First author: Sarvesh Gharat
In today’s era, a tremendous amount of data is generated by different observatories and manual classification of data is something which is practically impossible. Hence, to classify and categorize the objects there are multiple machine and deep learning techniques used. However, these predictions are overconfident and won’t be able to identify if the data actually belongs to the trained class. To solve this major problem of overconfidence, in this study we propose a novel Bayesian Neural Network which randomly samples weights from a distribution as opposed to the fixed weight vector considered in the frequentist approach.
First author: S. Komossa
We present a review of the topics of X-ray stellar tidal disruption events (TDEs) and changing-look active galactic nuclei (AGN). Stars approaching a supermassive black hole (SMBH) can be tidally disrupted and accreted. TDEs were first discovered in the X-ray regime and appear as luminous, giant-amplitude flares from inactive galaxies. The early X-ray observations with ROSAT also established the extreme X-ray spectral softness of these events with temperatures of order 50-100 eV that continues to be seen in the majority of more recently identified events.
First author: Nancy Yang
The gas-phase metallicity of galaxies encodes important information about galaxy evolution processes, in particular star formation, feedback, outflows and gas accretion, the relative importance of which can be extracted from systematic trends in the scatter of the mass-metallicity relation (MZR). Here, we use a sample of low redshift (0.02<z<0.055) galaxies from SDSS to investigate the nature of the scatter around the MZR, the observables and physical processes causing it, and its dependence on galaxy mass.
First author: Xiaoyu Xu
The early-type galaxy NGC 5195 (alternatively known as M51b) possesses extended gas features detected in multi-wavelength, postulated to be associated with previous activities of the central supermassive black hole (SMBH). Using integral field spectroscopic observations from the Canada-France-Hawaii Telescope (CFHT)/SITELLE, we report on the discovery of a new large-scale ionized gas structure traced by $[O III]$, $[N II]$, and H$\alpha$ line emission, extending to $\sim10\rm,kpc$ from the nucleus of NGC 5195.
First author: I. M. McHardy
We present fast (~200s sampling) ugriz photometry of the low mass AGN NGC 4395 with the Liverpool Telescope, followed by very fast (3s sampling) us, gs, rs, is and zs simultaneous monitoring with HiPERCAM on the 10.4m GTC. These observations provide the fastest ever AGN multiband photometry and very precise lag measurements. Unlike in all other AGN, gs lags us by a large amount, consistent with disc reprocessing but not with reprocessing in the Broad Line Region (BLR).
First author: Yukta Ajay
We present multiwavelength analyses of an active optical transient AT2021fxu which shows the appearance of previously absent broad emission lines in a recent optical spectrum, suggesting a Changing-look (CL) Active Galactic Nucleus (AGN). During the spectral transition, the brightness in the individual photometric bands increased up to $\approx$0.6 in the optical bands and up to $\approx$1.1 magnitudes in the UV bands. The brightening was accompanied by a blueward shift of the optical spectrum.
First author: Wolfram Kollatschny
IRAS23226-3843 has previously been classified as a changing-look AGN based on X-ray and optical spectral variations. In 2019, Swift observations revealed a strong rebrightening in X-ray and UV fluxes in comparison to observations in 2017. We took follow-up Swift, XMM-Newton, and NuSTAR observations together with optical spectra (SALT and SAAO 1.9m telescope) from 2019 until 2021. IRAS23226-3843 showed a strong X-ray and optical outburst in 2019.
First author: Xiao Fan
Recent observations show that the metallicity of the broad line region ($Z_{\rm BLR}$) in active galactic nuclei (AGNs) is solar-to-supersolar, which is positively correlated with the mass of supermassive black holes ($M_{\rm BH}$) and does not evolve with redshift up to $z \sim 7$. We revisit the $M_{\rm BH}-Z_{\rm BLR}$ correlation with more AGNs with $M_{\rm BH}\sim 10^{6-8} M_{\odot}$ and find that the positive correlation become flat in low-mass range.
First author: W. Ishibashi
Cool outflows are now commonly observed in galaxies, but their physical origin and driving mechanism remain unclear. Active galactic nucleus (AGN) feedback can potentially accelerate cool galactic outflows via cosmic rays (CR) and radiation pressure on dust. Here we investigate the relative importance of CR and radiation feedback in AGNs, and we analyse the physical conditions for outflow launching as a function of the black hole accretion flow mode.
First author: Connar Rowan
Motivated by the increasing number of gravitational wave detections of merging black holes (BHs) by LIGO-VIRGO-KAGRA, BH binary mergers in the discs of active galactic nuclei (AGN) is investigated as a possible merger channel. In this pathway, BHs in the large gas disc are expected to encounter one another, become mutually bound as a BH binary system through interaction with the gas in the disc and subsequently inspiral through gravitational torques induced by the local gas until merger.
