Astronomy & Astrophysics最新文献

{"title":"Using the STIX background detector as a proxy for GOES","authors":"Muriel Zoë Stiefel, Matej Kuhar, Olivier Limousin, Ewan C. M. Dickson, Anna Volpara, Gordon J. Hurford, Säm Krucker","doi":"10.1051/0004-6361/202452574","DOIUrl":"https://doi.org/10.1051/0004-6361/202452574","url":null,"abstract":"<i>Context.<i/> The Spectrometer/Telescope for Imaging X-Rays (STIX) on board Solar Orbiter was designed to observe solar flares in the X-ray range of 4−150 keV, providing spectral, temporal, and spatial information. Besides 30 imaging detectors, STIX has two additional detectors: the coarse flare locator (CFL) and the background (BKG) detector, which are used in the present study. Flares observed from Earth are classified using their peak X-ray flux observed by the Geostationary Operational Environmental Satellite (GOES) instruments. Given to the Solar Orbiter mission design, roughly half of all flares observed by STIX are located on the backside of the Sun. These flares lack a GOES-class classification.<i>Aims.<i/> In this paper, we describe the calibration of the BKG detector aperture sizes. Using the calibrated measurements of the BKG detector, we explore the relationship between the peak flux for flares jointly observed by STIX and GOES. This allows us to estimate the GOES flare classes of backside flares using STIX measurements.<i>Methods.<i/> We looked at the 500 largest flares observed by both STIX and GOES in the time range February 2021 to April 2023. The aperture size calibration was done by comparing 4−10 keV counts of the BKG detector with the CFL measurements. In a second step, we correlated the calibrated STIX BKG peak flux with the GOES peak flux for individual flares.<i>Results.<i/> We calibrated the BKG detector aperture sizes of STIX, which are now ready to be implemented into the ground-software (GSW) of STIX. Furthermore, we showed that for the larger flares (C class and above) a close power law fit exists between the STIX BKG and GOES peak flux, with a Pearson correlation coefficient of 0.97. This correlation provides a GOES proxy with a one sigma uncertainty of ≈11%. We were able to show that the BKG detector can reliably measure a broad range of GOES flare classes from roughly B5 up to at least X85 (assuming a radial distance of 1 AU). This makes it an interesting detector-concept for future space weather missions. Thus far, the largest flare observed by STIX to date is an estimated X16.5 ± 1.8 backside flare of May 20, 2024.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"44 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The relation between black hole spin, star formation rate, and black hole mass for supermassive black holes","authors":"Yongyun Chen, Qiusheng Gu, Junhui Fan, Xiaotong Guo, Dingrong Xiong, Xiaoling Yu, Xiaogu Zhong, Nan Ding","doi":"10.1051/0004-6361/202452655","DOIUrl":"https://doi.org/10.1051/0004-6361/202452655","url":null,"abstract":"Both theoretical models and observational evidence indicate that jets and/or outflows driven by central active supermassive black holes exert a significant feedback effect on the overall properties of their host galaxies. Theoretical models suggest that the spin of supermassive black holes drives relativistic jets. Therefore, we investigate the relationship between black hole spin, star formation rate, and black hole mass using a sample of 48 low-redshift supermassive black holes. By performing multiband fitting of spectral energy distribution, we derive the star formation rates and stellar masses of the host galaxies harbouring these supermassive black holes. Our main results are as follows: (i) For black holes with masses <i>M<i/><sub>BH<sub/> ≲ 10<sup>6.5<sup/> <i>M<i/><sub>⊙<sub/>, the spin increases with increasing black hole mass, suggesting that black hole growth is primarily driven by gas accretion, particularly in the coherent gas accretion regime. Conversely, for black holes with masses <i>M<i/><sub>BH<sub/> ≳ 10<sup>7.5<sup/> <i>M<i/><sub>⊙<sub/>, the spin decreases with increasing black hole mass, indicating that growth occurs mainly through mergers, inducing chaotic accretion. (ii) At low star formation rates, black hole spin increases with increasing star formation rates, consistent with gas accretion. However, at high star formation rates, black hole spin decreases with increasing star formation rates, suggesting black hole mergers. The value of the black hole spin may be used to diagnose the star formation rate of the host galaxies through active galactic nuclei activities. (iii) Our data and analysis confirm the well-known relation between stellar mass and black hole mass, with the fitting function log <i>M<i/><sub>BH<sub/> = 0.57log <i>M<i/><sub>*<sub/> + 1.94.