arXiv subjects

Erwan Quintin

Publications and source records attributed to Erwan Quintin.

16 recordsLinked to original sources

arXiv2026

Relativistic outflows power a quasi-periodic eruption: constraints on energetics, mass loss, and emission mechanisms

Quasi-periodic eruptions (QPEs) are recurring bursts of X-ray radiation originating from supermassive black holes (SMBHs). They are an unprecedented type of structured, high-amplitude SMBH variability, but the physical origins of their regularity, timescales, energetics, and emission are uncertain. We present new XMM-Newton observations of the QPEs in ZTF19acnskyy/``Ansky'', constituting the deepest observations of individual bursts in any source thus far. The X-ray spectra reveal time-evolving P Cygni profiles comprising blueshifted absorption and redshifted emission from L-shell transitions of Fe XIX-XXIV, with column densities $N_H\sim 10^{22-23}$ cm$^{-2}$ and bulk velocities of $|v_w/c|\sim 0.2$, indicating relativistic mass ejections during each eruption. We construct a time-dependent analytical model of a wind turning on to self-consistently compute its evolving luminosity and ionization properties, and find that the light curve and spectral lines can be simultaneously produced by a wide-angle outflow with $\dot{M}\sim 10^{-9}-10^{-8}\,M_\odot$ s$^{-1}$ kinetically powering the X-rays with an efficiency of $L_X/\dot{E}_K\sim 0.1$. Each eruption ejects $\sim 10^{-3}\,M_\odot$ and $\gtrsim 10^{49}$ erg of kinetic energy, setting an upper bound on the QPE lifetime of $\lesssim30$ years if the underlying mass reservoir is $\sim1 M_\odot$, and implying that the bursts may result in detectable multiwavelength signatures of reverberation and feedback. These measurements provide new quantitative constraints on QPE energetics, emission mechanisms, and the mass/energy they recycle into their circumnuclear environments, as well as an observational probe for direct comparison with physical models and hydrodynamical simulations of QPEs.

astro-ph.HE↗

arXiv2026

Observations of X-ray quasi-periodic eruptions

Quasi-periodic eruptions (QPEs) are a novel class of repeating nuclear transients, discovered exclusively in the X-ray band to date. Since their initial discovery in 2019, the QPE sample has grown to 13 sources, exhibiting large amplitude, quasi-regular eruptive variability patterns that are distinct from previously known modes of massive black hole variability. In this chapter, we provide a comprehensive overview of their observational characteristics. We review the X-ray spectral and timing properties of QPE eruptions, their long-term evolution, as well as the underlying quiescent emission, which is well described by thermally dominated, compact accretion disks. We discuss population-level emerging trends and selection biases, and present an updated census of their host galaxy properties. We also highlight the growing body of evidence pointing to strong connections between QPEs and tidal disruption events. Finally, we briefly summarize the key observational constraints on proposed QPE model interpretations, before looking ahead to the observational challenges and opportunities that will shape future progress in understanding this emerging population of nuclear transients.

astro-ph.HE↗

arXiv2026

The Dispersed Matter Planet Project Sample -- Detection limits, Occurrence Rates and New Planets

DMPP is a radial-velocity survey that aims to detect planets around stars exhibiting anomalous activity signatures, consistent with the presence of close-in evaporating planets. Here, we report the discovery of 7 new planetary signals in 5 different systems: DMPP-2c & d, HD67200/DMPP-6b & c, HD118006/DMPP-7b, HD191122/DMPP-8b, and HD200133/DMPP-9b. We update the orbital parameters of the DMPP-1, DMPP-2, and DMPP-3 systems, along with those of the planetary systems orbiting HD181433, HD39194, and HD89839. We derive detection limits for all 24 targets in our sample with adequate observational coverage, and test the DMPP hypothesis by calculating the occurrence rates for planets in this configuration. We find that the occurrence rates of planets in our sample with orbital periods shorter than $50~\mathrm{d}$ and masses in the range $3$-$10$ M$_\oplus$ are $83.0^{+27.1}_{-24.4}\%$, for $10$-$30$ M$_\oplus$ are $27.0^{+15.0}_{-11.2}\%$, and for $30$-$100$ M$_\oplus$ are $13.9^{+11.8}_{-7.5}\%$. This is significantly higher than the occurrence rates reported by other radial velocity surveys, providing strong support for the DMPP hypothesis.

