Utilising the power of MeerKAT, TRAPUM will discover numerous new pulsars and transient events in order to expand our knowledge of the populations of sources which emit at radio wavelengths on timescales ranging from microseconds to seconds. The discovery and continued study of these objects provides a powerful tool to improve our understanding of physics in extreme environments.
The science case for TRAPUM covers a broad range of neutron-star, galactic and extra-galactic astrophysics as well as gravitational and high-energy physics. The primary science objectives are:
This science-impact driven project plays to the strengths of the MeerKAT telescope in time-domain astrophysics, the excellent sensitivity allows for the detection of these very faint radio sources, and the high instantaneous spatial resolution enables localisation of events that last for a fraction of a second. This capability for localisation of radio transients is critical to the using and understanding the exotic and currently unknown origins of many of these events.
These science goals will be achieved through a series of targeted searches, capitalising on the sensitivity of MeerKAT to make significant new discoveries.
Read more about the survey plan below
Targeted pulsar searches of SNRs, PWNe, and unidentified Fermi gamma-ray
sources
Supernova remnants (SNRs), pulsar wind nebulae (PWNe) and Fermi gamma-ray sources host,
arguably, some of the most interesting radio pulsars. The discovery of a radio pulsar coincident
with a SNR/PWN/gamma-ray source is crucial for understanding the energy budget of such systems
and, vice-versa, multi-wavelength counterparts provide substantially more context for
understanding the nature of the radio pulsar itself. Discovering young pulsars associated with
SNRs or PWNe is important for understanding the Galactic neutron star formation rate, the nature
of the supernova explosion, and the injection of high-energy particles into the interstellar
medium. Unidentified Fermi gamma-ray sources provide a treasure map for deep pulsar searches
and, for example: the millisecond pulsars (MSPs) found can probe accretion physics (e.g.
"transitional" MSPs), provide new precision timers for the International Pulsar Timing Array, as
well as identify exotic binaries capable of testing gravity and/or constraining the neutron star
equation of state.
Globular Cluster Searches
Globular clusters (GCs) harbor a very large number of MSPs per unit stellar mass compared
with the Galactic plane. This is because the dense stellar environments in the cores
(104 − 103 M⊙ pc−3) promote collisions and exchange
interactions that create binaries capable of recycling old neutron stars to become MSPs. A total
of 146 pulsars have been discovered in globular clusters to date, the majority of them MSPs.
Some clusters are spectacularly prolific: Terzan 5 and 47 Tuc host 34 and 25 pulsars
respectively. Surveying them with MeerKAT therefore has the potential for rich and rapid reward.
| Target | Fraction |
|---|---|
| SNRs,PWNe,TeV & γ-ray | 44% |
| Globular Clusters | 33% |
| Nearby Galaxies | 22% |
Extragalactic pulsar and transient searches
MeerKAT has the sensitivity to reveal new pulsars and fast transients beyond the Milky Way.
Studying extragalactic pulsars we can help us understand the relationship between the formation
of neutron stars and their environement. Only 29 such extragalactic pulsars are known, and all
are located in the Magellanic Clouds. Using MeerKAT we will reach a survey sensitivity beyond
anything other survey performed before to study not only the Magellanic Clouds but also other
galaxies of the local group and beyond. Detecting pulsars and fast transients outside the local
group, and determining how much their signal was dispersed by the intergalactic medium will
begin to provide us with the tools needed to probe the structure of the intergalact medium.
Moreover, understanding the nearby population of giant pulse emitting, or radio-emitting
magnetars, has gained even more importance given that they are proposed models for at least some
of the fast radio bursts (FRBs) and this is further highlighted by the recent discovery of a
repeating FRB.
Towards a Galactic census
The known pulsar population has increased by nearly 50% sources, since 2010 when TRAPUM was
first envisioned.
This increase has been achieved by improving techniques and methods on existing telescopes, and
new telescopes like LOFAR.
Still, the task of finding even more pulsars could not be more timely.
