ABSTRACTS


Invited talks


Maria Teresa Botticella, Capodimonte Observatory, INAF-Napoli

SN rate in the local Universe

 The core collapse supernova rate provides a strong lower limit for the star formation rate. Progress in using it as a cosmic star formation rate tracer requires some confidence that it is consistent with more conventional star formation rate diagnostics in the nearby Universe. Complete and volume-limited SN and galaxy samples are crucial to perform a statistically meaningful analysis and the advent of large sets of multi-wavelength observations of nearby galaxies provide us the opportunity to compare SFRs based on CC SN rate and more established tracers in the same galaxy sample. The data are complete enough that we can take into account the different uncertainties and biases that affect these SFR diagnostics. Multi-wavelength data also allow us to study the effect of dust extinction, to constraint the fraction of missed SNe in optical SN searches  and to compare the spatial distribution of CC SNe with that of the SFR.



Zach Cano, University of Iceland

The progenitors of grbSNe
It is now accepted that a long-duration gamma-ray burst (GRB) is generated during the violent demise of a massive star whose properties are quite atypical to those of the general core-collapse supernova (ccSN) population. Determining the properties of the progenitor stars of gamma-ray burst supernovae (grbSNe) is of great interest within the GRB and SN communities. Why do only a tiny fraction of massive stars create a GRB? What are the special properties that the progenitor star must possess to produce a GRB Solving this puzzle requires a clever combination of observations and theory, with results from each helping to drive the state of the field forward. In this talk I will discuss the general properties of grbSNe in relation to other ccSNe, and describe how these observations are helping to constrain and differentiate between the leading theoretical progenitor models for grbSN production.



Tomas Dahlen, STScI

The relation between the core collapse supernova rate and the star formation rate

I will discuss the relation between the rate of exploding core collapse supernovae and the star formation rate. This includes a discussion on the systematic effects that has to be controlled in order to derive an accurate relation between the two rates. Particularly, how does extinction by dust in the host galaxies affect the observed number of supernovae, what are the fractions of different SN subtypes, how many SN are over luminous and what are the mass ranges of the progenitors? I will present results from supernova searches conducted with the Hubble Space Telescope, including rates derived from GOODS, as well as new results from the ongoing CANDELS multi-cycle treasury program.



Massimo Della Valle, Capodimonte Observatory, INAF-Napoli

What fraction of CCSNe give rise to GRBs ?
Several lines of evidence suggest that long duration Gamma-ray Bursts and SNe are coeval events within less than ~0.1 days. Current estimates of SN and GRB rates yield a ratio GRB/SNe-Ibc less (or much less) than 3%. However observations of GRB 060614 puzzled this scenario, pointing out the existence of long-duration Gamma-ray Burst not accompanied by bright supernovae.



Claes Fransson, Stockholm University

Observations and progenitor scenarios of Type IIn SNe

I will discuss recent multi-wavelength observations of Type IIn SNe, in particular SN 2005ip, 2006jd, 2009ip and in most detail SN 2010jl, and what these observations tell us about the SN environment and progenitor.



Avishay Gal-Yam, Weizmann Institute of Science

New frontiers in transient science from PTF and iPTF

The wide-field Palomar Transient Factory (PTF) survey has been scanning the sky for optical transients since 2009, discovering thousands of events. I will present science highlights from this survey, as well as new results from its ongoing extension, the intermediate PTF (iPTF), as well as prospects for near-future ground- and space-based wide-field transient surveys. An emerging theme is the real-time study of optical transients. For example, iPTF can currently study supernova explosions during the first hours post-explosion; future surveys will be able to move on to minute timescales. This real-time capability opens new scientific windows to study numerous optical transients, in ways previously only possible for much rarer high-energy (X- and Gamma-ray) transients.



