| 1. |
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| 2. |
- Abellán, F. J., et al.
(författare)
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Very Deep inside the SN 1987A Core Ejecta : Molecular Structures Seen in 3D
- 2017
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Ingår i: Astrophysical Journal Letters. - : Institute of Physics Publishing. - 2041-8205 .- 2041-8213. ; 842:2
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Tidskriftsartikel (refereegranskat)abstract
- Most massive stars end their lives in core-collapse supernova explosions and enrich the interstellar medium with explosively nucleosynthesized elements. Following core collapse, the explosion is subject to instabilities as the shock propagates outward through the progenitor star. Observations of the composition and structure of the innermost regions of a core-collapse supernova provide a direct probe of the instabilities and nucleosynthetic products. SN 1987A in the Large Magellanic Cloud is one of very few supernovae for which the inner ejecta can be spatially resolved but are not yet strongly affected by interaction with the surroundings. Our observations of SN 1987A with the Atacama Large Millimeter/submillimeter Array are of the highest resolution to date and reveal the detailed morphology of cold molecular gas in the innermost regions of the remnant. The 3D distributions of carbon and silicon monoxide (CO and SiO) emission differ, but both have a central deficit, or torus-like distribution, possibly a result of radioactive heating during the first weeks ("nickel heating"). The size scales of the clumpy distribution are compared quantitatively to models, demonstrating how progenitor and explosion physics can be constrained.
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| 3. |
- Ashall, C., et al.
(författare)
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Carnegie Supernova Project-II : Using Near-infrared Spectroscopy to Determine the Location of the Outer Ni-56 in Type Ia Supernovae
- 2019
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 875:2
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Tidskriftsartikel (refereegranskat)abstract
- We present the H-band wavelength region of 37 postmaximum light near-infrared spectra of three normal, nine transitional, and four subluminous type. Ia supernovae (SNe Ia), extending from +5. days to +20. days relative to the epoch of B-band maximum. We introduce a new observable, the blue-edge velocity, v(edge), of the prominent Fe/Co/Ni-peak H-band emission feature, which is quantitatively measured. The v(edge) parameter is found to decrease over subtype ranging from around -14,000 km s(-1) for normal SNe Ia, to -10,000 km s(-1) for transitional SNe. Ia, down to -5000 km s(-1) for the subluminous SNe. Ia. Furthermore, inspection of the +10 +/- 3 days spectra indicates that v(edge) is correlated with the color-stretch parameter, s(BV), and hence with peak luminosity. These results follow the previous findings that brighter SNe. Ia tend to have Ni-56 located at higher velocities as compared to subluminous objects. As v(edge) is a model-independent parameter, we propose it can be used in combination with traditional observational diagnostics to provide a new avenue to robustly distinguish between leading SNe. Ia explosion models.
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| 4. |
- Davis, S., et al.
(författare)
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SN 2013ai : A Link between Hydrogen-rich and Hydrogen-poor Core-collapse Supernovae
- 2021
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 909:2
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Tidskriftsartikel (refereegranskat)abstract
- We present a study of the optical and near-infrared (NIR) spectra of SN 2013ai along with its light curves. These data range from discovery until 380 days after explosion. SN 2013ai is a fast declining Type II supernova (SN II) with an unusually long rise time, 18.9 2.7 days in the V-band, and a bright V-band peak absolute magnitude of -18.7 0.06 mag. The spectra are dominated by hydrogen features in the optical and NIR. The spectral features of SN 2013ai are unique in their expansion velocities, which, when compared to large samples of SNe II, are more than 1,000 km s(-1) faster at 50 days past explosion. In addition, the long rise time of the light curve more closely resembles SNe IIb rather than SNe II. If SN 2013ai is coeval with a nearby compact cluster, we infer a progenitor zero-age main-sequence mass of similar to 17 M. After performing light-curve modeling, we find that SN 2013ai could be the result of the explosion of a star with little hydrogen mass, a large amount of synthesized Ni-56, 0.3-0.4 M, and an explosion energy of 2.5-3.0 x 10(51) erg. The density structure and expansion velocities of SN 2013ai are similar to those of the prototypical SN IIb, SN 1993J. However, SN 2013ai shows no strong helium features in the optical, likely due to the presence of a dense core that prevents the majority of gamma-rays from escaping to excite helium. Our analysis suggests that SN 2013ai could be a link between SNe II and stripped-envelope SNe.
