Investigated the effects of different magnetic field strengths and configurations on the structure of the stellar atmosphere of solar-type stars.

Hello there!
I'm Mason Ng, a final year Physics PhD Candidate at the MIT Department of Physics and the MIT Kavli Institute for Astrophysics and Space Research. I'm currently on the postdoc job market.
I use a range of techniques and tools to understand the evolution and dynamics of neutron star binaries!
masonng@mit.edu
About Me
I am Wei Chieh Ng (Mason) (personal pronouns: he/him).
I am currently a final-year graduate student at MIT's Department of Physics and the Kavli Institute for Astrophysics and Space Research. I mainly work with Professor Deepto Chakrabarty, Dr. Paul Ray, Dr. Ronald Remillard, and Dr. Jack Steiner on X-ray timing and spectroscopic analyses of neutron stars with the NICER data. I also work on X-ray spectropolarimetric observations of neutron stars from the recently launched Imaging X-ray Polarimetry Explorer with Dr. Herman Marshall here at MIT.
This website, like myself, are works in progress. Some of the design elements were inspired by Guðmundur Stefánsson. You can learn more about me and my previous endeavors in the other sections of my website.
CV
Here is the most recent version of my CV (September 2023).
This is my CV from prior to September 2018, though lightly edited to reflect my current position. I leave it here for posterity.
Current Research
My present work focuses on these areas:
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Understanding the evolution and dynamics of interacting neutron star binaries (through X-ray timing, spectroscopy)
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Developing and maintaining a pipeline for pulsation searches and systematic timing/spectral analysis on archival and incoming NICER data
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Using X-ray polarimetry to understand the magnetic field morphology and accretion geometries of compact objects (with the recently-ish launched Imaging X-ray Polarimetry Explorer)
Publications (ORCID; NASA/ADS Library)
First/Co-first author
5 Mason Ng, et al. 2023. X-ray and Radio Monitoring of the Neutron Star Low Mass X-ray Binary 1A 1744-361. Submitted to ApJ.
4 Mason Ng, et al. 2022. Spectral Evolution of Ultraluminous X-Ray Pulsar NGC 300 ULX-1. ApJ, 940, 138.
3 Herman L. Marshall, Mason Ng, et al. (IXPE Collaboration + Norbert S. Schulz, Deepto Chakrabarty) 2022. Observations of 4U 1626-67 with the Imaging X-ray Polarimetry Explorer. ApJ, 940, 70.
2 Mason Ng, Paul S. Ray, Peter Bult, Deepto Chakrabarty, et al. 2021. NICER Discovery of Millisecond Pulsations and an Ultracompact Orbit in IGR J17494-3030. ApJL, 908, 15.
1 M. Ng, N.M. Nielsen, G.G. Kacprzak et al. 2019. Kinematics of the OVI Circumgalactic Medium: Halo Mass Dependence and Outflow Signatures. ApJ, 886, 66.
Co-author
29 Manoj Mandal, et al. (12 co-authors including Mason Ng) 2023. Probing spectral and timing properties of the X-ray pulsar RX J0440.9+4431 in the giant outburst of 2022-2023. Submitted. arXiv:2306.08083.
28 Roberto Turolla, et al. (15 Tier 1 co-authors including Mason Ng) 2023. IXPE and XMM-Newton observations of the Soft Gamma Repeater SGR 1806-20. ApJ, 954, 88.
27 A. C. Albayati, et al. (12 co-authors including M. Ng) 2023. Thermonuclear Type-I X-ray Bursts and Burst Oscillations from the Eclipsing AMXP Swift J1749.4-2807. MNRAS, 524, 2477.
26 Christian Malacaria, et al. (19 Tier 1 co-authors including Mason Ng) 2023. A polarimetric-oriented X-ray stare at the accreting pulsar EXO 2030+375. A&A, 675, 29.
25 G. K. Jaisawal, et al. (9 co-authors including M. Ng) 2023. On the cyclotron absorption line and evidence of the spectral transition in SMC X-2 during 2022 giant outburst. MNRAS, 521, 3951.
