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.Comment: 7 pages, 1 figure, accepted version for the proceedings of the 'Black Hole Accretion Under the X-ray Microscope' Meeting held at ESAC in June 2022. Publisher : Astronomische Nachrichte

Recherche de populations de trous noirs non identifiées dans les archives en rayons X et multi-longueurs d'onde : application aux trous noirs de masse intermédiaire

Supermassive black holes (SMBH, 10^5-10^10 M_odot) have regularly been found at the center of massive galaxies. However, we still know little about their formation mechanism. Extremely luminous active galactic nuclei (AGN), revealing the presence of massive SMBHs, were detected in the high redshift Universe, a few 10^8 years after the Big Bang. A rapid growth mechanism is thus needed, such as a rapid accretion (beyond the Eddington limit) onto intermediate-mass black holes (IMBH, 10^2 - 10^5 M_odot), or the mergers of these black holes. Some of the original IMBHs may have avoided accretion or mergers, and thus still be found in the local Universe, for example as active dwarf galaxies. However, to date, the evidence for these IMBHs remains scarce. Conversely, stellar-mass black holes are found in the Milky Way and nearby galaxies. They are often detected in X-ray binaries (XRB), composed of a compact object - a neutron star or a black hole - accreting from a companion star. Ultraluminous X-ray sources (ULXs) may be a luminous version of the XRBs, and are thought to be powered by super-Eddingtonaccretion above the Eddington limit onto stellar-mass compact objects, but the most often the exact mechanism and the nature of the accretor are largely unknown. A few hyperluminous X-ray sources (HLXs, defined as ULXs with L_X> 10^{41} erg/s), may be good candidates for IMBHs. X-ray emission is a well-known signature of accreting systems, and thus X-ray surveys are the ideal place to search for new accreting black holes. The modern X-ray observatories Swift, XMM-Newton and Chandra have detected about a million point-like sources which are yet to be identified. With these and upcoming telescopes, an automated classification of X-ray sources becomes increasingly valuable. Using this approach could provide the cleanest samples possible, where currently contaminants limit population studies of ULXs, HLXs and active dwarf galaxy candidates. In this thesis I develop an automated and probabilistic classification of X-ray sources. The Swift-XRT, XMM-Newton and Chandra catalogues are cross-correlated with each othern with optical and infrared catalogues and with the highly complete census of galaxies GLADE. From these spatial, spectral, photometrical and timing properties, the classification identifies, amongst others, populations of AGN, stars and XRBs, and can be optimised to focus on one class. It efficiently retrieves AGN and stars, but other classes have small training samples limiting the classification performance. A citizen science experiment (CLAXSON) is proposed to enlarge these samples. The classification is then applied to X-ray sources overlapping GLADE galaxies. 1901 ULX candidates are accurately identified, where analysis indicates that it is the cleanest large sample in the current literature. Their spatial distribution, hardness, variability and rates in different environments are studied. I analyse their X-ray luminosity function and confirm the presence of a powerlaw break at a luminosity of 10^40 erg/s for spiral galaxies, tentatively proposed in previous studies. HLX candidates are inspected and cross-correlated with optical sources with redshift to remove possible contaminants. The resulting 191 HLX candidates are statistically compared to ULXs, showing tentative differences perhaps due to a different accretor mass range. Likewise, 91 active dwarf galaxy candidates are identified, where half of them appear to have an off-centre nucleus. I analyse the active fraction of dwarf galaxies in different bins of galaxy mass and limiting luminosity, and I estimate the intrinsic fraction harbouring a black hole. Assuming that these AGN and HLX candidates are indeed