Anders Jerkstrand, Queen's University Belfast

Nebular phase spectral modeling of core-collapse supernovae

Nebular phase supernova observations and modeling allows an analysis of the nucleosynthesis in the deep interior of massive stars. By computing the transformation of radioactive decay energy to emission lines from the various nuclear burning zones, observed spectra can be interpreted to yield constraints on the hydrostatic and explosive evolution of the star. I present results of such modeling for both hydrogen-rich (Type IIP) and hydrogen-poor (Type IIb) supernovae, from which several interesting conclusions on the progenitor masses, nucleosynthesis, and explosive mixing have emerged.



Oliver Krause, Max-Planck-Institut für Astronomie

Light Echoes of Core-Collapse Supernovae

Young Galactic supernova remnants are unique laboratories for supernova physics. Due to their proximity they provide us with the most detailed view of the outcome of a supernova. However, the exact spectroscopic types of their original explosions have been undetermined so far - hindering to link the wealth of multi-wavelength knowledge about their remnants with the diverse population of supernovae. Light echoes, reflections of the brilliant supernova burst of light by interstellar dust, provide a unique opportunity to re-observe today - with powerful scientific instruments of the 21st century - historic supernova explosions even after hundreds of years and to conclude on their nature. We review optical light-echo spectroscopy of historical core-collapse supernovae, in particular the youngest known CC SN Cas A. These observations finally recovered the missing spectroscopic classifications and provide new constraints on explosion models for future studies.



Giorgos Leloudas, Oskar Klein Centre, Stockholm University

Super-luminous supernovae and their host galaxies

In the recent years we have witnessed the discovery of a class of very luminous explosions, a.k.a. super-luminous supernovae. In the first part of the talk I will give a short overview of this booming field. I will try to cover some historical aspects, the observational properties and diversity of SLSNe and the proposed mechanisms explaining their luminosities. In addition, their potential for probing the high-z universe, the ISM and the IMF of dwarf galaxies. In the second part, I will present a large effort to study the host galaxies of super-luminous supernovae. Our team is using a number of telescopes, including the VLT, GTC, Magellan and smaller facilities, in order to obtain multi-wavelength imaging data and spectra of these hosts. Our purpose is to build their SEDs, determine their properties and measure their metallicities. These monstrous explosions seem to occur in very special environments.



Daniele Malesani, Dark Cosmology Centre

What we know for sure: most long GRBs come from exploding massive stars

That long-duration GRBs are produced in the explosion of massive stars is an observationally well-established fact. This in turn enables the use of long GRBs as cosmological probes of star formation at all redshifts. It is less certain which kind of stars do explode as GRBs. A similar SN explosion (properties comparable  to a factor of few) is observed for GRBs with extremely different energetics (spanning a factor of 10^6), as showcased by the recent low-redshift, high-power GRB 130427A. Constraining quantitatively the properties of GRB stellar progenitors is the next necessary step to pursue further the use of GRBs as cosmic probes.



Justyn Maund, Queen's University Belfast

The Progenitors of Core-collapse Supernovae

All stars with initial mass >8Msun are expected to end their lives as core-collapse supernovae. I will review the latest results from efforts to directly identify the progenitor stars of core-collapse supernovae in fortuitous pre-explosion images. Of particular importance to this field is our evolving understanding of the uncertainties in our analysis of the pre-explosion observations, and I will discuss the benefits that may be achieved by acquiring late-time observations of the sites of these explosions.



Andrea Pastorello, INAF-Padova Observatory

Impostors and interacting supernovae connection

Supernova impostors are transient events that mimic the observables of weak type IIn supernovae, showing narrow spectral lines that indicate relatively low ejecta velocities (a few hundreds km/s) and having absolute magnitudes of -11 to -15. During the outbursts, the luminosity of the star, usually a Luminous Blue Variable, exceed by several magnitudes the magnitude of the quiescent star. What triggers the outbursts is unclear, but it is generally accepted that these massive stars violate the Eddington luminosity limit, initiating major mass loss episodes. The interest towards these transients has mounted up because there are claims that some interacting supernovae (of type IIn or type Ibn) have been heralded by pre-SN eruptions. In this talk I will discuss a few representative examples of SN impostors and review observational evidences of a connection between them and genuine, interacting supernovae.