24 Paul A. Draghis, et al. (9 co-authors including Mason Ng) 2023. The Spin of a Newborn Black Hole: Swift J1728.9-3613. ApJ, 947, 39.
23 Mayura Balakrishnan, et al. (14 co-authors including Mason Ng) 2023. The Black Hole Candidate Swift J1728.9-3613 and the Supernova Remnant G351.9-0.9. ApJ, 947, 38.
22 G. C. Mancuso, et al. (10 co-authors including M. Ng) 2023. Detection of millihertz quasi-periodic oscillations in the low-mass X-ray binary 4U 1730–22 with NICER. MNRAS, 521, 5616.
21 Silvia Zane, et al. (26 Tier 1 co-authors including Mason Ng) 2023. A strong X-ray polarization signal from the magnetar 1RXS J170849.0-400910. ApJL, 944, 27.
20 Giulia Illiano, et al. (21 co-authors including Mason Ng) 2022. Timing analysis of the 2022 outburst of SAX J1808.4-3658: hints of an orbital shrinking. ApJL, 942, 40.
19 C. Malacaria, et al. (13 co-authors including M. Ng) 2022. The unaltered pulsar: GRO J1750-27, a super-critical X-ray neutron star that does not blink an eye. A&A, 669, 38.
18 Sergey S. Tsygankov, et al. (17 Tier 1 co-authors including Mason Ng) 2022. The X-ray polarimetry view of the accreting pulsar Cen X-3. ApJL, 941, 14.
17 Peter Bult, et al. (13 co-authors including Mason Ng) 2022. The thermonuclear X-ray bursts of 4U 1730-22. ApJ, 940, 81.
16 Roberto Taverna, et al. (21 Tier 1 co-authors including Mason Ng) 2022. Polarized x-rays from a magnetar. Science, 378, 646.
15 A. Sanna, et al. (14 co-authors including M. Ng) 2022. MAXI J1957+032: a new accreting millisecond X-ray pulsar in an ultra-compact binary. MNRAS, 516, L76.
14 Peter Bult, et al. (17 co-authors including Mason Ng) 2022. The Discovery of the 528.6 Hz Accreting Millisecond X-Ray Pulsar MAXI J1816-195. ApJL, 935, 32.
13 Tolga Guver, et al. (13 co-authors including Mason Ng) 2022. Burst-Disk Interaction in 4U 1636-536 as observed by NICER. ApJ, 935, 154.
12 A. Marino, et al. (20 co-authors including M. Ng) 2022. Outflows and spectral evolution in the eclipsing AMXP SWIFT J1749.4-2807 with NICER, XMM-Newton and NuSTAR. MNRAS, 515, 3838.
11 Kishalay De, et al. (26 co-authors including Mason Ng) 2022. SRGA J181414.6-225604: A New Galactic Symbiotic X-Ray Binary Outburst Triggered by an Intense Mass-loss Episode of a Heavily Obscured Mira Variable. ApJ, 935, 36.
10 A. Sanna, et al. (17 co-authors including M. Ng) 2022. On the peculiar long-term orbital evolution of the eclipsing accreting millisecond X-ray pulsar SWIFT J1749.4-2807. MNRAS, 514, 4385.
9 R.M. Ludlam, et al. (10 co-authors including Mason Ng) 2022. Radius Constraints from Reflection Modeling of Cygnus X-2 with NuSTAR and NICER. ApJ, 927, 112.
8 Dheeraj R. Pasham, et al. (18 co-authors including Mason Ng) 2021. Evidence for a Compact Object in the Aftermath of the Extra-Galactic Transient AT2018cow. NatAs, 6, 249.
7 The LIGO Scientific Collaboration; the Virgo Collaboration; the KAGRA Collaboration (including Mason Ng) 2021. Search for continuous gravitational waves from 20 accreting millisecond X-ray pulsars in O3 LIGO data. Phys. Rev. D 105, 022002.
6 Yuhan Yao, et al. (27 co-authors including Mason Ng) 2021. A Comprehensive X-ray Report on AT2019wey. ApJ, 920, 121.
5 Teruaki Enoto, Mason Ng, et al. (25 co-authors including Mason Ng) 2021. A Month of Monitoring the New Magnetar Swift J1555.2-5402 during an X-Ray Outburst. ApJL, 920, 4.
