Engineering topics

Hamuy, Mario

Publications and source records attributed to Hamuy, Mario.

7 records

DOE OSTI2025

It is not σ 8 : constraining the non-linear matter power spectrum with the Dark Energy Survey Year-5 supernova sample

The weak gravitational lensing magnification of Type Ia supernovae (SNe Ia) is sensitive to the matter power spectrum on scales $k\gt 1 h$ Mpc$^{-1}$, making it unwise to interpret SNe Ia lensing in terms of power on linear scales. We compute the probability density function of SNe Ia magnification as a function of standard cosmological parameters, plus an empirical parameter $A_{\rm mod}$ which describes the suppression or enhancement of matter power on non-linear scales compared to a cold dark matter only model. While baryons are expected to enhance power on the scales relevant to SN Ia lensing, other physics such as neutrino masses or non-standard dark matter may suppress power. Using the Dark Energy Survey Year-5 sample, we find $A_{\rm mod} = 0.77^{+0.69}_{-0.40}$ (68 per cent credible interval around the median). Although the median is consistent with unity there are hints of power suppression, with $A_{\rm mod} \lt 1.09$ at 68 per cent credibility.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2022

A puzzle solved after two decades: SN 2002gh among the brightest of superluminous supernovae

ABSTRACT We present optical photometry and spectroscopy of the superluminous SN 2002gh from maximum light to +204 d, obtained as part of the Carnegie Type II Supernova (CATS) project. SN 2002gh is among the most luminous discovered supernovae ever, yet it remained unnoticed for nearly two decades. Using Dark Energy Camera archival images we identify the potential supernova (SN) host galaxy as a faint dwarf galaxy, presumably having low metallicity, and in an apparent merging process with other nearby dwarf galaxies. We show that SN 2002gh is among the brightest hydrogen-poor SLSNe with MV = −22.40 ± 0.02, with an estimated peak bolometric luminosity of 2.6 ± 0.1 × 1044 erg s−1. We discount the decay of radioactive nickel as the main SN power mechanism, and assuming that the SN is powered by the spin-down of a magnetar we obtain two alternative solutions. The first case, is characterized by significant magnetar power leakage, and Mej between 0.6 and 3.2 M⊙, Pspin = 3.2 ms, and B = 5 × 1013 G. The second case does not require power leakage, resulting in a huge ejecta mass of about 30 M⊙, a fast spin period of Pspin ∼ 1 ms, and B ∼ 1.6 × 1014 G. We estimate a zero-age main-sequence mass between 14 and 25 M⊙ for the first case and of about 135 M⊙ for the second case. The latter case would place the SN progenitor among the most massive stars observed to explode as an SN.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS2012

Multi-wavelength Observations of the Enduring Type IIn Supernovae 2005ip and 2006jd1

We present an observational study of the Type IIn supernovae (SNe IIn) 2005ip and 2006jd. Broad-band UV, optical and near-IR photometry, and visual-wavelength spectroscopy of SN 2005ip complement and extend upon published observations to 6.5 years past discovery. Our observations of SN 2006jd extend from UV to mid-infrared wavelengths, and like SN 2005ip, are compared to reported X-ray measurements to understand the nature of the progenitor. Both objects display a number of similarities with the 1988Z-like subclass of SN IIn including: (i) remarkably similar early- and late-phase optical spectra, (ii) a variety of high ionization coronal lines, (iii) long-duration optical and near-IR emission and, (iv) evidence of cold and warm dust components. However, diversity is apparent including an unprecedented late-time r-band excess in SN 2006jd. The observed di erences are attributed to di erences between the mass-loss history of the progenitor stars. We conclude that the progenitor of SN 2006jd likely experienced a signi cant mass-loss event during its pre-SN evolution akin to the great 19th century eruption of eta Carinae. Contrarily, as advocated by Smith et al. (2009), we nd the circumstellar environment of SN 2005ip to be more consistent with a clumpy wind progenitor.