Sandra Savaglio, Max Planck Institute for Extraterrestrial Physics

Host galaxies of long gamma-ray bursts

The investigation of galaxies hosting long gamma-ray bursts (GRBs) offers the opportunity to explore regions of the universe which are observationally very hostile for traditional means, due to gas and dust absorption. A decade of GRB detections and research has brought to "light" a galaxy population that was not expected before. For instance, the cosmic chemical enrichment revealed by GRBs over billions of years is found to be much milder than what previously thought. One main unclear issue is whether the typical GRB host at low redshift is different from the high-z counterpart. The answer to this question may be closely related to the sharp decline of the cosmic rate of star formation, to the gas consumption and to the change in the galaxy merger rate, for z < 1. Another crucial issue is the recent discovery of several hosts at intermediate redshift with red color (some related to dark hosts), which can help to unveil the role of dust in our detection capabilities of the brightest objects in the universe. Finally, very distant GRB hosts (z > 5) have given so far elusive results, indicating very small galaxies, smaller than what is reached today with typical NIR deep surveys.



Contributed talks


Mattias Ergon, Stockholm University

SN 2011dh - Current state of research.

I will discuss the current state of research on the Type IIb SN 2011dh focusing on the results presented by our group in Maund et al. (2011), Bersten et al. (2012) and Ergon et al. (2013) as well as preliminary results from Jerkstrand et al. (in preparation) and Ergon et al. (in preparation). The observations published in these and other papers are among the best obtained ever, covering a wavelength range from radio to X-rays and two years later monitoring is still ongoing. I will mainly discuss the UV to MIR observations and the results we have obtained from these, in particular on the nature of the progenitor star. The luminosity of the SN is now considerably fainter than the yellow supergiant coincident with the SN confirming this star to be the progenitor. Several independent methods using both SN and progenitor observations gives consistent results regarding the nature of the progenitor and HST imaging in the year to come might confirm or rule out the presence of a companion star.



Jose Groh, Geneva Observatory

Predicting the look of massive stars before death

Stars more massive than about 8 Msun end their lives as a supernova (SN), an event of fundamental importance Universe-wide. The morphological appearance of massive stars before the SN event is very uncertain, both from a theoretical and observational perspective. In this talk, I will present coupled stellar evolution and atmospheric modeling of stars done with the Geneva and CMFGEN codes, for initial masses between 9 and 120 Msun. We are able to predict the high-resolution spectrum and broadband photometry, which can then be directly compared to the observations of SN progenitors. I will discuss the surprising predictions of spectral types of massive stars before death. Our models indicate that massive stars die as RSGs, LBVs, WNs, or WOs, depending on the initial mass and rotation. I will also discuss the detectability of SN progenitors.



Luca Izzo, Sapienza University of Rome and ICRANet

co-authors: Bianco, C. L.; Muccino, M.; Penacchioni, A. V.; Pisani, G. B.; Rueda, J. A.; Ruffini, R.; Wang, Y.

Observations of the IGC process in some GRBs-SNe and applications to cosmology

 The Induced Gravitational Collapse scenario was proposed recently to explain the connection between Gamma Ray Bursts and the related Supernovae Ib/c. We present the phenomenology of this mechanism in the prototype GRB 090618, and in an other good example, GRB 970828, explaining all the observational evidences and deriving the parameters of the NS and progenitor system. Moreover, we found a standard luminosity light curve behavior in the late-time X-ray emission of this subclass of GRBs, which implies the possibility to estimate the distance of GRB-SN-IGC event without an observed redshift. This method was successfully applied to other GRBs, which will be presented and discussed.