4 D.J.K. Buisson, et al. (26 co-authors including Mason Ng) 2021. Dips and eclipses in the X-ray binary Swift J1858.6-0814 observed with NICER. MNRAS, 503, 5600.
3 Peter Bult, et al. (4 co-authors including Mason Ng) 2021. Long term coherent timing of the accreting millisecond pulsar IGR J17062-6143. ApJ, 912, 120.
2 Peter Bult (12 co-authors including Mason Ng) 2020. The X-ray bursts of XTE J1739-285: a NICER sample. ApJ, 907, 79.
1 J.J. Eldridge, E.R. Stanway, et al. (7 co-authors including M. Ng) 2017. Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results. PASA, 34.
ATels and GCN Circulars
38 Pragati Pradhan, et al. (8 co-authors including Mason Ng) 2023. NuSTAR looks at Swift J0243.6+6124 during the rise of the 2023 outburst.
37 M. Ng, et al. 2023. NICER Monitors the Rise of the Be/X-ray Binary Swift J0243.6+6124.
36 A. Sanna, M. Ng, et al. (11 co-authors) 2023. NICER confirms a new outburst from IGR J17498-2921.
35 M. Ng, et al. 2023. NICER Detects Pulsations from Swift J0243.6+6124.
34 J. Homan, et al. (7 co-authors including M. Ng) 2023. NICER follow-up observations of transient activity from Terzan 1.
33 J. Homan, et al. (6 co-authors including M. Ng) 2023. NICER observations of MAXI J1834-021: possibly a distant black hole low-mass X-ray binary.
32 Sabyasachi Pal, et al. (15 co-authors including Mason Ng) 2023. Rebrightening of 1 Crab from LS V+44 17 observed by Swift/BAT and NICER.
31 Dheeraj Pasham, et al. (14 co-authors including M. Ng) 2022. NICER observations of X-ray transient LXT 221107A: an exceptional flare from the star HD 251108 (2RXS J060415.1+124554).
30 G. K. Jaisawal, et al. (5 co-authors including M. Ng) 2022. INTEGRAL/JEM-X and NICER follow-up observations of IGR J11435-6109 and 1E 1145.1-6141.
29 G. Illiano, et al. (11 co-authors including M. Ng) 2022. NICER observations of reflares from SAX J1808.4-3658.
28 J. Homan, et al. (9 co-authors including M. Ng) 2022. Strong changes in the X-ray behavior of XTE J1701-462.
27 Robin H. D. Corbet, et al. (13 co-authors including Mason Ng) 2022. Support for a 244 day Period in XTE J1829-098 from Swift BAT, MAXI and RXTE PCA Observations.
26 J. Homan, et al. (8 co-authors including M. Ng) 2022. XTE J1701-462 continues its rise in the soft state.
25 M. Ng, et al. 2022. NICER detects a type I X-ray burst from the M15 field.
24 A. Sanna, et al. (12 co-authors including M. Ng) 2022. NICER confirms a new outburst from SAX J1808.4-3658.
23 Michael T. Wolff, et al. (12 co-authors including Mason Ng) 2022. NICER monitoring of the outburst from the transient X-ray pulsar XTE J1829-098.
22 P. Bult, et al. (11 co-authors including M. Ng) 2022. NICER discovers the ultracompact binary orbit of MAXI J1957+032.
21 M. Ng , et al. 2022. NICER discovers 314 Hz pulsations from MAXI J1957+032.
20 P. Bult, et al. (11 co-authors including M. Ng) 2022. NICER measures the binary orbit of MAXI J1816-195.
19 P. Bult, M. Ng, et al. (14 co-authors) 2022. NICER detects 528 Hz pulsations and a thermonuclear X-ray burst from MAXI J1816-195.
