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1.
THE RISE OF SN 2014J IN THE NEARBY GALAXY M82
Ariel Goobar, Joel Johansson, Rahman Amanullah, Yi Cao, Mansi Kasliwal, Raphael Ferretti, Peter Nugent, Daniel Perley, Avishay Gal-Yam, Eran Ofek, S. P. Tendulkar, M. Dennefeld, Stefano Valenti, Iair Arcavi, D.P.K. Banerjee, V. Venkataraman, Brad Cenko, Tanja Petrushevska, T.J. Dupuy, M.C. Liu, 2014, original scientific article

Abstract: We report on the discovery of SN 2014J in the nearby galaxy M82. Given its proximity, it offers the best opportunity to date to study a thermonuclear supernova (SN) over a wide range of the electromagnetic spectrum. Optical, nearIR, and mid-IR observations on the rising light curve, orchestrated by the intermediate Palomar Transient Factory, show that SN 2014J is a spectroscopically normal Type Ia supernova (SN Ia), albeit exhibiting high-velocity features in its spectrum and heavily reddened by dust in the host galaxy. Our earliest detections start just hours after the fitted time of explosion. We use high-resolution optical spectroscopy to analyze the dense intervening material and do not detect any evolution in the resolved absorption features during the light curve rise. Similar to other highly reddened SNe Ia, a low value of total-to-selective extinction, RV 2, provides the best match to our observations. We also study pre-explosion optical and near-IR images from Hubble Space Telescope with special emphasis on the sources nearest to the SN location.
Found in: osebi
Keywords: dust, extinction – galaxies: individual (Messier 82) – supernovae: individual (SN 2014J)
Published: 22.01.2018; Views: 2199; Downloads: 0 
(1 vote)
.pdf Fulltext (2,55 MB)

2.
Time-varying sodium absorption in the Type Ia supernova 2013gh
Raphael Ferretti, R. Amanullah, Ariel Goobar, Joel Johansson, T. Petrushevska, 2016, original scientific article

Abstract: Context. Temporal variability of narrow absorption lines in high-resolution spectra of Type Ia supernovae (SNe Ia) is studied to search for circumstellar matter. Time series which resolve the profiles of absorption lines such as Na I D or Ca II H&K are expected to reveal variations due to photoionisation and subsequent recombination of the gases. The presence, composition, and geometry of circumstellar matter may hint at the elusive progenitor system of SNe Ia and could also affect the observed reddening law. Aims. To date, there are few known cases of time-varying Na I D absorption in SNe Ia, all of which occurred during relatively late phases of the supernova (SN) evolution. Photoionisation, however, is predicted to occur during the early phases of SNe Ia, when the supernovae peak in the ultraviolet. We attempt, therefore, to observe early-time absorption-line variations by obtaining high-resolution spectra of SNe before maximum light. Methods. We have obtained photometry and high-resolution spectroscopy of SNe Ia 2013gh and iPTF 13dge, to search for absorptionline variations. Furthermore, we study interstellar absorption features in relation to the observed photometric colours of the SNe. Results. Both SNe display deep Na I D and Ca II H&K absorption features. Furthermore, small but significant variations are detected in a feature of the Na I D profile of SN 2013gh. The variations are consistent with either geometric effects of rapidly moving or patchy gas clouds or photoionisation of Na I gas at R ≈ 1019 cm from the explosion. Conclusions. Our analysis indicates that it is necessary to focus on early phases to detect photoionisation effects of gases in the circumstellar medium of SNe Ia. Different absorbers such as Na I and Ca II can be used to probe for matter at different distances from the SNe. The nondetection of variations during early phases makes it possible to put limits on the abundance of the species at those distances.
Found in: osebi
Keywords: supernovae: general – supernovae: individual: SN 2013gh – dust, extinction – circumstellar matter – supernovae: individual: iPTF 13dge
Published: 23.01.2018; Views: 1855; Downloads: 0
.pdf Fulltext (1,84 MB)

3.
VizieR Online Data Catalog: Photometry of SN 2013gh and iPTF13dge (Ferretti+, 2016)
Raphael Ferretti, Tanja Petrushevska, complete scientific database or corpus

Abstract: Measured photometry of type Ia supernovae 2013gh and iPTF13dge are presented. Furthermore, the effective light-curve-width-corrected phase and the natural magnitude in specified filters have been computed. Thereby, the corresponding Galactic absorption (Ax_MW) and the filter corrections (Kx) to the corresponding rest-frame filter for SN 2011fe as described by Amanullah et al. (2015MNRAS.453.3300A) are presented. The corrected magnitude can be obtained as X-AXMW-KX. All corrections have been calculated after the SN 2011fe template has been reddened with the best-fit Fitzpatrick (1999PASP..111...63F) law, for each SN. Furthermore, the V magnitude and corrections for each phase phase are included. The V magnitude was either measured (M) or calculated (D) using the SNooPy model. The V magnitude is only shown for data points used in the colour analysis, with phases between -10 and +35-days. The corrected colour can be obtained as (X-AXMW-KX)-(V-AVMW-KV) and can be compared with the corresponding colour of SN 2011fe in order to study the reddening laws of the SNe.
Found in: osebi
Keywords: Supernovae, Photometry: UBV, Photometry: ugriz, Photometry: ultraviolet
Published: 23.01.2018; Views: 1984; Downloads: 0
.pdf Fulltext (439,40 KB)

