Cosmic Dawn
the First Stars

Professor Rennan Barkana studies the formation and evolution of the first stars. He constructs models in order to predict the properties of the galaxies in which the first stars formed, and studies ways to probe them, especially via radio-wave radiation from hydrogen atoms at a wavelength of 21 cm. In 2018 Barkana showed that an observation of radio waves from the early Universe may imply that the dark matter cooled the early cosmic gas. If confirmed by further measurements, this would be a milestone in physics, the first direct detection of the mysterious dark matter that makes up most of the matter in the Universe.

After graduating Summa Cum Laude from the University of Pennsylvania with a B.A. and double honors in Physics and Math, Barkana got his Ph.D. in Physics at age 23 from MIT. Following a postdoctoral stint at the Institute for Advanced Study in Princeton plus a year in Canada, he assumed a faculty position at Tel Aviv University, Israel, where he is a Professor and former Head of the Department of Astrophysics. Barkana has been a Guggenheim Fellow, a Moore Distinguished Scholar at Caltech, a Leverhulme Visiting Professor at Oxford, and a Distinguished Visiting Professor at UC Santa Cruz.
2015 - present   (Full) Professor, Tel Aviv University
2022   Theoretical Astrophysics Santa Cruz (TASC) Institute: Distinguished Visiting Professor, University of California, Santa Cruz, CA, USA
2021 - 2022   Member (Sabbatical Visitor), Astrophysics, Institute for Advanced Study, Princeton, NJ, USA
2016 - 2020   Head of the Department of Astrophysics, Tel Aviv University
2016   Visiting Professor, The Perimeter Institute, Waterloo, Canada
2015 - 2016   Leverhulme Visiting Professor, and Visiting Fellow of Mansfield College, University of Oxford, UK
2015   Lagrange Award winner, Institut D'Astrophysique de Paris (IAP), France
2009 - 2015   Associate Professor, Tel Aviv University
2008 (Spring)   Moore Distinguished Scholar, Caltech
2007 (Fall)   Visiting Associate Professor, ICRR, University of Tokyo
2001 - 2009   Senior Lecturer, Tel Aviv University (2006: Tenured)
2022   Theoretical Astrophysics Santa Cruz (TASC) Institute: Distinguished Visiting Professor, University of California, Santa Cruz, CA, USA
2015-16   Visiting Fellowship, Mansfield College, University of Oxford, UK
2015   Leverhulme Visiting Professorship, Leverhulme Trust, UK [link]
2015   Lagrange Award, Institut Lagrange de Paris (ILP), France [link]
2007 - 2008   Fellowship, John Simon Guggenheim Memorial Foundation [link]
2008   Moore Distinguished Scholar, Caltech
2007 - 2008   Radcliffe Institute Fellowship, Harvard (declined) [link]
2001 - 2004   Alon Fellowship, Israeli Council of Higher Education

