Editing Einstein@Home (section)

== Gamma-ray data analysis and results ==
On 1 July 2011 the project announced a new application to search for pulsars in data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope.<ref>{{Cite web|title=Launching Fermi-LAT Gamma Ray Pulsar Search {{!}} Einstein@Home|url=https://einsteinathome.org/de/content/launching-fermi-lat-gamma-ray-pulsar-search|access-date=2021-06-09|website=einsteinathome.org|archive-date=2021-06-09|archive-url=https://web.archive.org/web/20210609142113/https://einsteinathome.org/de/content/launching-fermi-lat-gamma-ray-pulsar-search|url-status=live}}</ref>

On 26 November 2013, the discovery of four young gamma-ray pulsars in LAT data by the Einstein@Home project was published.<ref name=":4">{{Cite journal|last1=Pletsch|first1=H. J.|last2=Guillemot|first2=L.|last3=Allen|first3=B.|last4=Anderson|first4=D.|last5=Aulbert|first5=C.|last6=Bock|first6=O.|last7=Champion|first7=D. J.|last8=Eggenstein|first8=H. B.|last9=Fehrmann|first9=H.|last10=Hammer|first10=D.|last11=Karuppusamy|first11=R.|title=Einstein@Home Discovery of Four Young Gamma-Ray Pulsars in Fermi Lat Data|date=2013-11-26|url=https://iopscience.iop.org/article/10.1088/2041-8205/779/1/L11|journal=The Astrophysical Journal|volume=779|issue=1|pages=L11|doi=10.1088/2041-8205/779/1/L11|issn=2041-8205|arxiv=1311.6427|bibcode=2013ApJ...779L..11P|s2cid=53588282|access-date=2021-06-09|archive-date=2021-06-09|archive-url=https://web.archive.org/web/20210609155124/https://iopscience.iop.org/article/10.1088/2041-8205/779/1/L11|url-status=live}}</ref> All four pulsars are located in the plane of our Galaxy and have spin frequencies of less than 10 Hertz and characteristic ages between 35,000 and 56,000 years. No radio waves were detected from any of the pulsars.

The discovery of the gamma-ray pulsar PSR J1906+0722 was published on 4 August 2015.<ref>{{Cite journal|last1=Clark|first1=C. J.|last2=Pletsch|first2=H. J.|last3=Wu|first3=J.|last4=Guillemot|first4=L.|last5=Ackermann|first5=M.|last6=Allen|first6=B.|last7=Angelis|first7=A. de|last8=Aulbert|first8=C.|last9=Baldini|first9=L.|last10=Ballet|first10=J.|last11=Barbiellini|first11=G.|title=PSR J1906+0722: An Elusive Gamma-Ray Pulsar|date=2015-08-04|url=https://iopscience.iop.org/article/10.1088/2041-8205/809/1/L2|journal=The Astrophysical Journal|language=en|volume=809|issue=1|pages=L2|doi=10.1088/2041-8205/809/1/l2|arxiv=1508.00779|bibcode=2015ApJ...809L...2C|s2cid=51946861|issn=2041-8213|access-date=2021-06-09|archive-date=2021-06-20|archive-url=https://web.archive.org/web/20210620130425/https://iopscience.iop.org/article/10.1088/2041-8205/809/1/L2|url-status=live}}</ref><ref>{{Cite web|title=Hidden in plain sight|url=https://www.aei.mpg.de/201837/hidden-in-plain-sight|access-date=2021-06-09|website=www.aei.mpg.de|language=en|archive-date=2021-06-09|archive-url=https://web.archive.org/web/20210609142106/https://www.aei.mpg.de/201837/hidden-in-plain-sight|url-status=live}}</ref> The discovery confirmed the pulsar nature of the object which had been suspected since 2012 based on the energy distribution of the gamma-ray photons observed by the LAT. The pulsar is young and energetic. In August 2009 it suffered one of the largest glitches observed from a gamma-ray pulsar. No radio pulsations were detected in any follow-up search, making PSR J1906+0722 likely radio-quiet. Advanced methods of timing the arrival times of gamma-ray pulsations were introduced to improve the parameter inference of astrophysical properties.

