SN 2019ehk: A Double-Peaked Ca-rich Transient with Luminous X-ray Emission and Shock-Ionized Spectral Features

Autor: Jacobson-Galán, Wynn V., Margutti, Raffaella, Kilpatrick, Charles D., Hiramatsu, Daichi, Perets, Hagai, Khatami, David, Foley, Ryan J., Raymond, John, Yoon, Sung-Chul, Bobrick, Alexey, Zenati, Yossef, Galbany, Lluís, Andrews, Jennifer, Brown, Peter J., Cartier, Régis, Coppejans, Deanne L., Dimitriadis, Georgios, Dobson, Matthew, Hajela, Aprajita, Howell, D. Andrew, Kuncarayakti, Hanindyo, Milisavljevic, Danny, Rahman, Mohammed, Rojas-Bravo, César, Sand, David J., Shepherd, Joel, Smartt, Stephen J., Stacey, Holland, Stroh, Michael, Swift, Jonathan J., Terreran, Giacomo, Vinko, Jozsef, Wang, Xiaofeng, Anderson, Joseph P., Baron, Edward A., Berger, Edo, Blanchard, Peter K., Burke, Jamison, Coulter, David A., DeMarchi, Lindsay, DerKacy, James M., Fremling, Christoffer, Gomez, Sebastian, Gromadzki, Mariusz, Hosseinzadeh, Griffin, Kasen, Daniel, Kriskovics, Levente, McCully, Curtis, Müller-Bravo, Tomás E., Nicholl, Matt, Ordasi, András, Pellegrino, Craig, Piro, Anthony L., Pál, András, Ren, Juanjuan, Rest, Armin, Rich, R. Michael, Sai, Hanna, Sárneczky, Krisztián, Shen, Ken J., Short, Philip, Siebert, Matthew, Stauffer, Candice, Szakáts, Róbert, Zhang, Xinhan, Zhang, Jujia, Zhang, Kaicheng
Rok vydání: 2020
Předmět:
Druh dokumentu: Working Paper
DOI: 10.3847/1538-4357/ab9e66
Popis: We present panchromatic observations and modeling of the Calcium-rich supernova 2019ehk in the star-forming galaxy M100 (d$\approx$16.2 Mpc) starting 10 hours after explosion and continuing for ~300 days. SN 2019ehk shows a double-peaked optical light curve peaking at $t = 3$ and $15$ days. The first peak is coincident with luminous, rapidly decaying $\textit{Swift}$-XRT discovered X-ray emission ($L_x\approx10^{41}~\rm{erg~s^{-1}}$ at 3 days; $L_x \propto t^{-3}$), and a Shane/Kast spectral detection of narrow H$\alpha$ and He II emission lines ($v \approx 500$ km/s) originating from pre-existent circumstellar material. We attribute this phenomenology to radiation from shock interaction with extended, dense material surrounding the progenitor star at $r<10^{15}$ cm and the resulting cooling emission. We calculate a total CSM mass of $\sim$ $7\times10^{-3}$ $\rm{M_{\odot}}$ with particle density $n\approx10^{9}\,\rm{cm^{-3}}$. Radio observations indicate a significantly lower density $n < 10^{4}\,\rm{cm^{-3}}$ at larger radii. The photometric and spectroscopic properties during the second light curve peak are consistent with those of Ca-rich transients (rise-time of $t_r =13.4\pm0.210$ days and a peak B-band magnitude of $M_B =-15.1\pm0.200$ mag). We find that SN 2019ehk synthesized $(3.1\pm0.11)\times10^{-2} ~ \rm{M_{\odot}}$ of ${}^{56}\textrm{Ni}$ and ejected $M_{\rm ej} = (0.72\pm 0.040)~\rm{M_{\odot}}$ total with a kinetic energy $E_{\rm k}=(1.8\pm0.10)\times10^{50}~\rm{erg}$. Finally, deep $\textit{HST}$ pre-explosion imaging at the SN site constrains the parameter space of viable stellar progenitors to massive stars in the lowest mass bin (~10 $\rm{M_{\odot}}$) in binaries that lost most of their He envelope or white dwarfs. The explosion and environment properties of SN 2019ehk further restrict the potential WD progenitor systems to low-mass hybrid HeCO WD + CO WD binaries.
Comment: 51 pages, 27 figures. Accepted for publication in ApJ
Databáze: arXiv
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