black holes, their black hole mass distribution suggests a large fraction of IMBHs. I analyse how this mass compares with galaxy mass. Differences are observed between the two types of candidates and interpreted in terms of IMBH formation mechanisms.Les trous noirs supermassifs (TNS, 10^5-10^10 M_odot) sont observés au centre de nombreuses galaxies massives. Pourtant, leur mécanisme de formation reste incertain. Une croissance rapide est nécessaire pour expliquer certains noyaux actifs de galaxies (AGN) vus à haut redshift, comme une accrétion rapide (au-delà de la limite d'Eddington) sur des trous noirs de masse intermédiaire (TNI, 10^2-10^5 M_odot), ou la fusion de ces trous noirs. Une partie de ces TNI pourrait avoir eu une faible croissance et se retrouver encore dans l'Univers local, par exemple sous forme de galaxies naines actives. Cependant, à ce jour, les preuves de l'existence de ces TNIs restent rares. À l'inverse, les trous noirs de masse stellaire sont présents dans la Voie lactée et les galaxies proches. Ils sont souvent détectés dans des binaires X (XRB), composées d'un objet compact - étoile à neutrons ou trou noir - qui accrète d'une étoile compagnon. Les sources X ultralumineuses (ULX), qui sont peut-être une version lumineuse des XRBs, seraient alimentées par l'accrétion super-Eddington sur des objets compacts de masse stellaire, mais le plus souvent sa nature et le mécanisme exact sont inconnus. Certaines sources X hyperlumineuse (HLX, défini comme un ULX ayant L_X>10^41 erg/s) pourraient être des bons candidats pour des TNIs. L'émission de rayons X étant une signature importante des systèmes accrétants, les relevés en rayons X sont l'endroit idéal pour trouver de nouveaux trous noirs. Les observatoires modernes en rayons X Swift, XMM-Newton et Chandra ont détecté environ un million de sources ponctuelles qui n'ont pas encore été identifiées. Avec ces télescopes et ceux à venir, une classification automatisée des sources de rayons X devient indispensable. Elle pourrait notamment réduire la part de contaminants qui sont souvent un frein dans l'étude des échantillons d'ULXs, HLXs et galaxies naines actives. Dans cette thèse, je développe une classification automatisée et probabiliste des sources de rayons X. Les catalogues Swift-XRT, XMM-Newton et Chandra sont corrélés entre eux et avec des catalogues optiques et infrarouges, ainsi que le recensement complet de galaxies GLADE. A partir de ces propriétés spatiales, spectrales, photométriques et temporelles, la classification identifie entre autres des populations d'AGN, d'étoiles et de XRBs, et peut être optimisée pour une classe d'intérêt. Les AGN et les étoiles sont classifiés avec précision, mais les autres classes ont de petits échantillons d'entraînement limitant la classification. Une expérience de science participative (CLAXSON) est proposée pour les augmenter. La classification est ensuite appliquée aux sources recouvrant les galaxies GLADE. 1901 candidats ULX sont identifiés, probablement l'échantillon le plus grand et propre de la littérature actuelle. Leurs distributions spatiale, spectrale et dans différents environnements sont étudiées. J'analyse leur fonction de luminosité et confirme la présence d'une cassure de la loi de puissance à L_X~10^40 erg/s pour les galaxies spirales. Les candidats HLX sont inspectés et de nombreux contaminants éliminés grâce à leur redshift. Les 191 candidats HLX restants sont comparés aux ULXs, montrant de légères différences peut-être dues à une gamme de masse d'accréteur différente. J'obtiens enfin 91 candidats galaxies naines actives. J'analyse la fraction active des galaxies dans différents intervalles de masse de galaxie et de luminosité limite, puis j'estime la fraction intrinsèque abritant un trou noir. En supposant que ces candidats AGN et HLX sont effectivement des trous noirs, leur distribution de masse de trou noir révèle une grande fraction de TNIs. J'analyse comment cette masse se compare à la masse de la galaxie. Des différences sont observées entre ces deux types de candidats et interprétées en termes de mécanismes de formation des TNIs