Research grants:
2020 - 2024   Israel Science Foundation Grant
2017 - 2020   Israel - China (ISF - NSFC) grant (with Chinese collaborators)
2017 - 2019   Templeton Foundation grant
2012 - 2015   Israel Space Agency grant (with Yoel Rephaeli)
2009 - 2012   U.S. National Science Foundation Grant (PI: Judd Bowman)
2009 - 2013   Israel Science Foundation Grant
2005 - 2010 (frozen 2007/8)   U.S.-Israel Binational Science Foundation Grant (with Avi Loeb)
2005 - 2008   Israel Science Foundation Grant
2002 - 2005   Israel Science Foundation Grant
2002 - 2005   U.S. National Science Foundation Grant (PI: Avi Loeb)
2003   NATO Grant (with Avi Loeb)
2014 -   Member of SKA (Square Kilometre Array) radio telescope Science Working Group and Key Science Project on the Epoch of Reionization and Cosmic Dawn (Coordinator of Focus Group on Theory/Physics)
2019 -   Member of NenuFar (New Extension in Nançay Upgrading LOFAR) radio telescope Key Science Project on Cosmic Dawn
2023   Member of Scientific Advisory Committee, conference on Neutral Hydrogen as a Cosmological Probe Across Cosmic Time, Nazareth, Israel
2020   Member of Scientific Organizing Committee, International Conference on the Emerging Issues in Cosmology and Particle Physics, Visva-Bharati University, India
2018   Co-organizer of "Cosmological Signals from Cosmic Dawn to the Present", Aspen Winter Conference on Astrophysics [link]
2015   Principal organizer of "Cosmology and First Light", an international conference at the Institut D'Astrophysique de Paris (IAP) [link]
2014 - 2015   Member of International Ph.D. Board of Scuola Normale Superiore, Pisa, Italy
2010   Principal organizer, Aspen Winter Astrophysics Conference on "The High Redshift Universe: A Multi-Wavelength View" [link]
2008   Member of Scientific Organizing Committee, 23'rd IAP (Paris) Colloquium
2007   Space Telescope Science Institute, Review Panel of Hubble Space Telescope proposals
2006   Principal organizer, John Bahcall Physics Day (Tel Aviv University) [link]
2006   Principal organizer, Aspen Winter Astrophysics Conference on "Cosmological Probes of Baryons and Dark Matter" [link]
Invited conference talks [36]:
2023   21 cm Cosmology - IFPU (Institute for Fundamental Physics of the Universe) Focus Week, Trieste, Italy
2023   URSI (International Union of Radio Science) GASS (General Assembly and Scientific Symposium) 2023, Sapporo, Japan
2023   Neutral Hydrogen as a Cosmological Probe Across Cosmic Time (Invited Review), Nazareth, Israel
2023   Frontiers in Cosmology, RRI, Bangalore, India
2022   Unsolved Problems in Astrophysics and Cosmology 2022, Jerusalem, Israel
2020   Next-Generation Cosmology with Next-Generation Radio Telescopes: II, Sexten Center for Astrophysics, Sesto, Italy
2020   International Conference on the Emerging Issues in Cosmology and Particle Physics, Visva-Bharati University, India (could not attend)
2019   30th Texas Symposium on Relativistic Astrophysics (invited plenary talk), Portsmouth, UK
2019   The Second Global 21cm Workshop, McGill University, Montreal, Canada (cannot attend)
2019   First Light (invited lecture series, advanced school), Sao Paolo, Brazil
2019   15th PATRAS Workshop on Axions, WIMPs, and WISPs, Freiburg, Germany (could not attend)
2018   TevPA2018 Conference, Berlin, Germany (could not attend)
2018   COSMO-18, Daejeon, South Korea (invited plenary talk; could not attend)
2018   Nonlinear Universe 2018 and EdBertFest, Smartno, Slovenia
2018   Thermal history of the Universe at intermediate redshift: progress with 21cm absorption measurements, CERN, Switzerland
2018   Next-Generation Cosmology with Next-Generation Radio Telescopes, Sexten Center for Astrophysics, Sesto, Italy
2017   Post Planck Cosmology: Enigma, Challenges and Visions, Pune, India
2017   Fundamental Physics with the Square Kilometre Array, Mauritius
2016   CMB Spectral Distortions from Cosmic Baryon Evolution, Raman Research Institute, Bangalore, India
2016   Cosmological Probes of Fundamental Physics, Weizmann Institute of Science, Israel
2016   Physics of Reionization and the Cosmic Dawn in the SKA Era, Sexten Center for Astrophysics, Sesto, Italy
2015   RESCEU APCosPA (Asia Pacific Organization for Cosmology and Particle Astrophysics) Summer School on Cosmology and Particle Astrophysics (Invited lecture series), Tokyo, Japan
2014   CASCA (Canadian Astronomical Society) Annual Meeting, Quebec City, Canada
2012   "Gamma Ray Bursts in the Era of Rapid Follow-up", Liverpool, UK
2012   CosmoBias: International Meeting on "Physical Bias in Cosmology" (Invited Review), Marseille, France
2011   "Hydrogen Cosmology" workshop at Harvard
2008   Harvard University Conference on "21cm Cosmology"
2008   "Cosmology with the CMB and LSS", School and workshop program, Tata Institute of Fundamental Research, India (Invited lecture series; could not attend)
2007   Workshop: "Early universe and physics beyond the standard model", Tokyo, Japan
2007   "HI Survival through Cosmic Times", Tuscany, Italy
2006   "From Planets to Galaxies", Budapest, Hungary
2004   Oort Workshop on "CMB and first objects at the end of the dark ages: observational consequences of reionization", Holland
2003   Kloster Irsee Workshop on "The Formation and Early Evolution of Galaxies", Germany
2002   "Early Cosmic Structures and the End of the Dark Ages", Elba, Italy
2001   Annual Meeting of the Israeli Physics Society, Tel Aviv, Israel
2000   Harvard University Conference on "The First Generation of Cosmic Structures"

