equivalent width of ∼700 eV and an absorption edge, the latter indicating strong absorption by a partial covering component. It is unclear whether the partial absorber is ionised. There is no significant evidence of a cyclotron resonant scattering feature. We did not detect any pulsations in the NuSTAR light curves, possibly on account of a large spin period that has gone undetected due to insufficient statistics at low frequencies or potentially large absorption that causes pulsations to be smeared out. Even so, the low persistent luminosity, the spectral parameters observed (photon index, Γ < 1.0), and the minuscule likelihood of detection of RSG-black hole systems suggest that the compact object is a neutron star.

We present a detailed study of the hydrogen density distribution in the local interstellar medium (ISM) using the X-ray absorption technique. Hydrogen column densities were precisely measured by fitting X-ray spectra from coronal sources observed during the initial eROSITA all-sky survey (eRASS1). Accurate distance measurements were obtained through cross-matching Galactic sources with the Gaia third data release (DR3). Despite the absence of a discernible correlation between column densities and distances or Galactic longitude, a robust correlation with Galactic latitude was identified. This suggests a decrease in ISM material density along the vertical direction away from the Galactic plane. To further investigate, we employed multiple density laws to fit the measured column densities, revealing constraints on height scale values (8 < h_z < 30 pc). Unfortunately, radial scales and central density remain unconstrained due to the scarcity of sources near the Galactic center. Subsequently, a 3D density map of the ISM was computed using a Gaussian processing approach, inferring hydrogen density distribution from hydrogen column densities. The results unveiled the presence of multiple beams and clouds of various sizes, indicative of small-scale structures. Large density regions were identified at approximately 100 pc, consistent with findings in dust reddening studies, potentially associated with the Galactic Perseus arm. Moreover, high-density regions were pinpointed in proximity to the Orion star-forming region and the Chamaeleon molecular complex, enriching our understanding of the intricate structure of the local interstellar medium.

High-significance evidences of the existence of a high-energy diffuse flux of cosmic neutrinos have emerged in the last decade from several observations by the IceCube Collaboration. The ANTARES neutrino telescope took data for 15 years in the Mediterranean Sea, from 2007 to 2022, and collected a high-purity all-flavour neutrino sample. The search for a diffuse cosmic neutrino signal using this dataset is presented in this article. This final analysis did not provide a statistically significant observation of the cosmic diffuse flux: this is converted into limits on the properties of the cosmic neutrino spectrum. In particular, given the sensitivity of the ANTARES neutrino telescope between 1 and 50 TeV, constraints on single-power-law hypotheses are derived for the cosmic diffuse flux below 20 TeV.

The SRG/eROSITA All-Sky Survey (eRASS) is expected to contain  100 quasars that emitted their light when the universe was less than a billion years old, i.e. at z>5.6. By selection, these quasars populate the bright end of the AGN X-ray luminosity function and their count offers a powerful demographic diagnostic of the parent super-massive black hole population. Of the >  400 quasars that have been discovered at z>5.6 to date, less than 15 X-ray detected. We present a pilot survey to uncover the elusive X-ray luminous end of the distant quasar population. We have designed a quasar selection pipeline based on optical, infrared and X-ray imaging data from DES DR2, VHS DR5, CatWISE2020 and the eRASS. The core selection method relies on SED template fitting. We performed optical follow-up spectroscopy with the Magellan/LDSS3 instrument for the redshift confirmation of a subset of candidates. We have further obtained a deeper X-ray image of one of our candidates with Chandra ACIS-S. We report the discovery of five new quasars in the redshift range 5.6 < z < 6.1. Two of these quasars are detected in eRASS and are by selection X-ray ultra-luminous. These quasars are also detected at radio frequencies. The first one is a broad absorption line quasar which shows significant X-ray dimming over 3.5 years, i.e. about 6 months in the quasar rest frame. The second radio-detected quasar is a jetted source with compact morphology. We show that a blazar configuration is likely for this source, making it the second most distant blazar known to date. With our pilot study, we demonstrate the power of eROSITA as a discovery machine for luminous quasars in the epoch of reionization. The X-ray emission of the two eROSITA detected quasars are likely to be driven by different high-energetic emission mechanisms a diversity which will be further explored in a future systematic full-hemisphere survey.