1. |
- Phillips, M. M., et al.
(författare)
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Carnegie Supernova Project-II : Extending the Near-infrared Hubble Diagram for Type Ia Supernovae to z ∼ 0.1
- 2019
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Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 131:995
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Tidskriftsartikel (refereegranskat)abstract
- 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 similar to 100 Type. Ia supernovae located in the smooth Hubble flow (0.03 less than or similar to z less than or similar to 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.
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2. |
- Burns, Christopher R., et al.
(författare)
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THE CARNEGIE SUPERNOVA PROJECT : LIGHT-CURVE FITTING WITH SNooPy
- 2011
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 141:1, s. 19-
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Tidskriftsartikel (refereegranskat)abstract
- In providing an independent measure of the expansion history of the universe, the Carnegie Supernova Project (CSP) has observed 71 high-z Type Ia supernovae (SNe Ia) in the near-infrared bands Y and J. These can be used to construct rest-frame i-band light curves which, when compared to a low-z sample, yield distance moduli that are less sensitive to extinction and/or decline-rate corrections than in the optical. However, working with NIR observed and i-band rest-frame photometry presents unique challenges and has necessitated the development of a new set of observational tools in order to reduce and analyze both the low-z and high-z CSP sample. We present in this paper the methods used to generate uBVgriYJH light-curve templates based on a sample of 24 high-quality low-z CSP SNe. We also present two methods for determining the distances to the hosts of SN Ia events. A larger sample of 30 low-z SNe Ia in the Hubble flow is used to calibrate these methods. We then apply the method and derive distances to seven galaxies that are so nearby that their motions are not dominated by the Hubble flow.
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3. |
- Clocchiatti, Alejandro, et al.
(författare)
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Late-time HST photometry of SN1994I : Hints of positron annihilation energy deposition
- 2008
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Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 120:865, s. 290-300
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Tidskriftsartikel (refereegranskat)abstract
- We present multicolor Hubble Space Telescope ( HST) WFPC2 broadband observations of the Type Ic SN 1994I obtained similar to 280 d after maximum light. We measure the brightness of the SN and, relying on the detailed spectroscopic database of SN 1994I, we transform the ground-based photometry obtained at early times to the HST photometric system, deriving light curves for the WFPC2 F439W, F555W, F675W, and F814W passbands that extend from 7 days before to 280 days after maximum. We use the multicolor photometry to build a quasi-bolometric light curve of SN 1994I, and compare it with similarly constructed light curves of other supernovae. In doing so, we propose and test a scaling in energy and time that allows for a more meaningful comparison of the exponential tails of different events. Through comparison with models, we find that the late-time light curve of SN 1994I is consistent with that of spherically symmetric ejecta in homologous expansion, for which the ability to trap the gamma-rays produced by the radioactive decay of Co-56 diminishes roughly as the inverse of time squared. We also find that by the time of the HST photometry, the light curve was significantly energized by the annihilation of positrons.
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4. |
- Folatelli, Gaston, et al.
(författare)
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UNBURNED MATERIAL IN THE EJECTA OF TYPE Ia SUPERNOVAE
- 2012
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 745:1, s. 74-
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Tidskriftsartikel (refereegranskat)abstract
- The presence of unburned material in the ejecta of normal Type Ia supernovae (SNe Ia) is investigated using early-time spectroscopy obtained by the Carnegie Supernova Project. The tell-tale signature of pristine material from a C+O white dwarf progenitor star is the presence of carbon, as oxygen is also a product of carbon burning. The most prominent carbon lines in optical spectra of SNe Ia are expected to arise from C II. We find that at least 30% of the objects in the sample show an absorption at approximate to 6300 angstrom which is attributed to C II lambda 6580. An alternative identification of this absorption as Ha is considered to be unlikely. These findings imply a larger incidence of carbon in SNe Ia ejecta than previously noted. We show how observational biases and physical conditions may hide the presence of weak C II lines, and account for the scarcity of previous carbon detections in the literature. This relatively large frequency of carbon detections has crucial implications on our understanding of the explosive process. Furthermore, the identification of the 6300 angstrom absorptions as carbon would imply that unburned material is present at very low expansion velocities, merely approximate to 1000 km s(-1) above the bulk of Si II. Based on spectral modeling, it is found that the detections are consistent with a mass of carbon of 10(-3) to 10(-2) M-circle dot. The presence of this material so deep in the ejecta would imply substantial mixing, which may be related to asymmetries of the flame propagation. Another possible explanation for the carbon absorptions may be the existence of clumps of unburned material along the line of sight. However, the uniformity of the relation between C II and Si II velocities is not consistent with such small-scale asymmetries. The spectroscopic and photometric properties of SNe Ia with and without carbon signatures are compared. A trend toward bluer color and lower luminosity at maximum light is found for objects which show carbon.
