diff --git a/FGRP1_discoveries.html b/FGRP1_discoveries.html index 51d0d957ebf7c678b55c52c69675c35a62e17d82..a104694e0c6b30e0c6904f5bc578829d8f3abadd 100644 --- a/FGRP1_discoveries.html +++ b/FGRP1_discoveries.html @@ -16,17 +16,16 @@ They are rapidly spinning neutron stars that emit pulses, observable from radio gamma-ray wavelengths.</p> <p>Searching for new pulsars is an enormous computational challenge, because their spin -frequencies, sky position and other parameters are unknown. Thus, this requires a blind -search, where one explicitly searches over a dense grid in parameter space. However, the +frequencies, sky position and other parameters are unknown in advance. Hence this is called a "blind" search, where one explicitly searches over a dense grid in parameter space. However, the number of discrete grid points to cover such multi-dimensional parameter spaces is tremendous and renders "brute forces approaches" computationally unfeasible.</p> <p>We have developed novel and much more efficient data-analysis methods for the volunteer supercomputer Einstein@Home, which ranks among the fastest 25 computer systems worldwide. -Einstein@Home has now discovered four new gamma-ray pulsars that were previously +Einstein@Home has enabled the discoveries of new gamma-ray pulsars that were previously inaccessible on computational grounds.</p> -<p>These radio and gamma-ray pulsar discoveries provide important contributions to advance +<p>These gamma-ray pulsar discoveries provide important contributions to advance our (yet very poor) understanding these stellar objects, their population, and their role in our Universe.</p> <br> @@ -34,36 +33,12 @@ in our Universe.</p> <!-- <a target="blank" href="img/skymap.jpg"><img align="left" vspace="20" hspace="20" style="width: 450px;" alt="skymap" src="img/skymap_small.jpg"></a> !--> -<h3>New Einstein@Home gamma-ray pulsar discoveries</h3> -<p>This page contains information about the Einstein@Home gamma-ray pulsar discoveries. For -each pulsar we list the volunteers whose computers discovered the pulsar, and the date at -which the pulsar was found.</p> +<h3>The Einstein@Home searches for new gamma-ray pulsars</h3> -<p>The plots on the right show the pulse profile of each pulsar in green, and the phase-folded -arrival times of all the gamma-ray photons on the far right. These plots require precise -knowledge of the pulsar sky position, its spin frequency, and spin frequency derivative. -Using these, each photon can be assigned a rotational phase, i.e., in which direction the -pulsar was pointing when the gamma-ray photon was emitted. Thus, we can reconstruct the -gamma-ray emission as a function of pulsar rotation phase and resolve the pulse profile.</p> - -<p>We also provide a list of selected characteristics for each -of the pulsars. Right ascension is one of the two celestial coordinates that specify the -sky position of the pulsar. Declination is the second of these. The spin frequency describes -how many time per second the pulsar is rotating. The first frequency derivative describes -how much the pulsar is slowing down over time. The energy required to emit electromagnetic -radiation is drawn from the pulsar rotation. The characteristic age is a rough estimate of -the pulsar's age, computed from the spin frequency and its derivative. Finally, the -spin-down power is a measure of the total energy emitted by the pulsar. For comparison, our -Sun outputs roughly 4 x 10<sup>33</sup> erg per second. All pulsars below have a much higher -spin-down power.</p> - -<br> -<h3>Update: Pulsar Discoveries from FGRP4</h3> - -<p>In August 2014, we began the 4<sup>th</sup> Einstein@Home survey for gamma-ray pulsars, or +<p>In 2014, we began the 4<sup>th</sup> Einstein@Home survey for gamma-ray pulsars, or "FGRP4". This survey incorporated many new advances that we learned during our previous -investigation of blind search methods. In addition, we were able to utilised the superior "Pass 8" +searches and investigation of blind search methods. In addition, we were able to utilised the superior "Pass 8" data from the <i>Fermi</i>-LAT team, and search in longer data sets than ever before. In combination, these improvements led to FGRP4 being our most sensitive survey to date.</p> @@ -78,10 +53,38 @@ As always, we are extremely grateful to all of our volunteers, especially those contributed to these new discoveries. To say "we couldn't have done it without you!" would be a terrible understatement!</p> -<br> -<h3>Timeline of <i>Fermi</i>-LAT Pulsar Discoveries</h3> +<p>Timeline of <i>Fermi</i>-LAT Blind-Search Pulsar Discoveries</p> <img style="width: 500px;" alt="Timeline" src="img/psrs_vs_time.png"> <br> +<p>The above plot illustrates the number of gamma-ray pulsars discovered in blind searches using NASA's Fermi Gamma-ray Space Telescope as a function of time (when the discoveries were published). Since the launch of the Fermi satellite in 2008, it has continuously scanning the entire sky and thus is providing an ever increasing data set. In principle, having more data available allows us to do more sensitive pulsar searches. However, at the time, the computational cost increases also rapidly with the longer data time spans. Thus, as the graphics shows, over the last few years the only new such discoveries were made with Einstein@Home, owing to the massive collective computing power provided by the Einstein@Home volunteers.</p> +<br> + + +<h3>The discoveries made by Einstein@Home volunteers in detail</h3> + +<p>Below we list for each pulsar the volunteers whose computers discovered the pulsar, +and the date at which the pulsar was found.</p> + +<p>We also provide a list of selected characteristics for each +of the pulsars. Right ascension is one of the two celestial coordinates that specify the +sky position of the pulsar. Declination is the second of these. The spin frequency describes +how many time per second the pulsar is rotating. The first frequency derivative describes +how much the pulsar is slowing down over time. The energy required to emit electromagnetic +radiation is drawn from the pulsar rotation. The characteristic age is a rough estimate of +the pulsar's age, computed from the spin frequency and its derivative. Finally, the +spin-down power is a measure of the total energy emitted by the pulsar. For comparison, our +Sun outputs roughly 4 x 10<sup>33</sup> erg per second. All pulsars below have a much higher +spin-down power.</p> + +<p>The graphics on the right show the pulse profile of each pulsar in green, and the phase-folded +arrival times of all the gamma-ray photons on the far right. These plots require precise +knowledge of the pulsar sky position, its spin frequency, and spin frequency derivative. +Using these, each photon can be assigned a rotational phase, i.e., in which direction the +pulsar was pointing when the gamma-ray photon was emitted. Thus, we can reconstruct the +gamma-ray emission as a function of pulsar rotation phase and resolve the pulse profile.</p> + +<br> + <!-- <div style="text-align: center;">