Compact objects in active galactic nuclei and X-ray binaries

Active galactic nuclei;X-ray binaries

Cackett, Edward M. ; Horne, K. (Keith) ; Horne, K. (Keith)

University:University of St Andrews

Department:Physics & Astronomy (School of)

关键词: Active galactic nuclei;    X-ray binaries;   

Others  :  https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/150/ecackett_thesis%5b1%5d.pdf?sequence=1&isAllowed=y

来源: DR-NTU

【 摘 要 】

In this thesis I study the inner-most regions of Active Galactic Nuclei (AGN) usingthe reverberation mapping technique, and neutron star low-mass X-ray binaries inquiescence using X-ray observations.Using the 13-year optical monitoring data for the AGN NGC 5548, the luminosity dependenceof the Hβ emitting radius was modelled using a delay map, finding thatthe radius scales with luminosity as predicted by recent theoretical models. Time-delaysbetween the continuum at different wavelengths in AGN can be used to probe the accretiondisc. Here, continuum time-delays in a sample of 14 AGN were used to measure the radialtemperature profile of the accretion discs, determine the nuclear extinction, and measuredistances to the objects. However, the distances measured correspond to a value forHubble's constant that is a factor of ~2 lower than the accepted value. The implicationsof this on the thermal disc reprocessing model are discussed.I present two Chandra observations of the neutron star transient in the globularcluster NGC 6440 in quiescence, where the power-law component to the spectrum is seento be variable between the observations, suggesting that there is ongoing residual accretion.From a Chandra observation of the globular cluster Terzan 1, I have identifed the likelyquiescent counterpart to a transient previously observed in outburst, and discuss the othersources within the cluster. Using Chandra and XMM-Newton monitoring observations oftwo neutron star transients (KS 1731-260 and MXB 1659-29) in quiescence I have foundthat the neutron star crusts in both sources have now returned to thermal equilibriumwith the core. These observations also indicate that the crusts in both sources may havea high thermal conductivity and that enhanced neutrino emission may be occurring in thecore. Finally, the discovery of an X-ray transient with XMM-Newton is presented, and theother sources in this observation discussed.