Magnetic fields are fundamental in regulating star formation and the evolution of molecular clouds. Zeeman splitting offers a unique method to directly measure line-of-sight magnetic field strengths in interstellar environments, from the diffuse ISM to dense cores. Observations of HI and OH absorption toward pulsars provide an unprecedented opportunity to measure magnetic fields with high precision, benefiting from pulsars' small angular sizes and reliable Stokes V spectra unaffected by instrumental effects. Our recent tentative Zeeman splitting detections in OH absorption toward PSR J1644-4559 with Parkes reveal magnetic field strengths that suggest magnetically subcritical states, where magnetic pressure counteracts gravity. This challenges conventional theories of subcritical cold neutral medium (CNM) transitioning to supercritical star-forming molecular clouds, emphasizing the need for detailed investigation. We propose a continuation of Zeeman splitting studies through high-sensitivity OH and HI absorption observations of pulsars PSR J1644-4559, J1721-3532, and J1852+0031 using Parkes. By employing an innovative phase-resolved spectral technique and extending integration times, we aim to enhance Zeeman detection sensitivity and study magnetic field transitions in the CNM and quiescent molecular clouds. This work will refine our understanding of subcritical-to-supercritical transitions in star formation, establish pulsar absorption as a robust probe of interstellar magnetic fields, and advance observational techniques critical to star formation studies.

Magnetic fields are fundamental in regulating star formation and the evolution of molecular clouds. Zeeman splitting offers a unique method to directly measure line-of-sight magnetic field strengths in interstellar environments, from the diffuse ISM to dense cores. Observations of HI and OH absorption toward pulsars provide an unprecedented opportunity to measure magnetic fields with high precision, benefiting from pulsars' small angular sizes and reliable Stokes V spectra unaffected by instrumental effects. Our recent tentative Zeeman splitting detections in OH absorption toward PSR J1644-4559 with Parkes reveal magnetic field strengths that suggest magnetically subcritical states, where magnetic pressure counteracts gravity. This challenges conventional theories of subcritical cold neutral medium (CNM) transitioning to supercritical star-forming molecular clouds, emphasizing the need for detailed investigation. We propose a continuation of Zeeman splitting studies through high-sensitivity OH and HI absorption observations of pulsars PSR J1644-4559, J1721-3532, and J1852+0031 using Parkes. By employing an innovative phase-resolved spectral technique and extending integration times, we aim to enhance Zeeman detection sensitivity and study magnetic field transitions in the CNM and quiescent molecular clouds. This work will refine our understanding of subcritical-to-supercritical transitions in star formation, establish pulsar absorption as a robust probe of interstellar magnetic fields, and advance observational techniques critical to star formation studies.

Magnetic fields are fundamental in regulating star formation and the evolution of molecular clouds. Zeeman splitting offers a unique method to directly measure line-of-sight magnetic field strengths in interstellar environments, from the diffuse ISM to dense cores. Observations of HI and OH absorption toward pulsars provide an unprecedented opportunity to measure magnetic fields with high precision, benefiting from pulsars' small angular sizes and reliable Stokes V spectra unaffected by instrumental effects. Our recent tentative Zeeman splitting detections in OH absorption toward PSR J1644-4559 with Parkes reveal magnetic field strengths that suggest magnetically subcritical states, where magnetic pressure counteracts gravity. This challenges conventional theories of subcritical cold neutral medium (CNM) transitioning to supercritical star-forming molecular clouds, emphasizing the need for detailed investigation. We propose a continuation of Zeeman splitting studies through high-sensitivity OH and HI absorption observations of pulsars PSR J1644-4559, J1721-3532, and J1852+0031 using Parkes. By employing an innovative phase-resolved spectral technique and extending integration times, we aim to enhance Zeeman detection sensitivity and study magnetic field transitions in the CNM and quiescent molecular clouds. This work will refine our understanding of subcritical-to-supercritical transitions in star formation, establish pulsar absorption as a robust probe of interstellar magnetic fields, and advance observational techniques critical to star formation studies.