Recherche de populations de trous noirs non identifiées dans les archives en rayons X et multi-longueurs d'onde : application aux trous noirs de masse intermédiaire

Supermassive black holes (SMBH, 10^5-10^10 M_odot) have regularly been found at the center of massive galaxies. However, we still know little about their formation mechanism. Extremely luminous active galactic nuclei (AGN), revealing the presence of massive SMBHs, were detected in the high redshift Universe, a few 10^8 years after the Big Bang. A rapid growth mechanism is thus needed, such as a rapid accretion (beyond the Eddington limit) onto intermediate-mass black holes (IMBH, 10^2 - 10^5 M_odot), or the mergers of these black holes. Some of the original IMBHs may have avoided accretion or mergers, and thus still be found in the local Universe, for example as active dwarf galaxies. However, to date, the evidence for these IMBHs remains scarce. Conversely, stellar-mass black holes are found in the Milky Way and nearby galaxies. They are often detected in X-ray binaries (XRB), composed of a compact object - a neutron star or a black hole - accreting from a companion star. Ultraluminous X-ray sources (ULXs) may be a luminous version of the XRBs, and are thought to be powered by super-Eddingtonaccretion above the Eddington limit onto stellar-mass compact objects, but the most often the exact mechanism and the nature of the accretor are largely unknown. A few hyperluminous X-ray sources (HLXs, defined as ULXs with L_X> 10^{41} erg/s), may be good candidates for IMBHs. X-ray emission is a well-known signature of accreting systems, and thus X-ray surveys are the ideal place to search for new accreting black holes. The modern X-ray observatories Swift, XMM-Newton and Chandra have detected about a million point-like sources which are yet to be identified. With these and upcoming telescopes, an automated classification of X-ray sources becomes increasingly valuable. Using this approach could provide the cleanest samples possible, where currently contaminants limit population studies of ULXs, HLXs and active dwarf galaxy candidates. In this thesis I develop an automated and probabilistic classification of X-ray sources. The Swift-XRT, XMM-Newton and Chandra catalogues are cross-correlated with each othern with optical and infrared catalogues and with the highly complete census of galaxies GLADE. From these spatial, spectral, photometrical and timing properties, the classification identifies, amongst others, populations of AGN, stars and XRBs, and can be optimised to focus on one class. It efficiently retrieves AGN and stars, but other classes have small training samples limiting the classification performance. A citizen science experiment (CLAXSON) is proposed to enlarge these samples. The classification is then applied to X-ray sources overlapping GLADE galaxies. 1901 ULX candidates are accurately identified, where analysis indicates that it is the cleanest large sample in the current literature. Their spatial distribution, hardness, variability and rates in different environments are studied. I analyse their X-ray luminosity function and confirm the presence of a powerlaw break at a luminosity of 10^40 erg/s for spiral galaxies, tentatively proposed in previous studies. HLX candidates are inspected and cross-correlated with optical sources with redshift to remove possible contaminants. The resulting 191 HLX candidates are statistically compared to ULXs, showing tentative differences perhaps due to a different accretor mass range. Likewise, 91 active dwarf galaxy candidates are identified, where half of them appear to have an off-centre nucleus. I analyse the active fraction of dwarf galaxies in different bins of galaxy mass and limiting luminosity, and I estimate the intrinsic fraction harbouring a black hole. Assuming that these AGN and HLX candidates are indeed black holes, their black hole mass distribution suggests a large fraction of IMBHs. I analyse how this mass compares with galaxy mass. Differences are observed between the two types of candidates and interpreted in terms of IMBH formation mechanisms.Les trous noirs supermassifs (TNS, 10^5-10^10 M_odot) sont observés au centre de nombreuses galaxies massives. Pourtant, leur mécanisme de formation reste incertain. Une croissance rapide est nécessaire pour expliquer certains noyaux actifs de galaxies (AGN) vus à haut redshift, comme une accrétion rapide (au-delà de la limite d'Eddington) sur des trous noirs de masse intermédiaire (TNI, 10^2-10^5 M_odot), ou la fusion de ces trous noirs. Une partie de ces TNI pourrait avoir eu une faible croissance et se retrouver encore dans l'Univers local, par exemple sous forme de galaxies naines actives. Cependant, à ce jour, les preuves de l'existence de ces TNIs restent rares. À l'inverse, les trous noirs de masse stellaire sont présents dans la Voie lactée et les galaxies proches. Ils sont souvent détectés dans des binaires X (XRB), composées d'un objet compact - étoile à neutrons ou trou noir - qui accrète d'une étoile compagnon. Les sources X ultralumineuses (ULX), qui sont peut-être une version lumineuse des XRBs, seraient alimentées par l'accrétion super-Eddington sur des objets compacts de masse stellaire, mais le plus souvent sa nature et le mécanisme exact sont inconnus. Certaines sources X hyperlumineuse (HLX, défini comme un ULX ayant L_X>10^41 erg/s) pourraient être des bons candidats pour des TNIs. L'émission de rayons X étant une signature importante des systèmes accrétants, les relevés en rayons X sont l'endroit idéal pour trouver de nouveaux trous noirs. Les observatoires modernes en rayons X Swift, XMM-Newton et Chandra ont détecté environ un million de sources ponctuelles qui n'ont pas encore été identifiées. Avec ces télescopes et ceux à venir, une classification automatisée des sources de rayons X devient indispensable. Elle pourrait notamment réduire la part de contaminants qui sont souvent un frein dans l'étude des échantillons d'ULXs, HLXs et galaxies naines actives. Dans cette thèse, je développe une classification automatisée et probabiliste des sources de rayons X. Les catalogues Swift-XRT, XMM-Newton et Chandra sont corrélés entre eux et avec des catalogues optiques et infrarouges, ainsi que le recensement complet de galaxies GLADE. A partir de ces propriétés spatiales, spectrales, photométriques et temporelles, la classification identifie entre autres des populations d'AGN, d'étoiles et de XRBs, et peut être optimisée pour une classe d'intérêt. Les AGN et les étoiles sont classifiés avec précision, mais les autres classes ont de petits échantillons d'entraînement limitant la classification. Une expérience de science participative (CLAXSON) est proposée pour les augmenter. La classification est ensuite appliquée aux sources recouvrant les galaxies GLADE. 1901 candidats ULX sont identifiés, probablement l'échantillon le plus grand et propre de la littérature actuelle. Leurs distributions spatiale, spectrale et dans différents environnements sont étudiées. J'analyse leur fonction de luminosité et confirme la présence d'une cassure de la loi de puissance à L_X~10^40 erg/s pour les galaxies spirales. Les candidats HLX sont inspectés et de nombreux contaminants éliminés grâce à leur redshift. Les 191 candidats HLX restants sont comparés aux ULXs, montrant de légères différences peut-être dues à une gamme de masse d'accréteur différente. J'obtiens enfin 91 candidats galaxies naines actives. J'analyse la fraction active des galaxies dans différents intervalles de masse de galaxie et de luminosité limite, puis j'estime la fraction intrinsèque abritant un trou noir. En supposant que ces candidats AGN et HLX sont effectivement des trous noirs, leur distribution de masse de trou noir révèle une grande fraction de TNIs. J'analyse comment cette masse se compare à la masse de la galaxie. Des différences sont observées entre ces deux types de candidats et interprétées en termes de mécanismes de formation des TNIs

