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Start Over Subject supernovae
91. Full Spitzer IRAC obs. of SN1987A rise and fall
ID:
ivo://CDS.VizieR/J/ApJ/890/2
Title:
Full Spitzer IRAC obs. of SN1987A rise and fall
Short Name:
J/ApJ/890/2
Date:
17 Jan 2022 00:19:48
Publisher:
CDS
Description:
Spitzer's final Infrared Array Camera observations of SN 1987A show the 3.6 and 4.5{mu}m emission from the equatorial ring (ER) continues a period of steady decline. Deconvolution of the images reveals that the emission is dominated by the ring, not the ejecta, and is brightest on the west side. Decomposition of the marginally resolved emission also confirms this, and shows that the west side of the ER has been brightening relative to the other portions of the ER. The infrared morphological changes resemble those seen in both the soft X-ray emission and the optical emission. The integrated ER light curves at 3.6 and 4.5{mu}m are more similar to the optical light curves than the soft X-ray light curve, though differences would be expected if dust is responsible for this emission and its destruction is rapid. Future observations with the James Webb Space Telescope will continue to monitor the ER evolution, and will reveal the true spectrum and nature of the material responsible for the broadband emission at 3.6 and 4.5{mu}m. The present observations also serendipitously reveal a nearby variable source, subsequently identified as a Be star, that has gone through a multiyear outburst during the course of these observations.
92. Gaia Alerts with LAMOST and SDSS
ID:
ivo://CDS.VizieR/J/other/ApSS/365.89
Title:
Gaia Alerts with LAMOST and SDSS
Short Name:
J/other/ApSS/365
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ESA-Gaia satellite is regularly producing Alerts on objects where photometric variability has been detected after several passages over the same region of the sky. The physical nature of these objects has often to be determined with the help of complementary observations from ground-based facilities. We have compared the list of Gaia Alerts (from the beginning in 2014 to Nov. 1st, 2018) with archival LAMOST and SDSS spectroscopic data. A search radius of 3" has been adopted. In using survey data, the date of the ground-based observation rarely corresponds to the date of the Alert, but this allows at least the identification of the source if it is persistent, or the host galaxy if the object was only transient like a supernova (SN). Some of the objects have several LAMOST observations, and we complemented this search by adding also SDSS DR15 data in order to look for long-term variability. A list of Gaia Nuclear Transients (GNT) from Kostrzewa-Rutkowska et al. (2018. 2018MNRAS.481..307K, Cat. J/MNRAS/481/307), has been included in this search also. We found 26 Gaia Alerts with spectra in LAMOST+SDSS labelled as stars, among which 12 have multi-epoch spectra. A majority of them are Cataclysmic Variables (CVs). Similarly, 206 Gaia Alerts have associated spectra labelled as galaxies, among which 49 have multi-epoch spectra. Those spectra were generally obtained on a date widely different from the Alert date, and are mostly emission-line galaxies with no particularity (except a few Seyferts), leading to the suspicion that most of the Alerts were due to a SN. As for the GNT list, we found 55 associated spectra labelled as galaxies, among them 13 with multi-epoch spectra. In these two galaxy samples, in only two cases, Gaia17aal and GNTJ170213+2543, was the date of the spectroscopic observation close enough to the Alert date: we find a trace of the SN itself in their LAMOST spectrum, both being now classified here as a type Ia SN. Compared to the galaxy sample from the Gaia alerts, the GNT sample has a higher proportion of AGNs, suggesting that some of the detected variations are also due to the AGN itself. Similarly for Quasars, we found only 30 Gaia Alerts but 68 GNT cases associated with single epoch quasar spectra in the databases. In addition to those, 12 plus 23 are quasars where multi-epoch spectra are available. For ten out of these 35, their multi-epoch spectra show appearance or disappearance of the broad Balmer lines and also variations in the continuum, qualifying them as "Changing Look Quasars" and therefore significantly increasing the available sample of such objects.
93. Gaia Nuclear Transient (GNT) cand.
ID:
ivo://CDS.VizieR/J/MNRAS/481/307
Title:
Gaia Nuclear Transient (GNT) cand.
Short Name:
J/MNRAS/481/307
Date:
21 Oct 2021
Publisher:
CDS
Description:
The high spatial resolution and precise astrometry and photometry of the Gaia mission should make it particularly apt at discovering and resolving transients occurring in, or near, the centres of galaxies. Indeed, some nuclear transients are reported by the Gaia Science Alerts (GSA) team, but not a single confirmed tidal disruption event (TDE) has been published. In order to explore the sensitivity of GSA, we performed an independent and systematic search for nuclear transients using Gaia observations. Our transient search is driven from an input galaxy catalogue (derived from the Sloan Digital Sky Survey Release 12). We present a candidate detection metric that is independent from the existing GSA methodology, to see if Gaia Alerts are biased against the discovery of nuclear transients, and in particular which steps may have an impact. Our technique does require significant manual vetting of candidates, making implementation in the GSA system impractical for daily operations, although it could be run weekly, which for month-to-year long transients would make a scientifically valuable addition. Our search yielded 480 nuclear transients, 5 of which were alerted and published by GSA. The list of (in some cases ongoing) transients includes candidates for events related to enhanced accretion on to a super-massive black hole and TDEs. An implementation of the detection methodology and criteria used in this paper as an extension of GSA could open up the possibility for Gaia to fulfil the role as a main tool to find transient nuclear activity as predicted in the literature.
