Einstein@Home Gamma-ray Pulsar Discoveries in Fermi-LAT Data

Info

Einstein@Home searches data from the Large Area Telescope (LAT) onboard NASA's Fermi Gamma-ray Space Telescope for signals from gamma-ray pulsars. Pulsars are very compact stars with extreme physical properties compared to normal matter. They are rapidly spinning neutron stars that emit pulses, observable from radio to gamma-ray wavelengths.

Searching for new pulsars is an enormous computational challenge, because their spin frequencies, sky position and other parameters are unknown in advance and must be covered a dense grid of search locations. The number of grid points required to cover such multi-dimensional parameter spaces is tremendous and renders "brute forces approaches" computationally unfeasible.

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 enabled the discoveries of new gamma-ray pulsars that were previously inaccessible on computational grounds.

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.

As always, we are extremely grateful to all of our volunteers, especially those whose computers contributed to these new discoveries. To say "we couldn't have done it without you!" would be a terrible understatement!

The Einstein@Home surveys for new gamma-ray pulsars

FGRP1

Einstein@Home's searches for gamma-ray pulsars began in 2011, using just over 3 years of Fermi-LAT data. Prior to this point, searches had been run "offline" on academic computing clusters. However, the computational cost of these searches increases rapidly with time, and so these searches quickly became infeasible. The much larger computational power offered by Einstein@Home allowed the search effort continue using longer data sets that provide increased sensitivity, and greater potential for discoveries. Four new pulsars were found in the first Einstein@Home Fermi Gamma-ray Pulsar survey (FGRP1).

FGRP4

In 2014, we began the 4^th Einstein@Home survey for gamma-ray pulsars, or "FGRP4". This survey incorporated many new advances that we learned during our previous searches and investigation of blind search methods. In addition, we were able to utilised the superior "Pass 8" data from the Fermi-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.

In total, FGRP4 discovered 19 new pulsars, including two millisecond pulsars (J1035-6720 and J1744-7619). This batch represented almost a third of all gamma-ray pulsars that had been discovered in blind searches at the time.

FGRP5

After the success of FGRP4, we began the fifth iteration of our survey, this time searching for pulsars in unidentified pulsar-like gamma-ray sources detected in the central region of the Milky Way, using almost 9 years of data. Later on, FGRP5 was expanded to search for pulsars in sources from the latest Fermi-LAT Fourth Source Catalog (4FGL) using 11.5 years of data.

To date we have made 14 new pulsar discoveries in FGRP5: 3 from the initial batch of inner-Galaxy sources, and 11 from 4FGL sources; and independently re-detected one pulsar recently discovered in a radio survey. FGRP5 is still ongoing, so we hope for more discoveries in the near future, and are preparing a publication with full details on the newly discovered pulsars.

FGRPB1

In addition to the isolated pulsar surveys (the FGRPX series), Einstein@Home also searches for binary gamma-ray pulsars. These searches are orders-of-magnitude more difficult than isolated pulsar surveys; the pulsar's orbital motion modulates its pulsed signal, and three extra parameters describing the size, period and phase of the orbit are required to account for this. Optical observations of candidate "black widow" and "redback" counterparts can constrain these parameters, reducing the search space to a more manageable (but still enormous!) volume.

Two binary millisecond pulsars have been found in FGRPB1: an extremely compact "black widow" pulsar, PSR J1653-0158, whose 75-minute orbit is the shortest of any known pulsar binary; and PSR J2039-5617, a "redback" pulsar with interesting long-term variable behavior.

Timeline of gamma-ray pulsar discoveries in searches of Fermi-LAT data.

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 Fermi satellite was launched in 2008, it has been 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 same time, the computational cost also increases rapidly with the longer data time spans. Thus, as the graphic shows, over the last few years nearly all discoveries were made with Einstein@Home, thanks to the massive collective computing power provided by the Einstein@Home volunteers.

The discoveries made by Einstein@Home volunteers in detail

Below we list for each pulsar the volunteers whose computers discovered the pulsar, and the date at which the pulsar was found.

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 10³³ erg per second. Most pulsars below have a much higher spin-down power.

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.