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"29 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A candidate quadruple AGN system at z ∼ 3","authors":"Eileen Herwig, Fabrizio Arrigoni Battaia, Eduardo Bañados, Emanuele P. Farina","doi":"10.1051/0004-6361/202452452","DOIUrl":"https://doi.org/10.1051/0004-6361/202452452","url":null,"abstract":"Multiple galaxies hosting active galactic nuclei (AGNs) at kiloparsec separations from each other are exceedingly rare, and in fact, only one quadruple AGN is known so far. These extreme densities of AGNs are expected to pinpoint protocluster environments and therefore should be surrounded by large galaxy overdensities. In this Letter, we present another quadruple AGN candidate at <i>z<i/> ∼ 3 including two SDSS quasars at a separation of roughly 480 kpc. The brighter quasar is accompanied by two AGN candidates (a type 1 AGN and a likely type 2 quasar) at a close (∼20 kpc) separation identified through emission line ratios, line widths, and high ionization lines, such as N V <i>λ<i/>1240. The extended Ly<i>α<i/> emission associated with the close triple system is more modest in extent and brightness compared to similar multiple AGN systems and could be caused by ram-pressure stripping of the type 2 quasar host during infall into the central dark matter halo. The predicted evolution of the system into a <i>z<i/> = 0 galaxy cluster with the AGN host galaxies forming the brightest cluster galaxy needs to be further tested by galaxy overdensity studies on large scales around the quadruple AGN candidate. If confirmed as a quadruple AGN with X-ray observations or rest-frame optical line ratios, this system would represent a second AGN quartet and be the highest-redshift multiplet and the closest high-redshift triplet known.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"208 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Euclid: A complete Einstein ring in NGC 6505⋆","authors":"C. M. O’Riordan, L. J. Oldham, A. Nersesian, T. Li, T. E. Collett, D. Sluse, B. Altieri, B. Clément, K. G. C. Vasan, S. Rhoades, Y. Chen, T. Jones, C. Adami, R. Gavazzi, S. Vegetti, D. M. Powell, J. A. Acevedo Barroso, I. T. Andika, R. Bhatawdekar, A. R. Cooray, G. Despali, J. M. Diego, L. R. Ecker, A. Galan, P. Gómez-Alvarez, L. Leuzzi, M. Meneghetti, R. B. Metcalf, M. Schirmer, S. Serjeant, C. Tortora, M. Vaccari, G. Vernardos, M. Walmsley, A. Amara, S. Andreon, N. Auricchio, H. Aussel, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, A. Basset, P. Battaglia, R. Bender, D. Bonino, E. Branchini, M. Brescia, J. Brinchmann, A. Caillat, S. Camera, V. Capobianco, C. Carbone, J. Carretero, S. Casas, F. J. Castander, M. Castellano, G. Castignani, S. Cavuoti, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, L. Corcione, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, G. De Lucia, A. M. Di Giorgio, J. Dinis, F. Dubath, C. A. J. Duncan, X. Dupac, S. Dusini, M. Farina, S. Farrens, F. Faustini, S. Ferriol, N. Fourmanoit, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, W. Gillard, B. Gillis, C. Giocoli, B. R. Granett, A. Grazian, F. Grupp, L. Guzzo, S. V. H. Haugan, J. Hoar, H. Hoekstra, W. Holmes, I. Hook, F. Hormuth, A. Hornstrup, P. Hudelot, K. Jahnke, M. Jhabvala, B. Joachimi, E. Keihänen, S. Kermiche, A. Kiessling, M. Kilbinger, R. Kohley, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, O. Lahav, R. Laureijs, D. Le Mignant, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, E. Maiorano, O. Mansutti, O. Marggraf, K. Markovic, M. Martinelli, N. Martinet, F. Marulli, R. Massey, E. Medinaceli, S. Mei, M. Melchior, Y. Mellier, E. Merlin, G. Meylan, M. Moresco, L. Moscardini, R. Nakajima, R. C. Nichol, S.