| 1. |
- Barack, Leor, et al.
(författare)
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Black holes, gravitational waves and fundamental physics : a roadmap
- 2019
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Ingår i: Classical and quantum gravity. - : IOP Publishing. - 0264-9381 .- 1361-6382. ; 36:14
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Forskningsöversikt (refereegranskat)abstract
- The grand challenges of contemporary fundamental physics dark matter, dark energy, vacuum energy, inflation and early universe cosmology, singularities and the hierarchy problem all involve gravity as a key component. And of all gravitational phenomena, black holes stand out in their elegant simplicity, while harbouring some of the most remarkable predictions of General Relativity: event horizons, singularities and ergoregions. The hitherto invisible landscape of the gravitational Universe is being unveiled before our eyes: the historical direct detection of gravitational waves by the LIGO-Virgo collaboration marks the dawn of a new era of scientific exploration. Gravitational-wave astronomy will allow us to test models of black hole formation, growth and evolution, as well as models of gravitational-wave generation and propagation. It will provide evidence for event horizons and ergoregions, test the theory of General Relativity itself, and may reveal the existence of new fundamental fields. The synthesis of these results has the potential to radically reshape our understanding of the cosmos and of the laws of Nature. The purpose of this work is to present a concise, yet comprehensive overview of the state of the art in the relevant fields of research, summarize important open problems, and lay out a roadmap for future progress. This write-up is an initiative taken within the framework of the European Action on 'Black holes, Gravitational waves and Fundamental Physics'.
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| 2. |
- Amanullah, Rahman, et al.
(författare)
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Diversity in extinction laws of Type Ia supernovae measured between 0.2 and 2 μm
- 2015
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 453:3, s. 3300-3328
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Tidskriftsartikel (refereegranskat)abstract
- We present ultraviolet (UV) observations of six nearby Type Ia supernovae (SNe Ia) obtained with the Hubble Space Telescope, three of which were also observed in the near-IR (NIR) with Wide-Field Camera 3. UV observations with the Swift satellite, as well as ground-based optical and NIR data provide complementary information. The combined data set covers the wavelength range 0.2-2 mu m. By also including archival data of SN 2014J, we analyse a sample spanning observed colour excesses up to E(B - V) = 1.4 mag. We study the wavelength-dependent extinction of each individual SN and find a diversity of reddening laws when characterized by the total-to-selective extinction R-V. In particular, we note that for the two SNe with E(B - V) greater than or similar to 1 mag, for which the colour excess is dominated by dust extinction, we find R-V = 1.4 +/- 0.1 and R-V = 2.8 +/- 0.1. Adding UV photometry reduces the uncertainty of fitted R-V by similar to 50 per cent allowing us to also measure R-V of individual low-extinction objects which point to a similar diversity, currently not accounted for in the analyses when SNe Ia are used for studying the expansion history of the Universe.
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| 3. |
- Amanullah, Rahman, et al.
(författare)
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THE PECULIAR EXTINCTION LAW OF SN 2014J MEASURED WITH THE HUBBLE SPACE TELESCOPE
- 2014
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Ingår i: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 788:2, s. L21-
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Tidskriftsartikel (refereegranskat)abstract
- The wavelength dependence of the extinction of Type Ia SN 2014J in the nearby galaxy M82 has been measured using UV to near-IR photometry obtained with the Hubble Space Telescope, the Nordic Optical Telescope, and the Mount Abu Infrared Telescope. This is the first time that the reddening of an SN Ia is characterized over the full wavelength range of 0.2-2 mu m. A total-to-selective extinction, R-V >= 3.1, is ruled out with high significance. The best fit at maximum using a Galactic type extinction law yields R-V = 1.4 +/- 0.1. The observed reddening of SN 2014J is also compatible with a power-law extinction, A(lambda)/A(V) = (lambda/lambda(V))(p) as expected from multiple scattering of light, with p = -2.1 +/- 0.1. After correcting for differences in reddening, SN 2014J appears to be very similar to SN 2011 fe over the 14 broadband filter light curves used in our study.
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| 4. |
- De, K., et al.
(författare)
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A hot and fast ultra-stripped supernova that likely formed a compact neutron star binary
- 2018
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 362:6411, s. 201-206
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Tidskriftsartikel (refereegranskat)abstract
- Compact neutron star binary systems are produced from binary massive stars through stellar evolution involving up to two supernova explosions. The final stages in the formation of these systems have not been directly observed. We report the discovery of iPTF 14gqr (SN 2014ft), a type Ic supernova with a fast-evolving light curve indicating an extremely low ejecta mass (approximate to 0.2 solar masses) and low kinetic energy (approximate to 2 x 10(50) ergs). Early photometry and spectroscopy reveal evidence of shock cooling of an extended helium-rich envelope, likely ejected in an intense pre-explosion mass-loss episode of the progenitor. Taken together, we interpret iPTF 14gqr as evidence for ultra-stripped supernovae that form neutron stars in compact binary systems.