Tuomas Kangas, University of Turku

co-authors: Seppo Mattila, Erkki Kankare

Spatial distributions of core-collapse supernovae in actively star-forming galaxies

Using pixel statistics, we investigate the correlation between locations of core-collapse supernovae (CCSNe) and Halpha, near-UV, R- and Ks-band light, to constrain the progenitors of CCSNe in a sample of 57 actively star-forming galaxies and the 86 CCSNe detected in them since 1990. We also analyse the radial distribution of the CCSNe in these galaxies, and determine an exponential fit to surface densities of CCSNe at different distances from the host galaxy core. We draw the following conclusions: (1) Type Ic SNe are more strongly correlated with H II regions (Halpha) and NUV- and Ks-bright regions than types II and Ib. These correlations are consistent with previous studies and indicate that type Ic progenitors may mostly be massive WR stars, while most type Ib progenitors may be stars of similar mass as those of type II, located in interacting binaries. (2) Type II SNe occur further away from the host galaxy core than stripped-envelope SNe, in agreement with previous studies. This may be due to a top-heavy IMF in regions of enhanced SF, combined with many SNe being missed in the central regions of actively star-forming galaxies. (3) We obtain a scale length of 0.23 R_{25} for the surface density of CCSNe in actively star-forming galaxies. This is less than that observed for CCSNe in normal spiral galaxies (0.29). The centralisation of the SN population we see in our galaxies is mostly due to a central excess of type Ibc/IIb SNe (scale length 0.19) compared to normal galaxies.



Erkki Kankare, University of Turku

co-authors: Seppo Mattila, Stuart Ryder

Core-collapse supernovae in luminous infrared galaxies

We have conducted a four year study of searching for core-collapse supernovae (CCSNe) in a sample of eight luminous (L_IR > 10^11 Lsun) infrared (IR) galaxies (LIRGs) using the Gemini-North Telescope with ALTAIR/NIRI laser guide star adaptive optics system. The high resolution and the usage of near-IR wavelengths are crucial for the discovery and follow-up of the obscured CCSNe in these dusty and actively star forming galaxies. The improved statistics of SNe discovered in LIRGs can be used as useful tools to independently trace and study the star formation, extinction distribution and supernova population in these galaxies. Furthermore, we were recently able to expand the results from studies of CCSNe in LIRGs in the local Universe also into higher redshift (z > ~1) where the LIRGs become the dominating source of star formation. This work has provided new correction factors for the `missing' SNe for studies of CCSN rates as a function of redshift.



Xue Li, Dark Cosmology Centre

co-authors: Jens Hjorth

The absolute magnitudes of GRB-SNe
We report the light curves in the rest frame V band derived for fourteen GRB-SNe with redshift z up to 1, using multi-band K corrections, and suitably corrected for the foreground extinction. These light curves indicate that the GRB-SNe have small intrinsic dispersion: 0.384 mag, in the absolute magnitudes in the rest frame V band. The dispersions of the absolute magnitudes of 70 Type Ia supernovae (z ∼ 0.08) are also estimated as a comparison. The dispersion is 0.453 mag. This result can be interpreted that GRB-SNe show a good property of constant intrinsic luminosities. Moreover, the absolute magnitudes appear to be correlated with the decline rate of the light curve in V band similar to Type Ia supernovae. Considering the wide application of Type Ia supernovae in the measurement of cosmological distance, it is possible that the GRB-SNe can also be used as cosmological standard candles.



Amati Lorenzo, INAF - IASF Bologna

co-authors: M. della Valle, F. Frontera, C. Guidorzi

Measuring cosmological parameters with GRBs: status and perspectives

Given their huge isotropic-equivalent radiated energies, up to more than 10^54 erg, and their redshift distribution extending up to more than z = 8, Gamma-Ray Bursts (GRB) are in principle a powerful tool for measuring the geometry and expansion rate of the Universe. However, they are not standard candles given that their luminosities span several orders of magnitude, even when considering possible collimation angles. In the recent years, several attempts to exploit the correlation between the photon energy at which the nuFnu spectrum peaks ("peak energy") and the radiated energy (or luminosity) for "standardizing" GRBs and using them as tools, complementary to other probes like SN Ia, BAO and the CMB, for the estimate of cosmological parameters have been made. These studies show that already with the present data set GRBs can provide a significant and independent confirmation of Omega_M < 1 (and around 0.25) for a flat LambdaCDM universe and that the measurements expected from present and next GRB experiments (e.g. Swift, Fermi/GBM, SVOM, UFFO) will allow us to constrain Omega_M, Omega_Lambda, and, in particular, to get clues on dark energy properties and evolution.