With new pulsars, new science is enabled, resulting from the bulk properties of the discovered
population, from discovered pulsars being probes of the surrounding medium, or by being
exceptional laboratories for testing theories of gravity. With MeerKAT being many times more
sensitive than Parkes, the previous largest dish used for pulsar searches in the South, the
search for pulsars in the
Galactic plane - the birth place of pulsars - provides a significant and rare sharp increase in
sensitivity for exploring the dynamic radio sky. The hundreds of beams combined with much
increased sensitivity mean a significant increase in search capability, making a large-scale
survey with MeerKAT not only possible, but in fact mandatory. With time provided by MPIfR’s
“S-Band Project”, TRAPUM will conduct a L-Band survey along parts of the inner Galaxy. This
TRAPUM survey will be the most sensitive survey of the inner Galactic plane ever conducted,
being the benchmark and testbed for the later SKA surveys.
Using pulsars to probe gravity, dark matter & stellar populations in the Galactic
Centre
The discovery of a pulsar closely orbiting the super-massive black hole at the centre of our
Galaxy, Sgr A*, would not only supersede all previous tests of General Relativity (GR) in\
the strong-field regime, it would also enable the space-time around a rotating black hole to be
probed with high precision and in a model independent fashion; for example, allowing tests of
the cosmic censorship conjecture and the no hair theorem. Such a "laboratory" for precision
tests of GR and black hole physics would be unrivalled by any future astrometric measurements of
the S-Stars. Furthermore, mass-segregation
in the central parsec may also lead to the presence of additional gravitational testbeds in the
form of stellar-mass pulsar black hole binaries. As part of the MPIfR “S-Band Project”, the
Max-Planck receivers will be used to conduct a sensitive survey of the innermost region of the
Galaxy in the vicinity of the black hole. The MPIfR will share the results with TRAPUM as input
for further studies.
Fast transients – working with MeerTRAP to
discovering and understand source populations
The fast transient landscape has changed dramatically since 2010 with the discovery of the
population of FRBs, including the revelation that some repeat, which are exciting in themselves
but also highlighted that the dynamic radio sky is still largely unexplored and with potentially
more rich rewards. MeerKAT’s unique combination of wide FoV, high sensitivity, and wide
bandwidth will provide supreme sensitivity per unit time and frequency making it a prime
instrument to study the transient sky. We will carry out commensal observing for fast
transients on all of the TRAPUM observations proposed here: High energy point sources
and SNRs, globular clusters and external galaxies.
Follow Up Timing
After the initial discovery of a pulsar, we want to extract as much science as possible by
follow-up timing. Therefore, it is an absolutely crucial aspect of characterising the new TRAPUM
pulsars to get a timing solution. In its most basic form this means getting an accurate
position, period and period derivative so that one can compare the pulsar properties with the
known pulsar population, and in particular for those sources that are found in our targeted
searches we are interested in knowing their characteristic ages and their spin-down energies to
compare with the SNRs and high energy emission, for example. We are also interested in
determining whether or not the sources are potentially high precision timers and so useful for
gravitational wave searches, and/or members of binary systems and so potentially useful for mass
determinations or tests of gravity.
With the most recent discoveries by the MeerKAT and FAST radio telescopes, the number of pulsars known in globular clusters has grown to 302, up from around 150 at the end of 2018. This doubling of the population in 5 years is a testament to the immense sensitivity of MeerKAT and FAST, with the TRAPUM project alone now accounting for 28% of all globular cluster pulsar discoveries!
We have recently initiated a project to search for exotic binary pulsars in TRAPUM globular cluster data using spare compute cycles of computers from volunteers all around the world. This is part of the already running Einstein@Home project, which has been running successfully for nearly two decades and has discovered more than 80 pulsars. Anyone with a personal computer can freely sign up as a volunteer following the instructions on the Einstein@Home website and join our large-scale effort for discovering unique pulsars.
The Nearby Galaxies working group has now published its first paper! It can be found in the "Publications" section of this website. Remarkably, the first two observations of the Large Magellanic Cloud already revealed 6 new pulsars! The Small Magellanic Cloud survey is also well under way with 7 pulsar discoveries, doubling the currently known population. In addition, nearby galaxies Sextans A and B have been surveyed and a Fast Radio Burst has been found serendipitously. A survey of NGC 253 is currently being processed. Details of our discoveries can be found on the DISCOVERIES page.
We are proud to announce that TRAPUM together with its sister project the MPIfR MeerKAT Galactic Plane Survey (MMGPS) have surpassed 100 pulsar discovieries. Given the source classes that TRAPUM has targeted, more than 60 of these new pulsars have periods below 30 milliseconds with 37 confirmed to be in binary systems. This represents more than a 10% increase in the total number of millisecond pulsars known. With the majority of the discovieres coming since the start of 2021 we are optimistic that we can continue our fantastic discovery rate into 2022 and beyond. Details of our discoveries can be found on the DISCOVERIES page.
