Type II supernovae from the Carnegie Supernova Project-I

III. Understanding SN II diversity through correlations between physical and observed properties

¹ Instituto de Astrofísica de La Plata (IALP), CCT-CONICET-UNLP. Paseo del Bosque s/n, B1900FWA La Plata, Argentina
e-mail: laureano@carina.fcaglp.unlp.edu.ar
² Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA La Plata, Argentina
³ Universidad Nacional de Río Negro. Sede Andina, Mitre 630, 8400 Bariloche, Argentina
⁴ European Southern Observatory, Alonso de Córdova 3107, Casilla 19, Santiago, Chile
⁵ Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan
⁶ Vice President and Head of Mission of AURA-O in Chile, Avda. Presidente Riesco 5335 Suite 507, Santiago, Chile
⁷ Hagler Institute for Advanced Studies, Texas A&M University, College Station, TX 77843, USA
⁸ CENTRA-Centro de Astrofísica e Gravitação and Departamento de Física, Instituto Superio Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisboa, Portugal
⁹ Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
¹⁰ Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
¹¹ Carnegie Observatories, Las Campanas Observatory, Casilla 601, La Serena, Chile
¹² Finnish Centre for Astronomy with ESO (FINCA), University of Turku, 20014 Turku, Finland
¹³ Tuorla Observatory, Department of Physics and Astronomy, 20014 University of Turku, Finland
¹⁴ Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, CA 91101, USA
¹⁵ Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
¹⁶ Department of Astronomy, University of California, 501 Campbell Hall, Berkeley, CA 94720-3411, USA
¹⁷ Data and Artificial Intelligence Initiative, Faculty of Physical and Mathematical Sciences, University of Chile, Santiago, Chile
¹⁸ Centre for Mathematical Modelling, Faculty of Physical and Mathematical Sciences, University of Chile, Santiago, Chile
¹⁹ Millennium Institute of Astrophysics, Santiago, Chile
²⁰ Department of Astronomy, Faculty of Physical and Mathematical Sciences, University of Chile, Santiago, Chile
²¹ Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
²² Department of Physics, Florida State University, 77 Chieftan Way, Tallahassee, FL 32306, USA
²³ George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA

Received: 30 October 2021
Accepted: 7 February 2022

Abstract

Type II supernovae (SNe II) show great photometric and spectroscopic diversity which is attributed to the varied physical characteristics of their progenitor and explosion properties. In this study, the third of a series of papers where we analyse a large sample of SNe II observed by the Carnegie Supernova Project-I, we present correlations between their observed and physical properties. Our analysis shows that explosion energy is the physical property that correlates with the highest number of parameters. We recover previously suggested relationships between the hydrogen-rich envelope mass and the plateau duration, and find that more luminous SNe II with higher expansion velocities, faster declining light curves, and higher ⁵⁶Ni masses are consistent with higher energy explosions. In addition, faster declining SNe II (usually called SNe IIL) are also compatible with more concentrated ⁵⁶Ni in the inner regions of the ejecta. Positive trends are found between the initial mass, explosion energy, and ⁵⁶Ni mass. While the explosion energy spans the full range explored with our models, the initial mass generally arises from a relatively narrow range. Observable properties were measured from our grid of bolometric LC and photospheric velocity models to determine the effect of each physical parameter on the observed SN II diversity. We argue that explosion energy is the physical parameter causing the greatest impact on SN II diversity, that is, assuming the non-rotating solar-metallicity single-star evolution as in the models used in this study. The inclusion of pre-SN models assuming higher mass loss produces a significant increase in the strength of some correlations, particularly those between the progenitor hydrogen-rich envelope mass and the plateau and optically thick phase durations. These differences clearly show the impact of having different treatments of stellar evolution, implying that changes in the assumption of standard single-star evolution are necessary for a complete understanding of SN II diversity.