FGRPB1 Discoveries Pulsar J1653-0158 Volunteers (Country): Yi-Sheng Wu (Taiwan) and Daniel Scott (USA) Survey: FGRPB1 Selected pulsar parameters: Right ascension: 16:53 Declination: -01:58 Spin frequency: 508.21 Hz First frequency derivate: -6.20 x 10-16 Hz/s Orbital period: 75 min Characteristic age: 37 Gyrs Spin-down power: 4.4 x 1033 erg/s Pulsar J2039-5617 Volunteers (Country): Peter Survey: FGRPB1 Selected pulsar parameters: Right ascension: 20:39 Declination: -56:17 Spin frequency: 377.23 Hz First frequency derivate: -2.02 x 10-15 Hz/s Orbital period: 5.3 h Characteristic age: 4 Gyrs Spin-down power: 2.5 x 1034 erg/s FGRP5 Discoveries Pulsar J0418+6635 This pulsar was originally discovered in radio data from the Green Bank Telescope, but independently detected shortly afterwards in our Einstein@Home survey Volunteers (Country): Antonio de Robertis and SALIX (Poland) Date: 01 Jun 2020 Survey: FGRP5 Selected pulsar parameters: Right ascension: 04:18 Declination: +66:35 Spin frequency: 343.62 Hz First frequency derivate: -1.61 x 10-15 Hz/s Characteristic age: 3.4 Gyrs Spin-down power: 2.2 x 1034 erg/s Pulsar J0744-2525 Volunteers (Country): Armin Burkhardt speaking for MPI/FKF (Germany) and ATLAS AEI Hannover (Germany) Date: 15 May 2020 Survey: FGRP5 Selected pulsar parameters: Right ascension: 07:44 Declination: -25:25 Spin frequency: 10.87 Hz First frequency derivate: -1.13 x 10-13 Hz/s Characteristic age: 1.5 Myrs Spin-down power: 4.8 x 1034 erg/s Pulsar J0802-5613 Volunteers (Country): ATLAS AEI Hannover (Germany) and localou Date: 18 Dec 2020 Survey: FGRP5 Selected pulsar parameters: Right ascension: 08:02 Declination: -56:13 Spin frequency: 3.65 Hz First frequency derivate: -3.68 x 10-14 Hz/s Characteristic age: 1.5 Myrs Spin-down power: 5.3 x 1033 erg/s Pulsar J1139-6247 Volunteers (Country): ATLAS AEI Hannover (Germany) Date: 19 Jul 2020 Survey: FGRP5 Selected pulsar parameters: Right ascension: 11:39 Declination: -62:47 Spin frequency: 8.30 Hz First frequency derivate: -2.79 x 10-13 Hz/s Characteristic age: 470 kyrs Spin-down power: 9.2 x 1034 erg/s Pulsar J1203-6242 Volunteers (Country): Lightstalker (Germany) and ATLAS AEI Hannover (Germany) Date: 26 May 2020 Survey: FGRP5 Selected pulsar parameters: Right ascension: 12:03 Declination: -62:42 Spin frequency: 9.94 Hz First frequency derivate: -4.36 x 10-12 Hz/s Characteristic age: 35 kyrs Spin-down power: 1.7 x 1036 erg/s Pulsar J1231-5113 Volunteers (Country): Sette Claudio and pinballlaryy Date: 12 Jun 2020 Survey: FGRP5 Selected pulsar parameters: Right ascension: 12:31 Declination: -51:13 Spin frequency: 4.84 Hz First frequency derivate: -2.74 x 10-15 Hz/s Characteristic age: 28 Myrs Spin-down power: 5.2 x 1032 erg/s Pulsar J1231-6511 Volunteers (Country): ATLAS AEI Hannover (Germany) Date: 28 Apr 2021 Survey: FGRP5 Selected pulsar parameters: Right ascension: 12:31 Declination: -65:11 Spin frequency: 4.04 Hz First frequency derivate: -4.64 x 10-13 Hz/s Characteristic age: 138 kyrs Spin-down power: 7.4 x 1034 erg/s Pulsar J1335-5656 Volunteers (Country): ATLAS AEI Hannover (Germany) and Michele Fornino (Italy) Date: 13 Aug 2020 Survey: FGRP5 Selected pulsar parameters: Right ascension: 13:35 Declination: -56:56 Spin frequency: 308.86 Hz First frequency derivate: -1.15 x 10-15 Hz/s Characteristic age: 4.9 Gyrs Spin-down power: 1.4 x 1034 erg/s Pulsar J1358-6025 Volunteers (Country): ATLAS