-M. Niemi, J. W. Nightingale, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, F. Raison, R. Rebolo, A. Renzi, J. Rhodes, G. Riccio, H.-W. Rix, E. Romelli, M. Roncarelli, E. Rossetti, B. Rusholme, R. Saglia, Z. Sakr, A. G. Sánchez, D. Sapone, B. Sartoris, P. Schneider, T. Schrabback, A. Secroun, G. Seidel, S. Serrano, C. Sirignano, G. Sirri, L. Stanco, J. Steinwagner, P. Tallada-Crespí, I. Tereno, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, L. Valenziano, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, A. Zacchei, G. Zamorani, E. Zucca, C. Burigana, P. Casenove, A. Mora, V. Scottez, M. Viel, M. Jauzac, H. Dannerbauer","doi":"10.1051/0004-6361/202453014","DOIUrl":"https://doi.org/10.1051/0004-6361/202453014","url":null,"abstract":"We report the discovery of a complete Einstein ring around the elliptical galaxy NGC 6505, at <i>z<i/> = 0.042. This is the first strong gravitational lens discovered in <i>Euclid<i/> and the first in an NGC object from any survey. The combination of the low redshift of the lens galaxy, the brightness of the source galaxy (<i>I<i/><sub>E<sub/> = 18.1 lensed, <i>I<i/><sub>E<sub/> = 21.3 unlensed), and the completeness of the ring make this an exceptionally rare strong lens, unidentified until its observation by <i>Euclid<i/>. We present deep imaging data of the lens from the <i>Euclid<i/> Visible Camera (VIS) and Near-Infrared Spectrometer and Photometer (NISP) instruments, as well as resolved spectroscopy from the <i>Keck<i/> Cosmic Web Imager (KCWI). The <i>Euclid<i/> imaging in particular presents one of the highest signal-to-noise ratio optical/near-infrared observations of a strong gravitational lens to date. From the KCWI data we measure a source redshift of <i>z<i/> = 0.406. Using data from the Dark Energy Spectroscopic Instrument (DESI) we measure a velocity dispersion for the lens galaxy of <i>σ<i/><sub>⋆<sub/> = 303 ± 15 km s<sup>−1<sup/>. We model the lens galaxy light in detail, revealing angular structure that varies inside the Einstein ring. After subtracting this light model from the VIS observation, we model the strongly lensed images, finding an Einstein radius of , corresponding to 2.1 kpc at the redshift of the lens. This is small compared to the effective radius of the galaxy, . Combining the strong lensing measurements with analysis of the spectroscopic data we estimate a dark matter fraction inside the Einstein radius of and a stellar initial mass-function (IMF) mismatch parameter of , indicating a heavier-than-Chabrier IMF in the centre of the galaxy.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"41 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MusE GAs FLOw and Wind (MEGAFLOW)","authors":"Maxime Cherrey, Nicolas F. Bouché, Johannes Zabl, Ilane Schroetter, Martin Wendt, Ivanna Langan, Joop Schaye, Lutz Wisotzki, Yucheng Guo, Ismael Pessa","doi":"10.1051/0004-6361/202451165","DOIUrl":"https://doi.org/10.1051/0004-6361/202451165","url":null,"abstract":"<i>Aims.<i/> The circumgalactic medium (CGM) is a key component in understanding the physical processes governing the flows of gas around galaxies. Quantifying its evolution and its dependence on galaxy properties is particularly important for our understanding of accretion and feedback mechanisms.<i>Methods.<i/> We selected a volume-selected sample of 66 isolated star-forming galaxies at 0.4 < <i>z<i/> < 1.5 with log(<i>M<i/><sub>⋆<sub/>/M<sub>⊙<sub/>) > 9 from the MusE GAs FLOw and Wind (MEGAFLOW) survey. Using Mg II<i>λλ<i/>2796,2803 absorptions in background quasars, we measured the covering fraction, <i>f<i/><sub><i>c<i/><sub/>, and quantified how the cool gas profile depends on galaxy properties (such as star formation rate (SFR), stellar mass (<i>M<i/><sub>⋆<sub/>) or azimuthal angle relative to the line of sight) and how these dependencies evolve with redshift.<i>Results.