Towards the end of 2021 the TRAPUM collaboration submitted its first report on operations to SARAO. The report detailed how the addition of instrumentation from TRAPUM has enabled MeerKAT to become a premium pulsar and fast transient discovery machine, with TRAPUM discovering 36 pulsars in 11 globulsar clusters, 3 pulsars in the Small Magellanic Cloud and 15 pulsars (of which 14 are millisecond pulsars) in Fermi-LAT sources. The collaboration received positive feedback from the review committee with the reviewers noting that "The TRAPUM team has demonstrated, through their hard work in collaboration with SARAO teams, that MeerKAT (and by extension SKA1-MID) can be a prolific pulsar search instrument. This required the development of novel instrumentation, and they are to be commended for their achievements. Their transparency in making discovery details public is also welcome. Given their activities and results so far, it would appear that the team is well poised to make major impacts in pulsar astrophysics."
We have started our observations of the Small Magellanic Cloud with TRAPUM in 2021. We have nearly completed four out of eight pointings in this L-band survey, which uses 769 coherent beams and the core dishes of MeerKAT. The survey is partially targeted to supernova remnants and pulsar wind nebulae. We have discovered several new extragalactic pulsars in the SMC, which you can read about on the DISCOVERIES webpage. We are also observing other nearby galaxies with the full array.
We have made our first observations of a set of Fermi Unidentified Sources with TRAPUM. We observed about a dozen sources using all the available telescopes and about 250 beams arranged to sample the entire gamma-ray error circle of the sources. This forms the first set of sources in our sample prepared for our initial shallow survey which is using the L-band receiver and will include a two-pass approach. News on DISCOVERIES soon.
TRAPUM has made its first observations! Using all the available telescopes 288 beams were formed and used to observe the clusters Terzan 5, 47 Tucanae and NGC 6624 for about 4 hours each. Data analysis is ongoing. Stand by for announcements of discoveries which will appear on our DISCOVERIES webpage.
Working with the MeerTIME team we have searched 10 Globular clusters using search mode data recorded using the PTUSE backends for a beam pointed at one of the known pulsars in the cluster. So far we have discovered 10 new pulsars and you can find a summary of the details of these pulsars at our DISCOVERIES webpage. The TRAPUM surveys will use between 250 and 400 beams to allow for covering the entire cluster and will be able to use all 64 dishes to give greater sensitivity.
A proposal describing the updated science case and observing request for TRAPUM has been submitted.
The TRAPUM website, trapum.org, has been launched. Publications, data releases and survey status updates will appear here once the survey is underway.
* Student
The management of the TRAPUM project will build upon experience gained from our membership in other large international collaborations such as LOFAR, the EPTA and SUPERB. An executive committee composed of the two PIs (Stappers and Kramer) and a further five members will be the decision making body responsible for organisation, membership, resolution, funding and planning. These five additional members correspond to approximately 10% of the total membership and will be drawn from each of the science working groups (see below), respecting diversity in nationality and gender, and will serve a limited term of no more than two years. The PIs will have the casting vote if required. While the science working groups will have significant overlap in membership and science topics they will have clear and distinct goals. In addition there will be two technology working groups which will work with and across all the science groups to provide the hardware, software and practical development necessary to meet the scientific goals. It is expected that the technology group members will have strong overlap with all the scientific groups, with at least one member from each present.
(Chen et al. 2021): ADS, ArXiv, DOI
We describe a wide-field beamformer for the MeerKAT radio telescope and outline strategies to optimally design pulsar and fast transient surveys.
(Ridolfi et al. 2021): ADS, ArXiv, DOI
We present the first eight pulsar discoveries made by MeerKAT. The eight pulsars are found in six different globular clusters and are all millisecond pulsars.
Pulsars: J1748-2446an, J1701-3006G, J1803-3002D, J1823-3021G, J0024-7204ac, J0024-7204ad, J1910-5959F, J1823-3021H
(Douglas et al. 2022): ADS, ArXiv, DOI
We report the discovery of two Black Widow millisecond pulsars in the globular cluster M28 with the MeerKAT telescope.