Jens Melinder, Stockholm University

co-authors: G. Östlin, T. Dahlen, S. Mattila, C. Fransson, M. Hayes, J. Sollerman, L. Mencia-Trinchant, E. Zackrisson

Core-collapse supernovae - rates and host galaxy properties

Supernova surveys have been used successfully to measure both cosmological parameters and the cosmic star formation history. I will give a brief review over the current status of surveys trying to estimate the core collapse supernova rate at intermediate redshift. Among these surveys is the SVISS (Stockholm VIMOS Supernova Survey) which targeted both Ia and core-collapse SNe and discovered 16 SNe at 0.1


Rupak Roy, Aryabhatta Research Institute of observational sciences (ARIES), Nainital, India

co-authors: A. J. Drake, J. M. Silverman, S. Benetti, R. Martin, S. Bose, E. Cappellaro, E. Kankare, A. Pastorello, Brajesh Kumar, A. V. Filippenko, D. Garcia-Alvarez, Brijesh Kumar, L. Tomasella, M. Turatto, S. Valenti

Optical photometric and spectroscopic follow-up observations of the luminous Supernova 2012aa

A few dedicated surveys like CRTS, LOSS, ROTSE, PTF, PanSTARRS, and LSQ discovered several stellar explosions which have an average absolute V-band peak magnitude of about -21, more than 2 mag brighter than normal stripped-envelope SNe. SN 2012aa, which was discovered on 29.6 January 2012 UT by the LOSS, has similar characteristics. From optical spectra it was characterized as a Type Ic SN. The event was also detected by the CRTS during its rising phase, with peak apparent unfiltered magnitude ~18. It was also observed in the BVRI bands along with good spectroscopic coverage over a time span of 100 days using different telescopes throughout the world. The SN is in a relatively distant (redshift z~0.08) host galaxy, with a line-of-sight reddening E(B-V)~0.2 mag. This value is comparable to the Galactic reddening (~0.1 mag). The derived absolute V-band peak magnitude is roughly -20.5 mag, a very luminous SN. The post-maximum decay rate is roughly 0.012 mag/day. This is much lower than that of normal stripped-envelope CCSNe (~0.06 mag/day) and comparable to the decay rate of overluminous events like CSS100217 and SN 2007bi. The preliminary derived mass of radioactive Ni is ~2.1 solar masses, which is a little less than that of CSS100217 and SN 2007bi, but significantly higher than that of normal stripped-envelope events. Here, we present the optical photometric and spectroscopic follow-up observations of this event, along with detailed modeling of the light curve and spectra.



Francesco Taddia, Stockholm University

Carnegie Supernova Project: Observations of Type IIn supernovae

Carnegie Supernova Project (CSP) optical and near-infrared light curves and visual-wavelength spectroscopy of the Type IIn SNe~2005kj, 2006aa, 2006bo, 2006qq, and 2008fq are presented. Combined with previously published observations of the Type~IIn SNe 2005ip and 2006jd, the full CSP sample is used to derive physical parameters that describe the nature of the interaction between the expanding SN ejecta and the circumstellar material (CSM). For each SN of our sample, we find counterparts, identifying objects similar to SNe~1994W (SN~2006bo), 1998S (SN~2008fq), and 1988Z (SN~2006qq). We present the unprecedented initial u-band plateau of SN~2006aa, and its peculiar late-time luminosity and temperature evolution. For each SN, mass-loss rates of 10^-4 - 10^-2 Msun yr^-1 are derived, assuming the CSM was formed by steady winds. Typically wind velocities of a few hundred km s^-1 are also computed. The CSP SN IIn sample seems to be divided into subcategories rather than to have exhibited a continuum of observational properties. The wind and mass-loss parameters would favor a luminous blue variable progenitor scenario. However the assumptions made to derive those parameters strongly influence the results, and therefore, other progenitor channels behind SNe~IIn cannot be excluded at this time.