On 16 November 2016 the discovery and timing measurements of PSR J1208−6238, the youngest known radio-quiet gamma-ray pulsar, were published.<ref>{{Cite journal|last1=Clark|first1=C. J.|last2=Pletsch|first2=H. J.|last3=Wu|first3=J.|last4=Guillemot|first4=L.|last5=Camilo|first5=F.|last6=Johnson|first6=T. J.|last7=Kerr|first7=M.|last8=Allen|first8=B.|last9=Aulbert|first9=C.|last10=Beer|first10=C.|last11=Bock|first11=O.|title=The Braking Index of a Radio-Quiet Gamma-Ray Pulsar|date=2016-11-15|journal=The Astrophysical Journal|language=en|volume=832|issue=1|pages=L15|doi=10.3847/2041-8205/832/1/l15|issn=2041-8213|arxiv=1611.01292|bibcode=2016ApJ...832L..15C|s2cid=54531854|doi-access=free }}</ref> Even though the inferred age is 2,700 years, no associated supernova remnant or pulsar wind nebula could be identified.

On 11 January 2017, the first results from a survey of 118 unidentified pulsar-like sources from the Fermi-LAT Catalog were published.<ref>{{Cite journal|last1=Clark|first1=C. J.|last2=Wu|first2=J.|last3=Pletsch|first3=H. J.|last4=Guillemot|first4=L.|last5=Allen|first5=B.|last6=Aulbert|first6=C.|last7=Beer|first7=C.|last8=Bock|first8=O.|last9=Cuéllar|first9=A.|last10=Eggenstein|first10=H. B.|last11=Fehrmann|first11=H.|title=The Einstein@Home Gamma-Ray Pulsar Survey. I. Search Methods, Sensitivity, and Discovery of New Young Gamma-Ray Pulsars|date=2017-01-05|journal=The Astrophysical Journal|language=en|volume=834|issue=2|pages=106|doi=10.3847/1538-4357/834/2/106|arxiv=1611.01015|bibcode=2017ApJ...834..106C|s2cid=5750104|issn=1538-4357|doi-access=free }}</ref> A total of 13 new pulsars were found. Most of them are young and were formed in supernovae several tens to hundreds of thousands of years ago. The discoveries and the methods used in the survey were published in the first of two associated papers. The second paper reports faint radio pulsations from two of the 13 gamma-ray pulsars, and presents modeling of the gamma-ray and radio pulse profiles with different geometric emission models.<ref>{{Cite journal|last1=Wu|first1=J.|last2=Clark|first2=C. J.|last3=Pletsch|first3=H. J.|last4=Guillemot|first4=L.|last5=Johnson|first5=T. J.|last6=Torne|first6=P.|last7=Champion|first7=D. J.|last8=Deneva|first8=J.|last9=Ray|first9=P. S.|last10=Salvetti|first10=D.|last11=Kramer|first11=M.|date=2018-02-15|title=The Einstein@Home Gamma-ray Pulsar Survey. II. Source Selection, Spectral Analysis, and Multiwavelength Follow-up|journal=The Astrophysical Journal|language=en|volume=854|issue=2|pages=99|doi=10.3847/1538-4357/aaa411|arxiv=1712.05395|bibcode=2018ApJ...854...99W|s2cid=73710263|issn=1538-4357|doi-access=free }}</ref>