94. Gaia Photometric Science Alerts
ID:
ivo://CDS.VizieR/J/A+A/652/A76
Title:
Gaia Photometric Science Alerts
Short Name:
J/A+A/652/A76
Date:
22 Feb 2022
Publisher:
CDS
Description:
Since July 2014, the Gaia mission has been engaged in a high-spatial- resolution, time-resolved, precise, accurate astrometric, and photometric survey of the entire sky. We present the Gaia Science Alerts project, which has been in operation since 1 June 2016. We describe the system which has been developed to enable the discovery and publication of transient photometric events as seen by Gaia. We outline the data handling, timings, and performances, and we describe the transient detection algorithms and filtering procedures needed to manage the high false alarm rate. We identify two classes of events: (1) sources which are new to Gaia and (2) Gaia sources which have undergone a significant brightening or fading. Validation of the Gaia transit astrometry and photometry was performed, followed by testing of the source environment to minimise contamination from Solar System objects, bright stars, and fainter near-neighbours. We show that the Gaia Science Alerts project suffers from very low contamination, that is there are very few false- positives. We find that the external completeness for supernovae, C_E_=0.46, is dominated by the Gaia scanning law and the requirement of detections from both fields-of-view. Where we have two or more scans the internal completeness is C_I_=0.79 at 3 arcsec or larger from the centres of galaxies, but it drops closer in, especially within 1 arcsec. The per-transit photometry for Gaia transients is precise to 1 per cent at G=13, and 3 per cent at G=19. The per- transit astrometry is accurate to 55 milliarcseconds when compared to Gaia DR2. The Gaia Science Alerts project is one of the most homogeneous and productive transient surveys in operation, and it is the only survey which covers the whole sky at high spatial resolution (subarcsecond), including the Galactic plane and bulge.
95. Galactic SNR ^44^Ti survey
ID:
ivo://CDS.VizieR/J/MNRAS/458/3411
Title:
Galactic SNR ^44^Ti survey
Short Name:
J/MNRAS/458/3411
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results of the deepest Galactic plane (|b|<17.5{deg}) survey in the 67.9 and 78.4keV nuclear de-excitation lines of titanium-44 (^44^Ti) performed using the data acquired with the IBIS/ISGRI instrument onboard the INTEGRAL satellite during 12yr of operation. The peak sensitivity of our survey reached an unprecedented level of 4.8x10^-6^ph/cm2/s (3{sigma}) that improves the sensitivity of the survey done by Compton Gamma-Ray Observatory/COMPTEL by a factor of ~5. As a result, constraining upper limits for all sources from the catalogue of Galactic supernova remnants (SNRs; Green, 2014, Cat. VII/272) are derived. These upper limits can be used to estimate the exposure needed to detect ^44^Ti emission from any known SNR using existing and prospective X- and gamma-ray telescopes. Among the youngest Galactic SNRs, only Cas A shows significant ^44^Ti emission flux in good agreement with the NuSTAR measurements. We did not detect any other sources of titanium emission in the Galactic plane at significance level higher than 5{sigma} confirming previous claims of the rarity of such ^44^Ti-producing SNRs.
96. GCVS, Vol. V.: Extragalactic Variable Stars
ID:
ivo://CDS.VizieR/II/205
Title:
GCVS, Vol. V.: Extragalactic Variable Stars
Short Name:
II/205
Date:
21 Oct 2021
Publisher:
CDS
Description:
This catalogue is the last volume of the world-only reference source on all known variable stars. It contains the first Catalogue of variable stars in external galaxies as well as a Catalogue of extragalactic supernovae.
97. Gemini/GMOS-S spectra of the type IIn SN 2010jl
ID:
ivo://CDS.VizieR/J/ApJ/894/111
Title:
Gemini/GMOS-S spectra of the type IIn SN 2010jl
Short Name:
J/ApJ/894/111
Date:
19 Jan 2022 13:05:54
Publisher:
CDS
Description:
The luminous Type IIn SN 2010jl shows strong signs of interaction between the SN ejecta and dense circumstellar material. Dust may be present in the unshocked ejecta; the cool, dense shell (CDS) between the shocks in the interaction region; or in the circumstellar medium (CSM). We present and model new optical and infrared photometry and spectroscopy of SN 2010jl from 82 to 1367 days since explosion. We evaluate the photometric and spectroscopic evolution using the radiative transfer codes MOCASSIN and DAMOCLES, respectively. We propose an interaction scenario and investigate the resulting dust formation scenarios and dust masses. We find that SN 2010jl has been continuously forming dust based on the evolution of its infrared emission and optical spectra. There is evidence for preexisting dust in the CSM as well as new dust formation in the CDS and/or ejecta. We estimate that 0.005-0.01M_{sun}_ of predominantly carbon dust grains has formed in SN 2010jl by ~1400 days post-outburst.
