I explore signatures of a possible dust formation in the late SN~2010jl that could be imprinted in the line blueshift and the radius evolution of the dusty infrared-emitting shell. I propose a simple model that permits one to reproduce emission lines of blueshifted hydrogen and helium emission lines. The model suggests that the hydrogen emission originates primarily from shocked fragmented circumstellar clumps partially obscured by the absorbing cool dense shell and by unshocked ejecta. In the He I 1.083 $μ$m line on day 178 this component is significantly weaker compared to broad component from unshocked ejecta that is obscured by the absorprion produced by ejecta itself. Simulations of late time ($t > 400$ d) H$α$ suggest that, apart from the dust in the cool dense shell, a significant amount of dust must form in the unshocked supernova ejecta. The supernova radius predicted by the interaction model coincides with the radius of the dusty shell recovered from late time (> 460 days) infrared data, which strongly support that infrared radiation indeed originates from supernova. The ejecta dust is presumably locked in opaque blobs.
We report four years of radio and X-ray monitoring of the Type IIn supernova SN 2006jd at radio wavelengths with the Very Large Array, Giant Metrewave Radio Telescope and Expanded Very Large Array; at X-ray wavelengths with {\em Chandra}, {\em XMM-Newton} and {\em Swift}-XRT. We assume that the radio and X-ray emitting particles are produced by shock interaction with a dense circumstellar medium. The radio emission shows an initial rise that can be attributed to free-free absorption by cool gas mixed into the nonthermal emitting region; external free-free absorption is disfavored because of th…
A model-dependent method is proposed to determine the location of the $γ$-ray emitting region for a given flat spectrum radio quasar (FSRQ). In the model, the extra-relativistic electrons are injected at the base of the jet and non-thermal photons are produced by both synchrotron radiation and inverse-Comtpon (IC) scattering in the energy dissipation region. The target photons dominating inverse-Comtpon scattering originate from both synchrotron photons and external ambient photon fields, and the energy density of external radiation field is a function of the distance between the position of d…
We report on robust measurements of elemental abundances of the Type IIn supernova SN 1978K, based on the high-resolution X-ray spectrum obtained with the Reflection Grating Spectrometer (RGS) onboard XMM-Newton. The RGS clearly resolves a number of emission lines, including N Ly$α$, O Ly$α$, O Ly$β$, Fe XVII, Fe XVIII, Ne He$α$ and Ne Ly$α$ for the first time from SN 1978K. The X-ray spectrum can be represented by an absorbed, two-temperature thermal emission model, with temperatures of $kT \sim 0.6$ keV and $2.7$ keV. The elemental abundances are obtained to be N $=$ $2.36_{-0.80}^{+0.88}$, …
We present new, late-time Hubble Space Telescope and Spitzer Space Telescope observations of the archetypal supernova (SN) impostor SN 1997bs. We show that SN 1997bs remains much fainter than its progenitor, posing a challenge for the canonical picture of late-time obscuration by dust forming in a shell ejected during the transient. The possibility that the star survived cloaked behind a dusty, steady wind is also disfavored. The simplest explanation is that SN 1997bs was a subluminous Type IIn SN, although it is currently impossible to rule out the possibility that the star survived either be…
The environmental dependence of mid-IR luminous dusty Supernovae
Hebei University（河北大学）；Institute of Space Sciences (ICE, CSIC)（空间科学研究所（ICE，CSIC））；University of Szeged（塞格德大学）；Space Telescope Science Institute（太空望远镜科学研究所）；Carnegie Mellon University（卡内基梅隆大学）
Recent mid-infrared interferometry observations of nearby active galactic nuclei (AGN) revealed that a significant part of the dust emission extends in the polar direction, rather than the equatorial torus/disk direction as expected by the traditional unification model. We study the X-ray signatures of this polar dusty gas with ray-tracing simulations. Different from those from the ionized gas, the scattered emission from the polar dusty gas produces self-absorption and neutral-like fluorescence lines, which are potentially a unique probe of the kinematics of the polar dusty gas. The anomalous…
We present low-resolution near-IR 0.8-2.5 um spectra of SN2009ip, taken immediately before, during, and just after its rapid brightening in late Sep/Oct 2012. The first epoch shows the same general spectral characteristics as the later epochs (smooth continuum, narrow H and HeI emission lines), but the IR continuum shape is substantially redder than the later epochs. The epoch 1 continuum can be approximated by reddening the peak-luminosity (epoch 3) spectrum by E(B-V)=1.0 mag, but the blue color seen in visual-wavelength spectra at the same time indicates that strong wavelength-dependent exti…
We present near infrared spectroscopy of the recurrent nova RS Oph obtained on several occasions after its latest outburst in 2006 February. The 1-5 mircon spectra are dominated by the red giant, but the H I, He I, and coronal lines present during the eruption are present in all our observations. From the fits of the computed infrared spectral energy distributions to the observed fluxes we find T_eff=4200+/-200,K for the red giant. The first overtone CO bands at 2.3 micron, formed in the atmosphere of the red giant, are variable. The spectra clearly exhibit an infrared excess due to dust emiss…
X-ray fluorescent lines are unique features of the reflection spectrum of the torus when irradiated by the central AGN. Their intrinsic line width can be used to probe the line-emitting region. Previous studies have focused on the Fe Ka line at 6.4 keV, which is the most prominent fluorescent line. These studies, however, are limited by the spectral resolution of currently available instruments, the best of which is $\sim1860$ km s$^{-1}$ afforded by the Chandra High-Energy Grating (HEG). The HEG spectral resolution is improved by a factor of 4 at 1.74 keV, where the Si Ka line is located. We …
