ABSTRACT
Strongly lensed supernovae (SNe) can be detected as multiply imaged or highly magnified transients. In order to compare the performances of these two observational strategies, we calculate ...expected discovery rates as a function of survey depth in five grizy filters and for different classes of SNe (types Ia, IIP, IIL, Ibc, and IIn). We find that detections via magnification is the only effective strategy for relatively shallow pre-LSST (Large Synoptic Sky Survey) surveys. For survey depths about the LSST capacity, both strategies yield comparable numbers of lensed SNe. SN samples from the two methods are to a large extent independent and combining them increases detection rates by about 50 per cent. While the number of lensed SNe detectable via magnification saturates at the limiting magnitudes of LSST, detection rates of multiply imaged SN still go up drastically at increasing survey depth. Comparing potential discovery spaces, we find that lensed SNe found via image multiplicity exhibit longer time delays and larger image separations making them more suitable for cosmological constraints than their counterparts found via magnification. We provide useful fitting functions approximating the computed discovery rates for different SN classes and detection methods. We find that the Zwicky Transient Factory will find about two type Ia and four core-collapse lensed SNe per year at a limiting magnitude of 20.6 in the r band. Applying a hybrid method which combines searching for highly magnified or multiply imaged transients, we find that LSST will detect 89 type Ia and 254 core-collapse lensed SNe per year. In all cases, lensed core-collapsed SNe will be dominated by type IIn SNe contributing to 80 per cent of the total counts, although this prediction relies quite strongly on the adopted spectral templates for this class of SNe. Revisiting the case of the lensed SN iPTF16geu, we find that it is consistent within the 2σ contours of predicted redshifts and magnifications for the intermediate Palomar Transient Factory survey.
The historic detection of gravitational waves from a binary neutron star merger (GW170817) and its electromagnetic counterpart led to the first accurate (sub-arcsecond) localization of a ...gravitational-wave event. The transient was found to be ∼10″ from the nucleus of the S0 galaxy NGC 4993. We report here the luminosity distance to this galaxy using two independent methods. (1) Based on our MUSE/VLT measurement of the heliocentric redshift (zhelio = 0.009783 0.000023), we infer the systemic recession velocity of the NGC 4993 group of galaxies in the cosmic microwave background (CMB) frame to be vCMB = 3231 53 km s−1. Using constrained cosmological simulations we estimate the line-of-sight peculiar velocity to be vpec = 307 230 km s−1, resulting in a cosmic velocity of vcosmic = 2924 236 km s−1 (zcosmic = 0.00980 0.00079) and a distance of Dz = 40.4 3.4 Mpc assuming a local Hubble constant of H0 = 73.24 1.74 km s−1 Mpc−1. (2) Using Hubble Space Telescope measurements of the effective radius (15 5 1 5) and contained intensity and MUSE/VLT measurements of the velocity dispersion, we place NGC 4993 on the Fundamental Plane (FP) of E and S0 galaxies. Comparing to a frame of 10 clusters containing 226 galaxies, this yields a distance estimate of DFP = 44.0 7.5 Mpc. The combined redshift and FP distance is DNGC 4993 = 41.0 3.1 Mpc. This "electromagnetic" distance estimate is consistent with the independent measurement of the distance to GW170817 as obtained from the gravitational-wave signal ( D GW = 43.8 − 6.9 + 2.9 Mpc) and confirms that GW170817 occurred in NGC 4993.