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| 5. |
- Foley, Ryan J., et al.
(författare)
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Extensive HST ultraviolet spectra and multiwavelength observations of SN 2014J in M82 indicate reddening and circumstellar scattering by typical dust
- 2014
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 443:4, s. 2887-2906
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Tidskriftsartikel (refereegranskat)abstract
- SN 2014J in M82 is the closest detected Type Ia supernova (SN Ia) in at least 28 yr and perhaps in 410 yr. Despite its small distance of 3.3 Mpc, SN 2014J is surprisingly faint, peaking at V = 10.6 mag, and assuming a typical SN Ia luminosity, we infer an observed visual extinction of A(V) = 2.0 +/- 0.1 mag. But this picture, with R-V = 1.6 +/- 0.2, is too simple to account for all observations. We combine 10 epochs (spanning a month) of HST/Space Telescope Imaging Spectrograph (STIS) ultraviolet through near-infrared spectroscopy with HST/Wide Field Camera 3 (WFC3), Katzman Automatic Imaging Telescope, and FanCam photometry from the optical to the infrared and nine epochs of high-resolution TRES (Tillinghast Reflection Echelle Spectrograph) spectroscopy to investigate the sources of extinction and reddening for SN 2014J. We argue that the wide range of observed properties for SN 2014J is caused by a combination of dust reddening, likely originating in the interstellar medium of M82, and scattering off circumstellar material. For this model, roughly half of the extinction is caused by reddening from typical dust (E(B - V) = 0.45 mag and R-V = 2.6) and roughly half by scattering off Large Magellanic Cloud-like dust in the circumstellar environment of SN 2014J.
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| 6. |
- Fransson, Claes, et al.
(författare)
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HIGH-DENSITY CIRCUMSTELLAR INTERACTION IN THE LUMINOUS TYPE IIn SN 2010jl : THE FIRST 1100 DAYS
- 2014
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 797:2
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Tidskriftsartikel (refereegranskat)abstract
- Hubble Space Telescope and ground-based observations of the Type IIn supernova (SN) 2010jl are analyzed, including photometry and spectroscopy in the ultraviolet, optical, and near-IR bands, 26-1128 days after first detection. At maximum, the bolometric luminosity was similar to 3 x 10(43) erg s(-1) and even at 850 days exceeds 10(42) erg s(-1). A near-IR excess, dominating after 400 days, probably originates in dust in the circumstellar medium (CSM). The total radiated energy is greater than or similar to 6.5x10(50) erg, excluding the dust component. The spectral lines can be separated into one broad component that is due to electron scattering and one narrow with expansion velocity similar to 100 km s(-1) from the CSM. The broad component is initially symmetric around zero velocity but becomes blueshifted after similar to 50 days, while remaining symmetric about a shifted centroid velocity. Dust absorption in the ejecta is unlikely to explain the line shifts, and we attribute the shift instead to acceleration by the SN radiation. From the optical lines and the X-ray and dust properties, there is strong evidence for large-scale asymmetries in the CSM. The ultraviolet lines indicate CNO processing in the progenitor, while the optical shows a number of narrow coronal lines excited by the X-rays. The bolometric light curve is consistent with a radiative shock in an r(-2) CSM with a mass-loss rate of M similar to 0.1 M(circle dot)yr(-1). The total mass lost is greater than or similar to 3 M-circle dot. These properties are consistent with the SN expanding into a CSM characteristic of a luminous blue variable progenitor with a bipolar geometry. The apparent absence of nuclear processing is attributed to a CSM that is still opaque to electron scattering.
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| 7. |
- Hsiao, E. Y., et al.