SKA and NenuFar (invitation-only) workshops/meetings [8]:
2023   NenuFAR Cosmic Dawn Plenary meeting, Groningen, the Netherlands
2022   NenuFAR Cosmic Dawn day (virtual conference)
2021   Second NenuFAR Cosmic Dawn workshop (virtual conference)
2020   First NenuFAR Cosmic Dawn workshop (virtual conference)
2018   SKA CD/EoR meeting, London, UK
2016   SKA 2016: Science for the SKA Generation (general conference + Key Science Project meeting), Goa, India
2015   SKA CD/EoR Science Team Workshop (conference for developing the science team for Cosmic Dawn / Epoch of Reionization measurements with the Square Kilometre Array), Groningen, the Netherlands
2015   The SKA Key Science Workshop (conference for developing scientific plans for the Square Kilometre Array), Stockholm, Sweden

Contributed conference talks [22]:
2021   4'th Global 21-cm Workshop, University of Colorado Boulder (virtual conference)
2020   3'rd Global 21-cm Workshop, Cambridge, UK (virtual conference)
2019   Barefoot Reionization: Exploring the First Billion Years of the Universe, Fitzroy Island, Qld, Australia
2019   Into the Starlight: The End of the Cosmic Dark Ages, Aspen, U.S.A.
2018   Cosmological Signals from Cosmic Dawn to the Present, Aspen, U.S.A.
2015   Cosmology and First Light, IAP, Paris, France
2014   CosPA 2014: 11th International Symposium on Cosmology & Particle Astrophysics, Auckland, New Zealand
2013   CosPA 2013: 10th International Symposium on Cosmology & Particle Astrophysics, Hawaii, U.S.A.
2010   CITA@25/Bond@60: The Theory of the Universe and Everything in It, Toronto, Canada
2010   The High Redshift Universe: A Multi-Wavelength View, Aspen, U.S.A.
2009   Focus week on non-Gaussianities in the sky, Tokyo, Japan
2006   Cosmological Probes of Baryons and Dark Matter, Aspen, U.S.A.
2005   Reionizing the Universe, Groningen, The Netherlands
2004   Galaxy-Intergalactic Medium Interactions, KITP, Santa Barbara, U.S.A.
2004   The Large Scale Structure of Gas and Mass in the High Redshift Universe, Technion, Israel
2004   The Large-Scale Distribution of Mass&Light in the Universe, Aspen, U.S.A.
2003   Stars and Structure Formation: From First Light to the Milky Way, Zurich, Switzerland
2003   Galaxy Formation, Jerusalem, Israel
2003   The Baryonic Universe, Aspen, U.S.A.
2000   The Physics of Galaxy Formation, Tsukuba, Japan
1999   Gravitational Lensing: Recent Progress and Future Goals, Boston, U.S.A.
1999   Cosmological Implications of the Local Group, Aspen, U.S.A.
Currently Looking for Students and Postdocs
[Press for full info]

Postdoc   Rajesh Mondal: 21-cm Cosmology, 2022 - present.
Ph.D.   Sudipta Sikder: 21-cm Cosmology, 2019 - present.