We study the multi-phase medium in the vicinity of the active galactic nucleus Centaurus A (Cen A). Combined high-resolution observations with the ALMA and Chandra observatories indicate that the hot X-ray emitting plasma coexists with the warm and cold media in Cen A. This complex environment is a source of CO lines with great impact for its diagnostics. We present the images from the two above-mentioned instruments covering the nuclear region (diameter of 10'' i.e., ~180 pc), and we study the conditions for plasma thermal equilibrium and possible coexistence of cool clouds embedded within th…
4C +21.35 is a flat-spectrum-radio-quasar-type blazar, in which the rapid variability of very high energy (VHE, $E_γ\gtrsim 100$\,GeV) emission as short as $\sim$ 10 minutes was observed by MAGIC Cherenkov telescopes, and the VHE spectrum extends up to at least 400\,GeV. In this paper, by using a flat broad-line region (BLR) structure, we study the location and properties of $γ$-ray emitting region of 4C +21.35 under the constraints of multiwavelength data. We fit three quasi-simultaneous spectral energy distributions (SEDs) using homogeneous one-zone leptonic model, in which the flat BLR with…
[Abridged] We present observations of PS16dtm, a luminous transient that occurred at the nucleus of a known Narrow-line Seyfert 1 galaxy hosting a 10$^6$ M$_\odot$ black hole. The transient was previously claimed to be a Type IIn SLSN due to its luminosity and hydrogen emission lines. The light curve shows that PS16dtm brightened by about two magnitudes in ~50 days relative to the archival host brightness and then exhibited a plateau phase for about 100 days followed by the onset of fading in the UV. During the plateau PS16dtm showed no color evolution, maintained a blackbody temperature of 1.…
In this second research note of a series of two, we aim to map the polarized flux emerging from a disk-born, dusty outflow as it was prescribed by Elvis (2000). His structure for quasars was achieved to unify the emission and absorption features observed in active galactic nuclei (AGN) and can be used as an alternative scenario to the typical dusty torus that is extensively used to account for AGN circumnuclear obscuration. Using Monte Carlo radiative transfer simulations, we model an obscuring outflow arising from an emitting accretion disk and examine the resulting polarization degree, polar…
The detection of several radio-loud narrow-line Seyfert 1 (NLS1) galaxies by the Fermi Gamma-Ray Space Telescope hints at the existence of a rare, new class of gamma-ray emitting active galactic nuclei with low black hole masses. Like flat spectrum radio quasars (FSRQs), their gamma-ray emission is thought to be produced via the external Compton mechanism whereby relativistic jet electrons upscatter a photon field external to the jet, e.g. from the accretion disc, broad line region (BLR) and dusty torus, to higher energies. Here we study the origin of the gamma-ray emission in the lowest-redsh…
The bright long-lived Type II SN 2021irp powered by aspherical circumstellar material interaction (I): Revealing the energy source with photometry and spectroscopy
We have collected near-infrared to X-ray data of 20 multi-epoch heavily reddened SDSS quasars to investigate the physical mechanism of reddening. Of these, J2317+0005 is found to be a UV cutoff quasar. Its continuum, which usually appears normal, decreases by a factor 3.5 at 3000Å, compared to its more typical bright state during an interval of 23 days. During this sudden continuum cut-off, the broad emission line fluxes do not change, perhaps due to the large size of the Broad Line Region (BLR), r > 23 / (1+z) days. The UV continuum may have suffered a dramatic drop out. However, there are so…
The $γ$-ray production mechanism and its localization in blazars are still a matter of debate. The main goal of this paper is to constrain the location of the high-energy emission in the blazar TXS 2013+370 and to study the physical and geometrical properties of the inner jet region on sub-pc scales. VLBI observations at 86 GHz and space-VLBI at 22 GHz allowed us to image the jet base with an angular resolution of $\sim$0.4 pc. By employing CLEAN imaging and Gaussian model-fitting, we performed a thorough kinematic analysis, which provided estimates of the jet speed, orientation, and component…
Supernovae Type Iax (SNe Iax) are less energetic and less luminous than typical thermonuclear explosions. A suggested explanation for the observed characteristics of this subclass is a binary progenitor system consisting of a CO white dwarf primary accreting from a helium star companion. A single-degenerate explosion channel might be expected to result in a dense circumstellar medium (CSM), although no evidence for such a CSM has yet been observed for this subclass. Here we present recent Spitzer observations of the SN Iax 2014dt obtained by the SPIRITS program nearly one year post-explosion t…
We present the updated census and statistics of Lyman-$α$ emitting long gamma-ray bursts host galaxies (LAE-LGRBs). We investigate the properties of a sub-sample of LAE-LGRBs and test the shell model commonly used to fit Lyman-$α$ (Ly$α$) emission line spectra. Among the LAE-LGRBs detected to date, we select a golden sample of four LAE-LGRBs allowing us to retrieve information on the host galaxy properties and of its interstellar medium gas. We fit their Ly$α$ spectra using the shell model, and constrain its parameters with the observed values. From the comparison of the statistics and propert…
We present an analysis of multi-timescale variability in line-of-sight X-ray absorbing gas as a function of optical classification in a large sample of Seyfert AGN to derive the first X-ray statistical constraints for clumpy-torus models. We systematically search for discrete absorption events in the vast archive of RXTE monitoring of dozens of nearby type I and Compton-thin type II AGN. We are sensitive to discrete absorption events due to clouds of full-covering, neutral or mildly ionized gas with columns >~ 10^(22-25) cm^-2 transiting the line of sight. We detect 12 eclipse events in 8 obje…