(författare)
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Carnegie Supernova Project-II : The Near-infrared Spectroscopy Program
- 2019
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Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 131:995
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Tidskriftsartikel (refereegranskat)abstract
- Shifting the focus of Type Ia supernova (SN Ia) cosmology to the near infrared (NIR) is a promising way to significantly reduce the systematic errors, as the strategy minimizes our reliance on the empirical width-luminosity relation and uncertain dust laws. Observations in the NIR are also crucial for our understanding of the origins and evolution of these events, further improving their cosmological utility. Any future experiments in the rest-frame NIR will require knowledge of the SN Ia NIR spectroscopic diversity, which is currently based on a small sample of observed spectra. Along with the accompanying paper, Phillips et al., we introduce the Carnegie Supernova Project-II (CSP-II), to follow-up nearby SNe Ia in both the optical and the NIR. In particular, this paper focuses on the CSP-II NIR spectroscopy program, describing the survey strategy, instrumental setups, data reduction, sample characteristics, and future analyses on the data set. In collaboration with the Harvard-Smithsonian Center for Astrophysics (CfA) Supernova Group, we obtained 661 NIR spectra of 157 SNe Ia. Within this sample, 451 NIR spectra of 90 SNe Ia have corresponding CSP-II follow-up light curves. Such a sample will allow detailed studies of the NIR spectroscopic properties of SNe Ia, providing a different perspective on the properties of the unburned material; the radioactive and stable nickel produced; progenitor magnetic fields; and searches for possible signatures of companion stars.
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| 8. |
- Hsiao, E. Y., et al.
(författare)
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Strong near-infrared carbon in the Type Ia supernova iPTF13ebh
- 2015
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 578
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Tidskriftsartikel (refereegranskat)abstract
- We present near-infrared (NIR) time-series spectroscopy, as well as complementary ultraviolet (UV), optical, and NIR data, of the Type Ia supernova (SN Ia) iPTF13ebh, which was discovered within two days from the estimated time of explosion. The first NIR spectrum was taken merely 2 : 3 days after explosion and may be the earliest NIR spectrum yet obtained of a SN Ia. The most striking features in the spectrum are several NIR C I lines, and the C I lambda 1.0693 mu m line is the strongest ever observed in a SN Ia. Interestingly, no strong optical C II counterparts were found, even though the optical spectroscopic time series began early and is densely cadenced. Except at the very early epochs, within a few days from the time of explosion, we show that the strong NIR C I compared to the weaker optical C II appears to be general in SNe Ia. iPTF13ebh is a fast decliner with Delta m(15)(B) = 1.79 +/- 0.01, and its absolute magnitude obeys the linear part of the width-luminosity relation. It is therefore categorized as a transitional event, on the fast-declining end of normal SNe Ia as opposed to subluminous/91bg-like objects. iPTF13ebh shows NIR spectroscopic properties that are distinct from both the normal and subluminous/91bg-like classes, bridging the observed characteristics of the two classes. These NIR observations suggest that composition and density of the inner core are similar to that of 91bg-like events, and that it has a deep-reaching carbon burning layer that is not observed in more slowly declining SNe Ia. There is also a substantial difference between the explosion times inferred from the early-time light curve and the velocity evolution of the Si II lambda 0.6355 mu m line, implying a long dark phase of similar to 4 days.
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| 9. |
- Kamenetzky, J., et al.
(författare)
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CARBON MONOXIDE IN THE COLD DEBRIS OF SUPERNOVA 1987A
- 2013
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Ingår i: ASTROPHYS J LETT. - 2041-8205. ; 773:2, s. L34-
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Tidskriftsartikel (refereegranskat)abstract
- We report spectroscopic and imaging observations of rotational transitions of cold CO and SiO in the ejecta of SN1987A, the first such emission detected in a supernova remnant. In addition to line luminosities for the CO J = 1-0, 2-1, 6-5, and 7-6 transitions, we present upper limits for all other transitions up to J = 13-12, collectively measured from the Atacama Large Millimeter Array, the Atacama Pathfinder EXperiment, and the Herschel Spectral and Photometric Imaging REceiver. Simple models show the lines are emitted from at least 0.01 M-circle dot of CO at a temperature >14 K, confined within at most 35% of a spherical volume expanding at similar to 2000 km s(-1). Moreover, we locate the emission within 1 '' of the central debris. These observations, along with a partial observation of SiO, confirm the presence of cold molecular gas within supernova remnants and provide insight into the physical conditions and chemical processes in the ejecta. Furthermore, we demonstrate the powerful new window into supernova ejecta offered by submillimeter observations.
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| 10. |
- Kamenetzky, J., et al.
