David Gonzalez

Optical and Infrared Photometry of the Nearby Type Ia Supernova 2001el

We present well-sampled optical (UBVRI) and infrared (JHK) light curves of the nearby (≈18.0 Mpc) Type Ia supernova SN 2001el, from 11 days before to 142 days after the time of B-band maximum. The data represent one of the best sets of optical and infrared photometry ever obtained for a Type Ia supernova (SN). Based on synthetic photometry using optical spectra of SN 2001el and optical and infrared spectra of SN 1999ee, we were able to devise filter corrections for the BVJHK photometry of SN 2001el, which to some extent resolve systematic differences between SN 2001el data sets obtained with different telescope/filter/instrument combinations. We also calculated V-minus-infrared color curves on the basis of a delayed detonation model and show that the theoretical color curves match the unreddened loci for Type Ia SNe with midrange decline rates to within 0.2 mag. Given the completeness of the light curves and the elimination of filter-oriented systematic errors to some degree, the data presented here will be useful for the construction of photometric templates, especially in the infrared. On the whole the photometric behavior of SN 2001el was quite normal. The second H-band maximum being brighter than the first H-band maximum is in accord with the prediction of Krisciunas et al. for Type Ia SNe with midrange decline rates. The photometry exhibits nonzero host extinction, with total AV = 0.57 ± 0.05 mag along the line of sight. NGC 1448, the host of SN 2001el, would be an excellent target for a distance determination using Cepheids.

Optical and infrared photometry of the type Ia supernovae 1991T, 1991bg, 1999ek, 2001bt, 2001cn, 2001cz, and 2002bo

We present optical and/or infrared photometry of the Type Ia supernovae SN 1991T, SN 1991bg, SN 1999ek, SN 2001bt, SN 2001cn, SN 2001cz, and SN 2002bo. All but one of these supernovae have decline rate parameters, Δm15(B), close to the median value of 1.1 for the whole class of Type Ia supernovae. The addition of these supernovae to the relationship between the near-infrared absolute magnitudes and Δm15(B) strengthens the previous relationships we have found in that the maximum light absolute magnitudes are essentially independent of the decline rate parameter. (SN 1991bg, the prototype of the subclass of fast-declining Type Ia supernovae, is a special case.) The dispersion in the Hubble diagram in JHK is only ~0.15 mag. The near-infrared properties of Type Ia supernovae continue to be excellent measures of the luminosity distances to the supernova host galaxies because of the need for only small corrections from the epoch of observation to maximum light, low dispersion in absolute magnitudes at maximum light, and the minimal reddening effects in the near-infrared.

The Type Ia Supernova 2004S, a Clone of SN 2001el, and the Optimal Photometric Bands for Extinction Estimation

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 56Ni. 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 RV = 2.15 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.

Optical and Infrared Photometry of the Unusual Type Ia Supernova 2000cx

ABSTRACT We present optical and infrared photometry of the unusual Type Ia supernova 2000cx. With the data of Li et al. and Jha, this constitutes the largest data set ever assembled for a Type Ia SN, more than 600 points in UBVRIJHK. We confirm the finding of Li et al. regarding the unusually blue B−V colors as SN 2000cx entered the nebular phase. Its I‐band secondary hump was extremely weak given its B‐band decline rate. The V minus near‐infrared colors likewise do not match loci based on other slowly declining Type Ia SNe, although V−K is the least “abnormal.” In several ways, SN 2000cx resembles other slow decliners, given its B‐band decline rate [ \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \ren...

Dynamical properties of liquid Al near melting: An orbital-free molecular dynamics study

The static and dynamic structure of liquid Al is studied using the orbital free ab initio molecular dynamics method. Two thermodynamic states along the coexistence line are considered, namely T=943 and 1323 K, for which x-ray and neutron scattering data are available. A kinetic-energy functional which fulfills a number of physically relevant conditions is employed, along with a local first-principles pseudopotential. In addition to a comparison with experiment, we also compare our ab initio results with those obtained from conventional molecular-dynamics simulations using effective interionic pair potentials derived from second-order pseudopotential perturbation theory.

THE FAST DECLINING TYPE Ia SUPERNOVA 2003gs, AND EVIDENCE FOR A SIGNIFICANT DISPERSION IN NEAR-INFRARED ABSOLUTE MAGNITUDES OF FAST DECLINERS AT MAXIMUM LIGHT*

We obtained optical photometry of SN 2003gs on 49 nights, from 2 to 494 days after T(B_(max)). We also obtained near-IR photometry on 21 nights. SN 2003gs was the first fast declining Type Ia SN that has been well observed since SN 1999by. While it was subluminous in optical bands compared to more slowly declining Type Ia SNe, it was not subluminous at maximum light in the near-IR bands. There appears to be a bimodal distribution in the near-IR absolute magnitudes of Type Ia SNe at maximum light. Those that peak in the near-IR after T(B_(max)) are subluminous in the all bands. Those that peak in the near-IR prior to T(B_(max)), such as SN 2003gs, have effectively the same near-IR absolute magnitudes at maximum light regardless of the decline rate Δm_(15)(B). Near-IR spectral evidence suggests that opacities in the outer layers of SN 2003gs are reduced much earlier than for normal Type Ia SNe. That may allow γ rays that power the luminosity to escape more rapidly and accelerate the decline rate. This conclusion is consistent with the photometric behavior of SN 2003gs in the IR, which indicates a faster than normal decline from approximately normal peak brightness.