Mining X-ray and multiwavelength archives for hidden black hole populations : application to intermediate-massblack holes

Les trous noirs supermassifs (TNS, 10^5-10^10 M_odot) sont observés au centre de nombreuses galaxies massives. Pourtant, leur mécanisme de formation reste incertain. Une croissance rapide est nécessaire pour expliquer certains noyaux actifs de galaxies (AGN) vus à haut redshift, comme une accrétion rapide (au-delà de la limite d'Eddington) sur des trous noirs de masse intermédiaire (TNI, 10^2-10^5 M_odot), ou la fusion de ces trous noirs. Une partie de ces TNI pourrait avoir eu une faible croissance et se retrouver encore dans l'Univers local, par exemple sous forme de galaxies naines actives. Cependant, à ce jour, les preuves de l'existence de ces TNIs restent rares. À l'inverse, les trous noirs de masse stellaire sont présents dans la Voie lactée et les galaxies proches. Ils sont souvent détectés dans des binaires X (XRB), composées d'un objet compact - étoile à neutrons ou trou noir - qui accrète d'une étoile compagnon. Les sources X ultralumineuses (ULX), qui sont peut-être une version lumineuse des XRBs, seraient alimentées par l'accrétion super-Eddington sur des objets compacts de masse stellaire, mais le plus souvent sa nature et le mécanisme exact sont inconnus. Certaines sources X hyperlumineuse (HLX, défini comme un ULX ayant L_X>10^41 erg/s) pourraient être des bons candidats pour des TNIs. L'émission de rayons X étant une signature importante des systèmes accrétants, les relevés en rayons X sont l'endroit idéal pour trouver de nouveaux trous noirs. Les observatoires modernes en rayons X Swift, XMM-Newton et Chandra ont détecté environ un million de sources ponctuelles qui n'ont pas encore été identifiées. Avec ces télescopes et ceux à venir, une classification automatisée des sources de rayons X devient indispensable. Elle pourrait notamment réduire la part de contaminants qui sont souvent un frein dans l'étude des échantillons d'ULXs, HLXs et galaxies naines actives. Dans cette thèse, je développe une classification automatisée et probabiliste des sources de rayons X. Les catalogues Swift-XRT, XMM-Newton et Chandra sont corrélés entre eux et avec des catalogues optiques et infrarouges, ainsi que le recensement complet de galaxies GLADE. A partir de ces propriétés spatiales, spectrales, photométriques et temporelles, la classification identifie entre autres des populations d'AGN, d'étoiles et de XRBs, et peut être optimisée pour une classe d'intérêt. Les AGN et les étoiles sont classifiés avec précision, mais les autres classes ont de petits échantillons d'entraînement limitant la classification. Une expérience de science participative (CLAXSON) est proposée pour les augmenter. La classification est ensuite appliquée aux sources recouvrant les galaxies GLADE. 1901 candidats ULX sont identifiés, probablement l'échantillon le plus grand et propre de la littérature actuelle. Leurs distributions spatiale, spectrale et dans différents environnements sont étudiées. J'analyse leur fonction de luminosité et confirme la présence d'une cassure de la loi de puissance à L_X~10^40 erg/s pour les galaxies spirales. Les candidats HLX sont inspectés et de nombreux contaminants éliminés grâce à leur redshift. Les 191 candidats HLX restants sont comparés aux ULXs, montrant de légères différences peut-être dues à une gamme de masse d'accréteur différente. J'obtiens enfin 91 candidats galaxies naines actives. J'analyse la fraction active des galaxies dans différents intervalles de masse de galaxie et de luminosité limite, puis j'estime la fraction intrinsèque abritant un trou noir. En supposant que ces candidats AGN et HLX sont effectivement des trous noirs, leur distribution de masse de trou noir révèle une grande fraction de TNIs. J'analyse comment cette masse se compare à la masse de la galaxie. Des différences sont observées entre ces deux types de candidats et interprétées en termes de mécanismes de formation des TNIs.Supermassive black holes (SMBH, 10^5-10^10 M_odot) have regularly been found at the center of massive galaxies. However, we still know little about their formation mechanism. Extremely luminous active galactic nuclei (AGN), revealing the presence of massive SMBHs, were detected in the high redshift Universe, a few 10^8 years after the Big Bang. A rapid growth mechanism is thus needed, such as a rapid accretion (beyond the Eddington limit) onto intermediate-mass black holes (IMBH, 10^2 - 10^5 M_odot), or the mergers of these black holes. Some of the original IMBHs may have avoided accretion or mergers, and thus still be found in the local Universe, for example as active dwarf galaxies. However, to date, the evidence for these IMBHs remains scarce. Conversely, stellar-mass black holes are found in the Milky Way and nearby galaxies. They are often detected in X-ray binaries (XRB), composed of a compact object - a neutron star or a black hole - accreting from a companion star. Ultraluminous X-ray sources (ULXs) may be a luminous version of the XRBs, and are thought to be powered by super-Eddingtonaccretion above the Eddington limit onto stellar-mass compact objects, but the most often the exact mechanism and the nature of the accretor are largely unknown. A few hyperluminous X-ray sources (HLXs, defined as ULXs with L_X> 10^{41} erg/s), may be good candidates for IMBHs. X-ray emission is a well-known signature of accreting systems, and thus X-ray surveys are the ideal place to search for new accreting black holes. The modern X-ray observatories Swift, XMM-Newton and Chandra have detected about a million point-like sources which are yet to be identified. With these and upcoming telescopes, an automated classification of X-ray sources becomes increasingly valuable. Using this approach could provide the cleanest samples possible, where currently contaminants limit population studies of ULXs, HLXs and active dwarf galaxy candidates. In this thesis I develop an automated and probabilistic classification of X-ray sources. The Swift-XRT, XMM-Newton and Chandra catalogues are cross-correlated with each othern with optical and infrared catalogues and with the highly complete census of galaxies GLADE. From these spatial, spectral, photometrical and timing properties, the classification identifies, amongst others, populations of AGN, stars and XRBs, and can be optimised to focus on one class. It efficiently retrieves AGN and stars, but other classes have small training samples limiting the classification performance. A citizen science experiment (CLAXSON) is proposed to enlarge these samples. The classification is then applied to X-ray sources overlapping GLADE galaxies. 1901 ULX candidates are accurately identified, where analysis indicates that it is the cleanest large sample in the current literature. Their spatial distribution, hardness, variability and rates in different environments are studied. I analyse their X-ray luminosity function and confirm the presence of a powerlaw break at a luminosity of 10^40 erg/s for spiral galaxies, tentatively proposed in previous studies. HLX candidates are inspected and cross-correlated with optical sources with redshift to remove possible contaminants. The resulting 191 HLX candidates are statistically compared to ULXs, showing tentative differences perhaps due to a different accretor mass range. Likewise, 91 active dwarf galaxy candidates are identified, where half of them appear to have an off-centre nucleus. I analyse the active fraction of dwarf galaxies in different bins of galaxy mass and limiting luminosity, and I estimate the intrinsic fraction harbouring a black hole. Assuming that these AGN and HLX candidates are indeed black holes, their black hole mass distribution suggests a large fraction of IMBHs. I analyse how this mass compares with galaxy mass. Differences are observed between the two types of candidates and interpreted in terms of IMBH formation mechanisms