(författare)
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CARBON MONOXIDE IN THE COLD DEBRIS OF SUPERNOVA 1987A
- 2013
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 773:2
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Tidskriftsartikel (refereegranskat)abstract
- We report spectroscopic and imaging observations of rotational transitions of cold CO and SiO in the ejecta of SN1987A, the first such emission detected in a supernova remnant. In addition to line luminosities for the CO J = 1-0, 2-1, 6-5, and 7-6 transitions, we present upper limits for all other transitions up to J = 13-12, collectively measured from the Atacama Large Millimeter Array, the Atacama Pathfinder EXperiment, and the Herschel Spectral and Photometric Imaging REceiver. Simple models show the lines are emitted from at least 0.01 M-circle dot of CO at a temperature >14 K, confined within at most 35% of a spherical volume expanding at similar to 2000 km s(-1). Moreover, we locate the emission within 1 '' of the central debris. These observations, along with a partial observation of SiO, confirm the presence of cold molecular gas within supernova remnants and provide insight into the physical conditions and chemical processes in the ejecta. Furthermore, we demonstrate the powerful new window into supernova ejecta offered by submillimeter observations.
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| 11. |
- Krisciunas, Kevin, et al.
(författare)
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THE MOST SLOWLY DECLINING TYPE Ia SUPERNOVA 2001ay
- 2011
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 142:3, s. 74-
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Tidskriftsartikel (refereegranskat)abstract
- We present optical and near-infrared photometry, as well as ground-based optical spectra and Hubble Space Telescope ultraviolet spectra, of the Type Ia supernova (SN) 2001ay. At maximum light the Si II and Mg II lines indicated expansion velocities of 14,000 km s-(1), while Si III and S II showed velocities of 9000 km s(-1). There is also evidence for some unburned carbon at 12,000 km s(-1). SN 2001ay exhibited a decline-rate parameter of Delta m(15)(B) = 0.68 +/- 0.05 mag; this and the B-band photometry at t greater than or similar to + 25 day past maximum make it the most slowly declining Type Ia SN yet discovered. Three of the four super-Chandrasekhar-mass candidates have decline rates almost as slow as this. After correction for Galactic and host-galaxy extinction, SN 2001ay had M(B) = -19.19 and M(V) = -19.17 mag at maximum light; thus, it was not overluminous in optical bands. In near-infrared bands it was overluminous only at the 2 sigma level at most. For a rise time of 18 days (explosion to bolometric maximum) the implied (56)Ni yield was (0.58 +/- 0.15)/alpha M(circle dot), with alpha = L(max)/E(Ni) probably in the range 1.0-1.2. The (56)Ni yield is comparable to that of many Type Ia SNe. The normal (56)Ni yield and the typical peak optical brightness suggest that the very broad optical light curve is explained by the trapping of gamma rays in the inner regions.
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| 12. |
- Levesque, E. M., et al.
(författare)
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THE HIGH-METALLICITY EXPLOSION ENVIRONMENT OF THE RELATIVISTIC SUPERNOVA 2009bb
- 2010
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Ingår i: The Astrophysical Journal Letters. - 2041-8205. ; 709:1, s. l26-L31
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the environment of the nearby (d approximate to 40 Mpc) broad-lined Type Ic supernova (SN) 2009bb. This event was observed to produce a relativistic outflow likely powered by a central accreting compact object. While such a phenomenon was previously observed only in long-duration gamma-ray bursts (LGRBs), no LGRB was detected in association with SN 2009bb. Using an optical spectrum of the SN 2009bb explosion site, we determine a variety of interstellar medium properties for the host environment, including metallicity, young stellar population age, and star formation rate. We compare the SN explosion site properties to observations of LGRB and broad-lined SN Ic host environments on optical emission line ratio diagnostic diagrams. Based on these analyses, we find that the SN 2009bb explosion site has a metallicity between 1.7 Z(circle dot) and 3.5 Z(circle dot), in agreement with other broad-lined SN Ic host environments and at odds with the low-redshift LGRB host environments and recently proposed maximum metallicity limits for relativistic explosions. We consider the implications of these findings and the impact that SN 2009bb's unusual explosive properties and environment have on our understanding of the key physical ingredient that enables some SNe to produce a relativistic outflow.
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| 13. |
- Lunnan, Ragnhild, et al.