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5. |
- Graves, Genevieve J. M., et al.
(författare)
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Limits from the Hubble Space Telescope on a Point Source in SN 1987A
- 2005
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 629, s. 944-959
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Tidskriftsartikel (refereegranskat)abstract
- We observed supernova 1987A (SN 1987A) with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) in 1999 September and again with the Advanced Camera for Surveys (ACS) on the HST in 2003 November. Our spectral observations cover ultraviolet (UV) and optical wavelengths from 1140 to 10266 Å, and our imaging observations cover UV and optical wavelengths from 2900 to 9650 Å. No point source is observed in the remnant. We obtain a limiting flux of Fopt<=1.6×10-14 ergs s-1 cm-2 in the wavelength range 2900-9650 Å for any continuum emitter at the center of the supernova remnant (SNR). This corresponds to an intrinsic luminosity of Lopt<=5×1033 ergs s-1. It is likely that the SNR contains opaque dust that absorbs UV and optical emission, resulting in an attenuation of ~35% due to dust absorption in the SNR. Correcting for this level of dust absorption would increase our upper limit on the luminosity of a continuum source by a factor of 1.54. Taking into account dust absorption in the remnant, we find a limit of Lopt<=8×1033 ergs s-1. We compare this upper bound with empirical evidence from point sources in other supernova remnants and with theoretical models for possible compact sources. We show that any survivor of a possible binary system must be no more luminous than an F6 main-sequence star. Bright young pulsars such as Kes 75 or the Crab pulsar are excluded by optical and X-ray limits on SN 1987A. Other nonplerionic X-ray point sources have luminosities similar to the limits on a point source in SN 1987A; RCW 103 and Cas A are slightly brighter than the limits on SN 1987A, while Pup A is slightly fainter. Of the young pulsars known to be associated with SNRs, those with ages <=5000 yr are all too bright in X-rays to be compatible with the limits on SN 1987A. Examining theoretical models for accretion onto a compact object, we find that spherical accretion onto a neutron star is firmly ruled out and that spherical accretion onto a black hole is possible only if there is a larger amount of dust absorption in the remnant than predicted. In the case of thin-disk accretion, our flux limit requires a small disk, no larger than 1010 cm, with an accretion rate no more than 0.3 times the Eddington accretion rate. Possible ways to hide a surviving compact object include the removal of all surrounding material at early times by a photon-driven wind, a small accretion disk, or very high levels of dust absorption in the remnant. It will not be easy to improve substantially on our optical-UV limit for a point source in SN 1987A, although we can hope that a better understanding of the thermal infrared emission will provide a more complete picture of the possible energy sources at the center of SN 1987A.
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6. |
- Kattner, ShiAnne, et al.