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| 5. |
- Ferretti, Raphael, et al.
(författare)
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Probing gas and dust in the tidal tail of NGC 5221 with the type Ia supernova iPTF16abc
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 606
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Tidskriftsartikel (refereegranskat)abstract
- Context. Type Ia supernovae (SNe Ia) can be used to address numerous questions in astrophysics and cosmology. Due to their wellknown 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 years. In the future, the gas clouds could become the locations of star formation. On a longer time scale, the clouds might diuse, 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.
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| 6. |
- Ferretti, Raphael, et al.
(författare)
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Time-varying sodium absorption in the Type Ia supernova 2013gh
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 592
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Tidskriftsartikel (refereegranskat)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 absorption-line 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 approximate to 10(19) 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.
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| 7. |
- Goobar, Ariel, et al.
(författare)
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iPTF16geu : A multiply imaged, gravitationally lensed type Ia supernova
- 2017
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 356:6335, s. 291-295
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of a multiply imaged, gravitationally lensed type Ia supernova, iPTF16geu (SN 2016geu), at redshift z = 0.409. This phenomenon was identified because the light from the stellar explosion was magnified more than 50 times by the curvature of space around matter in an intervening galaxy. We used high-spatial-resolution observations to resolve four images of the lensed supernova, approximately 0.3 arc seconds from the center of the foreground galaxy. The observations probe a physical scale of ~1 kiloparsec, smaller than is typical in other studies of extragalactic gravitational lensing. The large magnification and symmetric image configuration imply close alignment between the lines of sight to the supernova and to the lens. The relative magnifications of the four images provide evidence for substructures in the lensing galaxy.
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| 8. |
- Goobar, Ariel, et al.
(författare)
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THE RISE OF SN 2014J IN THE NEARBY GALAXY M82
- 2014
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Ingår i: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 784:1
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Tidskriftsartikel (refereegranskat)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, near-IR, 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, R-V less than or similar to 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.
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| 9. |
- Hung, T., et al.
(författare)
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Sifting for Sapphires : Systematic Selection of Tidal Disruption Events in iPTF
- 2018
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Ingår i: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 238:2
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Tidskriftsartikel (refereegranskat)abstract
- We present results from a systematic selection of tidal disruption events (TDEs) in a wide-area (4800 deg(2)), g+ R band, Intermediate Palomar Transient Factory experiment. Our selection targets typical optically selected TDEs: bright (> 60% flux increase) and blue transients residing in the centers of red galaxies. Using photometric selection criteria to down-select from a total of 493 nuclear transients to a sample of 26 sources, we then use follow-up UV imaging with the Neil Gehrels Swift Telescope, ground-based optical spectroscopy, and light curve fitting to classify them as 14 Type Ia supernovae (SNe Ia), 9 highly variable active galactic nuclei (AGNs), 2 confirmed TDEs, and 1 potential core-collapse supernova. We find it possible to filter AGNs by employing a more stringent transient color cut (g - r < -0.2 mag); further, UV imaging is the best discriminator for filtering SNe, since SNe Ia can appear as blue, optically, as TDEs in their early phases. However, when UV-optical color is unavailable, higher-precision astrometry can also effectively reduce SNe contamination in the optical. Our most stringent optical photometric selection criteria yields a 4.5: 1 contamination rate, allowing for a manageable number of TDE candidates for complete spectroscopic follow-up and real-time classification in the Zwicky Transient Facility era. We measure a TDE per galaxy rate of 1.7(-1.3)(+2.9) 10(-4) gal yr(-1) (90% CL in Poisson statistics). This does not account for TDEs outside our selection criteria, and thus may not reflect the total TDE population, which is yet to be fully mapped.
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| 10. |
- Leloudas, Georgios, et al.