AEI Hannover (Germany) and Thorin Oakenshield Date: 21 Jul 2020 Survey: FGRP5 Selected pulsar parameters: Right ascension: 13:58 Declination: -60:25 Spin frequency: 16.52 Hz First frequency derivate: -8.23 x 10-13 Hz/s Characteristic age: 318 kyrs Spin-down power: 5.4 x 1035 erg/s Pulsar J1447-5757 Volunteers (Country): ATLAS AEI Hannover (Germany) Date: 20 Mar 2021 Survey: FGRP5 Selected pulsar parameters: Right ascension: 14:47 Declination: -57:57 Spin frequency: 6.30 Hz First frequency derivate: -4.66 x 10-13 Hz/s Characteristic age: 214 kyrs Spin-down power: 1.2 x 1035 erg/s Pulsar J1649-3012 Volunteers (Country): Giper (Russia) and ATLAS AEI Hannover (Germany) Date: 21 Mar 2019 Survey: FGRP5 Selected pulsar parameters: Right ascension: 16:49 Declination: -30:12 Spin frequency: 292.02 Hz First frequency derivate: -1.13 x 10-15 Hz/s Characteristic age: 4.1 Gyrs Spin-down power: 1.3 x 1034 erg/s Pulsar J1736-3422 Volunteers (Country): ATLAS AEI Hannover (Germany) Date: 25 Aug 2020 Survey: FGRP5 Selected pulsar parameters: Right ascension: 17:36 Declination: -34:22 Spin frequency: 2.88 Hz First frequency derivate: -5.44 x 10-13 Hz/s Characteristic age: 84 kyrs Spin-down power: 6.2 x 1034 erg/s Pulsar J1742-3321 Volunteers (Country): halfmoon (China) and ATLAS AEI Hannover (Germany) Date: 17 Dec 2017 Survey: FGRP5 Selected pulsar parameters: Right ascension: 17:42 Declination: -33:21 Spin frequency: 6.98 Hz First frequency derivate: -6.18 x 10-14 Hz/s Characteristic age: 1.8 Myrs Spin-down power: 7.3 x 1034 erg/s Pulsar J1748-2815 Volunteers (Country): Syracuse University (USA) and MiguelAngel (Spain) Date: 18 Jul 2018 Survey: FGRP5 Selected pulsar parameters: Right ascension: 17:48 Declination: -28:15 Spin frequency: 9.98 Hz First frequency derivate: -3.52 x 10-13 Hz/s Characteristic age: 450 kyrs Spin-down power: 1.4 x 1035 erg/s Pulsar J2034+3632 Volunteers (Country): Daniel (USA) and Ron (USA) Date: 18 Dec 2020 Survey: FGRP5 Selected pulsar parameters: Right ascension: 20:34 Declination: -36:32 Spin frequency: 273.95 Hz First frequency derivate: -1.29 x 10-16 Hz/s Characteristic age: 34 Gyrs Spin-down power: 1.4 x 1033 erg/s FGRP4 Discoveries Pulsar J0002+6216 Volunteers (Country): James Drews, UW-Madison (USA) and Ralph Elwell (USA) Date: 31 Dec 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 00:02.58.17(2) Declination: +62:16:09.4(1) Spin frequency: 8.67 Hz First frequency derivate: -4.48 x 10-13 Hz/s Characteristic age: 306.3 kyrs Spin-down power: 1.5 x 1035 erg/s Pulsar J0359+5414 Volunteers (Country): Whelton A. Miller III (USA), ATLAS AEI Hannover (Germany) and Philip Horney (USA) Date: 15 Dec 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 03:59:26.01(2) Declination: +54:14:55.7(3) Spin frequency: 12.59 Hz First frequency derivate: -2.65 x 10-12 Hz/s Characteristic age: 75.2 kyrs Spin-down power: 1.3 x 1036 erg/s Pulsar J0631+0646 Volunteers (Country): Katagiri, Atsushi (Japan) and Nicholas Huwar Date: 20 Jan 2015 Survey: FGRP4 Selected pulsar parameters: Right ascension: 06:31:52.38(2) Declination: +06:46:14.2(7) Spin frequency: 9.01 Hz First frequency derivate: -2.94 x 10-13 Hz/s Characteristic age: 486.1 kyrs Spin-down power: 1.0 x 1035 erg/s Pulsar J1035-6720 Volunteers (Country): ATLAS AEI Hannover (Germany), Kurt Kovacs (USA), WSyS Date: 09 Dec 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 10:35:27.487(1) Declination: -67:20:12.692(6) Spin frequency: 348.19 Hz First frequency derivate: -5.63 x 10-15 Hz/s Characteristic age: 1.0 Gyrs Spin-down power: 7.5 x 1034 erg/s Pulsar J1057-5851 Volunteers (Country): Syracuse University HTC Campus Grid (USA) and Igor Yakushin, LIGO Laboratory (USA) Date: 28 Oct 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 10:57:09.5(2) Declination: -58:51:07(2) Spin frequency: 1.61 Hz First frequency derivate: -2.61 x 10-13 Hz/s Characteristic age: 97.7 kyrs Spin-down power: 1.7 x 1034 erg/s Pulsar J1105-6037 Volunteers (Country): ATLAS AEI Hannover (Germany) and Syracuse University HTC Campus Grid (USA) Date: 03 Oct 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 11:05:00.48(4) Declination: -60:37:16.3(3) Spin frequency: 5.13 Hz First frequency derivate: -5.75 x 10-13 Hz/s Characteristic age: 141.4 kyrs Spin-down power: 1.2 x 1035 erg/s Pulsar J1208-6238 Volunteers (Country): James Drews, UW-Madison (USA) and University of Houston, IT High Performance Computing (USA) Date: 03 Oct 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 12:08:13.96(6) Declination: -62:38:02.3(4) Spin frequency: 2.27 Hz First frequency derivate: -1.68 x 10-11 Hz/s Characteristic age: 2,700 yrs Spin-down power: 1.5 x 1036 erg/s Pulsar J1350-6225 Volunteers (Country): Petr Ruzicka (Czech Republic) and Bryden Kanngiesser (Canada) Date: 19 Jun 2015 Survey: FGRP4 Selected pulsar parameters: Right ascension: 13:50:44.45(1) Declination: -62:25:43.8(1) Spin frequency: 7.24 Hz First frequency derivate: -4.65 x 10-13 Hz/s Characteristic age: 246.4 kyrs Spin-down power: 1.3 x 1035 erg/s Pulsar J1528-5838 Volunteers (Country): fred c (USA) and Gabriel Vasquez (USA) Date: 25 Mar 2015 Survey: FGRP4 Selected pulsar parameters: Right ascension: 15:28:24.3(1) Declination: -58:38:01(1) Spin frequency: 2.81 Hz First frequency derivate: -1.96 x 10-13 Hz/s Characteristic age: 227.6 kyrs Spin-down power: 2.2 x 1034 erg/s Pulsar J1623-5005 Volunteers (Country): Lars Bollwinkel (Germany) and Greg Dorais (USA) Date: 04 Oct 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 16:23:04.11(1) Declination: -50:05:15.1(2) Spin frequency: 11.75 Hz First frequency derivate: -5.75 x 10-13 Hz/s Characteristic age: 323.9 kyrs Spin-down power: 2.7 x 1035 erg/s Pulsar J1624-4041 Volunteers (Country): Xio and Hung Tran (USA) Date: 20 Dec 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 16:24:09.927(9) Declination: -40:41:29.7(3) Spin frequency: 5.96 Hz First frequency derivate: -1.68 x 10-13 Hz/s Characteristic age: 562.9 kyrs Spin-down power: 3.9 x 1034 erg/s Pulsar J1641-5317 Volunteers (Country): James Drews, UW-Madison (USA) and ATLAS AEI Hannover (Germany) Date: 30 Dec 2015 Survey: FGRP4 Selected pulsar parameters: Right ascension: 16:41:15.91(6) Declination: -53:17:48.8(9) Spin frequency: 5.71 Hz First frequency derivate: -1.21 x 10-13 Hz/s Characteristic age: 750 kyrs Spin-down power: 2.7 x 1034 erg/s Pulsar J1650-4601 Volunteers (Country): Syracuse University HTC Campus Grid (USA) and Eric Schwartz (USA) Date: 17 Oct 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 16:50:18.62(2) Declination: -46:01:18.6(4) Spin frequency: 7.87 Hz First frequency derivate: -9.37 x 10-13 Hz/s Characteristic age: 133.0 kyrs Spin-down power: 2.9 x 1035 erg/s Pulsar J1744-7619 Volunteers (Country): Darrell Hoberer (USA), ATLAS AEI Hannover (Germany), Igor Yakushin, LIGO Laboratory (USA), and Keith Pickstone (UK) Date: 07 Dec 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 17:44:00.488(2) Declination: -76:19:14.710(9) Spin frequency: 213.33 Hz First frequency derivate: -4.41 x 10-16 Hz/s Characteristic age: 7.7 Gyrs Spin-down power: 3.7 x 1033 erg/s Pulsar J1817-1742 Volunteers (Country): Dave Billenness (Canada) and Jonathan L. Kerfoot (USA) Date: 24 Dec 2015 Survey: FGRP4 Selected pulsar parameters: Right ascension: 18:17:09.034(5) Declination: -17:42:01.1(6) Spin frequency: 6.68 Hz First frequency derivate: -9.18 x 10-13 Hz/s Characteristic age: 115 kyrs Spin-down power: 2.42 x 1035 erg/s Pulsar J1827-1446 Volunteers (Country): ATLAS AEI Hannover (Germany) and Igor Yakushin, LIGO Laboratory (USA) Date: 19 Dec 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 18:27:24.60(5) Declination: -14:46:28(4) Spin frequency: 2.00 Hz First frequency derivate: -1.82 x 10-13 Hz/s Characteristic age: 174.5 kyrs Spin-down power: 1.4 x 1034 erg/s Pulsar J1844-0346 Volunteers (Country): Aurélien FAUCHEUX (France) and Roger Gulbranson (USA) Date: 18 Nov 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 18:44:32.89(2) Declination: -03:46:30.6(9) Spin frequency: 8.86 Hz First frequency derivate: -1.21 x 10-11 Hz/s Characteristic age: 11.6 kyrs Spin-down power: 4.2 x 1036 erg/s Pulsar J1906+0722 Volunteers (Country): Connor Barry (USA) and Richard Johnson (USA) Date: 11 Sep 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 19:06:31.20(1) Declination: +07:22:55.8(4) Spin frequency: 8.97 Hz First frequency derivate: -2.88 x 10-12 Hz/s Characteristic age: 49.2 kyrs Spin-down power: 1.02 x 1036 erg/s Pulsar J2017+3625 Volunteers (Country): Kurt Gramoll (USA) and Michael Brandau (Germany) Date: 09 Sep 2014 Survey: FGRP4 Selected pulsar parameters: Right ascension: 20:17:55.84(1) Declination: +36:25:07.9(2) Spin frequency: 6.00 Hz First frequency derivate: -4.89 x 10-14 Hz/s Characteristic age: 1942.8 kyrs Spin-down power: 1.2 x 1034 erg/s FGRP1 Discoveries Pulsar J0554+3107 Volunteers (Country): David Z (Canada) and Test (France) Date: 06 Jan 2012 Survey: FGRP1 Selected pulsar parameters: Right ascension: 05:54:05.01(3) Declination: +31:07:41(4) Spin frequency: 2.15 Hz First frequency derivate: -0.66 x 10-12 Hz/s Characteristic age: 51.7 kyrs Spin-down power: 5.6 x 1034 erg/s Pulsar J1422-6138 Volunteers (Country): Mak-ino (Japan) and Thomas M. Jackson (USA) Date: 14 Dec 2011 Survey: FGRP1 Selected pulsar parameters: Right ascension: 14:22:27.07(1) Declination: -61:38:28(1) Spin frequency: 2.93 Hz First frequency derivate: -0.83 x 10-12 Hz/s Characteristic age: 55.8 kyrs Spin-down power: 9.6 x 1034 erg/s Pulsar J1522-5735 Volunteers (Country): The NEMO computing cluster (USA) and Chen (USA) Date: 30 Sep 2011 Survey: FGRP1 Selected pulsar parameters: Right ascension: 15:22:05.3(1) Declination: -57:35:00(1) Spin frequency: 9.79 Hz First frequency derivate: -2.99 x 10-12 Hz/s Characteristic age: 51.8 kyrs Spin-down power: 115.7 x 1034 erg/s Pulsar J1932+1916 Volunteers (Country): Doug Lean (Australia) and Hans-Peter Tobler (Germany) Date: 19 Sep 2011 Survey: FGRP1 Selected pulsar parameters: Right ascension: 19:32:19.70(4) Declination: +19:16:39(1) Spin frequency: 4.80 Hz First frequency derivate: -2.15 x 10-12 Hz/s Characteristic age: 35.4 kyrs Spin-down power: 40.7 x 1034 erg/s Einstein@Home Lars Nieder (Last Update: Jun 14, 2021)