(författare)
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The Standardizability of Type Ia Supernovae in the Near-Infrared : Evidence for a Peak-Luminosity Versus Decline-Rate Relation in the Near-Infrared
- 2012
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Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 124:912, s. 114-127
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Tidskriftsartikel (refereegranskat)abstract
- We analyze the standardizability of Type Ia supernovae (SNe Ia) in the near-infrared (NIR) by investigating the correlation between observed peak NIR (Y JH) absolute magnitude and postmaximum B-band decline rate [Delta m(15)(B)]. A sample of 27 low-redshift SNe Ia with well-observed NIR light curves observed by the Carnegie Supernova Project (CSP) between 2004 and 2007 is used. All 27 objects have premaximum coverage in optical bands, with a subset of 13 having premaximum NIR observations as well; coverage of the other 14 begins shortly after NIR maximum brightness. We describe the methods used to derive light-curve parameters (absolute peak magnitudes and decline rates) from both spline-and template-fitting procedures, and we confirm prior findings that fitting templates to SNe Ia light curves in the NIR is problematic due to the diversity of postmaximum behavior of objects that are characterized by similar Delta m(15)(B) values, especially at high decline rates. Nevertheless, we show that NIR light curves can be reasonably fit with a template, especially if the observations begin within 5 days after NIR maximum. SNe Ia appear to be better standardizable candles in the NIR bands than in the optical bands. For the subset of 13 objects in our data set that excludes the highly reddened and fast-declining SNe Ia and includes only those objects for which NIR observations began prior to 5 days after maximum light, we find modest (1.7 sigma) evidence for a peak-luminosity versus decline-rate relation in Y, and stronger evidence (2.8 sigma) in J and H. Using R-V values differing from the canonical value (R-V = 3.1) is shown to have little effect on the results. A Hubble diagram is presented for the NIR bands and the B band. The resulting scatter for the combined NIR bands is 0.13 mag, while the B band produces a scatter of 0.22 mag. Finally, we find evidence for a bimodal distribution in the NIR absolute magnitudes of fast-declining SNe Ia [Delta m(15)(B) > 1.7]. These data suggest that applying a correction to SNe Ia peak luminosities for decline rate is likely to be beneficial in the J and H bands to make SNe Ia more precise distance indicators, but of only marginal importance in the Y band.
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7. |
- Krisciunas, Kevin, et al.
(författare)
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THE MOST SLOWLY DECLINING TYPE Ia SUPERNOVA 2001ay
- 2011
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 142:3, s. 74-
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Tidskriftsartikel (refereegranskat)abstract
- We present optical and near-infrared photometry, as well as ground-based optical spectra and Hubble Space Telescope ultraviolet spectra, of the Type Ia supernova (SN) 2001ay. At maximum light the Si II and Mg II lines indicated expansion velocities of 14,000 km s-(1), while Si III and S II showed velocities of 9000 km s(-1). There is also evidence for some unburned carbon at 12,000 km s(-1). SN 2001ay exhibited a decline-rate parameter of Delta m(15)(B) = 0.68 +/- 0.05 mag; this and the B-band photometry at t greater than or similar to + 25 day past maximum make it the most slowly declining Type Ia SN yet discovered. Three of the four super-Chandrasekhar-mass candidates have decline rates almost as slow as this. After correction for Galactic and host-galaxy extinction, SN 2001ay had M(B) = -19.19 and M(V) = -19.17 mag at maximum light; thus, it was not overluminous in optical bands. In near-infrared bands it was overluminous only at the 2 sigma level at most. For a rise time of 18 days (explosion to bolometric maximum) the implied (56)Ni yield was (0.58 +/- 0.15)/alpha M(circle dot), with alpha = L(max)/E(Ni) probably in the range 1.0-1.2. The (56)Ni yield is comparable to that of many Type Ia SNe. The normal (56)Ni yield and the typical peak optical brightness suggest that the very broad optical light curve is explained by the trapping of gamma rays in the inner regions.
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8. |
- Krisciunas, Kevin, et al.