4.
High-redshift supernova rates measured with the gravitational telescope A 1689
Tanja Petrushevska, R. Amanullah, Ariel Goobar, S. Fabbro, Joel Johansson, Tor Kjellsson, Chris Lidman, K. Paech, Johan Richard, H. Dahle, Raphael Ferretti, J.P. Kneib, M. Limousin, Jakob Nordin, V. Stanishev, 2016, original scientific article

Abstract: Aims. We present a ground-based, near-infrared search for lensed supernovae behind the massive cluster Abell 1689 at z = 0.18, which is one of the most powerful gravitational telescopes that nature provides. Methods. Our survey was based on multi-epoch J-band observations with the HAWK-I instrument on VLT, with supporting optical data from the Nordic Optical Telescope. Results. Our search resulted in the discovery of five photometrically classified, core-collapse supernovae with high redshifts of 0.671 < z < 1.703 and magnifications in the range ∆m = −0.31 to −1.58 mag, as calculated from lensing models in the literature. Owing to the power of the lensing cluster, the survey had the sensitivity to detect supernovae up to very high redshifts, z ∼ 3, albeit for a limited region of space. We present a study of the core-collapse supernova rates for 0.4 ≤ z < 2.9, and find good agreement with previous estimates and predictions from star formation history. During our survey, we also discovered two Type Ia supernovae in A 1689 cluster members, which allowed us to determine the cluster Ia rate to be 0.14+0.19 −0.09 ± 0.01 SNuB h 2 (SNuB ≡ 10−12 SNe L −1 ,B yr−1), where the error bars indicate 1σ confidence intervals, statistical and systematic, respectively. The cluster rate normalized by the stellar mass is 0.10+0.13 −0.06 ± 0.02 in SNuM h 2 (SNuM ≡ 10−12 SNe M−1 yr−1). Furthermore, we explore the optimal future survey for improving the core-collapse supernova rate measurements at z & 2 using gravitational telescopes, and for detections with multiply lensed images, and we find that the planned WFIRST space mission has excellent prospects. Conclusions. Massive clusters can be used as gravitational telescopes to significantly expand the survey range of supernova searches, with important implications for the study of the high-z transient Universe.
Found in: osebi
Keywords: supernovae: general – gravitational lensing: strong – galaxies: star formation – galaxies: clusters: individual: A 1689 – techniques: photometric
Published: 23.01.2018; Views: 1918; Downloads: 0
.pdf Fulltext (2,64 MB)

5.
Testing for redshift evolution of Type Ia supernovae using the strongly lensed PS1-10afx at z = 1.4
Tanja Petrushevska, Rahman Amanullah, Mattia Bulla, Markus Kromer, Raphael Ferretti, Ariel Goobar, Semeli Papadogiannakis, 2017, original scientific article

Abstract: Context. The light from distant supernovae (SNe ) can be magnified through gravitational lensing when a foreground galaxy is located along the line of sight. This line-up allows for detailed studies of SNe at high redshift that otherwise would not be possible. Spectroscopic observations of lensed high-redshift Type Ia supernovae (SNe Ia) are of particular interest since they can be used to test for evolution of their intrinsic properties. The use of SNe Ia for probing the cosmic expansion history has proven to be an extremely powerful method for measuring cosmological parameters. However, if systematic redshift-dependent properties are found, their usefulness for future surveys could be challenged. Aims. We investigate whether the spectroscopic properties of the strongly lensed and very distant SN Ia PS1-10afx at z = 1.4, deviates from the well-studied populations of normal SNe Ia at nearby or intermediate distance. Methods. We created median spectra from nearby and intermediate-redshift spectroscopically normal SNe Ia from the literature at −5 and +1 days from light-curve maximum. We then compared these median spectra to those of PS1-10afx. Results. We do not find signs of spectral evolution in PS1-10afx. The observed deviation between PS1-10afx and the median templates are within what is found for SNe at low and intermediate redshift. There is a noticeable broad feature centred at λ ∼ 3500 Å, which is present only to a lesser extent in individual low- and intermediate-redshift SN Ia spectra. From a comparison with a recently developed explosion model, we find this feature to be dominated by iron peak elements, in particular, singly ionized cobalt and chromium.
Found in: osebi
Keywords: supernovae: individual: PS1-10afx – gravitational lensing: strong – supernovae: general
Published: 23.01.2018; Views: 1950; Downloads: 0
.pdf Fulltext (1,00 MB)