18 M. Ng, et al. 2022. NICER follow-up observations of 1A 1744-361.
17 A. Sanna, et al. (5 co-authors including M. Ng) 2021. NICER follow up of the new X-ray transient Swift J1729.5-3223.
16 P. Bult, et al. (9 co-authors including M. Ng) 2021. NICER detects a type I X-ray burst from 4U 1730-22.
15 M. Ng, et al. 2021. NICER Follow-up of the UCXB MAXI J0911-655.
14 M. Ng, et al. 2021. NICER detection of the X-ray pulsation of Bursting Pulsar GRO J1744-28.
13 M. Ng, et al. 2021. NICER measurement of the period derivative of magnetar Swift J1555.2-5402.
12 T. Enoto, M. Ng, et al. (17 co-authors) 2021. Initial results of a NICER X-ray monitoring of the magnetar, Swift J1555.2-5402.
11 P. Bult, et al. (7 co-authors including M. Ng) 2021. NICER follow-up observations of 4U 1705-32.
10 P. Bult, et al. (11 co-authors including M. Ng) 2021. NICER follow-up observations of MAXI J1803-298.
9 A. Sanna, et al. (7 co-authors including M. Ng) 2021. NICER observations of the new X-ray transient SWIFT J174038.1-273712.
8 A. Sanna, et al. (7 co-authors including M. Ng) 2021. NICER follow up of the new X-ray transient IGR J17533-2928.
7 J. Miller, et al. (6 co-authors including M. Ng) 2021. NICER Spectroscopy of MAXI J1848-015 in the Stellar Cluster GLIMPSE-C01.
6 P. Bult, et al. (9 co-authors including M. Ng) 2021. NICER detects pulsations from Swift J1749.4-2807.
5 M. Ng, et al. 2020. NICER detection of 376 Hz X-ray pulsations from IGR J17494-3030.
4 Y. Yao, et al. (9 co-authors including M. Ng) 2020. X-ray Brightening of AT2019wey.
3 D. J. K. Buisson, et al. (20 co-authors including M. Ng) 2020. NICER and NuSTAR detections of Type I bursts and periodic dips in Swift J1858.6-0814.
2 T. Enoto, et al., on behalf of the NICER Team (14 co-authors including Mason Ng) 2020. NICER detection of 1.36 sec periodicity from a new magnetar, Swift J1818.0-1607.
1 W. Iwakiri, et al. (11 co-authors including M. Ng) 2020. Initial NICER observations of the GRB 200205A = Swift J0840.7-3516 and detection of short X-ray flaring activity.
Presentations
Talks (* = virtual)
8 (Jan 2023) 241st Meeting of the American Astronomical Society. Seattle, Washington, USA. IXPE Observations of the Pulsar 4U 1626-67.
7 (Dec 2022) Nanyang Technological University Seminar. Singapore. IXPE Observations of the Neutron Star Low-Mass X-ray Binary 4U 1626-67.
6 (Nov 2022) JAXA/ISAS Seminar. Tokyo, Japan. IXPE Observations of the Neutron Star Low-Mass X-ray Binary 4U 1626-67.
5 (Nov 2022) Kyoto University Seminar. Kyoto, Japan. IXPE Observations of the Neutron Star Low-Mass X-ray Binary 4U 1626-67.
4 *(Sep 2022) Astrophysical Polarimetry in the Time-Domain Era. Lecco, Italy. IXPE Observations of the Pulsar 4U 1626-67.
3 (Jul 2022) Committee on Space Research (COSPAR) Assembly 2022. Athens, Greece. IXPE Observations of the Pulsar 4U 1626-67.
2 (Aug 2016; Invited) Auckland Astronomical Society. Auckland, New Zealand. Modelling the spectra of hot stars.
1 (Apr 2016) Royal Astronomical Society of New Zealand Conference. Napier, New Zealand. Modelling the spectra of hot stars.
Posters
4 (Mar 2023) 20th Divisional Meeting of the High Energy Astrophysics Division. Waikōloa, Hawai'i, USA. Discovery of a 7.8 Hz QPO from the High-Intensity Outburst of Dipping NS LMXB 1A 1744-361.
3 (Mar 2023) 20th Divisional Meeting of the High Energy Astrophysics Division. Waikōloa, Hawai'i, USA. IXPE Observations of the Pulsar 4U 1626-67.