Recherche de populations de trous noirs non identifiées dans les archives en rayons X et multi-longueurs d'onde : application aux trous noirs de masse intermédiaire

Supermassive black holes (SMBH, 10^5-10^10 M_odot) have regularly been found at the center of massive galaxies. However, we still know little about their formation mechanism. Extremely luminous active galactic nuclei (AGN), revealing the presence of massive SMBHs, were detected in the high redshift Universe, a few 10^8 years after the Big Bang. A rapid growth mechanism is thus needed, such as a rapid accretion (beyond the Eddington limit) onto intermediate-mass black holes (IMBH, 10^2 - 10^5 M_odot), or the mergers of these black holes. Some of the original IMBHs may have avoided accretion or mergers, and thus still be found in the local Universe, for example as active dwarf galaxies. However, to date, the evidence for these IMBHs remains scarce. Conversely, stellar-mass black holes are found in the Milky Way and nearby galaxies. They are often detected in X-ray binaries (XRB), composed of a compact object - a neutron star or a black hole - accreting from a companion star. Ultraluminous X-ray sources (ULXs) may be a luminous version of the XRBs, and are thought to be powered by super-Eddingtonaccretion above the Eddington limit onto stellar-mass compact objects, but the most often the exact mechanism and the nature of the accretor are largely unknown. A few hyperluminous X-ray sources (HLXs, defined as ULXs with L_X> 10^{41} erg/s), may be good candidates for IMBHs. X-ray emission is a well-known signature of accreting systems, and thus X-ray surveys are the ideal place to search for new accreting black holes. The modern X-ray observatories Swift, XMM-Newton and Chandra have detected about a million point-like sources which are yet to be identified. With these and upcoming telescopes, an automated classification of X-ray sources becomes increasingly valuable. Using this approach could provide the cleanest samples possible, where currently contaminants limit population studies of ULXs, HLXs and active dwarf galaxy candidates. In this thesis I develop an automated and probabilistic classification of X-ray sources. The Swift-XRT, XMM-Newton and Chandra catalogues are cross-correlated with each othern with optical and infrared catalogues and with the highly complete census of galaxies GLADE. From these spatial, spectral, photometrical and timing properties, the classification identifies, amongst others, populations of AGN, stars and XRBs, and can be optimised to focus on one class. It efficiently retrieves AGN and stars, but other classes have small training samples limiting the classification performance. A citizen science experiment (CLAXSON) is proposed to enlarge these samples. The classification is then applied to X-ray sources overlapping GLADE galaxies. 1901 ULX candidates are accurately identified, where analysis indicates that it is the cleanest large sample in the current literature. Their spatial distribution, hardness, variability and rates in different environments are studied. I analyse their X-ray luminosity function and confirm the presence of a powerlaw break at a luminosity of 10^40 erg/s for spiral galaxies, tentatively proposed in previous studies. HLX candidates are inspected and cross-correlated with optical sources with redshift to remove possible contaminants. The resulting 191 HLX candidates are statistically compared to ULXs, showing tentative differences perhaps due to a different accretor mass range. Likewise, 91 active dwarf galaxy candidates are identified, where half of them appear to have an off-centre nucleus. I analyse the active fraction of dwarf galaxies in different bins of galaxy mass and limiting luminosity, and I estimate the intrinsic fraction harbouring a black hole. Assuming that these AGN and HLX candidates are indeed black holes, their black hole mass distribution suggests a large fraction of IMBHs. I analyse how this mass compares with