(författare)
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Hydrogen-poor Superluminous Supernovae from the Pan-STARRS1 Medium Deep Survey
- 2018
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 852:2
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Tidskriftsartikel (refereegranskat)abstract
- We present light curves and classification spectra of 17 hydrogen-poor superluminous supernovae (SLSNe) from the Pan-STARRS1 Medium Deep Survey (PS1 MDS). Our sample contains all objects from the PS1. MDS sample with spectroscopic classification that are similar to either of the prototypes SN 2005ap or SN 2007bi, without an explicit limit on luminosity. With a redshift range 0.3 < z < 1.6, PS1. MDS is the first SLSN sample primarily probing the high-redshift population; our multifilter PS1 light curves probe the rest-frame UV emission, and hence the peak of the spectral energy distribution. We measure the temperature evolution and construct bolometric light curves, and find peak luminosities of (0.5-5) x 10(44) erg s(-1) and lower limits on the total radiated energies of (0.3-2) x 10(51) erg. The light curve shapes are diverse, with both rise and decline times spanning a factor of similar to 5 and several examples of double-peaked light curves. When correcting for the flux-limited nature of our survey, we find a median peak luminosity at 4000 angstrom of M-4000 = -21.1 mag and a spread of sigma = 0.7 mag.
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| 14. |
- Margutti, R., et al.
(författare)
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A PANCHROMATIC VIEW OF THE RESTLESS SN 2009ip REVEALS THE EXPLOSIVE EJECTION OF A MASSIVE STAR ENVELOPE
- 2014
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 780:1
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Tidskriftsartikel (refereegranskat)abstract
- The double explosion of SN 2009ip in 2012 raises questions about our understanding of the late stages of massive star evolution. Here we present a comprehensive study of SN 2009ip during its remarkable rebrightenings. High-cadence photometric and spectroscopic observations from the GeV to the radio band obtained from a variety of ground-based and space facilities (including the Very Large Array, Swift, Fermi, Hubble Space Telescope, and XMM) constrain SN 2009ip to be a low energy (E similar to 1050 erg for an ejecta mass similar to 0.5 M-circle dot) and asymmetric explosion in a complex medium shaped by multiple eruptions of the restless progenitor star. Most of the energy is radiated as a result of the shock breaking out through a dense shell of material located at similar to 5 x 10(14) cm with M similar to 0.1 M-circle dot, ejected by the precursor outburst similar to 40 days before the major explosion. We interpret the NIR excess of emission as signature of material located further out, the origin of which has to be connected with documented mass-loss episodes in the previous years. Our modeling predicts bright neutrino emission associated with the shock break-out if the cosmic-ray energy is comparable to the radiated energy. We connect this phenomenology with the explosive ejection of the outer layers of the massive progenitor star, which later interacted with material deposited in the surroundings by previous eruptions. Future observations will reveal if the massive luminous progenitor star survived. Irrespective of whether the explosion was terminal, SN 2009ip brought to light the existence of new channels for sustained episodic mass loss, the physical origin of which has yet to be identified.
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| 15. |
- Marion, G. H., et al.
(författare)
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Early Observations and Analysis of the Type Ia SN 2014J in M82
- 2015
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 798:1, s. 39-
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Tidskriftsartikel (refereegranskat)abstract
- We present optical and near infrared (NIR) observations of the nearby Type Ia SN 2014J. Seventeen optical and 23 NIR spectra were obtained from 10 days before (–10d) to 10 days after (+10d) the time of maximum B-band brightness. The relative strengths of absorption features and their patterns of development can be compared at one day intervals throughout most of this period. Carbon is not detected in the optical spectra, but we identify C I λ1.0693 in the NIR spectra. Mg II lines with high oscillator strengths have higher initial velocities than other Mg II lines. We show that the velocity differences can be explained by differences in optical depths due to oscillator strengths. The spectra of SN 2014J show that it is a normal SN Ia, but many parameters are near the boundaries between normal and high-velocity subclasses. The velocities for O I, Mg II, Si II, S II, Ca II, and Fe II suggest that SN 2014J has a layered structure with little or no mixing. That result is consistent with the delayed detonation explosion models. We also report photometric observations, obtained from –10d to +29d, in the UBVRIJH and Ksbands. The template fitting package SNooPy is used to interpret the light curves and to derive photometric parameters. UsingRV = 1.46, which is consistent with previous studies, SNooPy finds that AV = 1.80 for E(B – V)host = 1.23 ± 0.06 mag. The maximum B-band brightness of –19.19 ± 0.10 mag was reached on February 1.74 UT ± 0.13 days and the supernova has a decline parameter, Δm 15, of 1.12 ± 0.02 mag.