astro-ph.EP↗

arXiv2025

Discovering periodic and repeating nuclear transients in the XMM-Newton archives

The regions around massive black holes can show X-ray variability on timescales from seconds to decades. Observing many black holes over different timescales can enhance our chances of detecting variability coming from (partial) tidal disruption events, massive black hole binaries, changing state AGN, blazar activity and much more. X-ray catalogues with hundreds of thousands of detections are treasure troves of such sources, which require innovative methods to identify these black holes. We present the current XMM-Newton catalogues available and describe several examples of tidal disruption events (TDEs) and quasi-periodic eruption sources that have been found whilst mining this data. We describe preliminary work on a search for periodic variables in the XMM-Newton EPIC archival data, with the example of finding new massive black hole binaries. We also describe the STONKS pipeline that is now in the XMM-Newton automatic reduction pipeline and the near real-time alert system that allows the follow-up of new and fading transients. We provide examples of fading sources that are newly identified candidate TDEs.

astro-ph.HE↗

arXiv2025

Early Identification of Optical Tidal Disruption Events: A science module for the Fink broker

The detection of tidal disruption events (TDEs) is one of the key science goals of large optical time-domain surveys such as the Zwicky Transient Facility (ZTF) and the upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time. However, identifying TDEs in the vast alert streams produced by these surveys requires automated and reliable classification pipelines that can select promising candidates in real time. We developed a module within the Fink alert broker to identify TDEs during their rising phase. It was built to autonomously operate within the ZTF alert stream, producing a list of candidates every night and enabling spectral and multi-wavelength follow-up near peak brightness. All rising alerts are submitted to selection cuts and feature extraction using the Rainbow multi-band lightcurve fit. Best-fit values were used as input to train an XGBoost classifier with the goal of identifying TDEs. The training set was constructed using ZTF observations for objects with available classification in the Transient Name Server. Finally, candidates with high enough probability were visually inspected. The classifier achieves 76% recall, indicating strong performance in early-phase identification, despite the limited available information before peak. We show that, out of the known TDEs that pass the selection cuts, half of them are flagged as TDE before halfway in their rise, proving the feasibility of early classification. Additionally, new candidates were identified by applying the classifier on archival data, including a likely repeated TDE and some potential TDEs occurring in active galaxies. The module is implemented into the Fink alert processing framework, reporting each night a small number of candidates to dedicated communication channels through a user-friendly interface, for manual vetting and potential follow-up.

astro-ph.HE↗

arXiv2025

The population of hyperluminous X-ray sources as seen by XMM-Newton

Ultraluminous and hyperluminous X-ray sources (ULXs and HLXs) are among the brightest astrophysical objects in the X-ray sky. While ULXs most likely host stellar-mass compact objects accreting at super-Eddington rates, HLXs are compelling candidates for accreting intermediate-mass black holes. Our goal is to produce a clean sample of HLXs by removing possible contaminants and characterise the spectral properties of the remaining population. Starting with a set of 115 HLXs detected by XMM-Newton, we identified and removed contaminants (AGNs, X-ray diffuse emission detected as point-like, and tidal disruption event candidates) and retrieved 40 sources for which XMM-Newton spectra are available. We fitted them with an absorbed power law model and determined their unabsorbed luminosities and hardness ratios. We constructed the hardness-luminosity diagram, compared the results with the spectral properties of the HLX prototype, ESO 243-49 HLX-1, and conducted a deeper analysis on a few promising candidates. The resulting HLX population spans a luminosity range from $1\times10^{41}$ erg s$^{-1}$ to nearly $10^{43}$ erg s$^{-1}$ and is homogeneously spread in hardness between 0.5 and 5. Half of the population has hardness ratios higher than a typical AGN, and could be considered the extension of the ULX population at higher energies. We found four very soft outliers, which are characterised by steep power law spectra and no X-ray emission above 1$-$2 keV, similarly to ESO 243-49 HLX-1. Those with multi-epoch archival data show changes in luminosity up to almost two orders of magnitudes. We show that sources currently identified as HLXs can be more diverse than ULXs and disentangling between different types of objects is not trivial with currently available data. New observations would be beneficial to expand the current sample and uncover the true nature of many objects of this class.