(författare)
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The Type Ia supernova 2004s, a clone of SN 2001el, and the optimal photometric bands for extinction estimation
- 2007
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 133:1, s. 58-72
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Tidskriftsartikel (refereegranskat)abstract
- We present optical (UBVRI) and near-IR (YJHK) photometry of the normal Type Ia supernova (SN) 2004S. We also present eight optical spectra and one near-IR spectrum of SN 2004S. The light curves and spectra are nearly identical to those of SN 2001el. This is the first time we have seen optical and IR light curves of two Type Ia SNe match so closely. Within the one parameter family of light curves for normal Type Ia SNe, that two objects should have such similar light curves implies that they had identical intrinsic colors and produced similar amounts of Ni-56. From the similarities of the light-curve shapes we obtain a set of extinctions as a function of wavelength that allows a simultaneous solution for the distance modulus difference of the two objects, the difference of the host galaxy extinctions, and RV. Since SN 2001el had roughly an order of magnitude more host galaxy extinction than SN 2004S, the value of R-V = 2.15(-0.22)(+0.24) pertains primarily to dust in the host galaxy of SN 2001el. We have also shown via Monte Carlo simulations that adding rest-frame J-band photometry to the complement of BVRI photometry of Type Ia SNe decreases the uncertainty in the distance modulus by a factor of 2.7. A combination of rest-frame optical and near-IR photometry clearly gives more accurate distances than using rest-frame optical photometry alone.
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9. |
- Stritzinger, Maximilian, et al.
(författare)
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THE CARNEGIE SUPERNOVA PROJECT : SECOND PHOTOMETRY DATA RELEASE OF LOW-REDSHIFT TYPE Ia SUPERNOVAE
- 2011
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 142:5, s. 156-
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Tidskriftsartikel (refereegranskat)abstract
- The Carnegie Supernova Project (CSP) was a five-year observational survey conducted at Las Campanas Observatory that obtained, among other things, high-quality light curves of similar to 100 low-redshift Type Ia supernovae (SNe Ia). Presented here is the second data release of nearby SN Ia photometry consisting of 50 objects, with a subset of 45 having near-infrared follow-up observations. Thirty-three objects have optical pre-maximum coverage with a subset of 15 beginning at least five days before maximum light. In the near-infrared, 27 objects have coverage beginning before the epoch of B-band maximum, with a subset of 13 beginning at least five days before maximum. In addition, we present results of a photometric calibration program to measure the CSP optical (uBgVri) bandpasses with an accuracy of similar to 1%. Finally, we report the discovery of a second SN Ia, SN 2006ot, similar in its characteristics to the peculiar SN 2006bt.
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10. |
- Stritzinger, Maximilian, et al.
(författare)
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THE DISTANCE TO NGC 1316 (FORNAX A) FROM OBSERVATIONS OF FOUR TYPE Ia SUPERNOVAE
- 2010
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 140:6, s. 2036-2051
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Tidskriftsartikel (refereegranskat)abstract
- The giant elliptical galaxy NGC 1316 (Fornax A) is a well-studied member of the Fornax Cluster and a prolific producer of Type Ia supernovae (SNe Ia), having hosted four observed events since 1980. Here, we present detailed optical-and near-infrared light curves of the spectroscopically normal SN 2006dd. These data are used, along with previously published photometry of the normal SN 1980N and SN 1981D, and the fast-declining, low-luminosity SN 2006mr, to compute independent estimates of the host reddening for each SN, and the distance to NGC 1316. From the three normal SNe, we find a distance of 17.8 +/- 0.3 (random) +/- 0.3 (systematic) Mpc for H-o = 72. Distance moduli derived from the "EBV" and Tripp methods give the values that are mutually consistent with 4%-8%. Moreover, the weighted means of the distance moduli for these three SNe for three methods agree to within 3%. This consistency is encouraging and supports the premise that Type Ia SNe are reliable distance indicators at the 5% precision level or better. On the other hand, the two methods used to estimate the distance of the fast-declining SN 2006mr both yield a distance to NGC 1316 which is 25%-30% larger. This disparity casts doubt on the suitability of fast-declining events for estimating extragalactic distances. Modest-to-negligible host galaxy reddening values are derived for all four SNe. Nevertheless, two of them (SN 2006dd and SN 2006mr) show strong Na I D interstellar lines in the host galaxy system. The strength of this absorption is completely inconsistent with the small reddening values derived from the SN light curves if the gas in NGC 1316 is typical of that found in the interstellar medium of the Milky Way. In addition, the equivalent width of the Na lines in SN 2006dd appears to have weakened significantly some 100-150 days after explosion.
