An Unusual Transient in the Extremely Metal-Poor Galaxy SDSS J094332.35+332657.6 (Leoncino Dwarf)
arXiv:1804.11166 · doi:10.1093/mnras/sty1130
Abstract
We have serendipitously discovered that Leoncino Dwarf, an ultra-faint, low-metallicity record-holder dwarf galaxy, may have hosted a transient source, and possibly exhibited a change in morphology, a shift in the center of brightness, and peak variability of the main (host) source in images taken approximately 40 yr apart; it is highly likely that these phenomena are related. Scenarios involving a Solar System object, a stellar cluster, dust enshrouding, and accretion variability have been considered, and discarded, as the origin of the transient. Although a combination of time-varying strong and weak lensing effects, induced by an intermediate mass black hole (10 - 5 10 M) moving within the Milky Way halo (0.1 -- 4 kpc), can conceivably explain all of the observed variable galaxy properties, it is statistically highly unlikely according to current theoretical predictions, and, therefore, also discarded. A cataclysmic event such as a supernova/hypernova could have occurred, as long as the event was observed towards the later/late-stage descent of the light curve, but this scenario fails to explain the absence of a post-explosion source and/or host HII region in recent optical images. An episode related to the giant eruption of a luminous blue variable star, a stellar merger or a nova, observed at, or near, peak magnitude may explain the transient source and possibly the change in morphology/center of brightness, but can not justify the main source peak variability, unless stellar variability is evoked.
References in corpus (19)
- A bright millisecond radio burst of extragalactic origin
- The direct localization of a fast radio burst and its host
- Long gamma-ray bursts and core-collapse supernovae have different environments
- The relation between velocity dispersion and mass in simulated clusters of galaxies: dependence on the tracer and the baryonic physics
- Spectroscopy of superluminous supernova host galaxies. A preference of hydrogen-poor events for extreme emission line galaxies
- Bent by baryons: the low mass galaxy-halo relation
- Luminous Blue Variables are Antisocial: Their Isolation Implies that they are Kicked Mass Gainers in Binary Evolution
- Energetic eruptions leading to a peculiar hydrogen-rich explosion of a massive star
- Stellar Mergers Are Common
- The Rising Light Curves of Type Ia Supernovae
- J0811+4730: the most metal-poor star-forming dwarf galaxy known
- Zooming In on the Progenitors of Superluminous Supernovae With the HST
- Two New Calcium-Rich Gap Transients in Group and Cluster Environments
- Star Clusters Around Recoiled Black Holes in the Milky Way Halo
- Extremely Metal-Poor Galaxies: The Environment
- The isolation of Luminous Blue Variables: On subdividing the sample
- Extremely metal-poor galaxy DDO 68: the LBV, H-alpha shells and the most luminous stars
- On the dearth of ultra-faint extremely metal poor galaxies
- La Freccia Rossa: An IR-dark cloud hosting the Milky Way intermediate-mass black hole candidate