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| 16. |
- Marion, G. H., et al.
(författare)
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TYPE IIb SUPERNOVA SN 2011dh : SPECTRA AND PHOTOMETRY FROM THE ULTRAVIOLET TO THE NEAR-INFRARED
- 2014
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 781:2, s. 69-
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Tidskriftsartikel (refereegranskat)abstract
- We report spectroscopic and photometric observations of the Type IIb SN 201 ldh obtained between 4 and 34 days after the estimated date of explosion (May 31.5 UT). The data cover a wide wavelength range from 2000 angstrom in the ultraviolet (UV) to 2.4 mu m in the near-infrared (NIR). Optical spectra provide line profiles and velocity measurements of H I, He I, Call, and Fe It that trace the composition and kinematics of the supernova (SN). NIR spectra show that helium is present in the atmosphere as early as 11 days after the explosion. A UV spectrum obtained with the Space Telescope Imaging Spectrograph reveals that the UV flux for SN 2011dh is low compared to other SN IIb. Modeling the spectrum with SYNOW suggests that the UV deficit is due to line blanketing from TinH and Co II. The HI and He I velocities in SN 2011dh are separated by about 4000 km s(-1) at all phases. A velocity gap is consistent with models for a preexplosion structure in which a hydrogen-rich shell surrounds the progenitor. We estimate that the H shell of SN 2011dh is approximate to 8 times less massive than the shell of SN 1993J and approximate to 3 times more massive than the shell of SN 2008ax. Light curves (LCs) for 12 passbands are presented: UVW2, UVM2, UVW1, U, u', B, V, r', i', J, H, and Ks. In the B band, SN 2011dh reached peak brightness of 13.17 mag at 20.0 +/- 0.5 after the explosion. The maximum bolometric luminosity of 1.8 +/- 0.2 x 10(42) erg s(-1) occurred approximate to 22 days after the explosion. NIR emission provides more than 30% of the total bolometric flux at the beginning of our observations, and the NIR contribution increases to nearly 50% of the total by day 34. The UV produces 16% of the total flux on day 4, 5% on day 9, and 1% on day 34. We compare the bolometric LCs of SN 2011dh, SN 2008ax, and SN 1993J. The LC are very different for the first 12 days after the explosions, but all three SN IIb display similar peak luminosities, times of peak, decline rates, and colors after maximum. This suggests that the progenitors of these SN IIb may have had similar compositions and masses, but they exploded inside hydrogen shells that have a wide range of masses. SN 2011dh was well observed, and a likely progenitor star has been identified in preexplosion images. The detailed observations presented here will help evaluate theoretical models for this SN and lead to a better understanding of SN IIb.
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| 17. |
- Meixner, Margaret, et al.
(författare)
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Herschel and ALMA measurements of dust and molecules in supernova 1987A
- 2013
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Ingår i: Proceedings of Science. - 1824-8039. ; Part F113823
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Konferensbidrag (refereegranskat)abstract
- Dust production by supernovae is important in the dust life cycle of a galaxy. The explosion of SN 1987A was the nearest SN detected in the last 400 years, allowing us detailed studies of contemporary evolution of a supernova for the first time. In 2011, Matsuura et al. reported 0.4-0.7 M of dust in SN 1987A based on Herschel HERITAGE survey data, which is surprisingly large compared to prior measurements of supernovae. In this paper, we present our follow-up studies of this important discovery about SN 1987A using the Herschel Space Observatory and the Atacama Large Millimeter Array (ALMA). We highlight two important results, the detection of cold molecular gas and dust in the ejected material of SN 1987A. Our results suggest that SNe are significant producers of dust and molecules, as well as heavy elements, driving chemical evolution of galaxies.
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| 18. |
- Nicholl, M., et al.