<i/> The Mg II covering fraction of isolated galaxies is a strong function of impact parameter and is steeper than previously reported. The impact parameter, <i>b<i/><sub>50<sub/>, at which <i>f<i/><sub><i>c<i/><sub/> = 50% is <i>b<i/><sub>50<sub/> = 50 ± 7 kpc for > 0.5 Å. It is weakly correlated with SFR (∝SFR<sup>0.08 ± 0.09<sup/>) and decreases with cosmic time (∝(1 + <i>z<i/>)<sup>0.8 ± 0.7<sup/>), contrary to the expectation of increasingly larger halos with time. The covering fraction is also higher along the minor axis than along the major axis at the ≈2<i>σ<i/> level.<i>Conclusions.<i/> The CGM traced by Mg II is similar across the isolated galaxy population. Indeed, among the isolated galaxies with an impact parameter below 55 kpc, all have associated Mg II absorption with > 0.3 Å, resulting in a steep covering fraction, <i>f<i/><sub><i>c<i/><sub/>(<i>b<i/>).","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"12 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atmospheric dynamics of the hypergiant RW Cep during the Great Dimming","authors":"A. Kasikov, I. Kolka, A. Aret, T. Eenmäe, S. P. D. Borthakur, V. Checha, V. Mitrokhina, S. Yang","doi":"10.1051/0004-6361/202453546","DOIUrl":"https://doi.org/10.1051/0004-6361/202453546","url":null,"abstract":"<i>Context<i/>. The hypergiant RW Cep is one of the largest stars in the Galaxy. The evolution and mass loss of such stars have profound effects on their surrounding regions and their galaxy as a whole. Between 2020 and 2024, RW Cep experienced a historic mass-loss event known as the Great Dimming.<i>Aims<i/>. This study provides a spectroscopic analysis of RW Cep during the Great Dimming. We examine its atmospheric dynamics and place it in the context of the star’s variability behaviour since the early 2000s.<i>Methods<i/>. We conducted high-cadence spectroscopic observations of RW Cep during the dimming event using the Tartu Observatory 1.5-meter telescope and the Nordic Optical Telescope. We analysed the atmospheric dynamics by measuring the radial velocities and line depths of Fe I and other spectral lines.<i>Results<i/>. The radial velocities of the Fe I lines reveal a vertical velocity gradient of 10–20 km s<sup>−1<sup/> in the atmosphere, correlating with the strength of the spectral lines. Stronger lines, formed in higher atmospheric layers, have higher radial velocities. We measured the systemic velocity at −50.3 km s<sup>−1<sup/>. During the dimming, radial velocities were affected by additional emission from the ejected gas, which was blue-shifted relative to the absorption lines. Post-dimming, we observed large-scale atmospheric motions with an amplitude of ~25 km s<sup>−1<sup/>. Strong resonance lines of Ba II, K I, Na I, and Ca I showed stable central emission components at −56 km s<sup>−1<sup/>, which are likely of circumstellar origin.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hubble expansion signature on simulated halo density profiles","authors":"Giorgos Korkidis, Vasiliki Pavlidou","doi":"10.1051/0004-6361/202450415","DOIUrl":"https://doi.org/10.1051/0004-6361/202450415","url":null,"abstract":"<i>Context.<i/> Density profiles are important tools in galaxy cluster research, offering insights into clusters dynamical states and their relationship with the broader Universe. While these profiles provide valuable information about the matter content of the Universe, their utility in understanding its dark energy component has remained limited due to a lack of tools allowing us to study the transition from cluster portions that are relaxed and infalling, to those that are merging with the Hubble flow.<i>Aims.<i/> In this work we investigate signatures of this transition in stacked density profiles of simulated cluster-sized halos at different redshifts.<i>Methods.<i/> To highlight the Hubble flow around clusters, we used their turnaround radius to normalize stacked simulated density profiles and calculate their logarithmic slope. Then, we complement our analysis by modeling the outer portions of these profiles assuming Gaussian early Universe statistics and the spherical collapse model (SCM) without shell-crossing.<i>Results.<i/> We find the logarithmic slope of median cluster density profiles beyond the turnaround radius – where the Hubble flow dominates – to be Universal and well described by our model. Importantly, we find the slope of the profiles to diverge from the SCM prediction from within the turnaround radius where the actual profiles exhibit caustics which give rise to the splashback feature.