ESA Science & Technology - Publication Archive
Aims. Only a small number of these type of events have been observed and confirmed to date. The discovery of more cases would allow a number of fundamental conclusions to be drawn about properties such as the frequency of tidal disruption events, the distribution of quiescent black hole masses and their influence in the context of galaxy/AGN formation and evolution among others.
Methods. Comparing the XMM-Newton Slew Survey Source Catalogue with the ROSAT PSPC All-Sky Survey five galaxies have been detected a factor of up to 88 brighter in XMM-Newton with respect to ROSAT PSPC upper limits and presenting a soft X-ray colour. X-ray luminosities of these sources derived from slew observations have been found in the range 1041-1044 erg s-1, fully consistent with the tidal disruption model. This model predicts that during the peak of the outburst, flares reach X-ray luminosities up to 1045 erg s-1, which is close to the Eddington luminosity of the black hole, and afterwards a decay of the flux on a time scale of months to years is expected. Multi-wavelength follow-up observations have been performed on these highly variable objects in order to disentangle their nature and to investigate their dynamical evolution.
Results. Here we present sources coming from the XMM-Newton Slew Survey that could fit in the paradigm of tidal disruption events. X-ray and optical observations revealed that two of these objects are in full agreement with that scenario and three other sources that, showing signs of optical activity, need further investigation within the transient galactic nuclei phenomena.
This article is based on a multimedia presentation prepared by Rudolf von Steiger, Professor at the University of Bern and Director of the International Space Science Institute together with Thomas H. Zurbuchen, Associate Professor at the University of Michigan.
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In addition, the scientific community requirements are more and more challenging: demanding mission objectives lead to more complex mission concepts. Moreover, a quicker response time from approval to launch would be desirable, whilst keeping a very high overall level of reliability.
The main objective of this study is to review the application of recurring service modules as a potential answer to the challenges listed above.
The ESA Concurrent Design Facility (CDF) was requested and financed by ESA/ESTEC/SCIAM to carry out a feasibility study for an optical-near-infrared wide field imager (WFI). Such a mission would search for Type Ia supernovae over a given redshift range with optical and near infrared wavelength coverage. The overall aim of the mission would be to use supernova observations to model the changing rate of expansion of the universe and to determine the contributions of decelerating and accelerating energies such as the mass density and dark energy density. This model could be constructed using a Hubble diagram (redshift vs. magnitude) populated with supernovae measurements. This study is the first step in the feasibility assessment of a technology reference mission and a follow-on phase-A industrial study is foreseen for the payload, where most of the technology development is needed.
We present the first set of XMM-Newton EPIC observations in the 2 square degree COSMOS field. The strength of the COSMOS project is the unprecedented combination of a large solid angle and sensitivity over the whole multiwavelength spectrum. The XMM-Newton observations are very efficient in localizing and identifying active galactic nuclei (AGN) and clusters as well as groups of galaxies. One of the primary goals of the XMM-Newton Cosmos survey is to study the co-evolution of active galactic nuclei as a function of their environment in the Cosmic web. Here we present the log of observations, images and a summary of first research highlights for the first pass of 25 XMM-Newton pointings across the field. In the existing dataset we have detected 1416 new X-ray sources in the 0.5-2, 2-4.5 and 4.5-10 keV bands to an equivalent 0.5-2 keV flux limit of 7x10-16 erg cm-2 s-1. The number of sources is expected to grow to almost 2000 in the final coverage of the survey. From an X-ray color color analysis we identify a population of heavily obscured, partially leaky or reflecting absorbers, most of which are likely to be nearby, Compton-thick AGN.