Optical Photometry of the Type I[CLC]a[/CLC] Supernova 1999[CLC]ee[/CLC] and the Type I[CLC]b[/CLC]/[CLC]c[/CLC] Supernova 1999[CLC]ex[/CLC] in IC 5179

We present UBVRIz lightcurves of the Type Ia SN 1999ee and the Type Ib/c SN 1999ex, both located in the galaxy IC 5179. SN 1999ee has an extremely well sampled lightcurve spanning from 10 days before Bmax through 53 days after peak. Near maximum we find systematic differences ~0.05 mag in photometry measured with two different telescopes, even though the photometry is reduced to the same local standards around the supernova using the specific color terms for each instrumental system. We use models for our bandpasses and spectrophotometry of SN 1999ee to derive magnitude corrections (S-corrections) and remedy this problem. This exercise demonstrates the need of accurately characterizing the instrumental system before great photometric accuracies of Type Ia supernovae can be claimed. It also shows that this effect can have important astrophysical consequences since a small systematic shift of 0.02 mag in the B-V color can introduce a 0.08 mag error in the extinction corrected peak B magnitudes of a supernova and thus lead to biased cosmological parameters. The data for the Type Ib/c SN 1999ex present us with the first ever observed shock breakout of a supernova of this class. These observations show that shock breakout occurred 18 days before Bmax and support the idea that Type Ib/c supernovae are due to core collapse of massive stars rather than thermonuclear disruption of white dwarfs.

Do the photometric colors of Type II-P Supernovae allow accurate determination of host galaxy extinction?

We present infrared photometry of supernova (SN) 1999em, plus optical photometry, infrared photometry, and optical spectroscopy of SN 2003hn. Both objects were Type II-P SNe. The V – [RIJHK] color curves of these SNe evolved in a very similar fashion until the end of the plateau phase. This allows us to determine how much more extinction the light of SN 2003hn suffered compared to SN 1999em. Since we have an estimate of the total extinction suffered by SN 1999em from model fits of ground-based and space-based spectra as well as photometry of SN 1999em, we can estimate the total extinction and absolute magnitudes of SN 2003hn with reasonable accuracy. Since the host galaxy of SN 2003hn also produced the Type Ia SN 2001el, we can directly compare the absolute magnitudes of these two SNe of different types.

Structural, dynamic, and electronic properties of liquid tin: An ab initio molecular dynamics study

We report on a study of several structural, dynamic, and electronic properties of liquid Sn at a thermodynamic state close to the triple point (573 K) and another one at a higher temperature (1273 K). This study has been performed by ab initio molecular dynamics simulations using 205 atoms and around 20 ps of simulation time. The calculated static structures show a good agreement with the available experimental data. The dynamic structure factors fairly agree with their experimental counterparts obtained by inelastic x-ray scattering experiments, which display inelastic side peaks. The calculated dispersion relations exhibit a positive dispersion, although not so marked as suggested by the experiment; moreover, its slope at the long-wavelength limit compares favorably with the experimental sound velocity. Electron densities near selected triplets of atoms are similar to those appearing in the solid phases, but these features have an extremely short lifetime, so they should not be considered as solid remnants in the melt.

Optical and near-infrared observations of the peculiar type ia supernova 1999ac

We present 39 nights of optical photometry, 34 nights of IR photometry, and 4 nights of optical spectroscopy of the Type Ia supernova 1999ac. This supernova was discovered 2 weeks before maximum light, and observations were begun shortly thereafter. At early times its spectra resembled the unusual SN 1999aa and were characterized by very high velocities in the Ca II H and K lines but very low velocities in the Si II λ6355 line. The optical photometry showed a slow rise to peak brightness but, quite peculiarly, was followed by a more rapid decline from maximum. Thus, the B- and V-band light curves cannot be characterized by a single stretch factor. We argue that the best measure of the nature of this object is not the decline rate parameter Δm15(B). The B - V colors were unusual from 30 to 90 days after maximum light in that they evolved to bluer values at a much slower rate than normal Type Ia supernovae. The spectra and bolometric light curve indicate that this event was similar to the spectroscopically peculiar slow decliner SN 1999aa.