A puzzle solved after two decades: SN 2002gh among the brightest of superluminous supernovae

Abstract

We present optical photometry and spectroscopy of the superluminous SN 2002gh from maximum light to +202 days, obtained as part of the Carnegie Type II Supernova (CATS) project. SN 2002gh is among the most luminous discovered supernovae ever, yet it remained unnoticed for nearly two decades. Using Dark Energy Camera archival images we identify the potential SN host galaxy as a faint dwarf galaxy, presumably having low metallicity, and in an apparent merging process with other nearby dwarf galaxies. We show that SN 2002gh is among the brightest hydrogen-poor SLSNe with 𝑀 𝑉 = −22.40 ± 0.02, with an estimated peak bolometric luminosity of 2.6 ± 0.2 × 10 44 erg s −1 . We discount the decay of radioactive nickel as the main SN power mechanism, and assuming that the SN is powered by the spin down of a magnetar we obtain two alternative solutions. The first case, is characterized by significant magnetar power leakage, and 𝑀 ej between 0.8 and 1.6 𝑀 , 𝑃 spin = 3.4 ms, and 𝐵 = 5 × 10 13 G. The second case does not require power leakage, resulting in a huge ejecta mass of about 30 𝑀 , a fast spin period of 𝑃 spin ∼ 1 ms, and 𝐵 ∼ 1.6 × 10 14 G. We estimate a zero-age main-sequence mass between 16 and 19 𝑀 for the first case and of about 135 𝑀 for the second case. The latter case would place the SN progenitor among the most massive stars observed to explode as a SN.

Two years of optical and NIR observations of the superluminous supernova UID 30901 discovered by the UltraVISTA SN survey

“…A review of the literature reveals that the brightest SLSNe reported have absolute magnitudes in the range of −22.0 mag 𝑀 abs −22.5 mag (Smith et al 2007;Vreeswijk et al 2014;Smith et al 2016;De Cia et al 2018;Smith et al 2018;Lunnan et al 2018;Cartier et al 2021;Yin et al 2021). Therefore assuming that UID 30901 reached one of the brightest maximum luminosities reported for a SLSNe (𝑀 𝑟 ≈ −22.5), we can place an approximate redshift upper limit of 𝑧 0.7 for this SN.…”

“…(Smith et al 2007). The time of maximum light for the PS1 and DES SNe was computed using Gaussian process interpolation as described in Cartier et al (2021), and the light curves were corrected by Galactic reddening (𝐸 (𝐵 − 𝑉)) as reported by Schlafly & Finkbeiner (2011) using the Cardelli et al (1989) extinction law. For SN 2006gy the 𝐴 𝑅 values reported by Smith et al (2007) were used for the reddening correction, this is 𝐴 𝑅 = 0.43 and 𝐴 𝑅 = 1.25 for our galaxy and the SN host galaxy, respectively.…”

“…For SN 2006gy the 𝐴 𝑅 values reported by Smith et al (2007) were used for the reddening correction, this is 𝐴 𝑅 = 0.43 and 𝐴 𝑅 = 1.25 for our galaxy and the SN host galaxy, respectively. No k-corrections were applied to the light curves as we expect this correction to be of the order of a few tenths of magnitude for the highest redshift objects, which is small compared to the dispersion observed in the maximum luminosity and with the light curve shape diversity displayed by SLSNe (see De Lunnan et al 2018;Angus et al 2019;Cartier et al 2021).…”

Feeding post core collapse supernova explosion jets with an inflated main sequence companion

“…There are several possible energy sources to explain SLSNe (e.g., Wang et al 2019). One energy source model to account for the extra energy is a magnetar, i.e, a rapidly spinning-magnetic neutron star (NS) remnant of the core collapse supernova (CCSN; e.g., Greiner et al 2015;Metzger et al 2015;Kangas et al 2017;Kasen et al 2016;Chen et al 2017a;Mazzali et al 2017;Nicholl et al 2017;Yu et al 2017;Villar, Nicholl, & Berger 2018;Chatzopoulos & Tuminello 2019;Cartier et al 2021;Nicholl 2021;Gomez et al 2022; for a partial list of other energy sources see, e.g., Urvachev et al 2021 and.…”