We present an analysis of the final data release of the Carnegie Supernova Project I, focusing on the absolute calibration of the luminosity-decline rate relation for Type Ia supernovae (SNe Ia) ...using new intrinsic color relations with respect to the color-stretch parameter, sBV, enabling improved dust extinction corrections. We investigate to what degree the so-called fast-declining SNe Ia can be used to determine accurate extragalactic distances. We estimate the intrinsic scatter in the luminosity-decline rate relation and find it ranges from 0.13 mag to 0.18 mag with no obvious dependence on wavelength. Using the Cepheid variable star data from the SH0ES project, the SN Ia distance scale is calibrated and the Hubble constant is estimated using our optical and near-infrared sample, and these results are compared to those determined exclusively from a near-infrared subsample. The systematic effect of the supernova's host galaxy mass is investigated as a function of wavelength and is found to decrease toward redder wavelengths, suggesting this effect may be due to dust properties of the host. Using estimates of the dust extinction derived from optical and near-infrared wavelengths and applying these to the H band, we derive a Hubble constant , whereas using a simple B − V color correction applied to the B band yields . Photometry of two calibrating SNe Ia from the CSP-II sample, SN 2012ht and SN 2015F, is presented and used to improve the calibration of the SN Ia distance ladder.
We present final natural-system optical (ugriBV) and near-infrared (YJH) photometry of 134 supernovae (SNe) with probable white dwarf progenitors that were observed in 2004-2009 as part of the first ...stage of the Carnegie Supernova Project (CSP-I). The sample consists of 123 Type Ia SNe, 5 Type Iax SNe, 2 super-Chandrasekhar SN candidates, 2 Type Ia SNe interacting with circumstellar matter, and 2 SN 2006bt-like events. The redshifts of the objects range from to 0.0835; the median redshift is 0.0241. For 120 (90%) of these SNe, near-infrared photometry was obtained. Average optical extinction coefficients and color terms are derived and demonstrated to be stable during the five CSP-I observing campaigns. Measurements of the CSP-I near-infrared bandpasses are also described, and near-infrared color terms are estimated through synthetic photometry of stellar atmosphere models. Optical and near-infrared magnitudes of local sequences of tertiary standard stars for each supernova are given, and a new calibration of Y-band magnitudes of the Persson et al. standards in the CSP-I natural system is presented.
Abstract
We present a systematic study of the most luminous (
M
IR
Vega magnitudes brighter than −14) infrared (IR) transients discovered by the
SPitzer
InfraRed Intensive Transients Survey (SPIRITS) ...between 2014 and 2018 in nearby galaxies (
D
< 35 Mpc). The sample consists of nine events that span peak IR luminosities of
M
4.5,peak
between −14 and −18.2, show IR colors between 0.2 < (3.6–4.5) < 3.0, and fade on timescales between 55 days <
t
fade
< 480 days. The two reddest events (
A
V
> 12) show multiple, luminous IR outbursts over several years and have directly detected, massive progenitors in archival imaging. With analyses of extensive, multiwavelength follow-up, we suggest the following possible classifications: five obscured core-collapse supernovae (CCSNe), two erupting massive stars, one luminous red nova, and one intermediate-luminosity red transient. We define a control sample of all optically discovered transients recovered in SPIRITS galaxies and satisfying the same selection criteria. The control sample consists of eight CCSNe and one Type Iax SN. We find that 7 of the 13 CCSNe in the SPIRITS sample have lower bounds on their extinction of 2 <
A
V
< 8. We estimate a nominal fraction of CCSNe in nearby galaxies that are missed by optical surveys as high as
(90% confidence). This study suggests that a significant fraction of CCSNe may be heavily obscured by dust and therefore undercounted in the census of nearby CCSNe from optical searches.