astro-ph.HE↗

arXiv2025

Rapidly varying ionization features in a Quasi-periodic Eruption: a homologous expansion model for the spectroscopic evolution

Quasi-Periodic Eruptions (QPEs) are recurring bursts of soft X-ray emission from supermassive black holes (SMBHs), which a growing class of models explains via extreme mass-ratio inspirals (EMRIs). QPEs exhibit blackbody-like emission with significant temperature evolution, but the minimal information content of their almost pure-thermal spectra has limited physical constraints. Here we study the recently discovered QPEs in ZTF19acnskyy (``Ansky''), which show absorption-like features evolving dramatically within eruptions and correlating strongly with continuum temperature and luminosity, further probing the conditions underlying the emission surface. The absorption features are well-described by dense ionized plasma of column density $N_{\rm H}\gtrsim 10^{21}$ cm$^{-2}$, blueshift $0.06\lesssim v/c \lesssim 0.4$, and either collisional or photoionization equilibrium. With high-resolution spectra, we also detect ionized blueshifted emission lines suggesting a nitrogen over-abundance of $21.7^{+18.5}_{-11.0}\times$ solar. We interpret our results with orbiter-disk collisions in an EMRI system, in which each impact drives a shock that locally heats the disk and expels X-ray emitting debris undergoing radiation pressure-driven homologous expansion. We explore an analytical toy model that links the rapid change in absorption lines to the evolution of the ionization parameter and the photosphere radius, and suggest that $\sim 10^{-3}M_\odot$ ejected per eruption with expansion velocities up to $v_{\rm max}\sim 0.15c$, can reproduce the absorption features. With these assumptions, we show a P Cygni profile in a spherical expansion geometry qualitatively matches the observed line profiles. Our work takes a first step towards extending existing physical models for QPEs to address their implications for spectral line formation.

astro-ph.HE↗

arXiv2025

Discovery of Quasi-periodic Eruptions in the Tidal Disruption Event and Extreme Coronal Line Emitter AT2022upj: implications for the QPE/TDE fraction and a connection to ECLEs

Quasi-periodic eruptions (QPEs) are recurring soft X-ray transients emerging from the vicinity of supermassive black holes (SMBHs) in nearby, low-mass galaxy nuclei; about ten QPE hosts have been identified thus far. Here we report the \textit{NICER} discovery of QPEs in the optically-selected Tidal Disruption Event (TDE) and Extreme Coronal Line Emitter (ECLE) AT2022upj, exhibiting a large spread in recurrence times from 0.5-3.5 days, durations from 0.3-1 days, peak luminosities from $10^{42.5-43.0}$ erg s$^{-1}$, and erratic flare profiles. A wealth of evidence now links at least some QPEs to the newly-formed accretion flows emerging from TDEs; AT2022upj is the third QPE reported in an optically discovered TDE. Marginalizing over the uncertain distributions of QPE peak luminosity, recurrence time, delay after TDE peak, and lifetime, we use the burgeoning sample to make a Bayesian estimate that the fraction of optical TDEs resulting in QPEs within 5 years post-disruption is $9^{+9}_{-5}$\%. Along with AT2019qiz, AT2022upj also marks the second of the three optical TDE+X-ray QPEs showing coronal line emission, suggesting ECLEs may represent a subset of TDEs particularly efficient at forming QPEs and/or that sustained QPE X-ray emission contributes to coronal line emission in some galaxy nuclei.