Magnetic fields are fundamental in regulating star formation and the evolution of molecular clouds. Zeeman splitting offers a unique method to directly measure line-of-sight magnetic field strengths in interstellar environments, from the diffuse ISM to dense cores. Observations of HI and OH absorption toward pulsars provide an unprecedented opportunity to measure magnetic fields with high precision, benefiting from pulsars' small angular sizes and reliable Stokes V spectra unaffected by instrumental effects. Our recent tentative Zeeman splitting detections in OH absorption toward PSR J1644-4559 with Parkes reveal magnetic field strengths that suggest magnetically subcritical states, where magnetic pressure counteracts gravity. This challenges conventional theories of subcritical cold neutral medium (CNM) transitioning to supercritical star-forming molecular clouds, emphasizing the need for detailed investigation. We propose a continuation of Zeeman splitting studies through high-sensitivity OH and HI absorption observations of pulsars PSR J1644-4559, J1721-3532, and J1852+0031 using Parkes. By employing an innovative phase-resolved spectral technique and extending integration times, we aim to enhance Zeeman detection sensitivity and study magnetic field transitions in the CNM and quiescent molecular clouds. This work will refine our understanding of subcritical-to-supercritical transitions in star formation, establish pulsar absorption as a robust probe of interstellar magnetic fields, and advance observational techniques critical to star formation studies.

The magnetic field potentially regulates the process of star formation and the evolution of molecular clouds. It is inherently difficult to measure interstellar magnetic field strengths, with the measurement of Zeeman splitting a unique method to estimate the magnetic field strength along the line of sight directly. Despite the detection of Zeeman splitting in other mediums, there are as yet no Zeeman detections against compact background sources in quiescent molecular clouds or the cold neutral medium. Pulsars with extremely small solid angles and relatively high transverse velocities are ideal background sources to study the magnetic field in molecular clouds, providing a distinct signal to measure splitting against. There are four pulsars with OH absorption detections, namely PSR B1849+00, B1641-45, B1718-35, and B1749-28. We propose to utilize these four pulsars to explore the properties of the magnetic field and its variations within molecular clouds through both the Zeeman splitting of OH absorption and rotation measure estimations, between epochs. If a detection is confirmed, it will open a new window on the hard-to-measure magnetic fields in molecular clouds, independent of interpretation, thus shedding light on the physics of star formation and the interstellar medium.

J0045-7319 is a B star/pulsar binary in the Small Magellanic Cloud (SMC) with an orbital period of 51 days. The system is highly eccentric, with a closest approach of only 6 B-star radii, and it offers an unusual probe into massive stars in the SMC. Although similar systems exhibit strong dispersion measure (DM) variation during periastron arising from the stellar wind, observations in 1996 on the Parkes 70 cm receiver found no evidence of a wind from the B star. We propose a new set of observations on the Ultra-Wide Low-frequency receiver (UWL) designed to measure the wind. A null result will decrease the known upper limit on the B-star wind's contribution to DM by a factor of 9.

Roughly 1 in 10 O stars have been found to harbour extremely stable, ordered (usually dipolar) magnetic fields, which are of ~kG strength. The presence of such organized surface magnetic fields can channel and confine the outflowing stellar winds, creating a magnetosphere that can radiate in various wavebands. Several attempts were made to detect radio emissions from magnetic O-type stars at low frequencies. However, no detection was found, which can be explained by the absorption of non-thermal emission in sub-GHz frequencies due to the dense wind of such high mass-loss rate systems. The first exception to this scenario is the detection of sub-GHz radio emission with the upgraded Giant Metrewave Radio Telescope (uGMRT) from a binary O-star system HD 148937. The 325 MHz detection of this target makes it the lowest frequency detection of any magnetic massive star. The observed emission is non-thermal in nature, with radio luminosity much higher than expected. We attribute the possible emission mechanism to be either synchrotron emission from wind-wind collision, or Electron Cyclotron Maser Emission (ECME) from the magnetic primary. Given the extreme and unique nature of the radio emission from this system, we plan to follow up this target and make use of the high resolution of the LBA to pinpoint the emission region and the corresponding mechanism.

