Related papers: Luminosity source in supernova ASASSN-15nx with lo…
A thorough study of radio emission in Active Galactic Nuclei (AGN) is of fundamental importance to understand the physical mechanisms responsible for the emission and the interplay between accretion and ejection processes. High frequency…
To assess the effectiveness of optical emission as a probe of spatial asymmetry in core-collapse supernovae (CCSNe), we apply the radiative transfer software, \supernu, to a unimodal CCSN model. The \snsph\ radiation-hydrodynamics software…
Optical and ultraviolet observations of the Type IIn supernova 1995N at epochs between 321 and 1799 days after the explosion show three distinct velocity components. The narrow lines come from circumstellar gas and show both low and high…
The origin of the radio emission in active galactic nuclei (AGN) is still debated. Multiple physical mechanisms can contribute to the spectrum at these frequencies, including relativistic jets, the jet base, outflows, star formation, and…
iPTF15dtg is a Type Ic supernova (SN) showing a broad light curve around maximum light, consistent with massive ejecta if we assume a radioactive-powering scenario. We study the late-time light curve of iPTF15dtg, which turned out to be…
Study of the polarization of supernovae has suggested that the core collapse process may be intrinsically strongly asymmetric. There is a tentative trend for supernova with smaller envelopes showing more polarization, with Type Ic having…
ASASSN-14ko is a periodically repeating nuclear transient. We conducted high-cadence, multiwavelength observations of this source, revealing several recurrent early bumps and rebrightenings in its UV/optical light curves. The energy…
Multiwavelength observations of Type II supernovae have shown evidence for the interaction of supernovae with the dense slow winds from the red supergiant progenitor stars. Observations of planetary nebulae and the nebula around SN 1987A…
We present high-cadence ultraviolet (UV), optical, and near-infrared (NIR) data on the luminous Type II-P supernova SN 2017gmr from hours after discovery through the first 180 days. SN 2017gmr does not show signs of narrow, high-ionization…
The nature of an emerging class of rapidly fading supernovae (RFSNe)--characterized by their short-lived light curve duration, but varying widely in peak brightness--remains puzzling. Whether the RFSNe arise from low-mass thermonuclear…
Recently, a hydrogen-poor superluminous supernova (SLSN) iPTF15esb at redshift $z=0.224$ was reported, whose light curve (LC) and spectrum show several unusual characteristics. Its late-time spectrum shows a strong, broad H$\alpha $…
We present optical photometry and spectroscopy of SN 2016iet, an unprecedented Type I supernova (SN) at $z=0.0676$ with no obvious analog in the existing literature. The peculiar light curve has two roughly equal brightness peaks ($\approx…
A number of Anomalous X-ray Pulsars (AXPs) have recently been detected in the optical/IR wavelengths. We use their inferred brightness to place general constraints on any model for this emission within the magnetar framework. We find that…
We present XMM observations of the AGN SDSS 1430-0011. The low S/N spectrum of this source obtained in a snap shot Chandra observation showed an unusually flat continuum. With the follow up XMM observations we find that the source spectrum…
A macronova (kilonova) was discovered with a short gamma-ray burst, GRB 130603B, which is widely believed to be powered by the radioactivity of $r$-process elements synthesized in the ejecta of a neutron star binary merger. As an…
We have obtained new spectropolarimetric observations at visible wavelengths of the changing-look active galactic nucleus (AGN) Mrk 1018. The AGN direct spectrum shows an extremely weak continuum with faint broad H$\beta$ and H$\alpha$…
Recent interpretations of narrow, variable absorption lines detected in some Type Ia supernovae suggest that their progenitors are surrounded by dense, circumstellar material. Similar variations detected in the symbiotic recurrent nova…
We present results of an observation with Suzaku of the dipping, periodic bursting low mass X-ray binary XB 1323-619. Using the energy band 0.8 - 70 keV, we show that the source spectrum is well-described as the emission of an extended…
ASASSN-14ko was identified as an abnormal periodic nuclear transient with a potential decreasing period. Its outbursts in the optical and UV bands have displayed a consistent and smooth "fast-rise and slow-decay" pattern since its…
Recent discovery of the year-scale variability in the synchrotron X-ray emission of the supernova remnant (SNR) RX J1713.7-3946 has initiated our study of multi-epoch X-ray images and spectra of the young SNR Cassiopeia A based on the…