ASASSN-15lh (aka SN 2015L), a superluminal supernova, or hypernova?

[Astronuc]

My wife was listening to a video about superluminal supernova (Type Ic), ASASSN-15lh, or SN 2015L. It was discovered through the All Sky Automated Survey for SuperNovae (ASAS-SN). The event occurred in a galaxy ~3.82 billion ly from earth. Peak Apparent Magnitude was 16.9. The mass of ASSASN-15lh is 40 M_☉

It was first detected on June 14, 2015, located within a faint galaxy in the southern constellation Indus, and was the most luminous supernova-like object ever observed. At its peak, ASASSN-15lh was 570 billion times brighter than the Sun, and 20 times brighter than the combined light emitted by the Milky Way Galaxy. The emitted energy was exceeded by PS1-10adi

Ref: https://en.wikipedia.org/wiki/ASASSN-15lh

The Unexpected, Long-Lasting, UV Rebrightening of the Super-Luminous Supernova ASASSN-15lh
https://arxiv.org/abs/1605.00645

The nature of ASASSN-15lh is disputed.
https://en.wikipedia.org/wiki/ASASSN-15lh#Suggested_mechanisms

I wondered if the term 'hypernova' describes the event. Apparently it does.

The usage of the term hypernova from the late 20th century has since been refined to refer to those supernovae with unusually large kinetic energy. The first hypernova observed was SN 1998bw, with a luminosity 100 times higher than a standard Type Ib. This supernova was the first to be associated with a gamma-ray burst (GRB) and it produced a shockwave containing an order of magnitude more energy than a normal supernova. Other scientists prefer to call these objects simply broad-lined Type Ic supernovae. Since then the term has been applied to a variety of objects, not all of which meet the standard definition; for example ASASSN-15lh.

Ref: https://en.wikipedia.org/wiki/Hypernova

ASASSN-15lh was not the 'brightest' event however.

PS1-10adi was an unusual and highly energetic optical transient discovered by the Pan-STARRS survey on 15 August 2010. The explosion or transient event emitted 2.3×10⁵² ergs (2.3×10⁴⁵ Joules), exceeding ASASSN-15lh.

Ref: https://en.wikipedia.org/wiki/PS1-10adi

Pan-STARRS Project is the Panoramic Survey Telescope and Rapid Response System
Ref: https://en.wikipedia.org/wiki/Pan-STARRS

 

[BillTre]

My wife was listening to a video about superluminal supernova (Type Ic), ASASSN-15lh, or SN 2015L.

Wow. I wish my wife would do stuff like that.

 

[Astronuc]

Wow. I wish my wife would do stuff like that.

My wife just happened to be listening to a video on Science Channel. It caught my attention, partly due to the mention of killer stars, or death stars, and mostly because if mentioned ASASSN-15lh (which sounded like assassin). I then searched for references, and also search PF for any discussion. ASASSN-15lh was not explicitly mentioned on PF, so I initiated a discussion thread, since the mechanism is not resolved.
The video talks about how planetary systems are annihilated by such stellar explosions. I don't imagine an earth-like habitable (for us) planet exists in a solar system with a large star (30 to 40+ solar masses) would exist. Given that the event was 3.82 Gly from earth, we cannot determine if it had a planetary system surrounding it.
At the same time, there was also video on colliding neutron stars with a discussion of gravity waves, LIGO and the signature of colliding neutron stars.
ASASSN-15lh: A highly super-luminous supernova
https://www.science.org/doi/10.1126/science.aac9613

Abstract - We report the discovery of ASASSN-15lh (SN 2015L), which we interpret as the most luminous supernova yet found. At redshift z = 0.2326, ASASSN-15lh reached an absolute magnitude of M_u,AB = –23.5 ± 0.1 and bolometric luminosity L_bol = (2.2 ± 0.2) × 10⁴⁵ ergs s^–1, which is more than twice as luminous as any previously known supernova. It has several major features characteristic of the hydrogen-poor super-luminous supernovae (SLSNe-I), whose energy sources and progenitors are currently poorly understood. In contrast to most previously known SLSNe-I that reside in star-forming dwarf galaxies, ASASSN-15lh appears to be hosted by a luminous galaxy (MK ≈ –25.5) with little star formation. In the 4 months since first detection, ASASSN-15lh radiated (1.1 ± 0.2) × 10⁵² ergs, challenging the magnetar model for its engine.

Phys.org - Most-luminous supernova ever discovered
https://phys.org/news/2016-01-most-luminous-supernova.html#google_vignette

The newly found super-luminous supernova was discovered by the All Sky Automated Survey for SuperNovae team (ASAS-SN), an international collaboration headquartered at the Ohio State University, which uses a network of 14-centimeter telescopes around the world to scan the visible sky every two or three nights looking for very bright supernovae. The only all-sky variability survey in existence, it is capable of finding normal supernovae out to about 350 million light years from Earth.

The supernova's spectra matched that of other hydrogen-poor super-luminous supernovae. But it wasn't until further follow-up was conducted that the study's lead author Subo Dong of the Kavli Institute for Astronomy and Astrophysics (KIAA) at Peking University and the rest of the team realized how unusual the supernova is. It is two times more luminous than any supernova previously discovered. In fact, ASAS-SN-15lh at peak was almost 50 times more luminous than the entire Milky Way galaxy.

What's more, they determined that the galaxy where ASAS-SN-15lh formed is very atypical for a super-luminous supernova, which raises questions about how these types of supernovae form. Its host galaxy isn't the typical low-luminosity, star-forming galaxy where previous super-luminous supernovae have been spotted. ASAS-SN-15lh's galaxy is, in fact, more luminous than our own Milky Way.

I have not found a name or identifying number for the host galaxy.

Ohio State University, ASASSN-15lh Press Materials
https://www.astronomy.ohio-state.edu/asassn/ASASSN-15lh.html

https://www.icrar.org/black-hole-swallows-star/

ASASSN-15LH: A SUPERLUMINOUS ULTRAVIOLET REBRIGHTENING OBSERVED BY SWIFT and HUBBLE
Peter J. Brown et al 2016 ApJ 828 3
https://iopscience.iop.org/article/10.3847/0004-637X/828/1/3

 

[AlexB23]

My wife was listening to a video about superluminal supernova (Type Ic), ASASSN-15lh, or SN 2015L. It was discovered through the All Sky Automated Survey for SuperNovae (ASAS-SN). The event occurred in a galaxy ~3.82 billion ly from earth. Peak Apparent Magnitude was 16.9. The mass of ASSASN-15lh is 40 M_☉


Ref: https://en.wikipedia.org/wiki/ASASSN-15lh

The Unexpected, Long-Lasting, UV Rebrightening of the Super-Luminous Supernova ASASSN-15lh
https://arxiv.org/abs/1605.00645

The nature of ASASSN-15lh is disputed.
https://en.wikipedia.org/wiki/ASASSN-15lh#Suggested_mechanisms

I wondered if the term 'hypernova' describes the event. Apparently it does.

Ref: https://en.wikipedia.org/wiki/Hypernova

ASASSN-15lh was not the 'brightest' event however.

Ref: https://en.wikipedia.org/wiki/PS1-10adi

Pan-STARRS Project is the Panoramic Survey Telescope and Rapid Response System
Ref: https://en.wikipedia.org/wiki/Pan-STARRS

Do these massive stellar explosions release more energy than the sun over the entire 10 billion year lifetime in fractions of a second? It blows my mind how much energy are in these explosions.