galaxy mass. Differences are observed between the two types of candidates and interpreted in terms of IMBH formation mechanisms.Les trous noirs supermassifs (TNS, 10^5-10^10 M_odot) sont observés au centre de nombreuses galaxies massives. Pourtant, leur mécanisme de formation reste incertain. Une croissance rapide est nécessaire pour expliquer certains noyaux actifs de galaxies (AGN) vus à haut redshift, comme une accrétion rapide (au-delà de la limite d'Eddington) sur des trous noirs de masse intermédiaire (TNI, 10^2-10^5 M_odot), ou la fusion de ces trous noirs. Une partie de ces TNI pourrait avoir eu une faible croissance et se retrouver encore dans l'Univers local, par exemple sous forme de galaxies naines actives. Cependant, à ce jour, les preuves de l'existence de ces TNIs restent rares. À l'inverse, les trous noirs de masse stellaire sont présents dans la Voie lactée et les galaxies proches. Ils sont souvent détectés dans des binaires X (XRB), composées d'un objet compact - étoile à neutrons ou trou noir - qui accrète d'une étoile compagnon. Les sources X ultralumineuses (ULX), qui sont peut-être une version lumineuse des XRBs, seraient alimentées par l'accrétion super-Eddington sur des objets compacts de masse stellaire, mais le plus souvent sa nature et le mécanisme exact sont inconnus. Certaines sources X hyperlumineuse (HLX, défini comme un ULX ayant L_X>10^41 erg/s) pourraient être des bons candidats pour des TNIs. L'émission de rayons X étant une signature importante des systèmes accrétants, les relevés en rayons X sont l'endroit idéal pour trouver de nouveaux trous noirs. Les observatoires modernes en rayons X Swift, XMM-Newton et Chandra ont détecté environ un million de sources ponctuelles qui n'ont pas encore été identifiées. Avec ces télescopes et ceux à venir, une classification automatisée des sources de rayons X devient indispensable. Elle pourrait notamment réduire la part de contaminants qui sont souvent un frein dans l'étude des échantillons d'ULXs, HLXs et galaxies naines actives. Dans cette thèse, je développe une classification automatisée et probabiliste des sources de rayons X. Les catalogues Swift-XRT, XMM-Newton et Chandra sont corrélés entre eux et avec des catalogues optiques et infrarouges, ainsi que le recensement complet de galaxies GLADE. A partir de ces propriétés spatiales, spectrales, photométriques et temporelles, la classification identifie entre autres des populations d'AGN, d'étoiles et de XRBs, et peut être optimisée pour une classe d'intérêt. Les AGN et les étoiles sont classifiés avec précision, mais les autres classes ont de petits échantillons d'entraînement limitant la classification. Une expérience de science participative (CLAXSON) est proposée pour les augmenter. La classification est ensuite appliquée aux sources recouvrant les galaxies GLADE. 1901 candidats ULX sont identifiés, probablement l'échantillon le plus grand et propre de la littérature actuelle. Leurs distributions spatiale, spectrale et dans différents environnements sont étudiées. J'analyse leur fonction de luminosité et confirme la présence d'une cassure de la loi de puissance à L_X~10^40 erg/s pour les galaxies spirales. Les candidats HLX sont inspectés et de nombreux contaminants éliminés grâce à leur redshift. Les 191 candidats HLX restants sont comparés aux ULXs, montrant de légères différences peut-être dues à une gamme de masse d'accréteur différente. J'obtiens enfin 91 candidats galaxies naines actives. J'analyse la fraction active des galaxies dans différents intervalles de masse de galaxie et de luminosité limite, puis j'estime la fraction intrinsèque abritant un trou noir. En supposant que ces candidats AGN et HLX sont effectivement des trous noirs, leur distribution de masse de trou noir révèle une grande fraction de TNIs. J'analyse comment cette masse se compare à la masse de la galaxie. Des différences sont observées entre ces deux types de candidats et interprétées en termes de mécanismes de formation des TNIs