6.
Probing gas and dust in the tidal tail of NGC 5221 with the type Ia supernova iPTF16abc
Raphael Ferretti, Rahman Amanullah, Ariel Goobar, Tanja Petrushevska, 2017, original scientific article

Abstract: Context. Type Ia supernovae (SNe Ia) can be used to address numerous questions in astrophysics and cosmology. Due to their well known spectral and photometric properties, SNe Ia are well suited to study gas and dust along the lines-of-sight to the explosions. For example, narrow Na I D and Ca II H&K absorption lines can be studied easily, because of the well-defined spectral continuum of SNe Ia around these features. Aims. We aim to study the gas and dust along the line-of-sight to iPTF16abc, which occurred in an unusual location, in a tidal arm, 80 kpc from centre of the galaxy NGC 5221. Methods. Using a time-series of high-resolution spectra, we have examined narrow Na I D and Ca II H&K absorption features for variations in time, which would be indicative for circumstellar (CS) matter. Furthermore, we have taken advantage of the well known photometric properties of SNe Ia to determine reddening due to dust along the line-of-sight. Results. From the lack of variations in Na I D and Ca II H&K, we determine that none of the detected absorption features originate from the CS medium of iPTF16abc. While the Na I D and Ca II H&K absorption is found to be optically thick, a negligible amount of reddening points to a small column of interstellar dust. Conclusions. We find that the gas along the line-of-sight to iPTF16abc is typical of what might be found in the interstellar medium (ISM) within a galaxy. It suggests that we are observing gas that has been tidally stripped during an interaction of NGC 5221 with one of its neighbouring galaxies in the past ∼109 yr. In the future, the gas clouds could become the locations of star formation. On a longer time scale, the clouds might diffuse, enriching the circum-galactic medium (CGM) with metals. The gas profile along the line-of-sight should be useful for future studies of the dynamics of the galaxy group containing NGC 5221.
Found in: osebi
Keywords: supernovae: individual: iPTF16abc – galaxies: individual: NGC 5221 – galaxies: ISM – galaxies
Published: 23.01.2018; Views: 1592; Downloads: 0
.pdf Fulltext (1,57 MB)

7.
iPTF Discoveries of Recent Type Ia Supernovae
Raphael Ferretti, Tanja Petrushevska, 2016, other component parts

Abstract: The intermediate Palomar Transient Factory (ATel #4807) reports the discovery and classification of the following Type Ia SNe. Our automated candidate vetting to distinguish a real astrophysical source (1.0) from bogus artefacts (0.0) is powered by three generations of machine learning algorithms: RB2 (Brink et al. 2013MNRAS.435.1047B), RB4 (Rebbapragada et al. 2015AAS...22543402R) and RB5 (Wozniak et al. 2013AAS...22143105W).
Found in: osebi
Keywords: Supernovae, Transient
Published: 23.01.2018; Views: 1508; Downloads: 0
.pdf Fulltext (337,22 KB)

8.
iPTF Discoveries of Recent Type Ia Supernovae
Raphael Ferretti, T. Petrushevska, 2016, other component parts

Abstract: The intermediate Palomar Transient Factory (ATel #4807) reports the discovery and classification of the following Type Ia SNe. Our automated candidate vetting to distinguish a real astrophysical source (1.0) from bogus artifacts (0.0) is powered by three generations of machine learning algorithms: RB2 (Brink et al. 2013MNRAS.435.1047B), RB4 (Rebbapragada et al. 2015AAS...22543402R) and RB5 (Wozniak et al. 2013AAS...22143105W).
Found in: osebi
Keywords: Supernovae, Transients
Published: 23.01.2018; Views: 1656; Downloads: 0
.pdf Fulltext (339,92 KB)

9.
iPTF Discoveries of Recent Core-Collapse Supernovae
F. Taddia, Raphael Ferretti, C. Fremling, Anders Nyholm, S. Papadogiannakis, T. Petrushevska, L. Hangard, 2015, other component parts

Abstract: The intermediate Palomar Transient Factory (ATel #4807) reports the discovery and classification of the following Core-Collapse SNe. Our automated candidate vetting to distinguish a real astrophysical source (1.0) from bogus artifacts (0.0) is powered by three generations of machine learning algorithms: RB2 (Brink et al. 2013MNRAS.435.1047B), RB4 (Rebbapragada et al. 2015AAS...22543402R) and RB5 (Wozniak et al. 2013AAS...22143105W).
Found in: osebi
Keywords: Supernovae, Transients
Published: 24.01.2018; Views: 1678; Downloads: 0
.pdf Fulltext (379,21 KB)

10.
iPTF Discoveries of Recent Type Ia Supernovae
Raphael Ferretti, T. Petrushevska, 2015, other component parts

Abstract: The intermediate Palomar Transient Factory (ATel#4807) reports the following SNe Ia:
Found in: osebi
Keywords: supernovae, transients
Published: 25.01.2018; Views: 1455; Downloads: 0
.pdf Fulltext (79,85 KB)

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