Merge pull request #564 from xpsi-group/landingpage

Simplifying landing and overview pages

Author: drannawatts

docs/source/_static/Example_pulseprofile.png

@@ -31,13 +31,12 @@ Those involved in maintenance and development (technical and scientific).
 * Lucien Mauviard-Haag (lucien.mauviard-haag[at]irap.omp.eu), IRAP
 * Tuomo Salmi (tuomo.salmi[at]helsinki.fi), University of Helsinki
 * Pierre Stammler (pstammler[at]irap.omp.eu), IRAP
-* Serena Vinciguerra, University of Amsterdam
 * Anna Watts (a.l.watts[at]uva.nl), University of Amsterdam
 
 **Past members**
 
-Thomas E. Riley (t.riley.phd[at]gmail.com), the Initial Creator of X-PSI
-
+* Thomas E. Riley (t.riley.phd[at]gmail.com), the Initial Creator of X-PSI
+* Serena Vinciguerra
 
 .. _community:
 

docs/source/acknowledgements.rst

@@ -7,98 +7,18 @@ X-ray Pulse Simulation and Inference (X-PSI)
 **An open-source package for neutron star**
 **\ X-ray Pulse Simulation and Inference.** 
 
-X-PSI is designed to simulate rotationally-modified (pulsed) surface X-ray
-emission from neutron stars, taking into account relativistic effects on
-the emitted radiation. This can then be used to perform Bayesian statistical
-inference on real or simulated astronomical data sets. Model parameters of
+X-PSI is designed to simulate surface X-ray emission from rotating neutron stars, particularly for cases where the surface emission is not uniform, and the resulting emission can therefore be pulsed. It takes into account the effects of relativity on the emitted radiation. This can then be used to perform Bayesian statistical inference on real or simulated astronomical data sets. Model parameters of
 interest may include neutron star mass and radius (useful to constrain the
 properties of ultradense nuclear matter) or the system geometry and properties
-of the hot emitting surface-regions. To achieve this, X-PSI couples code for
-likelihood functionality (simulation) with existing open-source software for
+of the hot emitting regions on the neutron star surface. To achieve this, X-PSI couples code for likelihood functionality (simulation) with open-source software for
 posterior sampling (inference).
 
-X-PSI has been used most prominently (to date) in modelling pulsar data from 
-NASA's `Neutron Star Interior Composition Explorer (NICER) <https://www.nasa.gov/nicer>`_, for details see 
-:ref:`applications`.  
-
-
-Concept
-*******
-
-The video below, generated by X-PSI, shows a neutron star with non-uniform
-surface temperature, as it rotates. In this specific case the star hosts a
-photospheric radiation field whose asymmetry is driven by an underlying
-ocean wave (a buoyant :math:`r`-mode) of thermonuclear burning. The wave is
-effectively periodic over a small number of rotational cycles. The simulation
-was generated by feeding a wave solution, computed by Frank Chambers
-`(Chambers & Watts 2020) <https://ui.adsabs.harvard.edu/abs/2020MNRAS.491.6032C/abstract>`_ in the form of a field of temperatures in
-surface local-comoving frames (:math:`\sim\! 10^{6}\,\mathrm{K}`), to X-PSI
-for photospheric imaging. A number of simplifying assumptions are made in mode
-calculation and imaging, but this serves to illustrate the simulation and
-visualisation of a neutron star that pulses in the X-ray regime due to
-rotational modulation of some mode of radiative asymmetry at the surface.
-
-.. raw:: html
-
-    <video controls loop
-        <source src="_static/skymap_animated.mp4" width="600" height="600">
-    </video>
-
-
-Each panel displays a specific photon intensity sky map. Panels from top-left to
-bottom-right increase in photon energy. The intensity field in each panel is
-uniquely normalised to the maximum intensity over all phases and sky
-directions. The remarkable evolution of the image with photon energy is
-due to relativistic beaming: at energies much greater than the characteristic
-temperature, the contribution to the image is entirely dominated by the hottest
-region of the surface being relativistically beamed toward the observer as it
-approaches on the left-side of the star. This is the same effect seen in
-many other astrophysical simulations, particularly of images of (supermassive)
-accreting black holes (for instance by the Event Horizon Telescope
-collaboration), although it was interestingly omitted from the motion picture
-film Interstellar `(James et al. 2015) <https://ui.adsabs.harvard.edu/abs/2015CQGra..32f5001J/abstract>`_.
-
-The following image integrates (and thus averages) over waveband (a
-range of photon energies). We also decrease the mode frequency relative to the
-stellar spin frequency, such that the mode is not as equatorially trapped.\ [#]_
-
-.. raw:: html
-
-    <video controls loop
-        <source src="_static/skymap_animated_2.mp4" width="600" height="600">
-    </video>
-
-If one integrates over solid angle (i.e., over sky directions), one is left
-with a specific photon flux in a joint space of photon energy and time (i.e.,
-rotational phase). This is natural because galactic neutron stars subtend far
-too small a solid angle on the sky to be spatially resolved by any telescope:
-they are point sources. We must nevertheless account for the variation of
-intensity with sky direction if we are to compute the data-generating process.
-If one then integrates over phase, the phase-averaged spectrum of photons
-incident on a telescope is yielded; if one instead integrates over some
-waveband, a photon pulse-profile is yielded. The following displays
-several cycles of a phase-energy resolved pulse-profile generated by the more
-equatorially trapped, :math:`r`-mode rendered above.
-
 .. image:: _static/pulse_profile_example.png
 
-The integration over energy is, for likelihood function evaluation, modified
-by a kernel for the response of an X-ray telescope to the incident radiation
-field.
-
-.. rubric:: Footnotes
-
+X-PSI has been used extensively to model pulse profiles like the one shown above.  Pulse profiles indicate how the emission (flux and spectrum) of neutron stars varies as a function of their rotational phase.  X-PSI has been used extensively for Pulse Profile Modeling (PPM) of rotation-powered millisecond X-ray pulsars, in particular using data from NASA's `Neutron Star Interior Composition Explorer (NICER) <https://www.nasa.gov/nicer>`_.  It can also be used to model pulse profile data for accreting neutron stars, including accretion-powered millisecond X-ray pulsars and thermonuclear burst oscillation sources.  It has the facility to model polarized X-ray emission, and can also be used to simulate and model phase-averaged X-ray spectra.  For more details see :ref:`applications`.      
 
-.. [#] There are a number of visualisation possibilities. For instance, we
-       could average the image(s) over phase and/or energy to yield a single
-       static image; we could plot phase evolution in one spatial dimension
-       (with energy variation in the second) or two spatial dimensions
-       (perhaps with energy dependence rendered in time). We could also render
-       in space and/or time, variation of the images with stellar parameters
-       such as gravitational mass, and geometric parameters such as observer
-       inclination to the stellar rotation axis. We could plot
-       an image evolving in time, with other panels rendering a photon
-       specrum and a pulse-profile evolving in time with the image; here is
-       an `example <https://youtu.be/by3_6rWE7po>`_.
+Getting started
+*****************
 
+If you are new to X-PSI, you'll find full :ref:`install` instructions here, and to work through the tutorials we suggest you :ref:`start here<landing_page_tutorials>`.