(författare)
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Slowly fading super-luminous supernovae that are not pair-instability explosions
- 2013
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 502:7471, s. 346-
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Tidskriftsartikel (refereegranskat)abstract
- Super-luminous supernovae(1-4) that radiate more than 1044 ergs per second at their peak luminosity have recently been discovered in faint galaxies at redshifts of 0.1-4. Some evolve slowly, resembling models of 'pair-instability' supernovae(5,6). Such models involve stars with original masses 140-260 times that of the Sun that now have carbon-oxygen cores of 65-130 solar masses. In these stars, the photons that prevent gravitational collapse are converted to electron-positron pairs, causing rapid contraction and thermonuclear explosions. Many solar masses of Ni-56 are synthesized; this isotope decays to Fe-56 via Co-56, powering bright light curves(7,8). Such massive progenitors are expected to have formed from metal-poor gas in the early Universe(9). Recently, supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after the Big Bang) with a metallicity one-third that of the Sun was observed to look like a fading pair-instability supernova(1,10). Here we report observations of two slow-to-fade super-luminous supernovae that show relatively fast rise times and blue colours, which are incompatible with pair-instability models. Their late-time light-curve and spectral similarities to supernova 2007bi call the nature of that event into question. Our early spectra closely resemble typical fast-declining super-luminous supernovae(2,11,12), which are not powered by radio-activity. Modelling our observations with 10-16 solar masses of magnetar-energized(13,14) ejecta demonstrates the possibility of a common explosion mechanism. The lack of unambiguous nearby pair-instability events suggests that their local rate of occurrence is less than 6 x 10(-6) times that of the core-collapse rate.
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| 19. |
- Pan, Y. -C, et al.
(författare)
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500 days of SN 2013dy : spectra and photometry from the ultraviolet to the infrared
- 2015
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 452:4, s. 4307-4325
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Tidskriftsartikel (refereegranskat)abstract
- SN 2013dy is a Type Ia supernova (SN Ia) for which we have compiled an extraordinary data set spanning from 0.1 to similar to 500 d after explosion. We present 10 epochs of ultraviolet (UV) through near-infrared (NIR) spectra with Hubble Space Telescope/Space Telescope Imaging Spectrograph, 47 epochs of optical spectra (15 of them having high resolution), and more than 500 photometric observations in the BVrRiIZYJH bands. SN 2013dy has a broad and slowly declining light curve (Delta m(15)(B)= 0.92 mag), shallow Si II lambda 6355 absorption, and a low velocity gradient. We detect strong C II in our earliest spectra, probing unburned progenitor material in the outermost layers of the SN ejecta, but this feature fades within a few days. The UV continuum of SN 2013dy, which is strongly affected by the metal abundance of the progenitor star, suggests that SN 2013dy had a relatively high-metallicity progenitor. Examining one of the largest single set of high-resolution spectra for an SN Ia, we find no evidence of variable absorption from circumstellar material. Combining our UV spectra, NIR photometry, and high-cadence optical photometry, we construct a bolometric light curve, showing that SN 2013dy had a maximum luminosity of 10.0(-3.8)(+4.8) x 10(42) erg s(-1). We compare the synthetic light curves and spectra of several models to SN 2013dy, finding that SN 2013dy is in good agreement with a solar-metallicity W7 model.
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| 20. |
- Rest, A., et al.
(författare)
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DIRECT CONFIRMATION OF THE ASYMMETRY OF THE CAS A SUPERNOVA WITH LIGHT ECHOES
- 2011
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 732:1, s. 3-
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Tidskriftsartikel (refereegranskat)abstract
- We report the first detection of asymmetry in a supernova (SN) photosphere based on SN light echo (LE) spectra of Cas A from the different perspectives of dust concentrations on its LE ellipsoid. New LEs are reported based on difference images, and optical spectra of these LEs are analyzed and compared. After properly accounting for the effects of finite dust-filament extent and inclination, we find one field where the He I lambda 5876 and Ha features are blueshifted by an additional similar to 4000 km s(-1) relative to other spectra and to the spectra of the Type IIb SN 1993J. That same direction does not show any shift relative to other Cas A LE spectra in the Ca II near-infrared triplet feature. We compare the perspectives of the Cas A LE dust concentrations with recent three-dimensional modeling of the SN remnant (SNR) and note that the location having the blueshifted He I and Ha features is roughly in the direction of an Fe-rich outflow and in the opposite direction of the motion of the compact object at the center of the SNR. We conclude that Cas A was an intrinsically asymmetric SN. Future LE spectroscopy of this object, and of other historical SNe, will provide additional insight into the connection of the explosion mechanism to SN then to SNR, as well as give crucial observational evidence regarding how stars explode.