The discovery of two millisecond pulsars discovered by Einstein@Home through their pulsed gamma radiation was published on 28 February 2018.<ref>{{Cite journal|last1=Clark|first1=Colin J.|last2=Pletsch|first2=Holger J.|last3=Wu|first3=Jason|last4=Guillemot|first4=Lucas|last5=Kerr|first5=Matthew|last6=Johnson|first6=Tyrel J.|last7=Camilo|first7=Fernando|last8=Salvetti|first8=David|last9=Allen|first9=Bruce|last10=Anderson|first10=David|last11=Aulbert|first11=Carsten|date=2018-02-01|title=Einstein@Home discovers a radio-quiet gamma-ray millisecond pulsar|journal=Science Advances|language=en|volume=4|issue=2|pages=eaao7228|doi=10.1126/sciadv.aao7228|pmid=29503868|issn=2375-2548|pmc=5829974|arxiv=1803.06855|bibcode=2018SciA....4.7228C}}</ref><ref name=":3">{{Cite web|title=Einstein@Home discovers first millisecond pulsar visible only in gamma rays|url=https://www.aei.mpg.de/172466/einstein-home-discovers-first-millisecond-pulsar-visible-only-in-gamma-rays|access-date=2021-06-09|website=www.aei.mpg.de|language=en|archive-date=2021-06-09|archive-url=https://web.archive.org/web/20210609142105/https://www.aei.mpg.de/172466/einstein-home-discovers-first-millisecond-pulsar-visible-only-in-gamma-rays|url-status=live}}</ref> PSR J1035−6720, spinning at 348 Hertz, has detectable radio pulsations which were found in follow-up searches. The other discovery PSR J1744−7619 is the first radio-quiet millisecond pulsar ever discovered. The project also announced that it was searching for gamma-ray pulsars in binary systems, which are more difficult to find due to the additional orbital parameters.<ref name=":3" />

The first Einstein@Home discovery of a gamma-ray pulsar in a binary system was published on 22 October 2020.<ref>{{Cite journal|last1=Nieder|first1=L.|last2=Clark|first2=C. J.|last3=Kandel|first3=D.|last4=Romani|first4=R. W.|last5=Bassa|first5=C. G.|last6=Allen|first6=B.|last7=Ashok|first7=A.|last8=Cognard|first8=I.|last9=Fehrmann|first9=H.|last10=Freire|first10=P.|last11=Karuppusamy|first11=R.|date=2020-10-22|title=Discovery of a Gamma-Ray Black Widow Pulsar by GPU-accelerated Einstein@Home|journal=The Astrophysical Journal|language=en|volume=902|issue=2|pages=L46|doi=10.3847/2041-8213/abbc02|arxiv=2009.01513|bibcode=2020ApJ...902L..46N|s2cid=221507943|issn=2041-8213|doi-access=free }}</ref><ref>{{Cite web|title=Super heavyweight and flyweight in a cosmic dance|url=https://www.aei.mpg.de/545717/superschwergewicht-und-fliegengewicht-im-kosmischen-tanz|access-date=2021-06-09|website=www.aei.mpg.de|language=en|archive-date=2021-06-09|archive-url=https://web.archive.org/web/20210609142104/https://www.aei.mpg.de/545717/superschwergewicht-und-fliegengewicht-im-kosmischen-tanz|url-status=live}}</ref> PSR J1653-0158, a neutron star with about two solar masses and one of the highest known rotation frequencies of 508 Hertz, orbits the common center of mass with a companion of only 1% of the Sun's mass. The orbital period is 75 minutes, shorter than that of any comparable binary systems. The discovery was made using a GPU-accelerated version of a modified gamma-ray pulsar search code, which included binary orbital parameters. No radio waves were found in follow-up searches. A search for gravitational waves from the pulsar discovered no such emission. The pulsar is from a class known as black widow pulsars. The pulsar evaporates its companion with its energetic radiation and a particle wind. The ablated material fills the binary system with a cloud of plasma absorbing radio waves, but not gamma radiation.

