Preface: CSQCDIX

The 9th international workshop Compact Stars in the QCD phase diagram was held, during August 1-5 2022, Banff (Alberta, Canada) entitled “Compact IX (CSQCD IX): From RHIC to Astrophysics, Probing Quark-Gluon Plasma”. This series of meetings started 2001 Copenhagen (Denmark), and then continued 2009 Beijing (China), 2012 Guaruja (Brazil), 2014 Prerow (Germany), 2016 l’Aquila (Italy), 2017 Dubna (Russia), 2018 New York (NY, USA), 2020 at ICTS (India; on line). CSQCD workshops aim bring together physicists working strongly interacting dense matter with astrophysicists related astrophysical phenomena such as supernovae, gamma ray bursts pulsars. A profound theoretical description these necessarily involves equation state transport properties that are derived from non-perturbative quantum field theories, many-body physics phenomenological investigations. focussed recent explorations quark-gluon using colliders (e.g. LHC) renewed interest neutron quark astrophysics, particularly gravitational wave era. science sessions focused nuclear high baryon density, probing neutron-star laboratory, characterization critical endpoint diagram. phases discussed (in memory Stefan Schramm) well compact stars. Recent results constraining symmetry energy experiments, theory observations implications for stars were also presented. For first time series, talks highlighted importance waves as: (i) a tool probe transitions; (ii) probes reacting interfaces core Also featured data NICER star mergers materials science. present volume Journal Physics: Conference Series represents selected contributions participants workshop. Each submitted contribution has been peer reviewed Editors very grateful referees their careful support. Proceedings: Rachid Ouyed (University Calgary, Denis Leahy Nico Koning Tobias Fischer Wroclaw, Poland) Sumiyoshi Kohsuke (National Institute Technology, Numazu College, Japan) Massimo Mannarelli Laboratories Gran Sasso, Italy) Fridolin Weber (San Diego State University, USA) 1st May 2023