Darach Watson, University of Copenhagen

co-authors: Zafar, Tayyaba; Andersen, Anja C.; Fynbo, Johan P. U.; Gorosabel, Javier; Hjorth, Jens; Jakobsson, Páll; Krühler, Thomas; Laursen, Peter; Leloudas, Giorgos; Malesani, Daniele

The origin of soft X-ray absorption in gamma-ray burst afterglows

Gamma-ray burst (GRB) afterglows are potentially valuable probes of both their immediate star-forming environments and the galaxies in which they explode. Soft X-ray absorption in excess of Galactic is observed in the afterglows of most GRBs, but the correct solution to its origin has not been arrived at after more than a decade of work, preventing its use as a powerful diagnostic tool. We resolve this long-standing problem and find that absorption by He in the GRB's host H II region is responsible for most of the absorption. We show that the X-ray absorbing column density (N_H_X) is correlated with both the neutral gas column density and with the optical afterglow's dust extinction (A_V). We find that the correlation with the dust column has a strong redshift evolution, whereas the correlation with the neutral gas does not. From this we conclude that the column density of the X-ray absorption is correlated with the \emph{total gas} column density in the host galaxy rather than the metal column density. The strong redshift evolution of N_H_X / A_V is thus a reflection of the cosmic metallicity evolution of star-forming galaxies and we find it to be consistent with measurements of the redshift evolution of metallicities for GRB host galaxies. We conclude that the absorption of X-rays in GRB afterglows is caused by He in the H II region hosting the GRB. While dust is destroyed and metals are stripped of all of their electrons by the GRB to great distances, the abundance of He saturates the He-ionising UV continuum much closer to the GRB, allowing it to remain in the neutral or singly-ionised state. Helium X-ray absorption explains the correlation with total gas, the lack of strong evolution with redshift as well as the absence of dust, metal or hydrogen absorption features in the optical-UV spectra.






Posters






Martina Cardillo, Università di Roma Tor Vergata & INAF-IAPS

co-authors: Andrea Giuliani, Marco Tavani

SNRs and CRs: new challenges after a breakthrough

In the last few years, SNR study showed an increasingly complex scenario with a continuous elaboration of theoretical models; until now, providing an experimental unambiguous proof of the CR origin has been elusive. In this context the AGILE and Fermi gamma-ray satellites had a significant role. One year ago, AGILE found, for the first time, the proof of CR acceleration in the SNR W44. After this discovery, Fermi published new gamma-ray data of W44 confirming the AGILE results. In spite of this, theoretical interpretation of the SNR W44 features is still being debated. Here we will discuss new Fermi and new AGIL data, in the light of new CO data from NANTEN2 telescope, with the purpose to understand physics beyond observations in the context of DSA linear and nonlinear models.



Ting-Wan Chen, Queen's University Belfast

co-authors: S. Smartt, F. Bresolin (on behalf of a larger collaboration)

