A flux-calibrated, high-resolution atlas of optical sky emission from UVES

Hanuschik, R. W.

doi:10.1051/0004-6361:20030885

Cited by 189 publications

(216 citation statements)

References 11 publications

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“…The night sky spectrum is a combination of the atmospheric molecular emission, zodiacal light, and scattered star light, along with the moon contribution if any (Hanuschik 2003). We have developed a sky spectrum model from a principal component analysis (PCA) on 700 pure sky spectra obtained from standard star exposures in various observing conditions.…”

Section: Sky Subtractionmentioning

confidence: 99%

Evidence of environmental dependencies of Type Ia supernovae from the Nearby Supernova Factory indicated by local Hα

Rigault

Copin

Aldering

et al. 2013

A&A

213

288

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Context. Use of Type Ia supernovae (SNe Ia) as distance indicators has proven to be a powerful technique for measuring the darkenergy equation of state. However, recent studies have highlighted potential biases correlated with the global properties of their host galaxies, large enough to induce systematic errors into such cosmological measurements if not properly treated. Aims. We study the host galaxy regions in close proximity to SNe Ia in order to analyze relations between the properties of SN Ia events and environments where their progenitors most likely formed. In this paper we focus on local Hα emission as an indicator of young progenitor environments. Methods. The Nearby Supernova Factory has obtained flux-calibrated spectral timeseries for SNe Ia using integral field spectroscopy. These observations enabled the simultaneous measurement of the SN and its immediate vicinity. For 89 SNe Ia we measured or set limits on Hα emission, used as a tracer of ongoing star formation, within a 1 kpc radius around each SN. This constitutes the first direct study of the local environment for a large sample of SNe Ia with accurate luminosity, color, and stretch measurements. Results. Our local star formation measurements provide several critical new insights. We find that SNe Ia with local Hα emission are redder by 0.036 ± 0.017 mag, and that the previously noted correlation between stretch and host mass is driven entirely by the SNe Ia coming from locally passive environments, in particular at the low-stretch end. There is no such trend for SNe Ia in locally star-forming environments. Our most important finding is that the mean standardized brightness for SNe Ia with local Hα emission is 0.094 ± 0.031 mag fainter on average than for those without. This offset arises from a bimodal structure in the Hubble residuals, with one mode being shared by SNe Ia in all environments and the other one exclusive to SNe Ia in locally passive environments. This structure also explains the previously known host-mass bias. We combine the star formation dependence of this bimodality with the cosmic star formation rate to predict changes with redshift in the mean SN Ia brightness and the host-mass bias. The strong change predicted is confirmed using high-redshift SNe Ia from the literature. Conclusions. The environmental dependences in SN Ia Hubble residuals and color found here point to remaining systematic errors in the standardization of SNe Ia. In particular, the observed brightness offset associated with local Hα emission is predicted to cause a significant bias in current measurements of the dark energy equation of state. Recognition of these effects offers new opportunities to improve SNe Ia as cosmological probes. For instance, we note that the SNe Ia associated with local Hα emission are more homogeneous, resulting in a brightness dispersion of only 0.105 ± 0.012 mag. Key words. cosmology: observationsAppendix is available in electronic form at http://www.aanda.orgArticle published by EDP Sciences A66, page 1 of 17 A&A 560...

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Section: Sky Subtractionmentioning

confidence: 99%

Evidence of environmental dependencies of Type Ia supernovae from the Nearby Supernova Factory indicated by local Hα

Rigault

Copin

Aldering

et al. 2013

A&A

213

288

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“…Note that we do not include any sky lines in addition to the synthetic spectra, since sky subtraction in the Calcium triplet wavelength region is efficiently performed in observational studies (Hanuschik 2003).…”

Section: From Single-star Spectra To An Ifu Data Cubementioning

confidence: 99%

Understanding the central kinematics of globular clusters with simulated integrated-light IFU observations

Bianchini

Norris

Ven

et al. 2015

Mon. Not. R. Astron. Soc.

