The bright outburst of a new black hole candidate: Optical observations of MAXI J1820+070 from the Montsec observatory

The motivation of this thesis is to monitor the data of the 2018 outburst of the black hole candidate MAXI J1820+070. This project combines theoretical background about X-ray binaries with the experimental work done in the process of achieving optical magnitudes using a CCD camera: Telescopi Joan Oró ground based telescope. We present the optical light curves and colours of MAXI J1820+070 during the March-November 2018 outburst. After obtaining the magnitudes, using MAXI and Swift-UVOT as space observatories we extend our range to the X-ray band and study the different states and physical processes that occur in them. Finally, we give physical interpretation of all obtained data and characterize the spectral shape of the infrared, optical, UV and X-ray emission in the different components of MAXI J1820+070 outburst. We conclude that MAXI J1820+070 show the typical properties of a BHT: our results show the canonical BHT states, the disk irradiation changing in the soft state and the linear increase of the R-I colour indicating a cooling of the disk. We also give evidence that the optical emission in the soft state is bluer than in the hard