(författare)
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Supernova spectra below strong circumstellar interaction
- 2015
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 574
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Tidskriftsartikel (refereegranskat)abstract
- We construct spectra of supernovae (SNe) interacting strongly with a circumstellar medium (CSM) by adding SN templates, a black-body continuum, and an emission-line spectrum. In a Monte Carlo simulation we vary a large number of parameters, such as the SN type, brightness and phase, the strength of the CSM interaction, the extinction, and the signal to noise ratio (S/N) of the observed spectrum. We generate more than 800 spectra, distribute them to ten different human classifiers, and study how the different simulation parameters affect the appearance of the spectra and their classification. The SNe IIn showing some structure over the continuum were characterized as SNe IInS to allow for a better quantification. We demonstrate that the flux ratio of the underlying SN to the continuum f(v) is the single most important parameter determining whether a spectrum can be classified correctly. Other parameters, such as extinction, S/N, and the width and strength of the emission lines, do not play a significant role. Thermonuclear SNe get progressively classified as Ia-CSM, IInS, and IIn as f(v) decreases. The transition between Ia-CSM and IInS occurs at f(v) similar to 0.2-0.3. It is therefore possible to determine that SNe Ia-CSM are found at the (un-extincted) magnitude range -19.5 > M > -21.6, in very good agreement with observations, and that the faintest SN IIn that can hide a SN Ia has M = -20.1. The literature sample of SNe Ia-CSM shows an association with 91T-like SNe Ia. Our experiment does not support that this association can be attributed to a luminosity bias (91T-like being brighter than normal events). We therefore conclude that this association has real physical origins and we propose that 91T-like explosions result from single degenerate progenitors that are responsible for the CSM. Despite the spectroscopic similarities between SNe Ibc and SNe Ia, the number of misclassifications between these types was very small in our simulation and mostly at low S/N. Combined with the SN luminosity function needed to reproduce the observed SN Ia-CSM luminosities, it is unlikely that SNe Ibc constitute an important contaminant within this sample. We show how Type II spectra transition to IIn and how the H alpha profiles vary with f(v). SNe IIn fainter than M = -17.2 are unable to mask SNe IIP brighter than M = -15. A more advanced simulation, including radiative transfer, shows that our simplified model is a good first order approximation. The spectra obtained are in good agreement with real data.
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| 11. |
- Lochner, Michelle, et al.
(författare)
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Optimizing the LSST Observing Strategy for Dark Energy Science : DESC Recommendations for the Wide-Fast-Deep Survey
- 2018
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Cosmology is one of the four science pillars of LSST, which promises to be transformative for our understanding of dark energy and dark matter. The LSST Dark Energy Science Collaboration (DESC) has been tasked with deriving constraints on cosmological parameters from LSST data. Each of the cosmological probes for LSST is heavily impacted by the choice of observing strategy. This white paper is written by the LSST DESC Observing Strategy Task Force (OSTF), which represents the entire collaboration, and aims to make recommendations on observing strategy that will benefit all cosmological analyses with LSST. It is accompanied by the DESC DDF (Deep Drilling Fields) white paper (Scolnic et al.). We use a variety of metrics to understand the effects of the observing strategy on measurements of weak lensing, large-scale structure, clusters, photometric redshifts, supernovae, strong lensing and kilonovae. In order to reduce systematic uncertainties, we conclude that the current baseline observing strategy needs to be significantly modified to result in the best possible cosmological constraints. We provide some key recommendations: moving the WFD (Wide-Fast-Deep) footprint to avoid regions of high extinction, taking visit pairs in different filters, changing the 2x15s snaps to a single exposure to improve efficiency, focusing on strategies that reduce long gaps (>15 days) between observations, and prioritizing spatial uniformity at several intervals during the 10-year survey.
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| 12. |
- Lochner, Michelle, et al.
(författare)
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The Impact of Observing Strategy on Cosmological Constraints with LSST
- 2022
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Ingår i: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 259:2
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Tidskriftsartikel (refereegranskat)abstract
- The generation-defining Vera C. Rubin Observatory will make state-of-the-art measurements of both the static and transient universe through its Legacy Survey for Space and Time (LSST). With such capabilities, it is immensely challenging to optimize the LSST observing strategy across the survey's wide range of science drivers. Many aspects of the LSST observing strategy relevant to the LSST Dark Energy Science Collaboration, such as survey footprint definition, single-visit exposure time, and the cadence of repeat visits in different filters, are yet to be finalized. Here, we present metrics used to assess the impact of observing strategy on the cosmological probes considered most sensitive to survey design; these are large-scale structure, weak lensing, type Ia supernovae, kilonovae, and strong lens systems (as well as photometric redshifts, which enable many of these probes). We evaluate these metrics for over 100 different simulated potential survey designs. Our results show that multiple observing strategy decisions can profoundly impact cosmological constraints with LSST; these include adjusting the survey footprint, ensuring repeat nightly visits are taken in different filters, and enforcing regular cadence. We provide public code for our metrics, which makes them readily available for evaluating further modifications to the survey design. We conclude with a set of recommendations and highlight observing strategy factors that require further research.
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| 13. |
- Miller, A. A., et al.