Pulsars: J1824−2452M, J1824−2452N
(Ridolfi et al. 2022): ADS, ArXiv, DOI
We report the discovery of 13 new pulsars in the globular cluster NGC 1851 with the MeerKAT telescope.
Pulsars: J0514-4002B, J0514-4002C, J0514-4002D, J0514-4002E, J0514-4002F, J0514-4002G, J0514-4002H, J0514-4002I, J0514-4002J, J0514-4002K, J0514-4002L, J0514-4002M, J0514-4002N
(Vleeschower et al. 2022): ADS, ArXiv, DOI
We report the MeerKAT discovery of two pulsars in the globular cluster NGC 6440, as well as long-term timing solutions of the previously known pulsars NGC 6440C and NGC 6440D from multi-telescope data.
Pulsars: J1748−2021G, J1748−2021H
(Abbate et al. 2022): ADS, ArXiv, DOI
We report the discovery of four new pulsars in the globular cluster NGC 6624 with the MeerKAT telescope. One of these (J1823-3022) shows a large offset in its position and dispersion measure when compared to all the other pulsars in NGC 6624, making its association with the cluster uncertain.
Pulsars: J1823-3021I, J1823-3021J, J1823-3021K, J1823-3022
(Zhang et al. 2022): ADS, ArXiv, DOI
We report the discovery of a new pulsars (PSR J1740-5340B) in the globular cluster NGC 6397. The pulsar was found with the Parkes radio telecope and confirmed with the MeerKAT telescope in two TRAPUM observations. PSR J1740-5340B is an eclipsing redback in a 1.97-day orbit, the longest among all redbacks known.
Pulsars: PSR J1740-5340B
(Carli et al. 2022): ADS, ArXiv, DOI
As part of our survey of the Small Magellanic Cloud, we have published an upper limit on radio pulsations from X-ray pulsar J0058−7218. This limit is 7 times deeper than previous radio searches. This suggests that the radio emission of PSR J0058−7218 is not beamed towards Earth or that PSR J0058−7218 is similar to a handful of Pulsar Wind Nebulae systems that have a very low radio efficiency, such as PSR B0540−6919, the Large Magellanic Cloud Crab pulsar analogue.
Pulsar: PSR J0058-7218
(Clark et al. 2023): ADS, ArXiv, DOI
We present the discovery of 9 new millisecond pulsars, the first results from our targeted survey of unidentified Fermi-LAT gamma-ray sources. All but one of these new pulsars are in binary systems, of which two are eclipsing redbacks with optical counterparts.
Pulsars: J1036-4353, J1526-2744, J1623-6936, J1709-0333, J1757-6032, J1803-6707, J1823-3543, J1858-5422, J1906-1754
(Balakrishnan et al. 2023): ADS, ArXiv, DOI
We report the re-discovery of PSR J2140−2311B located in the globular cluster M30 and detected using the MeerKAT telescope. This pulsar has eluded detections for the past 20 years and its orbital parameters have been a mystery until now. PSR J2140−2311B has an orbital period of 6.2 days and is in a highly eccentric orbit (e = 0.879) around either a WD/NS. We also measured wdot from pulsar timing and assuming GR, we present here the total mass of the system. This pulsar is located 1.2(1)' from the cluster center and likely formed as a result of a secondary exchange encounter.
Pulsars: PSR J2140−2311B
(Padmanabh et al. 2023): ADS, ArXiv, DOI
We present here the overview and setup for the 3000 hour Max-Planck-Institut fuer Radioastronomie (MPIfR) MeerKAT Galactic Plane survey (MMGPS). The survey is unique by operating in a commensal mode, addressing key science objectives of the survey including the discovery of new pulsars and transients as well as studies of Galactic magnetism, the interstellar medium and star formation rates. We have so far discovered 78 new pulsars including 17 confirmed binary systems of which two are potential double neutron star systems. We have also developed an imaging pipeline sensitive to the order of a few tens of micro-Jansky with a spatial resolution of a few arcseconds. Further science operations with an in-house built S-Band receiver operating between 1.7-3.5 GHz are about to commence.