Ph.D.   Anastasia Fialkov: 21-cm Cosmology, 2011 - 2013 (first part of Ph.D. was supervised by Nissan Itzhaki). Postdoc positions: Junior Research Chair at École Normale Supérieure, Paris; Harvard ITC Fellow. Faculty: Royal Society Fellow and Lecturer at the Institute of Astronomy at the University of Cambridge (permanent position). [website].
Ph.D.   Smadar Naoz: "The First Generation of Galaxies and 21-cm Fluctuations", 2009. Postdoc positions: Northwestern University; Harvard ITC Fellow; Einstein Fellow. Faculty: Associate Professor at UCLA, 2015 Sloan Fellow, 2020 Helen B. Warner prize winner. [website].
Ph.D.   Itamar Reis: 21-cm Cosmology, 2019 - 2021 (also supervised by Dovi Poznanski). Did not pursue postdoc (personal decision).
Ph.D.   Aviad Cohen: 21-cm Cosmology, 2013 - 2018 (also M.Sc., joined direct Ph.D. program in 2014). Did not pursue postdoc (personal decision).
Ph.D.   Eli Visbal: 21-cm Cosmology, 2011 - 2013 (While not formally my student, this Harvard graduate student's summer project with me became a Nature paper and an important part of his thesis). Postdoc: Columbia University; Flatiron Institute. Faculty: Assistant Professor at the University of Toledo.
Ph.D.   Doron Lemze (jointly advised with Tom Broadhurst and Yoel Rephaeli): "Modeling clusters and starburst galaxies", 2007 - 2010. Postdoc: Johns Hopkins University.
Postdoc   Andrea Morandi: 21-cm Cosmology, 2010 - 2012.
M.Sc.   Alon Banet: 21-cm Cosmology, 2018 - 2020.
M.Sc.   Shay Noter: "Halo Statistics - A New Alternative to Simulations", 2005 - 2007.
M.Sc.   Oren Zoran: "A Cosmic Relation between Extinction and Star Formation", 2004 - 2006.
Postdoctoral positions:
2000 - 2001   Postdoctoral Fellow, Canadian Institute for Theoretical Astrophysics (Toronto)
1997 - 2000   Postdoctoral Member, Institute for Advanced Study (Princeton)

1997 Ph.D. in Physics; Massachusetts Institute of Technology (M.I.T.)
1993 B.A. in Math and Physics (Summa Cum Laude, with Honors in both majors); University of Pennsylvania

Personal information:
1973 Born in Haifa, Israel
Citizenship: Israel and U.S.
Married to Riki and father to Or and Ariel

Playing violin; here is a concert with my daughter; also see my Shostakovich page
Playing chess (USCF rating 1900)
Scuba diving (certified Advanced Open Water); here I am with an aquatic friend
Research Interests:
Theoretical Astrophysics and Cosmology: 21-cm cosmology, formation of the first stars and quasars, cosmic dawn and cosmic reionization, dark matter, galaxy formation, large-scale structure, and gravitational lensing.

Key Publications (chronological order; selected through high citation count and/or high impact journal):
  • "Prospects for precision cosmology with the 21 cm signal from the dark ages", Rajesh Mondal, Rennan Barkana, Nature Astronomy 7, 1025 (2023) [link].
  • "Astrophysical constraints from the SARAS 3 non-detection of the cosmic dawn sky-averaged 21-cm signal", Harry T.J. Bevins, Anastasia Fialkov, Eloy de Lera Acedo, Will J. Handley, Saurabh Singh, Ravi Subrahmanyan, Rennan Barkana, Nature Astronomy 6, 1473 (2022) [link].
  • "Strong constraints on light dark matter interpretation of the EDGES signal", Rennan Barkana, Nadav J. Outmezguine, Diego Redigol, and Tomer Volansky, Physical Review D , 98,103005 (2018).
  • "Constraining Baryon-Dark Matter Scattering with the Cosmic Dawn 21-cm Signal", Anastasia Fialkov, Rennan Barkana, and Aviad Cohen, Physical Review Letters , 121, 011101 (2018).
  • "Possible interaction between baryons and dark-matter particles revealed by the first stars", Rennan Barkana, Nature , 555, 71 (2018) [link].
  • Book: The Encyclopedia of Cosmology, Volume 1: "Galaxy Formation and Evolution", Rennan Barkana, World Scientific Series in Astrophysics, World Scientific Publishing Co (2018) [link].
  • "The rise of the first stars: Supersonic streaming, radiative feedback, and 21-cm cosmology", Rennan Barkana, Physics Reports (Invited Review), 645, 1 (2016) [link] .
  • "Large-Scale Distribution of Total Mass versus Luminous Matter from Baryon Acoustic Oscillations: First Search in the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey Data Release 10", Maayane Soumagnac, Rennan Barkana, C. G. Sabiu, A. Loeb, A. J. Ross, F. B. Abdalla, S. T. Balan, and O. Lahav, Physical Review Letters , 116, 201302 (2016).
  • "Reconstructing the nature of the first cosmic sources from the anisotropic 21-cm signal", Anastasia Fialkov, Rennan Barkana, and Aviad Cohen, Physical Review Letters , 114, 101303 (2015).
  • "The observable signature of late heating of the Universe during cosmic reionization", Anastasia Fialkov, Rennan Barkana, and Eli Visbal, Nature , 506, 197 (2014) [link].
  • "The signature of the first stars in atomic hydrogen at redshift 20", Eli Visbal, Rennan Barkana, Anastasia Fialkov, Dmitriy Tseliakhovich, and Chris Hirata, Nature , 487, 70 (2012) [link].
  • "The First Stars in the Universe and Cosmic Reionization", Rennan Barkana, Science (Invited Review), 313, 931 (2006).
  • "Detecting the Earliest Galaxies Through Two New Sources of 21cm Fluctuations", Rennan Barkana and Abraham Loeb, The Astrophysical Journal , 626, 1 (2005).
  • "A Method for Separating the Physics from the Astrophysics of High-Redshift 21cm Fluctuations", Rennan Barkana and Abraham Loeb, The Astrophysical Journal Letters, 624, 65 (2005).
  • "Unusually Large Fluctuations in the Statistics of Galaxy Formation at High Redshift", Rennan Barkana and Abraham Loeb, The Astrophysical Journal , 609, 474 (2004).
  • "Spectral Signature of Cosmological Infall Around the First Quasars", Rennan Barkana and Abraham Loeb, Nature , 421, 341 (2003) [link] .
  • "Constraints on Warm Dark Matter from Cosmological Reionization", Rennan Barkana, Zoltán Haiman, and Jeremiah P. Ostriker, The Astrophysical Journal , 558, 482 (2001).
  • "In the Beginning: The First Sources of Light and the Reionization of the Universe", Rennan Barkana and Abraham Loeb, Physics Reports (Invited Review), 349, 125 (2001) [link] .
  • "The Reionization of the Universe by the First Stars and Quasars", Rennan Barkana and Abraham Loeb, Annual Reviews of Astronomy and Astrophysics (Invited Review), 39, 19 (2001).
  • "Fuzzy Cold Dark Matter: The Wave Properties of Ultralight Particles", Wayne Hu, Rennan Barkana and Andrei Gruzinov, Physical Review Letters , 85, 1158 (2000).
  • "The Photoevaporation of Dwarf Galaxies during Reionization", Rennan Barkana and Abraham Loeb, The Astrophysical Journal , 523, 54 (1999).
The full, up-to-date listing of my publications in ADS, including (and ordered by) citations, is here.
A list of papers that cite mine in ADS (most recent appear first) is here. Also, my full CV and publications (usually not so uptodate) are here.
Currently teaching Physics 2A (Electricity & Magnetism) for Chemists.
Full teaching history is available here.

Prof. Rennan Barkana

Department of Astrophysics
School of Physics and Astronomy
Tel Aviv University, ISRAEL

  Studying the Cosmic Dark Ages from the Moon: News links


("Gas" refers to all of the ordinary matter, the only component that we really understand)

69% Complete (info)
26% Complete (success)
GAS 5%
5% Complete (warning)
DM radio sky Me with SKA antenna


In recent decades, the biggest discoveries in physics have come from astronomy (dark matter, dark energy, gravitational waves, and black holes). In March 2018 I announced an exciting potential discovery that could represent another example of deriving fundamental physics from astronomical observations.

Astronomers have been searching for a radio-wave signal that had been predicted to be a sign of the formation of the first stars in the early Universe. Bowman and colleagues reported the first such detection, obtained with their EDGES radio telescope. The signal had a much larger amplitude than expected, presenting a puzzle. I realized that this surprising signal can be explained by combining two factors: the first stars, and dark matter. The first stars in the universe turned on the radio signal as expected, while the dark matter collided with the ordinary matter and cooled it down. Extra-cold material naturally explains the strong radio signal.

If true, this would have enormous implications in answering one of the most basic questions: What is the Universe made of? Indeed, this would be the first direct clue about the nature of the mysterious dark matter that makes up most of the matter in the Universe. For example, physicists expected that dark matter would be made up of heavy particles, but the discovery indicates low-mass particles.

Caution is needed, since the EDGES measurement is the first of its kind. Independent confirmation is now being attempted, and the first experiment that reached comparable sensitivity (SARAS3) disfavored the EDGES result (at a 2 sigma statistical significance). Much more information is expected within a few years. I predicted that the dark matter may have produced a specific pattern of radio waves on the sky (the colorful image above or to the left of this text is an example), which can be detected with a large array of radio antennas. One such array is the SKA, the largest radio telescope in the world, now under construction (the second image shows me next to an SKA antenna prototype, at Cambridge University). Such an observation with the SKA would confirm that the first stars have indeed revealed the dark matter.

More info, audio/video, and links available here.

Intro to Field (Hebrew)

1. Early 2020 TED-style talk (12.5 min) about "Mankind, the Universe, and Dark Matter"
2. Early 2018 explanation (4 min) on The First Stars (Hebrew with English subtitles)

Physics colloquium (2022)

Video file (52 min, 2022)

Discovery? (English and Hebrew)

Dark Matter Revealed by the First Stars, (2.5 min, 2018): English version, Hebrew version

Favorite Quotes

Quotes from Feynman, Einstein, and many others

Link to Quotes page


My courses at Tel Aviv University

Link to Teaching page


My tribute to Shostakovich (plus a few other masterpieces)

Link to Shostakovich page

Research and Outreach Links:
Physics colloquium (2022) (52 min video).
TED-style talk in Hebrew (2020) about "Mankind, the Universe, and Dark Matter" (12.5 min video).
Research highlight (2018): Dark matter revealed by the first stars (Nature): Link.
Research highlight (2014): Cosmic heating and early black holes (Nature): Link.
Research highlight (2012): The First Stars at Redshift 20 (Nature): Link.
A news article (2009) in Science on 21-cm cosmology: Link, PDF.
Media appearances (2014) on gravity waves from inflation (in Hebrew): Link.
Radio Interview in Hebrew on the Cosmic Microwave Background (4.38 MB, 6:23 min, MP3).
Popular Lecture in Hebrew on Cosmology (81 min video + power point lecture).
Prof. Rennan Barkana
School of Physics and Astronomy
Tel Aviv University
Tel Aviv, 6997801
Office: Kaplun 111
Cell Phone: 972-526-313116
Office Phone: 972-3-6405993
Fax: 972-3-6408179
Secy: 972-3-6407414 (Daniella)
email: [send]