HET Spectroscopic Observation and Modeling of SLSN 2019neq

ATel #13085; R. Konyves-Toth (Konkoly Obs.), J. Vinko (Konkoly Obs., U Szeged, UT Austin), B. P. Thomas (ICG Portsmouth, UT Austin), J. C. Wheeler (UT Austin)
on 6 Sep 2019; 18:23 UT
Credential Certification: Jozsef Vinko (vinko@astro.as.utexas.edu)

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We report an optical spectrum (range 364 - 1000 nm) of SN 2019neq (ZTF19abpbopt, R.A. = 17:54:26.736, Dec. = +47:15:40.56) taken with the 10m Hobby-Eberly Telescope "Low Resolution Spectrograph-2" (LRS2) at McDonald Observatory by Sergey Rostopchin on 2019-09-01.2 UT. This young, nearby (z ~ 0.1) Superluminous Supernova (SLSN) was discovered by the Zwicky Transient Facility (AstroNote-2019-79) and classified as a Type-I SLSN based on the similarity with the spectrum of SN 2005ap.

The new spectrum consists of several broad features superimposed on a hot continuum. Narrow emission lines due to [O III] and H-alpha from the host galaxy are apparent, confirming the redshift announced in the discovery report.

We modeled the spectrum using the spectral synthesis code SYN++ (Thomas, R., 2013, ASCL 1308.008). After correcting for Milky Way reddening (E(B-V) ~ 0.03 mag), host galaxy redshift (z ~ 0.1075) and applying v_phot = 21,000 km/s and T_phot = 15,000 K for the photospheric velocity and temperature, we were able to model the "W-like" feature between 450 - 490 nm with O II (as usually done for SLSNe-I) and other features with Si III, Fe II and Co III. Alternatively, the "W-like" feature can also be fit with a combination of C III, O III, and Si III. This latter model, which does not contain O II, also needs the presence of C II and Si IV in addition to Fe II and Co III.

We conclude that beyond the spectral similarity to SN 2005ap, this chemical composition, especially the lack of H and He features, fully confirm that SN 2019neq is unambiguously a Type-I SLSN around maximum light.

Further follow-up observations are planned.