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.
|SNRs,PWNe,TeV & γ-ray||44%|
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.
Although not yet granted observing time we also consider here the exciting possibility of the detectability of Lorimer-burst brightness (30 Jy and >400-σ) FRBs with a MeerKAT Fly’s Eye experiment (i.e. single-dish observing). In Fly’s Eye mode, MeerKAT will instantaneously cover 0.8 × 64 = 51.2 deg2, and will therefore be able to detect rare, bright transient events. Finally, alongside the sheer increase in the number of FRBs detected the other major development is that FRB 121102 has exhibited repeated bursts seen both at Arecibo and with the GBT (Scholz et al. 2016). These bursts are characterised by a range of flux density and strongly varying spectral indices and a wide range of modulation indices that have so far prevented the detection of any possible underlying periodicity. The repeating nature indicates that they are not from a cataclysmic event and suggest that at least some FRBs are possibly associated with neutron star origins, like magnetars or giant pulses from radio pulsars. Crucial to understanding what this means for the FRB population as a whole is determining if all FRBs repeat or whether there are multiple classes.
Follow Up Timing (To be proposed for)
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.
We are proud to announce that TRAPUM together with its sister project the MPIfR Galactic Plane Survey (MGPS) 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.
* PhD 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.
We describe a wide-field beamformer for the MeerKAT radio telescope and outline strategies to optimally design pulsar and fast transient surveys.
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
We report the discovery of two Black Widow millisecond pulsars in the globular cluster M28 with the MeerKAT telescope.
Pulsars: J1824−2452M, J1824−2452N
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
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
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
Our public engagement programme focuses on the distinct areas: the public at large, and school children in particular. The school-focused thrust engages children in South Africa and other SKA-node-bearing countries as a first priority, but with a global component as well. The content of the various components listed below relates to the TRAPUM mission, which focuses on radio transients and pulsars. Below are the main components planned in our public engagement programme for TRAPUM: