Authors: Jordan Mirocha (McGill), Daniel Jacobs (Arizona State), Josh Dillon (UC-Berkeley), Steve Furlanetto (UCLA), Jonathan Pober (Brown), Adrian Liu (McGill), James Aguirre (UPenn), Yacine Ali-Haïmoud (NYU), Marcelo Alvarez (UC-Berkeley), Adam Beardsley (Arizona State), George Becker (UC-Riverside), Judd Bowman (Arizona State), Patrick Breysse (CITA), Volker Bromm (UT-Austin), Jack Burns (¶¶ÒõÂÃÐÐÉä-Boulder), Xuelei Chen (Chinese Academy of Sciences), Tzu-Ching Chang (JPL), Hsin Chiang (McGill), Joanne Cohn (UC-Berkeley), David DeBoer (UC-Berkeley), Cora Dvorkin (Harvard), Anastasia Fialkov (Sussex), Nick Gnedin (Fermilab), Bryna Hazelton (Washington), Masui Kiyoshi (MIT), Saul Kohn (Vanguard Group), Leon Koopmans (Kapteyn Astronomical Institute), Ely Kovetz (Ben-Gurion), Paul La Plante (UPenn), Adam Lidz (UPenn), Yin-Zhe Ma (KwaZulu-Natal), Yi Mao (Tsinghua), Andrei Mesinger (Scuola Normale Superiore), Julian Muñoz (Harvard), Steven Murray (Arizona State), Aaron Parsons (UC-Berkeley), Jonathan Pritchard (Imperial College London), Jonathan Sievers (McGill), Eric Switzer (Goddard), Nithyanandan Thyagarajan (NRAO), Eli Visbal (Flatiron), Matias Zaldarriaga (Institute for Advanced Study)
Abstract: The "cosmic dawn" refers to the period of the Universe's history when stars and black holes first formed and began heating and ionizing hydrogen in the intergalactic medium (IGM). Though exceedingly difficult to detect directly, the first stars and black holes can be constrained indirectly through measurements of the cosmic 21-cm background, which traces the ionization state and temperature of intergalactic hydrogen gas. In this white paper, we focus on the science case for such observations, in particular those targeting redshifts z ≳ 10 when the IGM is expected to be mostly neutral. 21-cm observations provide a unique window into this epoch and are thus critical to advancing first star and black hole science in the next decade.