Determining the Type, Redshift, and Age of a Supernova Spectrum

By S. Blondin, J. Tonry. 2006

400 citations recorded by the source corpus.

We present an algorithm to identify the type of an SN spectrum and to determine its redshift and age. This algorithm, based on the correlation techniques of Tonry & Davis, is implemented in the Supernova Identification (SNID) code. It is used by members of ongoing high-redshift SN searches to distinguish between Type Ia and Ib/c SNe and to identify "peculiar" SNe Ia. We develop a diagnostic to quantify the quality of a correlation between the input and template spectra, which enables a formal evaluation of the associated redshift error. Furthermore, by comparing the correlation redshifts obtained using SNID with those determined from narrow lines in the SN host galaxy spectrum, we show that accurate redshifts (with a typical error σz ≲ 0.01) can be determined for SNe Ia without a spectrum of the host galaxy. Last, the age of an input spectrum is determined with a typical accuracy σt ≲ 3 days, shown here by using high-redshift SNe Ia with well-sampled light curves. The success of the correlation technique confirms the similarity of some SNe Ia at low and high redshifts. The SNID code, which will be made available to the community, can also be used for comparative studies of SN spectra, as well as comparisons between data and models.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/ea08622bf220f357e16a2f7be14c09cddd586908

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In Astronomy and Astrophysics

1. A. Filippenko
2. S. Smartt
3. E. Berger
4. A. Riess
5. N. Smith
6. S. Jha
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In Nuclear and High Energy Physics

1. S. Smartt
2. A. Filippenko
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7. R. Kirshner
8. Weidong Li

Citations in the corpus

• THE CARNEGIE SUPERNOVA PROJECT: FIRST PHOTOMETRY DATA RELEASE OF LOW-REDSHIFT TYPE Ia SUPERNOVAE (2009, methodology): “Spectral identification was performed using the SuperNova IDentification tool SNID (Blondin & Tonry 2007).”
• TYPE Ia SUPERNOVA RATE MEASUREMENTS TO REDSHIFT 2.5 FROM CANDELS: SEARCHING FOR PROMPT EXPLOSIONS IN THE EARLY UNIVERSE (2014, methodology): “Fitting the composite spectrum with the SuperNova IDentification (SNID) software (Blondin & Tonry 2007), we find the best template match is a Type Ia SN at z=1.59.”
• A CONTINUUM OF H- TO He-RICH TIDAL DISRUPTION CANDIDATES WITH A PREFERENCE FOR E+A GALAXIES (2014, methodology): “These events were typed using both visual and automatic classifications carried out with the SN spectral fitting codes Superfit (Howell et al. 2005) and SNID (Blondin & Tonry 2007).”
• TYPE Iax SUPERNOVAE: A NEW CLASS OF STELLAR EXPLOSION (2012, methodology): “By artificially smoothing the spectra (Blondin & Tonry 2007) to broaden the spectral features and also blueshifting the spectra, one can produce spectra that are similar to what one would expect if the SN simply had a higher ejecta velocity.”
• Berkeley Supernova Ia Program – I. Observations, data reduction and spectroscopic sample of 582 low-redshift Type Ia supernovae (2012, methodology): “We performed automated spectral classification of our full spectral c© 2012 RAS, MNRAS 000, 1–34 dataset10 using the SuperNova IDentification code (SNID; Blondin & Tonry 2007).”
• TYPE Ia SUPERNOVAE STRONGLY INTERACTING WITH THEIR CIRCUMSTELLAR MEDIUM (2013, methodology): “PREVIOUSLY KNOWN SNE IA-CSM In order to find SNe Ia-CSM that may have previously been classified as SNe IIn, we use the SuperNova IDentification code (SNID; Blondin & Tonry 2007).”
• THE CARNEGIE SUPERNOVA PROJECT: SECOND PHOTOMETRY DATA RELEASE OF LOW-REDSHIFT TYPE Ia SUPERNOVAE (2010, methodology): “Values of ∆m15 were computed using the SNooPy Python package (SNooPy; Burns et al. 2011), while the SuperNova IDentification code (SNID; Blondin & Tonry 2007) provided aid in determining spectral subtypes.”
• PESSTO: survey description and products from the first data release by the Public ESO Spectroscopic Survey of Transient Objects (2014, methodology): “In both cases, SNID finds the same best fitting template (SN 1991bg, z = 0.018, age +1.9 d), giving us confidence that the rapid reduced spectra are adequate for classification purposes.”
• The Carnegie Supernova Project. I. Third Photometry Data Release of Low-redshift Type Ia Supernovae and Other White Dwarf Explosions (2017, methodology): “However, the second-closest galaxy, CGCG108−013, which lies 50″ from the SN and has =z 0.0322helio , was determined by Foley et al. (2010) to be the most likely host using the SuperNova IDentification code (SNID; Blondin & Tonry 2007).”
• OPTICAL SPECTRA OF 73 STRIPPED-ENVELOPE CORE-COLLAPSE SUPERNOVAE (2014, methodology): “Thus, we reclassify this SN from an SN Ic to an SN Ia, remove it from our stripped SN sample, and are reminded that spectra of young SNe Ic can look similar to those of older SNe Ia (e.g., Blondin & Tonry 2007).”
• CHARACTERIZING THE V-BAND LIGHT-CURVES OF HYDROGEN-RICH TYPE II SUPERNOVAE (2014, methodology): “Therefore, to further constrain this epoch, matchingof spectra to those of a library of spectral templates was used through employing the Supernova Identification (SNID) code (Blondin & Tonry 2007).”
• OPTICAL DISCOVERY OF PROBABLE STELLAR TIDAL DISRUPTION FLARES (2010, methodology): “Employing the widely-used cross correlation method (Tonry & Davis 1979) for identifying SNe, using SNID (Blondin & Tonry 2007) on the host-subtracted spectrum, gives the best match to be an early SN type IIn spectrum, but this match is not very convincing: the degree of cross-correlation of the best”
• Nearby Supernova Rates from the Lick Observatory Supernova Search. II. The Observed Luminosity Functions and Fractions of Supernovae in a Complete Sample (2010, methodology): “With the help of the “Supernova Identification code” (SNID; Blondin & Tonry 2007), some recent SNe have been classified as SN IIb.”
• VARIABLE SODIUM ABSORPTION IN A LOW-EXTINCTION TYPE Ia SUPERNOVA, (2009, methodology): “…in the databases used by both fitting packages; the differences between the two lie in their fitting methods and treatment of color information (see Blondin & Tonry 2007), but since SN 2002bo and SN 2005cf were similar events in many respects (e.g., line velocities) we do not regard these fit…”
• COSMOLOGICAL CONSTRAINTS FROM MEASUREMENTS OF TYPE Ia SUPERNOVAE DISCOVERED DURING THE FIRST 1.5 yr OF THE Pan-STARRS1 SURVEY (2013, methodology): “SNID provides a quantitative assessment that a particular SN is of a given class at a given redshift.”
• THE SPECTROSCOPIC DIVERSITY OF TYPE Ia SUPERNOVAE (2000, methodology): “We cross-checked the classifications of all supernovae in our sample with those reported in circulars using the SNID code of Blondin & Tonry (2007).”