Stritzinger, Maximilian↗

NASA NTRS1994

The Type Ia supernova 1989B in NGC 3627 (M66)

We report extensive optical photometry and spectroscopy of the Type Ia supernova 1989B. Maximum light in B occurred approximately seven days after discovery on JD 2447565.3 +/- 1.0 (1989 February 7.8 +/- 1.0) at a magnitude of 12.34 +/- 0.05. The UBV light curves of this supernova were very similar to those of other well observed Type Ia events such as SN 1981B and SN 1980N. From a comparison of the UBVRIJHK photometry, we derive an extinction for SN 1989B of E(B-V) = 0.37 +/- 0.03 mags relative to the unobscured Type Ia SN 1980N. The properties of the dust responsible for the reddening of SN 1989B appear to have been similar to those of normal dust in the Milky Way. In particular, we find no evidence for an unusually low value of the ratio of the total to selective absorption. We derive a distance modulus of delta mu(sub 0) = -1.62 +/- 0.03 mag relative to the Type Ia SN 1980N. We present optical spectra which provide essentially continuous coverage of the spectral evolution of SN 1989B over the first month following B maximum. These data show the transition from the maximum-light spectrum, in which lines of elements such as Ca, Si, S, Mg, and O are most prominent, to the Fe-dominated spectrum observed a few weeks after maximum. This transition occurred quite smoothly over a two-week period following B maximum. Comparison of the spectra of SN 1989B with data for two other well observed Type Ia supernovae -- 1981B and 1986G -- reveals subtle differences in the relative strengths of the S II and Si II absorption lines at maximum light. However, these differences disappeared within a week or so after maximum with the onset of the Fe-dominated phase.

Wells, Lisa A.↗

NASA NTRS1994

The distances to five Type II supernovae using the expanding photosphere method, and the value of H(sub 0)

We have used observations gathered at Cerro Tololo Inter-American Observatory (CTIO) to measure distances by the expanding photosphere method (EPM) to five Type II supernovae. These supernovae lie at redshifts from cz = 1100 km/s to cz = 5500 km/s, and increase to 18 the number of distances measured using EPM. We compare distances derived to 11 Type II supernovae with distances to their galaxies measured using the Tully-Fisher method. We find that the Tully-Fisher distances average 11% +/- 7% smaller. The comparison shows no significant evidence of any large distance-dependent bias in the Tully-Fisher distances. We employ the sample of EPM distances from 4.5 Mpc to 180 Mpc to derive a value for the Hubble constant. We find H(sub 0) = 73 +/- 6 (statistical) +/- 7 (systematic) km/s/Mpc.

Schmidt, Brian P.↗

NASA NTRS1994

The expanding photosphere method applied to SN 1992am AT cz = 14 600 km/s

We present photometry and spectroscopy of Supernova (SN) 1992am for five months following its discovery by the Calan Cerro-Tololo Inter-American Observatory (CTIO) SN search. These data show SN 1992am to be type II-P, displaying hydrogen in its spectrum and the typical shoulder in its light curve. The photometric data and the distance from our own analysis are used to construct the supernova's bolometric light curve. Using the bolometric light curve, we estimate SN 1992am ejected approximately 0.30 solar mass of Ni-56, an amount four times larger than that of other well studied SNe II. SN 1992am's; host galaxy lies at a redshift of cz = 14 600 km s(exp -1), making it one of the most distant SNe II discovered, and an important application of the Expanding Photsphere Method. Since z = 0.05 is large enough for redshift-dependent effects to matter, we develop the technique to derive luminosity distances with the Expanding Photosphere Method at any redshift, and apply this method to SN 1992am. The derived distance, D = 180(sub -25) (sup +30) Mpc, is independent of all other rungs in the extragalactic distance ladder. The redshift of SN 1992am's host galaxy is sufficiently large that uncertainties due to perturbations in the smooth Hubble flow should be smaller than 10%. The Hubble ratio derived from the distance and redshift of this single object is H(sub 0) = 81(sub -15) (sup +17) km s(exp -1) Mpc(exp -1). In the future, with more of these distant objects, we hope to establish an independent and statistically robust estimate of H(sub 0) based solely on type II supernovae.

Schmidt, Brian P.↗

NASA NTRS1993

SN 1991bg - A type Ia supernova with a difference

While SN 1991bg is an unusual type Ia SN in such a feature as the brief duration of the photospheric phase, which ended only two weeks after maximum, it shares with other Ia SNs strong Si II and Ca II lines near maximum light. In addition, the light and color curve slopes are almost identical with the templates at late times. The spectral evolution of SN 1991bg is also unique but not unrecognizable; nevertheless, the peculiarities associated with this event complicate the fundamental question as to whether the Ia SNs make good standard candles.

Leibundgut, Bruno↗