astro-ph.HE↗

arXiv2025

The EXOD search for faint transients in XMM-Newton observations. Part II

The XMM-Newton observatory has accumulated a vast archive of over 17,000 X-ray observations over the last 25 years. However, the standard data processing pipelines may fail to detect certain types of transient X-ray sources due to their short-lived or dim nature. Identifying these transient sources is important for understanding the full range of temporal X-ray behaviour, as well as understanding the types of sources that could be routinely detected by future missions such as Athena. This work aims to reprocess XMM-Newton archival observations using newly developed dedicated software in order to identify neglected and missed transient X-ray sources that were not detected by the existing pipeline. We use a new approach that builds upon previous methodologies, by transforming event lists into data cubes, which are then searched for transient variability in short time windows. Our method enhances the detection capabilities in the Poisson regime by accounting for the statistical properties of sparse count rates, and allowing for transient search in previously discarded periods of high background activity. Our reprocessing efforts identified 32,247 variable sources at the 3-sigma level and 4,083 sources at the 5-sigma level in 12,926 XMM archival observations. We highlight four noteworthy sources: A candidate quasi-periodic eruption (QPE), a new magnetar candidate, a previously undetected Galactic hard X-ray burst and a possible X-ray counterpart to a Galactic radio pulsar. Our method demonstrates a new, fast, and effective way to process event list data from XMM-Newton, which is efficient in finding rapid outburst-like or eclipsing behaviour. This technique can be adapted for use with future telescopes, such as Athena, and can be generalised to other photon counting instruments operating in the low-count Poisson regime.

astro-ph.HE↗

arXiv2024

Eppur si muove: Evidence of disc precession or a sub-milliparsec SMBH binary in the QPE-emitting galaxy GSN 069

X-ray quasi-periodic eruptions (QPEs) are intense soft X-ray bursts from the nuclei of nearby low-mass galaxies typically lasting about one hour and repeating every few. Their physical origin remains debated, although so-called impacts models in which a secondary orbiting body pierces through the accretion disc around the primary supermassive black hole (SMBH) in an extreme mass-ratio inspiral (EMRI) system are considered promising. In this work, we study the QPE timing properties of GSN 069, the first galactic nucleus in which QPEs were identified, primarily focusing on Observed minus Calculated (O-C) diagrams. The O-C data in GSN 069 are consistent with a super-orbital modulation on tens of days whose properties do not comply with the impacts model. We suggest that rigid precession of a misaligned accretion disc or, alternatively, the presence of a second SMBH forming a sub-milliparsec binary with the inner EMRI is needed to reconcile the model with the data. In both cases, the quiescent accretion disc emission should also be modulated on similar timescales. Current X-ray monitoring indicates that this might be the case, although a longer baseline of higher-cadence observations is needed to confirm the tentative X-ray flux periodicity on firm statistical grounds. Future dedicated monitoring campaigns will be crucial to test the overall impacts plus modulation model in GSN 069, and to distinguish between the two proposed modulating scenarios. If our interpretation is correct, QPEs in GSN 069 represent the first electromagnetic detection of a short-period EMRI system in an external galaxy, opening the way to future multi-messenger astronomical observations. [abridged]

