MUSE Integral Field Unit Observation of the Compact Objects in the Globular Cluster NGC 6397
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Globular clusters are very old groups of stars. Due to their age and the gravitationalinteractions dominating the dynamics of the clusters, they are home to a significant fractionof compact binaries. The formation and evolution of these kinds of binaries is still notcompletely understood. Of special interest is the globular cluster NGC 6397 as it is theclosest core-collapsed cluster and has therefore been extensively studied with instrumentslike the Chandra X-ray Observatory, the Hubble Space Telescope, and more recently in theoptical with the Multi Unit Spectroscopic Explorer (MUSE), installed on the Very LargeTelescope (VLT). Integral field spectrographs, like MUSE, have many advantages comparedto traditional long slit spectroscopic instrument, as spectra are obtained for every pixeland thus for every object in the large field of view (1' x 1'). Here we present an analysisof the compact binary population in NGC 6397 taken with MUSE. The goal is to furtherunderstand the characteristics of the proposed bimodal population of cataclysmic variables(CVs) in the cluster, which have been suggested to be of primordial and dynamically formedorigins. In this work we were able to spectrocopically confirm two new CV candidates as wellas retrieve the spectra of three previously identified CVs. Spectral analysises of the extractedspectra allow us to estimate the mass ratio for a sample of the identified CVs. We also wereable to compare the magnitude in the R band with previous observation of NGC 6397 todetermine if any of the CVs were observed during an outburst. From the spectral emissionand absorption lines we were also able to estimate the possible type of the companion andexamine the magnetic nature of the CVs. We specifically searched for Helium II lines assignature of magnetism, and Titanium Oxide lines from a M type companion. We show thatthis shallow observation of NGC 6397 with MUSE is a good starting point to finally obtainoptical spectra of compact objects in globular clusters but that with deeper observations amore complete study of the CVs and other compact objects can be carried out.
Place, publisher, year, edition, pages
2016. , 38 p.
Technology, Compact Objects, Globular Cluster, MUSE, Spectroscopy
IdentifiersURN: urn:nbn:se:ltu:diva-55752Local ID: c956f513-b94f-4301-b641-46fb7673fa78OAI: oai:DiVA.org:ltu-55752DiVA: diva2:1029136
Subject / course
Student thesis, at least 30 credits
Space Engineering, master's level
Guillot, SebastienBarabash, Victoria
Validerat; 20160810 (global_studentproject_submitter)2016-10-042016-10-04Bibliographically approved