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The detection of intermediate mass black holes in the centres of globular clusters is highly controversial, as complementary observational methods often deliver significantly different results. In order to understand these discrepancies, we develop a procedure to simulate integral field unit (IFU) observations of globular clusters: Simulating IFU Star Cluster Observations (SISCO). The input of our software are realistic dynamical models of globular clusters that are then converted in a spectral data cube. We apply SISCO to Monte Carlo cluster simulations from Downing et al. (2010), with a realistic number of stars and concentrations. Using independent realisations of a given simulation we are able to quantify the stochasticity intrinsic to the problem of observing a partially resolved stellar population with integrated-light spectroscopy. We show that the luminosity-weighted IFU observations can be strongly biased by the presence of a few bright stars that introduce a scatter in the velocity dispersion measurements up to 40% around the expected value, preventing any sound assessment of the central kinematic and a sensible interpretation of the presence/absence of an intermediate mass black hole. Moreover, we illustrate that, in our mock IFU observations, the average kinematic tracer has a mass of 0.75 M , only slightly lower than the mass of the typical stars examined in studies of resolved line-of-sight velocities of giant stars. Finally, in order to recover unbiased kinematic measurements we test different masking techniques that allow us to remove the spaxels dominated by bright stars, bringing the scatter down to a level of only a few percent. The application of SISCO will allow to investigate state-of-the-art simulations as realistic observations.

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“…The bands are ordered in terms of the value of their r-centroid, and one sees that there is no particular trend; the values of the ratio cluster around the normalized Figure 7. UVES/VLT spectrum of the Herzberg I 4-4 band [Hanuschik, 2003] and a DIATOM simulation of that band. ratio of 1.0.…”

Section: Astronomical Sky Spectra and The Uves/vlt Databasementioning

confidence: 99%

O(¹S → ¹D,³P) branching ratio as measured in the terrestrial nightglow

et al. 2006

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[1] The branching ratio of the two optically forbidden atmospheric emission lines, O( 1 S À 1 D) at 557.7 nm and O( 1 S À 3 P) at 297.2 nm, is a fixed number in the upper atmosphere because the O( 1 S) level is common to both lines. The value for the ratio A(557.7)/A(297.2) currently recommended by NIST is 16.7, and the ratio found in the laboratory is somewhat larger. Field observations require space-based instruments, in which case calibration between the two wavelength regions is the critical issue. We circumvent this problem by using the O 2 (A-X) Herzberg I emission system as a bridge between the UV region below 310 nm and the ground-accessible region above that wavelength. These two spectral regions can be separately calibrated in terms of intensity, and the results of a disparate set of observations (satellite, rocket, ground-based sky spectra) lead to a quite consistent value of 9.8 ± 1.0 for A(557.7)/A(297.2). This conclusion has consequences for auroral and dayglow processes and for spectral calibration. It is particularly important to ascertain the cause of the substantial difference between this value and those from theory.

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A flux-calibrated, high-resolution atlas of optical sky emission from UVES

Cited by 189 publications

References 11 publications

Evidence of environmental dependencies of Type Ia supernovae from the Nearby Supernova Factory indicated by local Hα

Evidence of environmental dependencies of Type Ia supernovae from the Nearby Supernova Factory indicated by local Hα

Understanding the central kinematics of globular clusters with simulated integrated-light IFU observations

O(¹S → ¹D,³P) branching ratio as measured in the terrestrial nightglow

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A flux-calibrated, high-resolution atlas of optical sky emission from UVES

Cited by 189 publications

References 11 publications

Evidence of environmental dependencies of Type Ia supernovae from the Nearby Supernova Factory indicated by local Hα

Evidence of environmental dependencies of Type Ia supernovae from the Nearby Supernova Factory indicated by local Hα

Understanding the central kinematics of globular clusters with simulated integrated-light IFU observations

O(1S → 1D,3P) branching ratio as measured in the terrestrial nightglow

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O(¹S → ¹D,³P) branching ratio as measured in the terrestrial nightglow