astro-ph.HE↗

arXiv2024

jaxspec : a fast and robust Python library for X-ray spectral fitting

Context. Inferring spectral parameters from X-ray data is one of the cornerstones of high-energy astrophysics, and is achieved using software stacks that have been developed over the last twenty years and more. However, as models get more complex and spectra reach higher resolutions, these established software solutions become more feature-heavy, difficult to maintain and less efficient. Aims. We present jaxspec, a Python package for performing this task quickly and robustly in a fully Bayesian framework. Based on the JAX ecosystem, jaxspec allows the generation of differentiable likelihood functions compilable on core or graphical process units (resp. CPU and GPU), enabling the use of robust algorithms for Bayesian inference. Methods. We demonstrate the effectiveness of jaxspec samplers, in particular the No U-Turn Sampler, using a composite model and comparing what we obtain with the existing frameworks. We also demonstrate its ability to process high-resolution spectroscopy data and using original methods, by reproducing the results of the Hitomi collaboration on the Perseus cluster, while solving the inference problem using variational inference on a GPU. Results. We obtain identical results when compared to other softwares and approaches, meaning that jaxspec provides reliable results while being $\sim 10$ times faster than existing alternatives. In addition, we show that variational inference can produce convincing results even on high-resolution data in less than 10 minutes on a GPU. Conclusions. With this package, we aim to pursue the goal of opening up X-ray spectroscopy to the existing ecosystem of machine learning and Bayesian inference, enabling researchers to apply new methods to solve increasingly complex problems in the best possible way. Our long-term ambition is the scientific exploitation of the data from the newAthena X-ray Integral Field Unit (X-IFU).

astro-ph.IM↗

arXiv2024

Fragments of harmony amid apparent chaos: a closer look at the X-ray quasi-periodic eruptions of the galaxy RX J1301.9+2747

Quasi-periodic eruptions (QPEs) are an extreme X-ray variability phenomenon associated with low-mass supermassive black holes. First discovered in the nucleus of the galaxy GSN 069, they have been so far securely detected in five other galaxies, including RX J1301.9+2747. When detected, the out-of-QPE emission (quiescence) is consistent with the high-energy tail of thermal emission from an accretion disk. We present the X-ray and radio properties of RX J1301.9+2747, both in quiescence and during QPEs. We analyse X-ray data taken during five XMM-Newton observations between 2000 and 2022. The last three observations were taken in coordination with radio observations with the Karl G. Jansky Very Large Array. We also make use of EXOSAT, ROSAT, and Chandra archival observations taken between 1983 and 2009. XMM-Newton detected 34 QPEs of which 8 have significantly lower amplitudes than the others. No correlated radio/X-ray variability was observed during QPEs. In terms of timing properties, the QPEs in RX J1301.9+2747 do not exhibit the striking regularity observed in the discovery source GSN 069. In fact there is no clear repetition pattern between QPEs: the average time separation between their peaks is about four hours, but it can be as short as one, and as long as six hours. The QPE spectral properties of RX J1301.9+2747 as a function of energy are however very similar to those of GSN 069 and of other QPE sources. The quiescent emission of RX J1301.9+2747 is more complex than that of GSN 069, as it requires a soft X-ray excess-like component in addition to the thermal emission from the accretion disk. Its long-term X-ray quiescent flux variations are of low-amplitude and not strictly monotonic, with a general decay over $\sim 22$ years. We discuss our observational results in terms of some of the ideas and models that have been proposed so far for the physical origin of QPEs.

astro-ph.HE↗

arXiv2023

Statistical study of a large and cleaned sample of ultraluminous and hyperluminous X-ray sources

Ultra-/hyper-luminous X-ray sources (ULX/HLX) could be interesting laboratories to improve our understanding of the supermassive black hole growth through super-Eddington accretion episodes and successive mergers of lighter holes. ULXs are thought to be powered by super-Eddington accretion on stellar-mass compact objects, while HLXs may be explained by accretion on intermediate-mass black holes (IMBHs). However, a significant portion of ULX/HLX derived from catalog searches are background AGN. Here we build samples of ULX/HLX from recent XMM-Newton, Swift-XRT and Chandra catalogs and the GLADE catalog of galaxies. We aim to characterize the frequency, environment and X-ray properties of ULXs and HLXs to better assess their differences and understand their populations. After a thorough classification of these X-ray sources, we remove 42% of S/N>3 sources, shown to be contaminants, to obtain the cleanest sample of ULX/HLX to date. From a sample of 1342 ULXs and 191 HLXs, we study their frequency, hardness, variability, radial distribution, and preferred environment. We build their Malmquist-corrected X-ray luminosity functions (XLF) and compare them with previous studies. The large sample size allows us to statistically compare ULXs and HLXs and assess differences in their nature. The interpretation of HLXs as IMBHs is investigated. A significant break is seen in the XLF at ~$10^{40}$erg/s. Our ULX sample, containing ~2% of contaminants, confirms that ULXs are located preferentially in spiral or star-forming galaxies. Some HLXs are significantly softer that ULXs and XRBs. Unlike ULXs, HLXs seem to reside equally in spiral as well as lenticular and elliptical galaxies and 35% of them have an optical counterpart. We estimate their mass and find 120 of them in the range of $2000-10^5 M_\odot$. Most HLXs seem consistent with an accreting massive black hole in a dwarf galaxy satellite.