98. Gravitational lensing of SN 1997ff
ID:
ivo://CDS.VizieR/J/ApJ/561/106
Title:
Gravitational lensing of SN 1997ff
Short Name:
J/ApJ/561/106
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the effects of gravitational lensing due to intervening galaxies on the recently discovered Type Ia supernova at z~1.7, SN 1997ff, in the Hubble Deep Field North. We find that it is possible to obtain a wide range of magnifications by varying the mass and/or the velocity dispersion normalization of the lensing galaxies. In order to be able to use SN 1997ff to constrain the redshift-distance relation, very detailed modeling of the galaxies to control the systematic effects from lensing is necessary. Thus, we argue that, based on our current limited knowledge of the lensing galaxies, it is difficult to use SN 1997ff to constrain the values of {Omega}_M_ and {Omega}_{Lambda}, or even to place severe limits on gray dust obscuration or luminosity evolution of Type Ia supernovae.
99. GRB 081007 and GRB 090424 light curves
ID:
ivo://CDS.VizieR/J/ApJ/774/114
Title:
GRB 081007 and GRB 090424 light curves
Short Name:
J/ApJ/774/114
Date:
21 Oct 2021
Publisher:
CDS
Description:
We discuss the results of the analysis of multi-wavelength data for the afterglows of GRB 081007 and GRB 090424, two bursts detected by Swift. One of them, GRB 081007, also shows a spectroscopically confirmed supernova, SN 2008hw, which resembles SN 1998bw in its absorption features, while the maximum magnitude may be fainter, up to 0.7mag, than observed in SN 1998bw. Bright optical flashes have been detected in both events, which allows us to derive solid constraints on the circumburst-matter density profile. This is particularly interesting in the case of GRB 081007, whose afterglow is found to be propagating into a constant-density medium, yielding yet another example of a gamma-ray burst (GRB) clearly associated with a massive-star progenitor which did not sculpt the surroundings with its stellar wind. There is no supernova component detected in the afterglow of GRB 090424, likely due to the brightness of the host galaxy, comparable to the Milky Way. We show that the afterglow data are consistent with the presence of both forward- and reverse-shock emission powered by relativistic outflows expanding into the interstellar medium. The absence of optical peaks due to the forward shock strongly suggests that the reverse-shock regions should be mildly magnetized. The initial Lorentz factor of outflow of GRB 081007 is estimated to be {Gamma}~200, while for GRB 090424 a lower limit of {Gamma}>170 is derived. We also discuss the prompt emission of GRB 081007, which consists of just a single pulse. We argue that neither the external forward-shock model nor the shock-breakout model can account for the prompt emission data and suggest that the single-pulse-like prompt emission may be due to magnetic energy dissipation of a Poynting-flux-dominated outflow or to a dissipative photosphere.
100. GRB 190829A/SN 2019oyw spectra
ID:
ivo://CDS.VizieR/J/A+A/646/A50
Title:
GRB 190829A/SN 2019oyw spectra
Short Name:
J/A+A/646/A50
Date:
21 Oct 2021
Publisher:
CDS
Description:
Gamma-ray burst (GRB) 190829A (z=0.0785) was detected by Fermi and Swift and also at very high energy (VHE) by the High-Energy Stereoscopic System (H.E.S.S.) telescopes. The prompt emission displayed two emission episodes separated by a quiescent gap of ~40s. We present the 10.4m Gran Telescopio CANARIAS (GTC) observations of the afterglow of GRB 190829A and its underlying supernova. We also compare GRB190829A to GRB180728A, a GRB with similar behaviour, and discuss the implications on underlying physical mechanisms producing these two GRBs. We present multi-band photometric data along with spectroscopic follow-up observations taken with the 10.4m GTC telescope. Together with the data from the prompt emission, the 10.4m GTC data are used to understand the emission mechanisms and possible progenitor. A detailed analysis of the multi-band observations of the afterglow requires the cooling frequency to pass between the optical and X-ray bands at early epochs. The afterglow then transitions to the underlying supernova (SN) 2019oyw, which dominates later on. Although the prompt emission temporal properties of GRB 190829A and GRB 180728A are similar, the two pulses are different in the spectral domain. We find that SN 2019oyw associated with GRB 190829A is powered by Ni decay and is a Type Ic-BL SN. The spectroscopic and photometric properties of this SN are consistent with those observed for SN 1998bw, but evolved earlier.