The prevalence of millisecond pulsars (MSPs) in and around the Galactic center and the bulge has been one of the key questions in pulsar astronomy. In addition to finding more exotic and interesting binary systems at and around the Galactic center and bulge due to the enhanced density of stars/stellar remnants, MSPs are also proposed to be one of the candidates to explain the observed Fermi gamma-ray excess. However, most of the MSPs discovered so far are field (disk) MSPs or those in globular clusters. Initial steps towards addressing the question of Galactic center/bulge MSPs were made with the discovery of the first MSPs in a Galactic filament, but more progress comes from the discovery of a sample of MSPs around the Galactic center. Blind surveys targeting MSPs can suffer from many observational biases that smear the pulses due to binary acceleration, scattering from the enhanced density, and so on, which increases the parameter space for discovery and can sometimes make the problem intractable. However, if pulsar candidates can be identified reliably from imaging surveys, then targeted observations can make the problem tractable in identifying the pulsations. We followed up a sample of polarized sources identified in the MeerKAT bulge imaging survey and discovered a sample of 16 new MSPs. Here we request the timing observations of 8 interesting MSPs (a subset of our discovery sample), to study the binary nature of these sources and their potential inclusion in pulsar timing array efforts.

The Spitzer Space Telescope Survey of the Large Magellanic Cloud Legacy Project Surveying the Agents of a Galaxy's Evolution (SAGE) traces the life cycle of observable matter that drives the evolution of a galaxy's appearance. SAGE has revealed over 6 million sources including ~150,000 evolved stars, ~50,000 young stellar objects and the diffuse interstellar medium with column densities > 1.2×1021 cm -2. The data will provide fundamental insights into the physical processes of the interstellar medium, the formation of new stars and the injection of mass by evolved stars and their relationships on the galaxy-wide scale of the Large Magellanic Cloud.To be included in a Catalog, each source has to meet a number of criteria. The source had to be nearly point like with a correlation value 0.89. In regions where there is a significant structure in the surrounding region (identified as having a sigma > 0.25 in a 120" width square box), the source had to have a correlation value >0.91. There are a small number of sources with 24 um magnitudes between 4 and 8 which have unusually low uncertainties (i.e., high S/N). The origin of these sources is under investigation and seems to be related to edge effects in the AORs. In the meantime, these sources were removed from the 24 um catalogs. Finally, all sources had to have signal-to-noise values >5. The final catalogs likely have a few remaining unreliable sources, but we estimate this to be at the less than 1% error.The Full Lists contain ALL the sources extracted from the mosaics, thus a user should be aware that it contains spurious sources. The full list may be useful to search for the potential counterparts to known sources.

The prevalence of millisecond pulsars (MSPs) in and around the Galactic center and the bulge has been one of the key questions in pulsar astronomy. In addition to finding more exotic and interesting binary systems at and around the Galactic center and bulge due to the enhanced density of stars/stellar remnants, MSPs are also proposed to be one of the candidates to explain the observed Fermi gamma-ray excess. However, most of the MSPs discovered so far are field (disk) MSPs or those in globular clusters. Initial steps towards addressing the question of Galactic center/bulge MSPs were made with the discovery of the first MSPs in a Galactic filament, but more progress comes from the discovery of a sample of MSPs around the Galactic center. Blind surveys targeting MSPs can suffer from many observational biases that smear the pulses due to binary acceleration, scattering from the enhanced density, and so on, which increases the parameter space for discovery and can sometimes make the problem intractable. However, if pulsar candidates can be identified reliably from imaging surveys, then targeted observations can make the problem tractable in identifying the pulsations. We followed up a sample of polarized sources identified in the MeerKAT bulge imaging survey and discovered a sample of 16 new MSPs. Here we request the timing observations of 8 interesting MSPs (a subset of our discovery sample), to study the binary nature of these sources and their potential inclusion in pulsar timing array efforts.