Anna Lia Longinotti

ESA XMM-Newton Research Fellow


I graduated in Astronomy at Bologna University in 2002. My Master's
degree was obtained after one year spent at the Istituto di
Astrofisica Spaziale e Fisica Cosmica (IASF-BO), where I started
working on X-ray Astronomy and Active Galactic Nuclei.

Later I moved to London where I've been a Ph.D student at Imperial
College for three years under the supervision of Prof. Kirpal
Nandra. I got my Ph.D in December 2005 with a thesis on
"Relativistic signatures of Black Holes in the X-ray spectra of
AGN".

My main research interest lies in the field of AGN physics. AGN
are thought to be powered by accretion onto supermassive black
holes. Observations in the X-ray domain are privileged in studying
accretion processes since the innermost region of an AGN radiates
predominantly in this wave band. Therefore, X-rays can reveal
important information on the nuclear region, the structure of the
accretion disc and circumnuclear matter in general. 

I have been working on X-ray spectroscopy of Type 1 AGN with the
goal to investigate the presence of relativistic spectral
signatures. One of the most compelling pieces of evidence for the
presence of accretion discs in AGN has been the observation of an
Fe K fluorescence emission line with asymmetric profile distorted
by the gravity. It is now less clear how commom are these lines in
AGN and one of my research guidelines consists in determining
which fraction of unobscured AGN shows this feature. 

Recently, detection of X-ray narrow spectral features in the 5-7
keV band is becoming increasingly common in AGN observations.
Such lines are mostly interpreted as arising from Iron atoms.  When
observed with some displacement from their rest frame position
these lines carry the potential to study the motion of
circumnuclear gas in AGN, providing another diagnostic of the
effects of the gravitational field of the central black hole.
Energy-shifted emission lines are thought to arise from localized
hot spots on the accretion disc, induced by X-ray flares, whereas 
energy-shifted absorption lines may originate in high velocity  gas
outflowing from the nucleus or inflowing towards it.  These narrow
features have been often found with marginal statistical
significance. I am carrying out a systematic search for narrow
features using spectra of bright type 1 AGNs available in the
XMM-Newton archive. The aim of this work is to characterise the
occurrence of the narrow features phenomenon on a large sample of
objects and to estimate the significance of the features through
Monte Carlo simulations.

I will be also working on observations of individual Seyfert 1
Galaxies to study the warm absorber properties through high
resolution spectra and to perform time-resolved spectroscopy and
variability analysis.