Pulsars: J0853−4648, J0916−5243, J0917−4413, J0922−4534, J0927−5242, J0933−4604, J0936−4750, J0948−5549, J0954−5754, J1001−5603, J1015−5359, J1020−5510, J1020−6158, J1030−6008, J1034−5817, J1034−5934, J1039−6108, J1039−6208, J1051−6214, J1108−6329, J1134−6207, J1138−6154, J1148−6546, J1155−6529, J1208−5936, J1212−5838, J1231−5929, J1232−5843, J1244−6437, J1306−6043, J1316−6147, J1328−6605, J1338−6425, J1352−6141, J1353−6341, J1359−6242, J1408−6009, J1409−6011, J1413−5936, J1426−6136, J1436−6405, J1449−6339, J1452−5549, J1454−5416, J1500−6054, J1510−5254, J1512−6029, J1520−5402, J1526−5652, J1529−5102, J1529−5609, J1530−5724, J1536−6142, J1536−6149, J1540−5821, J1543−5439, J1547−5056, J1554−4854, J1554−5906, J1604−4832, J1610−4938, J1614−4608, J1615−5609, J1623−4608, J1623−4931, J1633−4859, J1636−4217, J1645−4836, J1649−3752, J1649−4230, J1650−5025, J1652−5154, J1702−4145, J1704−3549, J1706−4020, J1708−4843, J1716−3811, J1806−2125
(Bernadich et al. 2023): ADS, ArXiv, DOI
We present follow-up study of PSR J1208-5936, a 28.71-ms recycled pulsar in a double neutron star system with an orbital period of 0.632 days and an orbital eccentricity of 0.348, merging within the Hubble time. From one year of timing we detected the relativistic advance of periastron of 0.918(1) deg/yr, resulting in a total system mass of 2.586(5) solar masses. Using the sensitivity of the MMGPS-L survey and the fact of PSR J1208-5936 discovery, we provide updated estimates of the neutron star merger rate.
Pulsars: J1208-5936
(Chen et al. 2023): ADS, ArXiv, DOI
We report the discovery of 13 new pulsars in globular cluster Omega Centauri. With this discovery and the known pulsars, we discuss the ratio between isolated and binaries pulsars and how they were formed in this cluster.
Pulsars: J1326-4728F, J1326-4728G, J1326-4728H, J1326-4728I, J1326-4728J, J1326-4728K, J1326-4728L, J1326-4728M, J1326-4728N, J1326-4728O, J1326-4728P, J1326-4728Q, J1326-4728R
(Men et al. 2023): ADS, ArXiv, DOI
We describe a novel, efficient approach to candidate folding for large-scale pulsar surveys. The approach is implemented in the PulsarX software package and is tested on the MMGPS and TRAPUM surveys where we show that the cost of dedipsersion can be reduced by upto a factor of 50 when compared to traditional approaches.
(Clark et al. 2023): ADS, ArXiv, DOI
We present the detection of eclipses in the gamma-ray pulsations from 7 binary millisecond pulsars. These eclipses allow us to better constrain the masses of the pulsars in these systems, by providing us with information on the angles from which we view these binaries. TRAPUM observations contributed to the timing solution for one of the pulsars included in this search.
Pulsars: J0838−2827, J0955−3949, J2333−5526
(Motta et al. 2023): ADS, ArXiv, DOI
We report on the serendipitous discovery of a radio nebula with cometary-like morphology. The feature, which we named ‘the Mini Mouse’ based on its similarity to the previously discovered ‘Mouse’ nebula, was observed with MeerKAT and we localisted the known young pulsar J1914+1054g to the head of the nebula.
Pulsars: J1914+1054g
(Abbate et al. 2023): ArXiv, DOI
We present the discovery of two isolated pulsars in the globular cluster NGC 6522. The discoveries confirm predictions of previous theories for the pulsar populations in late-stage core-collapsed globular clusters.
Pulsars: J1803−3002E, J1803−3002F, J1803−3002C
Our public engagement program is focused on two primary areas: reaching the general public and engaging with school children, particularly in South Africa and other countries associated with the SKA project.
Below are the main components of our public engagement program for TRAPUM:
Introduce young astronomers to the fascinating science behind the TRAPUM project and the power of the MeerKAT radio telescope with this kid-friendly booklet.
Stay up-to-date with the latest TRAPUM news on social media:
TRAPUM data are generally large with only specific data sets being retained for future use (e.g. candidate sets and beams of particular scientific interest, such as those on the cores of globular clusters). We are working with SARAO to provide open access to some of these data and will update here when download links are available. In the meantime available TRAPUM data may be released upon reasonable request.