We present an updated analysis of the intrinsic colors of Type Ia supernova (SNe Ia) using the latest data release of the Carnegie Supernova Project. We introduce a new light-curve parameter very ...similar to stretch that is better suited for fast-declining events, and find that these peculiar types can be seen as extensions to the population of "normal" SNe Ia. With a larger number of objects, an updated fit to the Lira relation is presented along with evidence for a dependence on the late-time slope of the B - V light-curves with stretch and color. Using the full wavelength range from u to H band, we place constraints on the reddening law for the sample as a whole and also for individual events/hosts based solely on the observed colors. The photometric data continue to favor low values of R sub(V), though with large variations from event to event, indicating an intrinsic distribution. We confirm the findings of other groups that there appears to be a correlation between the derived reddening law, R sub(V), and the color excess, E(B - V), such that larger E(B - V) tends to favor lower R sub(V). The intrinsic u-band colors show a relatively large scatter that cannot be explained by variations in R sub(V) or by the Goobar power-law for circumstellar dust, but rather is correlated with spectroscopic features of the supernova and is therefore likely due to metallicity effects.
SPitzer InfraRed Intensive Transients Survey-SPIRITS-is an ongoing survey of nearby galaxies searching for infrared (IR) transients with Spitzer/IRAC. We present the discovery and follow-up ...observations of one of our most luminous (M4.5 = −17.1 0.4 mag, Vega) and reddest (3.6 − 4.5 = 3.0 0.2 mag) transients, SPIRITS 15c. The transient was detected in a dusty spiral arm of IC 2163 (D 35.5 Mpc). Pre-discovery ground-based imaging revealed an associated, shorter-duration transient in the optical and near-IR (NIR). NIR spectroscopy showed a broad ( 8400 km s−1), double-peaked emission line of He i at 1.083 m, indicating an explosive origin. The NIR spectrum of SPIRITS 15c is similar to that of the Type IIb SN 2011dh at a phase of 200 days. Assuming an AV = 2.2 mag of extinction in SPIRITS 15c provides a good match between their optical light curves. The NIR light curves, however, show some minor discrepancies when compared with SN 2011dh, and the extreme 3.6-4.5 color has not been previously observed for any SN IIb. Another luminous (M4.5 = −16.1 0.4 mag) event, SPIRITS 14buu, was serendipitously discovered in the same galaxy. The source displays an optical plateau lasting 80 days, and we suggest a scenario similar to the low-luminosity Type IIP SN 2005cs obscured by AV 1.5 mag. Other classes of IR-luminous transients can likely be ruled out in both cases. If both events are indeed SNe, this may suggest that 18% of nearby core-collapse SNe are missed by currently operating optical surveys.
Carnegie Supernova Project-II Phillips, M. M.; Contreras, Carlos; Hsiao, E. Y. ...
Publications of the Astronomical Society of the Pacific,
01/2019, Letnik:
131, Številka:
995
Journal Article
Recenzirano
Odprti dostop
The Carnegie Supernova Project-II (CSP-II) was an NSF-funded, four-year program to obtain optical and near-infrared observations of a “Cosmology” sample of ∼100 Type Ia supernovae located in the ...smooth Hubble flow (0.03 ≲ z ≲ 0.10). Light curves were also obtained of a “Physics” sample composed of 90 nearby Type Ia supernovae at z ≤ 0.04 selected for near-infrared spectroscopic timeseries observations. The primary emphasis of the CSP-II is to use the combination of optical and near-infrared photometry to achieve a distance precision of better than 5%. In this paper, details of the supernova sample, the observational strategy, and the characteristics of the photometric data are provided. In a companion paper, the near-infrared spectroscopy component of the project is presented.