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| 21. |
- Soderberg, A. M., et al.
(författare)
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A relativistic type Ibc supernova without a detected gamma-ray burst
- 2010
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 463:7280, s. 513-515
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Tidskriftsartikel (refereegranskat)abstract
- Long duration gamma-ray bursts (GRBs) mark(1) the explosive death of some massive stars and are a rare sub-class of type Ibc supernovae. They are distinguished by the production of an energetic and collimated relativistic outflow powered(2) by a central engine (an accreting black hole or neutron star). Observationally, this outflow is manifested(3) in the pulse of gamma-rays and a long-lived radio afterglow. Until now, central-engine driven supernovae have been discovered exclusively through their gamma-ray emission, yet it is expected(4) that a larger population goes undetected because of limited satellite sensitivity or beaming of the collimated emission away from our line of sight. In this framework, the recovery of undetected GRBs may be possible through radio searches(5,6) for type Ibc supernovae with relativistic outflows. Here we report the discovery of luminous radio emission from the seemingly ordinary type Ibc SN 2009bb, which requires a substantial relativistic outflow powered by a central engine. A comparison with our radio survey of type Ibc supernovae reveals that the fraction harbouring central engines is low, about one per cent, measured independently from, but consistent with, the inferred(7) rate of nearby GRBs. Independently, a second mildly relativistic supernova has been reported(8).
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| 22. |
- Soderberg, A. M., et al.
(författare)
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Discovery of a Relativistic Supernova Without a Gamma-ray Trigger
- 2009
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Annan publikation (populärvet., debatt m.m.)abstract
- Type Ibc supernovae (SNe Ibc) mark the gravitational collapse of some massive stars (M > 20 Msun) propelling several solar masses of material to typical velocities of ~10,000 km/s. The closely-related but exceedingly rare class of long-duration gamma-ray bursts (GRBs) produce, in addition, a relativistic outflow powered by a central engine (accreting black hole or neutron star) and have been found exclusively through their gamma-ray signal. Here we report the discovery of luminous radio emission from the seemingly ordinary Type Ibc SN 2009bb which outshines that of all other SNe Ibc observed on a comparable timescale. These observations require a substantial mildly-relativistic outflow and indicate that the explosion was powered by a central engine, thus representing the first such event discovered without the aid of a gamma-ray trigger. A comparison with our extensive radio survey of SNe Ibc reveals that the fraction of such events is low (roughly 1 percent), measured independently from, and yet consistent with, the inferred rate of nearby GRBs. This discovery marks the observational realization that long-wavelength surveys will soon rival gamma-ray satellites in pinpointing nearby engine-driven explosions.
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| 23. |
- Wang, Xiaofeng, et al.
(författare)
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Evidence for type ia supernova diversity from ultraviolet observations with the hubble space telescope
- 2012
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 749:2, s. 126-
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Tidskriftsartikel (refereegranskat)abstract
- We present ultraviolet (UV) spectroscopy and photometry of four Type Ia supernovae (SNe 2004dt, 2004ef, 2005M, and 2005cf) obtained with the UV prism of the Advanced Camera for Surveys on the Hubble Space Telescope. This data set provides unique spectral time series down to 2000 angstrom. Significant diversity is seen in the near-maximum-light spectra (similar to 2000-3500 angstrom) for this small sample. The corresponding photometric data, together with archival data from Swift Ultraviolet/Optical Telescope observations, provide further evidence of increased dispersion in the UV emission with respect to the optical. The peak luminositiesmeasured in the uvw1/F250W filter are found to correlate with the B-band light-curve shape parameter Delta m(15)(B), but with much larger scatter relative to the correlation in the broadband B band (e.g., similar to 0.4 mag versus similar to 0.2 mag for those with 0.8 mag < Delta m(15)(B) < 1.7 mag). SN 2004dt is found as an outlier of this correlation (at > 3 sigma), being brighter than normal SNe Ia such as SN 2005cf by similar to 0.9 mag and similar to 2.0 mag in the uvw1/F250W and uvm2/F220W filters, respectively. We show that different progenitor metallicity or line-expansion velocities alone cannot explain such a large discrepancy. Viewing-angle effects, such as due to an asymmetric explosion, may have a significant influence on the flux emitted in the UV region. Detailed modeling is needed to disentangle and quantify the above effects.
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