astro-ph.HE↗

arXiv2023

Tidal disruption events and quasi periodic eruptions

Tidal disruption events (TDEs) occur when a star passes close to a massive black hole, so that the tidal forces of the black hole exceed the binding energy of a star and cause it to be ripped apart. Part of the matter will fall onto the black hole, causing a strong increase in the luminosity. Such events are often seen in the optical or the X-ray (or both) or even at other wavelengths such as in the radio, where the diversity of observed emission is still poorly understood. The XMM-Newton catalogue of approximately a million X-ray detections covering 1283$^2$ degrees of sky contains a number of these events. Here I will show the diverse nature of a number of TDEs discovered in the catalogue and discuss their relationship with quasi periodic eruptions.

astro-ph.HE↗

arXiv2023

XMM2ATHENA, the H2020 project to improve XMM-Newton analysis software and prepare for Athena

XMM-Newton, a European Space Agency observatory, has been observing the X-ray, ultra-violet and optical sky for 23 years. During this time, astronomy has evolved from mainly studying single sources to populations and from a single wavelength, to multi-wavelength or messenger data. We are also moving into an era of time domain astronomy. New software and methods are required to accompany evolving astronomy and prepare for the next generation X-ray observatory, Athena. Here we present XMM2ATHENA, a programme funded by the European Union's Horizon 2020 research and innovation programme. XMM2ATHENA builds on foundations laid by the XMM-Newton Survey Science Centre (XMM-SSC), including key members of this consortium and the Athena Science ground segment, along with members of the X-ray community. The project is developing and testing new methods and software to allow the community to follow the X-ray transient sky in quasi-real time, identify multi-wavelength or messenger counterparts of XMM-Newton sources and determine their nature using machine learning. We detail here the first milestone delivery of the project, a new online, sensitivity estimator. We also outline other products, including the forthcoming innovative stacking procedure and detection algorithms to detect the faintest sources. These tools will then be adapted for Athena and the newly detected or identified sources will enhance preparation for observing the Athena X-ray sky.

astro-ph.IM↗

arXiv2021

A new candidate pulsating ULX in NGC 7793

We report here the discovery of NGC 7793 ULX-4, a new transient ultraluminous X-ray source (ULX) in NGC 7793, a spiral galaxy already well known for harbouring several ULXs. This new source underwent an outburst in 2012, when it was detected by \textit{XMM-Newton} and the \textit{Swift} X-ray telescope. The outburst reached a peak luminosity of 3.4$\times 10^{39}$ erg\ s$^{-1}$ and lasted for about 8 months, after which the source went below a luminosity of $10^{37}$ erg\ s$^{-1}$; previous \textit{Chandra} observations constrain the low-state luminosity below $\sim$ 2$\times 10^{36}$ erg\ s$^{-1}$, implying a variability of at least a factor 1000. We propose four possible optical counterparts, found in archival HST observations of the galaxy. A pulsation in the \textit{XMM-Newton} signal was found at 2.52 Hz, with a significance of $\sim3.4\,σ$, and an associated spin-up of $\dot{f} = 3.5\times10^{-8}$ Hz.s$^{-1}$. NGC 7793 is therefore the first galaxy to host more than one pulsating ULX.

astro-ph.HE↗