Abstract
We present detailed ultraviolet, optical, and near-infrared light curves of the Type Ia supernova (SN) 2012fr, which exploded in the Fornax cluster member NGC 1365. These precise ...high-cadence light curves provide a dense coverage of the flux evolution from −12 to +140 days with respect to the epoch of
B
-band maximum (
t
B
max
). Supplementary imaging at the earliest epochs reveals an initial slow and nearly linear rise in luminosity with a duration of ∼2.5 days, followed by a faster rising phase that is well reproduced by an explosion model with a moderate amount of
56
Ni mixing in the ejecta. From our analysis of the light curves, we conclude that: (i) the explosion occurred <22 hr before the first detection of the supernova, (ii) the rise time to peak bolometric (
λ
> 1800 Å) luminosity was 16.5 ± 0.6 days, (iii) the supernova suffered little or no host-galaxy dust reddening, (iv) the peak luminosity in both the optical and near-infrared was consistent with the bright end of normal Type Ia diversity, and (v) 0.60 ± 0.15
M
⊙
of
56
Ni was synthesized in the explosion. Despite its normal luminosity, SN 2012fr displayed unusually prevalent high-velocity Ca
ii
and Si
ii
absorption features, and a nearly constant photospheric velocity of the Si
ii
λ
6355 line at ∼12,000
km
s
−
1
that began ∼5 days before
t
B
max
. We also highlight some of the other peculiarities in the early phase photometry and the spectral evolution. SN 2012fr also adds to a growing number of Type Ia supernovae that are hosted by galaxies with direct Cepheid distance measurements.
We present an analysis of the diversity of V-band light-curves of hydrogen-rich type II supernovae. Analyzing a sample of 116 supernovae, several magnitude measurements are defined, together with ...decline rates at different epochs, and time durations of different phases. It is found that magnitudes measured at maximum light correlate more strongly with decline rates than those measured at other epochs: brighter supernovae at maximum generally have faster declining light-curves at all epochs. We find a relation between the decline rate during the "plateau" phase and peak magnitudes, which has a dispersion of 0.56 mag, offering the prospect of using type II supernovae as purely photometric distance indicators. Our analysis suggests that the type II population spans a continuum from low-luminosity events which have flat light-curves during the "plateau" stage, through to the brightest events which decline much faster. A large range in optically thick phase durations is observed, implying a range in progenitor envelope masses at the epoch of explosion. During the radioactive tails, we find many supernovae with faster declining light-curves than expected from full trapping of radioactive emission, implying low mass ejecta. It is suggested that the main driver of light-curve diversity is the extent of hydrogen envelopes retained before explosion. Finally, a new classification scheme is introduced where hydrogen-rich events are typed as simply "SN II" with an "s2" value giving the decline rate during the "plateau" phase, indicating its morphological type.
This is the first release of optical spectroscopic data of low-redshift Type Ia supernovae (SNe Ia) by the Carnegie Supernova Project including 604 previously unpublished spectra of 93 SNe Ia. The ...observations cover a range of phases from 12 days before to over 150 days after the time of B-band maximum light. With the addition of 228 near-maximum spectra from the literature, we study the diversity among SNe Ia in a quantitative manner. For that purpose, spectroscopic parameters are employed such as expansion velocities from spectral line blueshifts and pseudo-equivalent widths (pW). The values of those parameters at maximum light are obtained for 78 objects, thus providing a characterization of SNe Ia that may help to improve our understanding of the properties of the exploding systems and the thermonuclear flame propagation. Two objects, namely, SNe 2005M and 2006is, stand out from the sample by showing peculiar Si II and S II velocities but otherwise standard velocities for the rest of the ions. We further study the correlations between spectroscopic and photometric parameters such as light-curve decline rate and color. In agreement with previous studies, we find that the pWof Si II absorption features are very good indicators of light-curve decline rate. Furthermore, we demonstrate that parameters such as pW2 (Si II 4130) and pW6 (Si II 5972) provide precise calibrations of the peak B-band luminosity with dispersions of approximately 0.15 mag. In the search for a secondary parameter in the calibration of peak luminosity for SNe Ia, we find a approximately 2sigma -3sigma correlation between B-band Hubble residuals and the velocity at maximum light of S II and Si II lines.
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