2 (Mar 2022) 19th Divisional Meeting of the High Energy Astrophysics Division. Pittsburgh, Pennsylvania, USA. NICER Pulsation Search and Spectroscopy of the Original Black Widow Pulsar, PSR B1957+20.
1 (Dec 2019) Celebrating 20 Years of Chandra Science Symposium. Boston, Massachusetts, USA. Spectral Evolution of NGC 300 ULX-1.
Past Research
I previously worked on many facets of astrophysics...
In reverse chronological order,
Studied absorber kinematics of 31 OVI absorbers, which exhibited a strong halo mass dependence, where absorbers hosted by L* galaxies have the largest velocity dispersions compared with lower masses and group environments, due to a match between virial temperature and the temperature at which OVI ionization fraction is greatest. Total column densities follow the same behavior, consistent with simulations. Relative absorber--galaxy kinematics of the same sample was studied, though the mass dependence was first normalized out to account for the range of halo masses in the sample. Non-virialized motions due to outflowing gas was observed. Accreting gas signatures were not observed due to multiple line-of-sight structures that were observed, resulting in "kinematic blurring". These results indicate that OVI is not an accurate probe of baryon cycle processes.
There were two projects I carried out:
1) I performed evidence calculations with a trio of codes (CosmoMC, PolyChord, and ModeCode) on several inflationary models, most notable of which is the inflection point inflationary model. Results obtained showed that it is comparable in likelihood to quadratic potentials.
2) I also looked at quantifying the impacts of dark matter on the cosmic microwave background using the 2015 Planck likelihoods, in order to demonstrate the predictive power of dark matter. It was found that dark matter was needed at least at the $10^{100}$ level. While the physical effects of dark matter are well-understood, this quantitative calculation has not been reported in the literature.owave Background.
The results are all summarized in my Senior thesis (US)/Honours thesis (NZ/Aus).
The project involved training a computer to predict image quality from the SkyMapper telescope by considering environmental conditions and telescope configurations. The SkyMapper telescope atop Siding Spring Observatory surveys the entire Southern sky in multiple wavelengths. SkyMapper will inevitably find millions of celestial objects. One result was that the angle of rotation of the CCD camera resulted in visibly lower quality images. Once this was discovered, the SkyMapper team disabled that telescope setting.
Working with Georgie Taylor, we created over 1300 stellar atmosphere models for use in BPASS, the state-of-the-art code incorporating binary stellar systems to predict properties of stellar populations. Results of our work have contributed to the analysis of the recently announced gravitational waves, where it was concluded that similar events are more likely to occur in low-metallicity environments.
Advocacy and Outreach
I am the Vice-Chair of the MIT Graduate Student Council External Affairs Board (GSC EAB), and am responsible for general programming and maintaining the EAB newsletter (see latest (October 2022) here). The GSC EAB is broadly the external arm of the MIT GSC, advocating on behalf of MIT graduate students in issues of concern to the group (e.g., climate change, research funding). We typically liaise with staffers in Congress and the Biden administration through letters and meetings. We have also sent out statements endorsing certain and relevant legislation (see here.) Most recently, I have led an Astrobites article on the formation of the Graduate Research and Development (GRAD) Caucus in the House of Representatives.
I have co-led the PhysGAAP initiative, where we provide application guidance resources to prospective applicants to reduce the barriers for application to the MIT Physics PhD program, and to address the underrpresentation of students from historically excluded communities. We provide a mentorship program, virtual webinars, as well as a Q&A service. More information can be found here. Please reach out to me if you would like me to speak to your student group about demystifying the graduate school admissions process! This is a free service.
I am also a part of MIT Astrogazers, a group of MIT astrophysics graduate students, who take out telescopes on clear nights to the public and invites them to marvel at bright celestial targets like the Moon, Saturn, and Jupiter (when they are up!)
Personal History
Travel
Resources
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Here are some resources that you should check out, especially if you are thinking about undertaking graduate studies in astrophysics/physics!
- Application Guidance for the MIT Physics Ph.D. program
- Astrobites