A second discovery of a gamma-ray pulsar in an unusual binary system was reported on 2 February 2021.<ref>{{Cite journal|title=Einstein@Home discovery of the gamma-ray millisecond pulsar PSR J2039–5617 confirms its predicted redback nature|url=https://academic.oup.com/mnras/article/502/1/915/5999074|journal=Monthly Notices of the Royal Astronomical Society|access-date=2021-06-09|archive-date=2021-06-09|archive-url=https://web.archive.org/web/20210609153413/https://academic.oup.com/mnras/article/502/1/915/5999074|url-status=live}}</ref><ref>{{Cite web|title=Einstein@Home reveals true identity of mysterious gamma-ray source|url=https://www.aei.mpg.de/283541/einstein-home-reveals-true-identity-of-mysterious-gamma-ray-source|access-date=2021-06-09|website=www.aei.mpg.de|language=en|archive-date=2021-06-09|archive-url=https://web.archive.org/web/20210609142144/https://www.aei.mpg.de/283541/einstein-home-reveals-true-identity-of-mysterious-gamma-ray-source|url-status=live}}</ref> It was thought to be a "redback" millisecond pulsar system, but no pulsations from the neutron star had been observed. Optical observations of the pulsar companion were used to constrain the orbital parameters of the system. A thus targeted search for gamma-ray pulsations with Einstein@Home found a low-mass pulsar spinning at 377 Hertz in a 5.5 hour orbit with a companion of about a fifth of a solar mass. Precision timing of the gamma-ray pulsations revealed unpredictable changes in the orbital period of up to ten milliseconds. They might be linked to changes in the mass distribution of the companion caused by its magnetic activity, which in turn would affect the pulsar orbit through the changing external gravitational field.

The discovery of 14 previously unknown gamma-ray pulsars in Fermi-LAT data was announced by the project on 15 June 2021.<ref>{{Cite web|title=14 new Einstein@Home pulsar discoveries in Fermi-LAT data {{!}} Einstein@Home|url=https://einsteinathome.org/de/content/14-new-einsteinhome-pulsar-discoveries-fermi-lat-data|access-date=2021-06-16|website=einsteinathome.org|archive-date=2021-06-16|archive-url=https://web.archive.org/web/20210616045419/https://einsteinathome.org/de/content/14-new-einsteinhome-pulsar-discoveries-fermi-lat-data|url-status=live}}</ref>

In November 2023 the Third Fermi Large Area Telescope Catalog of Gamma-Ray Pulsars was published.<ref>{{Cite journal |last1=Smith |first1=D. A. |last2=Abdollahi |first2=S. |last3=Ajello |first3=M. |last4=Bailes |first4=M. |last5=Baldini |first5=L. |last6=Ballet |first6=J. |last7=Baring |first7=M. G. |last8=Bassa |first8=C. |last9=Becerra Gonzalez |first9=J. |last10=Bellazzini |first10=R. |last11=Berretta |first11=A. |last12=Bhattacharyya |first12=B. |last13=Bissaldi |first13=E. |last14=Bonino |first14=R. |last15=Bottacini |first15=E. |date=2023-12-01 |title=The Third Fermi Large Area Telescope Catalog of Gamma-Ray Pulsars |journal=The Astrophysical Journal |volume=958 |issue=2 |pages=191 |doi=10.3847/1538-4357/acee67 |arxiv=2307.11132 |bibcode=2023ApJ...958..191S |issn=0004-637X |doi-access=free }}</ref> The catalog lists 39 pulsars discovered with Einstein@Home and 14 with Einstein@Home methods implemented on a large compute cluster.<ref>{{Cite web |title=A new Fermi Gamma Ray Pulsar Catalog has just been published! |url=https://einsteinathome.org/de/content/new-fermi-gamma-ray-pulsar-catalog-has-just-been-published |access-date=2023-12-11 |website=einsteinathome.org}}</ref> The catalog also includes 13 candidate spider pulsar systems, that could be targets for future searches for their gamma-ray pulsations with Einstein@Home.

As of December 2023, the Einstein@Home project had discovered a total of 39 gamma-ray pulsars in Fermi LAT data.<ref name=":1" />