(författare)
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Color Me Intrigued : The Discovery of iPTF 16fnm, an SN 2002cx-like Object
- 2017
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 848:1
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Tidskriftsartikel (refereegranskat)abstract
- 0 Modern wide-field, optical time-domain surveys must solve a basic optimization problem: maximize the number of transient discoveries or minimize the follow-up needed for the new discoveries. Here, we describe the Color Me Intrigued experiment, the first from the intermediate Palomar Transient Factory (iPTF) to search for transients simultaneously in the g(PTF') and R-PTF bands. During the course of this experiment, we discovered iPTF 16fnm, a new member of the 02cx-like subclass of Type Ia supernovae (SNe). iPTF 16fnm peaked at Mg-PTF = -15.09 +/- 0.17 mag, making it the second-least-luminous known SN Ia. iPTF 16fnm exhibits all the hallmarks of the 02cx-like class: (i) low luminosity at peak, (ii) low ejecta velocities, and (iii) a non-nebular spectrum several months after peak. Spectroscopically, iPTF 16fnm exhibits a striking resemblance to two other low-luminosity 02cx-like SNe: SN. 2007qd and SN 2010ae. iPTF 16fnm and SN 2005hk decline at nearly the same rate, despite a 3 mag difference in brightness at peak. When considering the full subclass of 02cx-like SNe, we do not find evidence for a tight correlation between peak luminosity and decline rate in either the g ' or r ' band. We measure the relative rate of 02cx-like SNe to normal SNe Ia and find r(N02cx/NIa) = 33(-25)(+158)%. We further examine the g ' - r ' evolution of 02cx-like SNe and find that their unique color evolution can be used to separate them from 91bg-like and normal SNe Ia. This selection function will be especially important in the spectroscopically incomplete Zwicky Transient Facility/Large Synoptic Survey Telescope (LSST) era. Finally, we close by recommending that LSST periodically evaluate, and possibly update, its observing cadence to maximize transient science.
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| 14. |
- Petrushevska, Tanja, et al.
(författare)
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High-redshift supernova rates measured with the gravitational telescope A 1689
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 594
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Tidskriftsartikel (refereegranskat)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 Delta 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 similar to 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(-0.09)(+0.19) SNuB h(2) (SNuB 10(-12) SNe L-circle dot,B(-1) yr(-1)), where the error bars indicate 1 sigma confidence intervals, statistical and systematic, respectively. The cluster rate normalized by the stellar mass is 0.10(-0.06)(+0.13) +/- 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 greater than or similar to 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.
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| 15. |
- Petrushevska, Tanja, 1985-
(författare)
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Search for lensed supernovae behind the galaxy cluster Abell 1689
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Distant supernovae probe the history of cosmic expansion and star formation, and provide important information on their progenitor models. Investigation of supernovae type Ia for are needed to reveal any evolution in their intrinsic properties, and thus their utility as existing distance indicators. One approach to extend the redshift range beyond the reach of our telescopes is to use galaxy clusters as gravitational telescopes. Conversely, lensed supernovae can be used as probes for testing cluster lens model predictions. In this licentiate thesis, I present a 5-year ground based near-infrared search for gravitationally magnified supernovae behind the galaxy cluster A1689. Abell 1689, at z=0.187, is a one of the best-studied clusters with an extended Einstein radius, making it particularly suited as a gravitational telescope. Our search resulted in the discovery of one highly magnified supernova type II at z=1.703 and two transient objects (probably type IIP and Ia, in host galaxies at redshifts and ), which is in agreement with the survey expectations.
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| 16. |
- Petrushevska, Tanja, et al.
(författare)
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Searching for supernovae in the multiply-imaged galaxies behind the gravitational telescope A370
- 2018
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 614
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Tidskriftsartikel (refereegranskat)abstract
- Aims. Strong lensing by massive galaxy clusters can provide magnification of the flux and even multiple images of the galaxies that he behind them. This phenomenon facilitates observations of high-redshift supernovae (SNe) that would otherwise remain undetected. Type la supernovae (SNe la) detections are of particular interest because of their standard brightness, since they can be used to improve either cluster lensing models or cosmological parameter measurements.Methods. We present a ground-based, near-infrared search for lensed SNe behind the galaxy cluster Abell 370. Our survey was based on 15 epochs of J-band observations with the HAWK-I instrument on the Very Large Telescope (VLT). We use Hubble Space Telescope (HST) photometry to infer the global properties of the multiply-imaged galaxies. Using a recently published lensing model of Abell 370, we also present the predicted magnifications and time delays between the images.Results. In our survey, we did not discover any live SNe from the 13 lensed galaxies with 47 multiple images behind Abell 370. This is consistent with the expectation of 0.09 +/- 0.02 SNe calculated based on the measured star formation rate. We compare the expectations of discovering strongly lensed SNe in our survey and that performed with HST during the Hubble Frontier Fields (HFF) programme. We also show the expectations of search campaigns that can be conducted with future facilities, such as the James Webb Space Telescope (JWST) or the Wide-Field Infrared Survey Telescope (WFIRST). We show that the NIRCam instrument aboard the JWST will be sensitive to most SN multiple images in the strongly lensed galaxies and thus will be able to measure their time delays if observations are scheduled accordingly.
