256 research outputs found
Coronal Line Emitters are Tidal Disruption Events in Gas-Rich Environments
Some galaxies show little to no sign of active galactic nucleus (AGN)
activity, yet exhibit strong coronal emission lines (CLs) relative to common
narrow emission lines. Many of these coronal lines have ionization potentials
of eV, thus requiring strong extreme UV and/or soft X-ray flux. It
has long been thought that such events are powered by tidal disruption events
(TDEs), but owing to a lack of detailed multi-wavelength follow-up, such a
connection has not been firmly made. Here we compare coronal line emitters
(CLEs) and TDEs in terms of their host-galaxy and transient properties. We find
that the mid-infrared (MIR) colors of CLE hosts in quiescence are similar to
TDE hosts. Additionally, many CLEs show evidence of a large dust reprocessing
echo in their mid-infrared colors, a sign of significant dust in the nucleus.
The stellar masses and star formation rates of the CLE hosts are consistent
with TDE hosts, and both populations reside within the green valley. The
blackbody properties of CLEs and TDEs are similar, with some CLEs showing hot
(T K) blackbody temperatures. Finally, the location of CLEs on
the peak-luminosity/decline-rate parameter space is much closer to TDEs than
many other major classes of nuclear transients. Combined, these provide strong
evidence to confirm the previous claims that CLEs are indeed TDEs in gas-rich
environments. We additionally propose a stricter threshold of CL flux [O III] flux to better exclude AGNs from the sample of CLEs.Comment: 9 pages, 7 figures. Will be submitted to MNRAS. Comments welcom
ASASSN-16ae: A Powerful White-Light Flare on an Early-L Dwarf
We report the discovery and classification of SDSS~J053341.43+001434.1
(SDSS0533), an early-L dwarf first discovered during a powerful magnitude flare observed as part of the ASAS-SN survey. Optical and
infrared spectroscopy indicate a spectral type of L0 with strong H
emission and a blue NIR spectral slope. Combining the photometric distance,
proper motion, and radial velocity of SDSS0533 yields three-dimensional
velocities of ~km~s, indicating
that it is most likely part of the thick disk population and probably old. The
three detections of SDSS0533 obtained during the flare are consistent with a
total -band flare energy of at least ~ergs (corresponding
to a total thermal energy of at least ~erg),
placing it among the strongest detected M dwarf flares. The presence of this
powerful flare on an old L0 dwarf may indicate that stellar-type magnetic
activity persists down to the end of the main sequence and on older ML
transition dwarfs.Comment: 7 pages, 3 tables, 2 figures; accepted to ApJ Letters; updated to
reflect referee response and proof correction
The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
The All-Sky Automated Survey for Supernovae (ASAS-SN) is working towards
imaging the entire visible sky every night to a depth of V~17 mag. The present
data covers the sky and spans ~2-5~years with ~100-400 epochs of observation.
The data should contain some ~1 million variable sources, and the ultimate goal
is to have a database of these observations publicly accessible. We describe
here a first step, a simple but unprecedented web interface
https://asas-sn.osu.edu/ that provides an up to date aperture photometry light
curve for any user-selected sky coordinate. Because the light curves are
produced in real time, this web tool is relatively slow and can only be used
for small samples of objects. However, it also imposes no selection bias on the
part of the ASAS-SN team, allowing the user to obtain a light curve for any
point on the celestial sphere. We present the tool, describe its capabilities,
limitations, and known issues, and provide a few illustrative examples.Comment: 8 pages, 9 figures, submitted to PAS
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