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

International audienceUltra-/hyperluminous X-ray sources (ULX/HLX) could be interesting laboratories to further 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 onto stellar-mass compact objects, while HLXs may be accreting intermediate mass black holes (IMBH). However, a significant portion of the sample of ULX/HLX candidates derived from catalogue searches are background AGN. Here we build ULX and HLX samples from recent XMM-Newton, Swift-XRT and Chandra catalogues and the GLADE catalogue of galaxies. We aim to characterise the frequency, environment, hardness and variability 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 the occupation fraction, hardness, variability, radial distribution and preferred environment of the sources. We build their Malmquist-corrected X-ray luminosity functions (XLF) and compare them with previous studies. We statistically compare ULXs and HLXs and assess the differences in their nature. The interpretation of HLXs as IMBHs is investigated. A significant break is seen in the XLF at $\sim 10^{40}$ erg/s. Our ULX sample, having $\leq 2$% of contaminants, confirms that ULXs are located preferentially in spiral galaxies and galaxies with higher star-formation rates. Unlike ULXs, HLXs seem to reside equally in spiral and lenticular/elliptical galaxies. 35% of the HLX candidates have an optical counterpart, and we estimate the mass of 120 of them in the range of $2000-10^5 M_\odot$. Most HLXs are consistent with an accreting massive black hole in a dwarf galaxy satellite

Classification probabiliste des sources de rayons X appliquées aux catalogues de Swift-XRT et XMM-Newton

International audienceContext. Serendipitous X-ray surveys have proven to be an efficient way to find rare objects e.g. tidal disruption events, changing-look AGN, binary quasars, ultraluminous X-ray sources, intermediate mass black holes. With the advent of very large X-ray surveys, an automated classification of X-ray sources becomes increasingly valuable. Aims. This work proposes a revisited Naive Bayes Classification of the X-ray sources in the Swift-XRT and XMM-Newton catalogs into 4 classes − AGN, star, X-ray binary (XRB) and cataclysmic variable (CV) − based on their spatial, spectral and timing properties and their multiwavelength counterparts. An outlier measure is used to identify objects of other nature. The classifier is optimized to maximize the classification performance of a chosen class (here X-ray binaries) and it is adapted to data mining purposes. Methods. We augmented the X-ray catalogs with multiwavelength data, source class, and variability properties. We then built a reference sample of about 25000 X-ray sources of known nature. From this sample the distribution of each property is carefully estimated and taken as reference to assign probabilities of belonging to each class. The classification is then performed on the whole catalog, combining the information from each property. Results. Using the algorithm on the Swift reference sample we retrieved 99%, 98%, 92% and 34% of AGN, stars, XRBs and CVs respectively, and the false positive rates are 3%, 1%, 9% and 15%. Similar results are obtained on XMM sources. When applied to a carefully selected test sample, representing 55% of the X-ray catalog, the classification gives consistent results in terms of distributions of source properties. A substantial fraction of sources not belonging to any class is efficiently retrieved using the outlier measure, as well as AGN and stars with properties deviating from the bulk of their class. Our algorithm is then compared to a Random Forest method, showing similar performance but the algorithm presented in this paper improved insight into the grounds of each classification. Conclusions. This robust classification method can be tailored to include additional or different source classes and applied to other X-ray catalogs. The transparency of the classification compared to other methods makes it a useful tool in the search for homogeneous populations or rare source types, including multi-messenger events. Such a tool will be increasingly valuable with the development of surveys of unprecedented size, such as LSST, SKA and Athena, and the search for counterparts of multi-messenger events

