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Shmuel Bialy

ASTROPHYSICS

We study how gas collapses to form new stars, and how these stars shape the interstellar medium in galaxies

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The Universe by the Numbers

Extreme scales that define the Interstellar Medium

1
atoms/cm³

Average density of the interstellar medium — a billion times emptier than the best vacuum on Earth

50
Mach

Typical gas velocity in molecular clouds — far beyond any man-made supersonic vehicle

1000000
Years

Typical time needed to form a single Sun-like star from a collapsing molecular gas cloud

5
Degrees above absolute zero

Temperature of molecular cloud cores, among the coldest naturally occurring gas in the universe

THE LAB

The Star Formation & Insterstellar Medium Lab at the Technion

SHMUEL BIALY

PI

I’m Shmuel Bialy, a Senior Lecturer (Assistant Professor) in the Physics Department at the Technion — Israel Institute of Technology.

My research focuses on the interstellar medium (ISM): how it shapes star formation, how forming stars feed back into it, and how these processes drive galaxy evolution across cosmic time. I combine analytic theory, numerical simulations, and observations, including with JWST, to address these questions.

Before joining the Technion, I was an ITC Prize Fellow at Harvard CfA and a CTC Prize Fellow at the University of Maryland. I completed my PhD at Tel Aviv University under Amiel Sternberg.

My Publications on NASA ADS / Google Scholar / Technion page

In our group

we combine multi-physics magneto-hydrodynamics simulations with analytic techniques to study the process of star-formation and galaxy evolution.

We collaborate

with observers to compare theory with observations in galaxies today and in high redshift galaxies forming in the Early Universe.

More To It

Our research is interdisciplinary, involving knowledge from different fields: chemistry, turbulence, hydrodynamics, atomic physics, and cosmology (see Research and Talks).

I combine a love of space and computer science to investigate the structure, composition, formation, and evolution of minor and major planets, in our Solar System and beyond.

Uri Malamud

Senior Researcher

I’m a graduate student at the Technion researching cosmic rays in the interstellar medium, with broader interests in particle physics and astrochemistry.

Amit Chemke

Graduate Student

A multidisciplinary researcher with a background spanning mathematics, physics, and computation, Benjamin brings expertise in mathematical theory, signal processing, and international scientific collaboration to the group’s work on the interstellar medium.

Benjamin Bairrington

Graduate Student

I am breathing and living Physics

Andrey Anisimov

Graduate Student

I’m a third-year undergraduate physics student at the Technion, working to map the distribution and structure of the Cold Neutral Medium using 3D dust-density maps and observational data. Outside of research, I find inspiration in painting, nature, and stargazing.

Dana Bar

Undergraduate Student

I was born in Gedera in 2001, and I’ve been passionate about physics for as long as I can remember.

Matan Berko

Undergraduate Student

I was captivated by the beauty of interstellar clouds and the complex dynamics of cosmic turbulence, which led me to join the group to explore phase transitions between the hot and cold phases of the interstellar medium.

Jonathan Shelest

Undergraduate Student

I am working on characterizing the 3D structure and dynamics of cold interstellar clouds. I am using comprehensive magneto-hydrodynamical (MHD) simulations (RAMSES) and radiative transfer and comparing the simulated clouds with 21cm observations in the Milky Way Galaxy.

Yedidya Arbel

Graduate Student

Galaxies Are Our LaboratoryTheory, Observations and SimulationsMaster and PhD Positions are available
Join Us!

The ISM in 3D

Explore simulations and observations of the interstellar medium

Click, Rotate, and zoom

Launch interactive 3D simulation Click to load (about 8 MB)
A Turbulent ISM Simulation (Left)

  • Box scale: 200 parsec (600 light-years).
  • Simulation Includes: gravity, heating and cooling, chemistry, radiation, cosmic rays, and magnetic fields.
  • RAMSES magneto-hydrodynamic code.
  • Visit Github (page / rep) for more details!

More 3D Visualizations:

SLICES THROUGH A MOLECULAR CLOUD

MILKY WAY’S DUST

PER-TAU SHELL

THERMAL PHASES

PHASES’ DISTRIBUTION IN THE MILKY WAY

Talks

Colloquia, conference talks, and public outreach across interstellar medium physics and star formation

Turbulence & Chemistry

How interstellar turbulence shapes the chemistry of the ISM

click to watch

Turbulence & Chemistry

Talk
Description

Turbulence produces density fluctuations in the interstellar medium, which in turn drive variations in the abundance of atomic and molecular species. Observations of molecular abundances with radio and sub-mm telescopes, combined with analytic and numerical models, can shed new light on the origin of interstellar turbulence.

