The field of tidal disruption events (TDEs) always active, has exploded in the last five years, both in terms of the number of events being found and the breadth of detail which is being revealed. In this talk I give an overview of the current state of the field, focusing on the accretion disc physics revealed by the drastic changes of accretion rate experienced as the event evolves. The...
When a star passes too close to a supermassive black hole (SMBH) it can be destroyed, temporarily increasing the accretion rate onto the SMBH. Such tidal disruption events (TDEs) produce bright flares across the electromagnetic spectrum that provide a unique window into the central region of a galaxy, including the previously dormant black hole. Radio observations of TDEs are essential for...
Active galactic nuclei (AGN) are powered by the accretion of material onto a supermassive black hole (SMBH) but the structure of this flow is not well understood. Standard accretion disc models match only to zeroth order in predicting the substantial energy dissipated in optically-thick material producing a strong blue/UV continuum. More detailed comparisons to the observed spectral shapes...
Blazars are highly variable radio-loud AGN, with jets closely aligned with the line-of-sight. These sources can be observed over the entire electromagnetic spectrum and are well monitored at, e.g., radio or gamma-ray wavelengths. The eROSITA telescope with its all-sky survey presents a unique opportunity to obtain an unbiased view of the blazar population in the X-ray band. By matching the...
X-ray Quasi-Periodic Eruptions (QPEs) are high-amplitude bursts of X-ray radiation recurring every few hours and originating near the central black holes in galactic nuclei of low-mass galaxies. So far, only a handful of such events has been found, although with rising interest in the broader community given their observational and theoretical connection with tidal disruption events and,...
eROSITA's time-domain capabilities have enabled the discovery and characterization of four new quasi-periodic X-ray eruption (QPE) sources. A wealth of X-ray follow-up observations exists, as does a large number of theoretical models that can broadly explain the X-ray properties of QPEs. While characterizing these sources in more detail with X-ray observations is valuable, multi-wavelength...
The flux magnification by strong gravitational lensing allows detailed observations of QSOs at high redshifts which would otherwise only be possible for a few extremly luminous objects. Recently there has also been renewed interest in the study of lensed QSOs due to the possibility of independent and accurate measurements of the Hubble constant using time-delay cosmography in lensed QSO...
Multiwavelength information is crucial for a complete understanding of the Universe. In the era of big data, large-number statistics is the ideal tool to characterize the demography of galaxy populations and understand the complex phenomena involved in galaxy evolution. Within SPIDERS (Spectroscopic Identification of ERosita Sources), we selected eROSITA X-ray sources to be observed in the...
A complete census of SMBH increases our understanding of the role of AGN evolution over cosmic time. As AGN detection is less affected by obscuration effects in the X-ray window, eROSITA offers increased likelihood and purity in detecting these objects. That being said, a substantial fraction of spectroscopic redshifts for AGN identified by eROSITA will be available only in 2-3 years from now...
AT2021lwx/ZTF20abrbeie, also known as Scary Barbie, is an ultra-luminous optically discovered transient at z $\sim$ 1 with no previously cataloged host. It is the most energetic non-jetted transient ever observed, exhibiting a single optical brightening by a factor of over 100 to an optical luminosity of $few \times 10^{46}$ erg s$^{-1}$, surpassing any known optical transient. Here, we...