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11. |
- Stritzinger, Maximilian, et al.
(författare)
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The He-Rich Core-Collapse Supernova 2007Y : Observations from X-Ray to Radio Wavelengths
- 2009
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 696:1, s. 713-728
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Tidskriftsartikel (refereegranskat)abstract
- A detailed study spanning approximately a year has been conducted on the Type Ib supernova (SN) 2007Y. Imaging was obtained from X-ray to radio wavelengths, and a comprehensive set of multi-band (w2m2w1u'g'r'i'UBVYJHKs ) light curves and optical spectroscopy is presented. A virtually complete bolometric light curve is derived, from which we infer a 56Ni mass of 0.06 M sun. The early spectrum strongly resembles SN 2005bf and exhibits high-velocity features of Ca II and Hα during late epochs the spectrum shows evidence of an ejecta-wind interaction. Nebular emission lines have similar widths and exhibit profiles that indicate a lack of major asymmetry in the ejecta. Late phase spectra are modeled with a non-LTE code, from which we find 56Ni, O, and total-ejecta masses (excluding He) to be 0.06, 0.2, and 0.42 M sun, respectively, below 4500 km s-1. The 56Ni mass confirms results obtained from the bolometric light curve. The oxygen abundance suggests that the progenitor was most likely a ≈3.3 M sun He core star that evolved from a zero-age-main-sequence mass of 10-13 M sun. The explosion energy is determined to be ≈1050 erg, and the mass-loss rate of the progenitor is constrained from X-ray and radio observations to be lsim10-6 M sun yr-1. SN 2007Y is among the least energetic normal Type Ib SNe ever studied. Partly based on observations collected at the European Southern Observatory, La Silla and Paranal Observatories, Chile (ESO Programme 078.D-0048 and 380.D-0272).
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12. |
- Wang, Xiaofeng, et al.
(författare)
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Evidence for type ia supernova diversity from ultraviolet observations with the hubble space telescope
- 2012
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 749:2, s. 126-
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Tidskriftsartikel (refereegranskat)abstract
- We present ultraviolet (UV) spectroscopy and photometry of four Type Ia supernovae (SNe 2004dt, 2004ef, 2005M, and 2005cf) obtained with the UV prism of the Advanced Camera for Surveys on the Hubble Space Telescope. This data set provides unique spectral time series down to 2000 angstrom. Significant diversity is seen in the near-maximum-light spectra (similar to 2000-3500 angstrom) for this small sample. The corresponding photometric data, together with archival data from Swift Ultraviolet/Optical Telescope observations, provide further evidence of increased dispersion in the UV emission with respect to the optical. The peak luminositiesmeasured in the uvw1/F250W filter are found to correlate with the B-band light-curve shape parameter Delta m(15)(B), but with much larger scatter relative to the correlation in the broadband B band (e.g., similar to 0.4 mag versus similar to 0.2 mag for those with 0.8 mag < Delta m(15)(B) < 1.7 mag). SN 2004dt is found as an outlier of this correlation (at > 3 sigma), being brighter than normal SNe Ia such as SN 2005cf by similar to 0.9 mag and similar to 2.0 mag in the uvw1/F250W and uvm2/F220W filters, respectively. We show that different progenitor metallicity or line-expansion velocities alone cannot explain such a large discrepancy. Viewing-angle effects, such as due to an asymmetric explosion, may have a significant influence on the flux emitted in the UV region. Detailed modeling is needed to disentangle and quantify the above effects.
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