I am a graduate student of astrophysics at the Johns Hopkins Univerisity (JHU). I love physics, math, philosophy, classical music, kendo, and anime. Recently, I am reading an astonishing book: A Logical Journey: From Gödel to Philosophy.

Research

I like to view astrophysical problems from both perspectives of physics and statistics using survey data. My interests range from the evolution of universe to stars and planets.

New statistics for cosmology and astrophysics

Textures and patterns are ubiquitous in astronomical data but challenging to quantify. The scattering transform provides a new powerful statistic for these features. It borrows ideas from convolutional neural nets (CNNs), but shares advantages of traditional statistics. In two recent papers ([1], [2]), I discussed in depth how to intuitively understand this new statistic which is still unfamiliar to most physicists, and I showed that on weak lensing mass maps it outperforms classic statistics and is on a par with CNNs. The first paper won an award of astrostatistics and was reported by this astrobites blog.

Discoveries about white dwarfs from Gaia satellite

I also work on white dwarfs, the destiny of most stars in the universe. Using data from the Gaia space mission, I discovered a new population of white dwarfs that cool extremely slowly and some others that are merger products. My work has led to two papers (click the figures below), one of which was highlighted by astrobites and AAS Nova.

To make white dwarf research easier, I also built a publically available package WD_models in python for transformation between white dwarf photometry and physical properties.

Spectra of meteors

In high school, my twin brother (who is studying philosophy now) and I found an efficient way to take spectra of meteors with digital camera. We designed a prism device that can screw in front of a lens. We ordered several from a factory, and sold them to other amateurs of astronomy. Shown below is one spectrum of the Geminid meteor shower, taken in 2010. We are considering making a new batch of this prism device, with an estimated cost of around 100 dollars each. If you are interested, please contact us!

Education

Johns Hopkins University

Department of Physics and Astronomy
2017-2021(expected), M.A., Ph.D.
Advisor: Prof. Brice Ménard

Peking University (北京大学)

Department of Astronomy
2012-2016, B.S.
Advisor: Prof. Eric Peng (彭逸西)

Publications

First author:

Cheng, S. & Ménard, B., Weak lensing scattering transform: dark energy and neutrino mass sensitivity, 2021, arXiv:2103.09247

Cheng, S., Ting, Y.-S., Ménard, B., & Bruna, J., A new approach to observational cosmology using the scattering transform, 2020, MNRAS, 499, 5902

Cheng, S., Cummings, J. D., Ménard, B., & Toonen, S., Double White Dwarf Merger Products among High-mass White Dwarfs, 2020, ApJ, 891, 160

Cheng, S., Two delays in white dwarf evolution revealed by Gaia, 2019, Proceedings of IAU, 15(S357), 175

Cheng, S., Cummings, J. D., Ménard, B., A Cooling Anomaly of High-mass White Dwarfs, 2019, ApJ, 886, 100

Cheng, S., Cheng, S., Meteor spectral observation with DSLR, normal lens and prism, 2011, JIMO, 39, 39

Others:

Lu, C. X., Schlaufman, K. C., Cheng, S., An Increase in Small-planet Occurrence with Metallicity for Late-type Dwarf Stars in the Kepler Field and Its Implications for Planet Formation, 2020, AJ, 160, 253

Bauer, E. B., Schwab, J., Bildsten, L., and Cheng, S., Multi-Gigayear White Dwarf Cooling Delays from Clustering-Enhanced Gravitational Sedimentation, 2020, ApJ, 902, 93

Camisassa, M. E., Althaus, L. G., Torres, S., Córsico, A. H., Cheng, S., Rebassa-Mansergas, A., Forever young white dwarfs: when stellar ageing stops, 2020, arXiv:2008.03028

Chandra, V., Hwang, H.-C., Zakamska, N. L., Cheng, S., A Gravitational Redshift Measurement of the White Dwarf Mass–Radius Relation, 2020, ApJ, 899, 146

Marigo, P., Cummings, J. D., et al., Carbon star formation as seen through the non-monotonic initial–final mass relation, 2020, Nature Astronomy, full text here

Contacts

s.cheng@jhu.edu
+1 443 207 1532
Bloomberg 506
3400 N. Charles St., Johns Hopkins University
Baltimore, MD21218, USA

Sky Altas (Aladin)