Spectroscopy of High-Redshift Supernovae from the ESSENCE Project: The First Two Years

Abstract

We present the results of spectroscopic observations of targets discovered during the first two years of the ESSENCE project. The goal of ESSENCE is to use a sample of ~200 Type Ia supernovae (SNe Ia) at moderate redshifts (0.2 < z < 0.8) to place constraints on the equation of state of the Universe. Spectroscopy not only provides the redshifts of the objects, but also confirms that some of the discoveries are indeed SNe Ia. This confirmation is critical to the project, as techniques developed to determine luminosity distances to SNe Ia depend upon the knowledge that the objects at high redshift are the same as the ones at low redshift. We describe the methods of target selection and prioritization, the telescopes and detectors, and the software used to identify objects. The redshifts deduced from spectral matching of high-redshift SNe Ia with low-redshift SNe Ia are consistent with those determined from host-galaxy spectra. We show that the high-redshift SNe Ia match well with low-redshift templates. We include all spectra obtained by the ESSENCE project, including 52 SNe Ia, 5 core-collapse SNe, 12 active galactic nuclei, 19 galaxies, 4 possibly variable stars, and 16 objects with uncertain identifications.

arXiv comment38 pages, 9 figures (many with multiple parts), submitted to AJ

References in corpus (21)

• Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
• Measurements of Omega and Lambda from 42 High-Redshift Supernovae
• Type Ia Supernova Discoveries at z>1 From the Hubble Space Telescope: Evidence for Past Deceleration and Constraints on Dark Energy Evolution
• Discovery of a Supernova Explosion at Half the Age of the Universe and its Cosmological Implications
• Cosmological Results from High-z Supernovae
• The High-Z Supernova Search: Measuring Cosmic Deceleration and Global Cur vature of the Universe Using Type Ia Supernovae
• New Constraints on ${\Omega }_M$, ${\Omega }_{\Lambda }$, and w from an Independent Set of Eleven High-Redshift Supernovae Observed with HST
• Supernova Limits on the Cosmic Equation of State
• 23 High Redshift Supernovae from the IfA Deep Survey: Doubling the SN Sample at z>0.7
• ESI, a new Keck Observatory echellette spectrograph and imager
• The Hubble Higher-Z Supernova Search: Supernovae to z=1.6 and Constraints on Type Ia Progenitor Models
• Detailed Analysis of Early to Late-Time Spectra of Supernova 1993J
• A High Intrinsic Peculiarity Rate Among Type Ia Supernovae
• Microslit Nod-shuffle Spectroscopy - a technique for achieving very high densities of spectra
• Time Dilation from Spectral Feature Age Measurements of Type Ia Supernovae
• Not Color Blind: Using Multiband Photometry to Classify Supernovae
• Identification of Type Ia Supernovae at Redshift 1.3 and Beyond with the Advanced Camera for Surveys on HST
• Optical Spectra of Type Ia Supernovae at z=0.46 and z=1.2
• Spectroscopic confirmation of high-redshift supernovae with the ESO VLT
• Redshift-Independent Distances to Type Ia Supernovae
• Photometric Identification of Young Stripped-Core Supernovae

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• Berkeley Supernova Ia Program I: Observations, Data Reduction, and Spectroscopic Sample of 582 Low-Redshift Type Ia Supernovae
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• Hubble Space Telescope and Ground-Based Observations of Type Ia Supernovae at Redshift 0.5: Cosmological Implications
• SN~2012cg: Evidence for Interaction Between a Normal Type Ia Supernova and a Non-Degenerate Binary Companion
• Verifying the Cosmological Utility of Type Ia Supernovae: Implications of a Dispersion in the Ultraviolet Spectra
• A Measurement of the Rate of type-Ia Supernovae at Redshift $z\approx$ 0.1 from the First Season of the SDSS-II Supernova Survey
• The Carnegie Supernova Project: First Near-Infrared Hubble Diagram to z~0.7
• Spectral Identification of an Ancient Supernova using Light Echoes in the LMC
• Using Line Profiles to Test the Fraternity of Type Ia Supernovae at High and Low Redshifts
• SNLS Spectroscopy: Testing for Evolution in Type Ia Supernovae
• Bayesian Estimation Applied to Multiple Species: Towards cosmology with a million supernovae
• The Young and Bright Type Ia Supernova ASASSN-14lp: Discovery, Early-Time Observations, First-Light Time, Distance to NGC 4666, and Progenitor Constraints
• Time Dilation in Type Ia Supernova Spectra at High Redshift
• Measurement of Ω_m, Ω_Λ from a blind analysis of Type Ia supernovae with CMAGIC: Using color information to verify the acceleration of the Universe
• Constraining Cosmic Evolution of Type Ia Supernovae
• Quantitative comparison between Type Ia supernova spectra at low and high redshifts: A case study
• First-Year Spectroscopy for the SDSS-II Supernova Survey
• The ESO/VLT 3rd year Type Ia supernova data set from the Supernova Legacy Survey
• Spectra of High-Redshift Type Ia Supernovae and a Comparison with their Low-Redshift Counterparts
• Spectroscopy of High-Redshift Supernovae from the ESSENCE Project: The First Four Years
• Type IIb Supernova SN 2011dh: Spectra and Photometry from the Ultraviolet to the Near-Infrared
• Lightcurves of Type Ia Supernovae from Near the Time of Explosion
• Probing bulk flow with nearby SNe Ia data
• Hubble Space Telescope Observations of Nine High-Redshift ESSENCE Supernovae
• The Relation Between Ejecta Velocity, Intrinsic Color, and Host-Galaxy Mass for High-Redshift Type Ia Supernovae
• Type II Supernova Light Curves and Spectra From the CfA
• Astronomical Distance Determination in the Space Age. Secondary distance indicators
• Dark energy, gravitation and supernovae
• Diversity of supernovae Ia determined using equivalent widths of Si II 4000
• ASASSN-15hy: an under-luminous, red 03fg-like type Ia supernova
• Supernovae and Cosmology
• On the future of Gamma-Ray Burst Cosmology
• A photometric search for transients in galaxy clusters
• Light Curves of 213 Type Ia Supernovae from the ESSENCE Survey
• PHotometry Assisted Spectral Extraction (PHASE) and identification of SNLS supernovae
• Spectroscopy of twelve Type Ia supernovae at intermediate redshift
• Deciphering the cosmic star formation history and the Nature of Type Ia Supernovae by Future Supernova Surveys
• Time-dependent diffusive interactions between dark matter and dark energy in the context of $k-$essence cosmology
• Spectroscopic observations of eight supernovae at intermediate redshift
• Constraining dust and color variations of high-z SNe using NICMOS on Hubble Space Telescope
• Optical Cross Correlation Filters: An Economical Approach for Identifying SNe Ia and Estimating their Redshifts