<i>Conclusions.<i/> We suggest utilizing this divergence from the spherical collapse model as a method to identify the turnaround radius in stacked cluster density profiles, offering a new perspective on understanding cluster dynamics and their cosmological implications.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"162 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The cold neutral medium in filaments at high Galactic latitudes","authors":"P. M. W. Kalberla","doi":"10.1051/0004-6361/202452771","DOIUrl":"https://doi.org/10.1051/0004-6361/202452771","url":null,"abstract":"<i>Context.<i/> The H I distribution at high Galactic latitudes has been found to be filamentary and closely related to the far infrared (FIR) in caustics with coherent velocity structures. These structures trace the orientation of magnetic field lines.<i>Aims.<i/> Recent absorption observations with the Australian SKA Pathfinder Telescope have led to major improvements in the understanding of the physical properties of the cold neutral medium (CNM) at high Galactic latitudes. We use these results to explore how far the physical state of the CNM may be related with caustics in H I and FIR.<i>Methods.<i/> We traced filamentary FIR and H I structures and probed the absorption data for coincidences in position and velocity.<i>Results.<i/> Of the absorption positions, 57% are associated with known FIR/H I caustics, filamentary dusty structures with a coherent velocity field. The remaining part of the absorption sample is coincident in position and velocity with genuine H I filaments that are closely related to the FIR counterparts. Thus, within the current sensitivity limitations, all the positions with H I absorption lines are associated with filamentary structures in FIR and/or H I. We summarize the physical parameters for the CNM along filaments in the framework of filament velocities <i>v<i/><sub>fil<sub/> that have been determined from a Hessian analysis of FIR and H I emission data. Velocity deviations between absorption components and filament velocities are due to local turbulence, and we determine for the observed CNM an average turbulent velocity dispersion of 2.48 < <i>δ<i/><i>v<i/><sub>turb<sub/> < 3.9 km s<sup>−1<sup/>. The CNM has a mean turbulent Mach number of <i>M<i/><sub>t<sub/> = 3.4 ± 1.6 km s<sup>−1<sup/>.<i>Conclusions.<i/> Most, if not all, of the CNM in the diffuse interstellar medium at high Galactic latitudes is located in filaments, identified as caustics with the Hessian operator.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"79 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transit-timing variations in the AU Mic system observed with CHEOPS★","authors":"Á. Boldog, Gy. M. Szabó, L. Kriskovics, L. Borsato, D. Gandolfi, M. Lendl, M. N. Günther, A. Heitzmann, T. G. Wilson, A. Brandeker, Z. Garai, Y. Alibert, R. Alonso, T. Bárczy, D. Barrado Navascues, S. C. C. Barros, W. Baumjohann, W. Benz, N. Billot, C. Broeg, A. Collier Cameron, A. C. M. Correia, Sz. Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, A. Deline, O. D. S. Demangeon, B.-O. Demory, A. Derekas, B. Edwards, J. A. Egger, D. Ehrenreich, A. Erikson, A. Fortier, L. Fossati, M. Fridlund, K. Gazeas, M. Gillon, M. Güdel, P. Guterman, Ch. Helling, K. G. Isaak, L. L. Kiss, E. Kopp, J. Korth, K. W. F. Lam, J. Laskar, A. Lecavelier des Etangs, A. Luntzer, D. Magrin, G. Mantovan, L. Marafatto, P. F. L. Maxted, B. Merín, C. Mordasini, M. Munari, V. Nascimbeni, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, D. Piazza, G. Piotto, D. Pollacco, K. Poppenhaeger, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, M. Rieder, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, A. M. S. Smith, S. G. Sousa, R. Southworth, M. Stalport, S. Sulis, S. Udry, S. Ulmer-Moll, V. Van Grootel, J. Venturini, E. Villaver, N. A. Walton, T. Zingales","doi":"10.1051/0004-6361/202452699","DOIUrl":"https://doi.org/10.1051/0004-6361/202452699","url":null,"abstract":"<i>Context<i/>. AU Mic is a very active M dwarf star with an edge-on debris disk and two known transiting sub-Neptunes with a possible third planetary companion. The two transiting planets exhibit significant transit-timing variations (TTVs) that are caused by the gravi tational interaction between the bodies in the system.