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| 17. |
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| 18. |
- Petrushevska, Tanja, 1985-
(författare)
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Supernovae seen through gravitational telescopes
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Galaxies, and clusters of galaxies, can act as gravitational lenses and magnify the light of objects behind them. The effect enables observations of very distant supernovae, that otherwise would be too faint to be detected by existing telescopes, and allows studies of the frequency and properties of these rare phenomena when the universe was young. Under the right circumstances, multiple images of the lensed supernovae can be observed, and due to the variable nature of the objects, the difference between the arrival times of the images can be measured. Since the images have taken different paths through space before reaching us, the time-differences are sensitive to the expansion rate of the universe. One class of supernovae, Type Ia, are of particular interest to detect. Their well known brightness can be used to determine the magnification, which can be used to understand the lensing systems.In this thesis, galaxy clusters are used as gravitational telescopes to search for lensed supernovae at high redshift. Ground-based, near-infrared and optical search campaigns are described of the massive clusters Abell 1689 and 370, which are among the most powerful gravitational telescopes known. The search resulted in the discovery of five photometrically classified, core-collapse supernovae at redshifts of 0.671Magnification from a galaxy lens also allows for detailed studies of the supernova properties at high redshift that otherwise would not be possible. Spectroscopic observations of lensed high-redshift supernovae Type Ia are of special interest since they can be used to test for evolution of the standard candle nature of these objects. If systematic redshift-dependent properties are found, their utility for future surveys could be challenged. In the thesis it is shown that the strongly lensed and very distant supernova Type Ia PS1-10afx at z=1.4, does not deviate from the well-studied nearby and intermediate populations of normal supernovae Type Ia.In a different study, the discovery of the first resolved multiply-imaged gravitationally lensed supernova Type Ia is also reported.
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| 19. |
- Petrushevska, Tanja, et al.
(författare)
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Testing for redshift evolution of Type Ia supernovae using the strongly lensed PS1-10afx at z=1.4
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 603
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Tidskriftsartikel (refereegranskat)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 lambda similar to 3500 angstrom 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.
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| 20. |
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| 21. |
- Schulze, Steve, et al.
(författare)
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The Palomar Transient Factory Core-collapse Supernova Host-galaxy Sample. I. Host-galaxy Distribution Functions and Environment Dependence of Core-collapse Supernovae
- 2021
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Ingår i: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 255:2
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Tidskriftsartikel (refereegranskat)abstract
- Several thousand core-collapse supernovae (CCSNe) of different flavors have been discovered so far. However, identifying their progenitors has remained an outstanding open question in astrophysics. Studies of SN host galaxies have proven to be powerful in providing constraints on the progenitor populations. In this paper, we present all CCSNe detected between 2009 and 2017 by the Palomar Transient Factory. This sample includes 888 SNe of 12 distinct classes out to redshift z approximate to 1. We present the photometric properties of their host galaxies from the far-ultraviolet to the mid-infrared and model the host-galaxy spectral energy distributions to derive physical properties. The galaxy mass function of Type Ic, Ib, IIb, II, and IIn SNe ranges from 10(5) to 10(11.5) M (circle dot), probing the entire mass range of star-forming galaxies down to the least-massive star-forming galaxies known. Moreover, the galaxy mass distributions are consistent with models of star-formation-weighted mass functions. Regular CCSNe are hence direct tracers of star formation. Small but notable differences exist between some of the SN classes. Type Ib/c SNe prefer galaxies with slightly higher masses (i.e., higher metallicities) and star formation rates than Type IIb and II SNe. These differences are less pronounced than previously thought. H-poor superluminous supernovae (SLSNe) and SNe Ic-BL are scarce in galaxies above 10(10) M (circle dot). Their progenitors require environments with metallicities of < 0.4 and < 1 solar, respectively. In addition, the hosts of H-poor SLSNe are dominated by a younger stellar population than all other classes of CCSNe. Our findings corroborate the notion that low metallicity and young age play an important role in the formation of SLSN progenitors.
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