The origin of dust in galaxies is still a mystery. The majority of the refractory elements are produced in supernova explosions, but it is unclear how and where dust grains condense and grow, and how ...they avoid destruction in the harsh environments of star-forming galaxies. The recent detection of 0.1 to 0.5 solar masses of dust in nearby supernova remnants suggests in situ dust formation, while other observations reveal very little dust in supernovae in the first few years after explosion. Observations of the spectral evolution of the bright SN 2010jl have been interpreted as pre-existing dust, dust formation or no dust at all. Here we report the rapid (40 to 240 days) formation of dust in its dense circumstellar medium. The wavelength-dependent extinction of this dust reveals the presence of very large (exceeding one micrometre) grains, which resist destruction. At later times (500 to 900 days), the near-infrared thermal emission shows an accelerated growth in dust mass, marking the transition of the dust source from the circumstellar medium to the ejecta. This provides the link between the early and late dust mass evolution in supernovae with dense circumstellar media.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT
We present Hubble Space Telescope imaging of a pre-explosion counterpart to SN 2019yvr obtained 2.6 yr before its explosion as a type Ib supernova (SN Ib). Aligning to a post-explosion ...Gemini-S/GSAOI image, we demonstrate that there is a single source consistent with being the SN 2019yvr progenitor system, the second SN Ib progenitor candidate after iPTF13bvn. We also analysed pre-explosion Spitzer/Infrared Array Camera (IRAC) imaging, but we do not detect any counterparts at the SN location. SN 2019yvr was highly reddened, and comparing its spectra and photometry to those of other, less extinguished SNe Ib we derive $E(B-V)=0.51\substack{+0.27\\
-0.16}$ mag for SN 2019yvr. Correcting photometry of the pre-explosion source for dust reddening, we determine that this source is consistent with a log (L/L⊙) = 5.3 ± 0.2 and $T_{\mathrm{eff}} = 6800\substack{+400\\
-200}$ K star. This relatively cool photospheric temperature implies a radius of 320$\substack{+30\\
-50}~\mathrm{ R}_{\odot}$, much larger than expectations for SN Ib progenitor stars with trace amounts of hydrogen but in agreement with previously identified SN IIb progenitor systems. The photometry of the system is also consistent with binary star models that undergo common envelope evolution, leading to a primary star hydrogen envelope mass that is mostly depleted but still seemingly in conflict with the SN Ib classification of SN 2019yvr. SN 2019yvr had signatures of strong circumstellar interaction in late-time (>150 d) spectra and imaging, and so we consider eruptive mass-loss and common envelope evolution scenarios that explain the SN Ib spectroscopic class, pre-explosion counterpart, and dense circumstellar material. We also hypothesize that the apparent inflation could be caused by a quasi-photosphere formed in an extended, low-density envelope, or circumstellar matter around the primary star.
Abstract
We present preexplosion optical and infrared (IR) imaging at the site of the type II supernova (SN II) 2023ixf in Messier 101 at 6.9 Mpc. We astrometrically registered a ground-based image ...of SN 2023ixf to archival Hubble Space Telescope (HST), Spitzer Space Telescope (Spitzer), and ground-based near-IR images. A single point source is detected at a position consistent with the SN at wavelengths ranging from HST
R
band to Spitzer 4.5
μ
m. Fitting with blackbody and red supergiant (RSG) spectral energy distributions (SEDs), we find that the source is anomalously cool with a significant mid-IR excess. We interpret this SED as reprocessed emission in a 8600
R
⊙
circumstellar shell of dusty material with a mass ∼5 × 10
−5
M
⊙
surrounding a
log
(
L
/
L
⊙
)
=
4.74
±
0.07
and
T
eff
=
3920
−
160
+
200
K RSG. This luminosity is consistent with RSG models of initial mass 11
M
⊙
, depending on assumptions of rotation and overshooting. In addition, the counterpart was significantly variable in preexplosion Spitzer 3.6 and 4.5
μ
m imaging, exhibiting ∼70% variability in both bands correlated across 9 yr and 29 epochs of imaging. The variations appear to have a timescale of 2.8 yr, which is consistent with
κ
-mechanism pulsations observed in RSGs, albeit with a much larger amplitude than RSGs such as
α
Orionis (Betelgeuse).
The unprecedented optical and near-infrared lightcurves of the first electromagnetic counterpart to a gravitational-wave source, GW170817, a binary neutron star merger, exhibited a strong evolution ...from blue to near-infrared (a so-called "kilonova" or "macronova"). The emerging near-infrared component is widely attributed to the formation of r-process elements that provide the opacity to shift the blue light into the near-infrared. An alternative scenario is that the light from the blue component gets extinguished by dust formed by the kilonova and subsequently is re-emitted at near-infrared wavelengths. We test here this hypothesis using the lightcurves of AT 2017gfo, the kilonova accompanying GW170817. We find that of the order of of carbon is required to reproduce the optical/near-infrared lightcurves as the kilonova fades. This putative dust cools from ∼2000 K at ∼4 days after the event to ∼1500 K over the course of the following week, thus requiring dust with a high condensation temperature, such as carbon. We contrast this with the nucleosynthetic yields predicted by a range of kilonova wind models. These suggest that at most of carbon is formed. Moreover, the decay in the inferred dust temperature is slower than that expected in kilonova models. We therefore conclude that in current models of the blue component of the kilonova, the near-infrared component in the kilonova accompanying GW170817 is unlikely to be due to dust.