<i>Aims<i/>. Using photometrical observations taken with the CHaracterizing ExOPlanet Satellite (CHEOPS), we aim to constrain the plan etary radii, the orbital distances, and the periods of AU Mic b and c. Furthermore, our goal is to determine the superperiod of the TTVs for AU Mic b and to update the transit ephemeris for both planets. Additionally, based on the perceived TTVs, we study the possible presence of a third planet in the system.<i>Methods<i/>. We conducted ultra-high precision photometric observations with CHEOPS in 2022 and 2023. We used Allesfitter to fit the planetary transits and to constrain the planetary and orbital parameters. We combined our new measurements with results from previous years to determine the periods and amplitudes of the TTVs. We applied dynamical modelling based on TTV measurements from the 2018–2023 period to reconstruct the perceived variations.<i>Results<i/>. We found that the orbital distances and periods for AU Mic b and c agree with the results from previous works. However, the values for the planetary radii deviate slightly from previous values, which we attribute to the effect of spots on the stellar surface. AU Mic c showed very strong TTVs, with transits that occurred ∼80 minutes later in 2023 than in 2021. Through a dynamical analysis of the system, we found that the observed TTVs can be explained by a third planet with an orbital period of ∼12.6 days and a mass of 0.203<sub>−0.024<sub/><sup>+0.022<sup/> M<sub>⊕<sub/>. We explored the orbital geometry of the system and found that AU Mic c has a misaligned retrograde orbit. The limited number of AU Mic observations prevented us from determining the exact dynamical configuration and planetary parameters. Further monitoring of the system with CHEOPS might help to improve these results.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"51 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Repeated pattern of γ-ray flares in the blazar PKS 1502+106 coincident with the IC190730A neutrino event","authors":"Dmitry Blinov, Polina Novikova","doi":"10.1051/0004-6361/202453361","DOIUrl":"https://doi.org/10.1051/0004-6361/202453361","url":null,"abstract":"<i>Context.<i/> It has been demonstrated that at least 10% of the brightest blazars in the fourth Fermi-LAT catalog of <i>γ<i/>-ray sources exhibit repeating patterns of <i>γ<i/>-ray flares. These events may be associated with the presence of a non-uniform sheath surrounding a fast jet spine in some blazars. Theoretical models suggest that such a sheath could facilitate neutrino production in these structured jets.<i>Aims.<i/> We aim to test the marginal statistical evidence previously reported for a connection between repeating patterns of <i>γ<i/>-ray flares in blazars and high-energy neutrino events that are positionally consistent with these sources.<i>Methods.<i/> We identified a repeating pattern of flares in the <i>γ<i/>-ray light curve of the blazar PKS 1502+106, which lies within the 50% uncertainty region of the IC190730A neutrino candidate event. This occurrence is combined with two other high-energy (≥200 TeV) neutrino events from ICECAT-1, which arrived in both positional and temporal coincidence with two blazars exhibiting ongoing repeating flare patterns. We conducted a Monte Carlo simulation to evaluate the likelihood of accidental coincidences between the repeating flare patterns and neutrino events, accounting for potential unrecognized systematic uncertainties in the arrival directions of the ICECAT-1 events.<i>Results.<i/> Our findings indicate the probability of a random coincidence, in both time and arrival direction for three high-energy neutrino candidates and three blazars with ongoing recurring patterns of <i>γ<i/>-ray flares, is 1.56 × 10<sup>−3<sup/> (3.2<i>σ<i/>).","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"31 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}