Talk Details

Our Lab

A short introduction to the Star Formation and ISM Lab at the Technion

click to watch

Our Lab

Talk
Description

This is where I talk about boring stuff but make it exciting, watch me do my magic

Talk Details
  • CATEGORY: chemicals and other nonsense
  • DATE: 26th April, 2014
  • TAGS: Stars, Galaxy, Me Handsome!

far-UV Radiation

Modeling far-ultraviolet radiation across galaxy types and redshifts, and its role in regulating the multiphase ISM and star formation

click to watch

far-UV Radiation

Talk
Description

Far-ultraviolet photons from massive stars are the dominant heating source of the ISM, controlling its multiphase structure, molecular composition, and potentially self-regulating star formation. This talk presents analytic and numerical models of the FUV interstellar radiation field from local to high-redshift galaxies, and from massive to dwarf systems.

Talk Details
  • Based on Bialy (2020), ApJ — ADS

Per-Tau Shell

A public outreach video: A giant spherical cavity in space, carved by supernovae, that triggered the formation of the Perseus and Taurus molecular clouds

click to watch

Per-Tau Shell

Talk
Description

Astronomers mapping interstellar dust discovered a huge spherical cavity — the Per-Tau Shell — showing that supernovae led to the formation of two nearby star-forming molecular clouds. This short video was produced by the Center for Astrophysics | Harvard & Smithsonian as part of the press release accompanying the discovery.

Talk Details

Supernovae & Cosmic Rays

A colloquium covering stellar feedback, the discovery of the Per-Tau Shell, and the promise of JWST for probing low-energy cosmic rays

click to watch

Supernovae & Cosmic Rays

Talk
Description

Stars form through gravitational collapse of interstellar clouds, but the process is regulated by energy injected back into the ISM by the forming stars themselves. This talk reviews supernovae, cosmic rays, and FUV radiation as key feedback agents, presents the Per-Tau Shell as the first 3D observational evidence for supernova-triggered star formation, and discusses how JWST can constrain the poorly-known low-energy cosmic-ray spectrum.

Talk Details
  • Tel Aviv University, 2021. Host: Prof. Lev Vaidman

Multiphase ISM

A tutorial on the multiphase ISM and its analogies with the circumgalactic medium, for understanding turbulent multiphase gas across scales

click to watch

Multiphase ISM

Talk
Description

This is where I talk about boring stuff but make it exciting, watch me do my magic

Talk Details
  • Tutorial — “Fundamentals of Gaseous Halos” workshop
  • KITP/UCSB, January 20, 2021.
  • Presenter: Shmuel Bialy (Harvard)

CV & Publications

Research Posts
Publications

NASA ADS

Google Scholar

CV

Link to CV

Media & Outreach

Bridging the Gap Between Research and Public Understanding

Science advances when discoveries reach beyond academic circles. Here’s how our research has captured public attention and contributed to broader scientific literacy.

Invisible Particles That Control Star Birth Measured for First Time

Technion’s Website


Additional Links: Times of Israel | YNet (Hebrew) | Ha yad’an (Hebrew) | University of Duisburg-Essen (German) | NewsRu (Russian)

Gigantic Cavity in Space Sheds New Light on How Stars Form

Harvard CfA’s Website


Additional links: The Independent | Wikipedia | AAS-NOVA | VICE | Gizmodo ScienceAlert | UniverseToday | The PerTau shell website

Water Could Have Been Abundant in the First Billion Years

Harvard CfA’s Website



Additional links: IFLScience | AstronomyNow | ScienceDaily | ​​​​​​​SciNews

Turbulence-Driven Astrochemistry: Resolving Molecular Abundance Puzzles in Interstellar Clouds

Harvard CfA’s Website

Additional Links: Phys.org

“A Star is Born”

a podcast series on the Israeli national radio introducing basic topics in astrophysics and cosmology

Link: Kan Radio (Hebrew)

CATS

An open source online database of magneto-hydrodynamical simulations for open source research and visualization

Link: mhdturbulence.com

Contact Me

Keep In Touch

Tel.: +972 (055) 317 9920

Technion City, Haifa 3200003, Israel

sbialy@technion.ac.il