Abstract
Seeing pristine material from the donor star in a type Ia supernova (SN Ia) explosion can reveal the nature of the binary system. In this paper, we present photometric and spectroscopic ...observations of SN 2020esm, one of the best-studied SNe of the class of “super-Chandrasekhar” SNe Ia (SC SNe Ia), with data obtained −12 to +360 days relative to peak brightness, obtained from a variety of ground- and space-based telescopes. Initially misclassified as a type II supernova, SN 2020esm peaked at
M
B
= −19.9 mag, declined slowly (Δ
m
15
(
B
) = 0.92 mag), and had particularly blue UV and optical colors at early times. Photometrically and spectroscopically, SN 2020esm evolved similarly to other SC SNe Ia, showing the usual low ejecta velocities, weak intermediate-mass elements, and the enhanced fading at late times, but its early spectra are unique. Our first few spectra (corresponding to a phase of ≳10 days before peak) reveal a nearly pure carbon/oxygen atmosphere during the first days after explosion. This composition can only be produced by pristine material, relatively unaffected by nuclear burning. The lack of H and He may further indicate that SN 2020esm is the outcome of the merger of two carbon/oxygen white dwarfs. Modeling its bolometric light curve, we find an
56
Ni mass of
1.23
−
0.14
+
0.14
M
☉
and an ejecta mass of
1.75
−
0.20
+
0.32
M
☉
, in excess of the Chandrasekhar mass. Finally, we discuss possible progenitor systems and explosion mechanisms of SN 2020esm and, in general, the SC SNe Ia class.
Abstract
JWST Near Infrared Camera (NIRCam) observations at 1.5–4.5
μ
m have provided broadband and narrowband imaging of the evolving remnant of SN 1987A with unparalleled sensitivity and spatial ...resolution. Comparing with previous marginally spatially resolved Spitzer Infrared Array Camera (IRAC) observations from 2004 to 2019 confirms that the emission arises from the circumstellar equatorial ring (ER), and the current brightness at 3.6 and 4.5
μ
m was accurately predicted by extrapolation of the declining brightness tracked by IRAC. Despite the regular light curve, the NIRCam observations clearly reveal that much of this emission is from a newly developing outer portion of the ER. Spots in the outer ER tend to lie at position angles in between the well-known ER hotspots. We show that the bulk of the emission in the field can be represented by five standard spectral energy distributions, each with a distinct origin and spatial distribution. This spectral decomposition provides a powerful technique for distinguishing overlapping emission from the circumstellar medium and the supernova ejecta, excited by the forward and reverse shocks, respectively.
Abstract We present an analysis of Type Ia supernovae (SNe Ia) from the Carnegie Supernova Project I and II and extend the Hubble diagram from optical to near-infrared wavelengths ( uBgVriYJH ). We ...calculate the Hubble constant, H 0 , using various distance calibrators: Cepheids, the tip of the red giant branch (TRGB), and surface brightness fluctuations (SBFs). Combining all methods of calibration, we derive H 0 = 71.76 ± 0.58 (stat) ± 1.19 (sys) km s −1 Mpc −1 from the B band and H 0 = 73.22 ± 0.68 (stat) ± 1.28 (sys) km s −1 Mpc −1 from the H band. By assigning equal weight to the Cepheid, TRGB, and SBF calibrators, we derive the systematic errors required for consistency in the first rung of the distance ladder, resulting in a systematic error of 1.2 ∼ 1.3 km s −1 Mpc −1 in H 0 . As a result, relative to the statistics-only uncertainty, the tension between the late-time H 0 we derive by combining the various distance calibrators and the early-time H 0 from the cosmic microwave background is reduced. The highest precision in SN Ia luminosity is found in the Y band (0.12 ± 0.01 mag), as defined by the intrinsic scatter ( σ int ). We revisit SN Ia Hubble residual-host mass correlations and recover previous results that these correlations do not change significantly between the optical and near-infrared wavelengths. Finally, SNe Ia that explode beyond 10 kpc from their host centers exhibit smaller dispersion in their luminosity, confirming our earlier findings. A reduced effect of dust in the outskirts of hosts may be responsible for this effect.
We present the discovery and optical follow-up of the faintest supernova-like transient known. The event (SN 2019gsc) was discovered in a star-forming host at 53 Mpc by ATLAS. A detailed multicolor ...light curve was gathered with Pan-STARRS1 and follow-up spectroscopy was obtained with the Nordic Optical Telescope and Gemini-North. The spectra near maximum light show narrow features at low velocities of 3000-4000 km s−1, similar to the extremely low-luminosity SNe 2010ae and 2008ha, and the light curve displays a similar fast decline (Δm15(r) = 0.91 0.10 mag). SNe 2010ae and 2008ha have been classified as SNe Iax, and together the three either make up a distinct physical class of their own or are at the extreme low-luminosity end of this diverse supernova population. The bolometric light curve is consistent with a low kinetic energy of explosion (Ek ∼ 1049 erg s−1), a modest ejected mass (Mej ∼ 0.2 M ), and radioactive powering by 56Ni (MNi ∼ 2 × 10−3 M ). The spectra are quite well reproduced with radiative transfer models (TARDIS) and a composition dominated by carbon, oxygen, magnesium, silicon, and sulfur. Remarkably, all three of these extreme Iax events are in similar low-metallicity star-forming environments. The combination of the observational constraints for all three may be best explained by deflagrations of near MCh hybrid carbon-oxygen-neon white dwarfs that have short evolutionary pathways to formation.
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