Probabilistic classification of X-ray sources applied to Swift-XRT and XMM-Newton catalogs

International audienceContext. Serendipitous X-ray surveys have proven to be an efficient way to find rare objects, for example tidal disruption events, changing-look active galactic nuclei (AGN), binary quasars, ultraluminous X-ray sources, and intermediate mass black holes. With the advent of very large X-ray surveys, an automated classification of X-ray sources becomes increasingly valuable.Aims. This work proposes a revisited naive Bayes classification of the X-ray sources in the Swift-XRT and XMM-Newton catalogs into four classes – AGN, stars, X-ray binaries (XRBs), and cataclysmic variables (CVs) – based on their spatial, spectral, and timing properties and their multiwavelength counterparts. An outlier measure is used to identify objects of other natures. The classifier is optimized to maximize the classification performance of a chosen class (here XRBs), and it is adapted to data mining purposes.Methods. We augmented the X-ray catalogs with multiwavelength data, source class, and variability properties. We then built a reference sample of about 25 000 X-ray sources of known nature. From this sample, the distribution of each property was carefully estimated and taken as reference to assign probabilities of belonging to each class. The classification was then performed on the whole catalog, combining the information from each property.Results. Using the algorithm on the Swift reference sample, we retrieved 99%, 98%, 92%, and 34% of AGN, stars, XRBs, and CVs, respectively, and the false positive rates are 3%, 1%, 9%, and 15%. Similar results are obtained on XMM sources. When applied to a carefully selected test sample, representing 55% of the X-ray catalog, the classification gives consistent results in terms of distributions of source properties. A substantial fraction of sources not belonging to any class is efficiently retrieved using the outlier measure, as well as AGN and stars with properties deviating from the bulk of their class. Our algorithm is then compared to a random forest method; the two showed similar performances, but the algorithm presented in this paper improved insight into the grounds of each classification.Conclusions. This robust classification method can be tailored to include additional or different source classes and can be applied to other X-ray catalogs. The transparency of the classification compared to other methods makes it a useful tool in the search for homogeneous populations or rare source types, including multi-messenger events. Such a tool will be increasingly valuable with the development of surveys of unprecedented size, such as LSST, SKA, and Athena, and the search for counterparts of multi-messenger events

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

[Context] Ultraluminous and hyperluminous X-ray (ULX and HLX) sources could constitute interesting laboratories to further 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 onto stellar-mass compact objects, while HLXs are of an unknown nature, but they could be good candidates for accreting intermediate mass black holes (IMBHs). However, a significant portion of the sample of ULX and HLX candidates derived from catalogue searches are in fact background active galactic nuclei (AGN).[Aims] Here we build samples of ULXs and HLXs from the three largest X-ray catalogues available, compiled from XMM-Newton, Swift-XRT, and Chandra detections, and the GLADE catalogue containing 1.7 million galaxies at D  3 which were shown to be contaminants, to obtain the cleanest sample of ULXs and HLXs to date. From a sample of 1342 ULXs and 191 HLXs detected with a S/N > 3σ, we study the occupation fraction, hardness, variability, radial distribution, and preferred environment of the sources. We built their Malmquist-corrected X-ray luminosity functions (XLFs) and compared them with previous studies. Thanks to the unprecedented size of the sample, we were able to statistically compare ULXs and HLXs and assess the differences in their nature. The interpretation of HLXs as IMBHs is investigated.[Results] A significant break is seen in the XLF at ∼1040 erg s−1. With our ULX sample, containing ≲2% of contaminants, we are able to confirm that ULXs are located preferentially in spiral galaxies and galaxies with higher star formation rates. While X-ray binaries (XRBs), ULXs, and most HLXs share common hardness and variability distributions, a fraction of HLXs appear significantly softer. Unlike ULXs, HLXs seem to reside equally in spiral as well as lenticular and elliptical galaxies. We note that 35% of the HLX candidates have an optical counterpart, and we estimate the mass of 120 of them to be in the range of 2 × 103 − 105 M⊙. Most of the HLX population is found to be consistent with an accreting massive black hole in a dwarf galaxy satellite of the primary host. This diverse nature needs to be confirmed with deeper optical and infrared observations, as well as upcoming X-ray facilities.This work benefited from support from the CNES. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement n°101004168, the XMM2ATHENA project.Peer reviewe

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

International audienceXMM-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