Host galaxy environments of the super-luminous supernovae

Super-luminous supernovae have a tendency to occur in faint host galaxies which are likely to have low mass and low metallicity. While these extremely luminous explosions have been observed from z = 0.1 to 4, the closest explosions allow more detailed investigations of their host galaxies. We present detailed analysis of the host galaxies of SN 2010gx (z = 0.23) and PTF-12dam (z = 0.107). SN 2010gx was classified as a super-luminous stripped-envelope supernova, and we found its host is a dwarf galaxy (Mg = -17.42 $\pm$ 0.17) with a high specific star formation rate. It has a remarkably low metallicity of 12 + log (O/H) = 7.5 $\pm$ 0.1 dex as determined from the detection of the [O III] $\lambda4363$ line. PS1-12arh is a 2007bi-like supernova, with a slowly fading light curve. It also occurred in a small galaxy (physical size = 2.34 kpc), which is similar with the host of SN 2010gx, but its absolute magnitude (Mg = -19.42 $\pm$ 0.10) is much brighter. The host galaxy has extremely strong emission lines, and we detect a wealth of emission lines such as [OIII] 4363, [OI] 6300/6364, [SIII] 9069/9532. Careful calibration of the emission line fluxes indicate a metallicity of 12 + log (O/H) = 8.0 $\pm$ 0.2 dex (using the direct method). In this poster, we show the comparison of the differences of the host galaxy from two super-luminous supernovae, and establish how the environment (i.e stellar progenitor metallicity) could help to explain the low volumetric rates ($\sim$ $10^{-4}$ of the core-collapse population) of the super-luminous supernova. We propose that these SNe are magnetar driven, and that this mechanism may be causally linked to low metallicity progenitor stars.



Mattias Ergon, Stockholm University

SN 2011dh - Two years later

The Type IIb SN 2011dh is one of the best observed SNe ever. Observations covering a wavelength range from radio to X-rays have been presented in a number of papers and two years later monitoring is still ongoing. This poster presents and summarize observations and results presented by our group in Maund et al. (2011), Bersten et al. (2012) and Ergon et al. (2013) as well as preliminary results from Jerkstrand et al. (in preparation) and Ergon et al. (in preparation). The luminosity of the SN is now considerably fainter than the yellow supergiant coincident with the SN confirming this star to be the progenitor. Several independent methods using both SN and progenitor observations gives consistent results regarding the nature of the progenitor and HST imaging in the year to come might confirm or rule out the presence of a binary companion.



Jussi Harmanen, University of Turku

co-authors: Mattila Seppo, Kankare Erkki

Photometric and spectroscopic monitoring of the type IIn supernova 2011ap

We have observed the light curves of supernova (SN) 2011ap in the spectral bands of U,B,V,R,I,J,H,K. The SN was discovered in type Sc D galaxy IC 1277 (z~0.024) in 16 February 2011. The SN was identified to be type IIn. They are characterized by narrow emission lines emerging from strong interaction with the interstellar medium surrounding the SN at the time of explosion. The observations begun two weeks before the maximum and continued about four months. In addition to the photometric observations also ten optical spectra were taken. Observations were made with several telescopes including New Technology Telescope in La Silla, William Herschel Telescope and Nordic Optical Telescope in La Palma.



Dolunay Kocak, Ege University, Department of Astronomy and Space Sciences

co-authors: Tugce İcli, G.Cisem Boz

The interacting binary system OO Aql

In this study we present photometric and spectroscopic variation analysis and orbital period study of an interacting system OO Aql. Simultaneous solution of the light and radial velocity curves provide us a determination of new set of stellar physical parameters for the primary and the secondary companions. Analyses of the mid-eclipse times indicate a period increase of $\frac{P}{\dot{P}}=4\times 10^{7}$ yr that can be interpreted in terms of the mass transfer $\frac{dM}{dt}=5\times 10^{-8}$ M$_{\odot}$/yr from the less massive component to the more massive component. Our new solution confirmed that OO Aql is a multiple system in the form of AB + C + D.



Katia Migotto, Stockholm University

co-authors: Claes Fransson, Peter Lundqvist, Jason Spyromilio, Josefine Larsson, Seppo Mattila, Bruno Leibundgut, Robert Kirshner, Per Gröningsson

Time evolution of emission lines from inner ring of SN 1987A

We present preliminary results from high resolution VLT/UVES spectra of the inner circumstellar ring in SN 1987A at different epochs, as well as an analysis of the time evolution of the emission lines from the aforementioned region. Furthermore, the optical light curves are compared to the time evolution of X-ray emission, in addition to HST narrow and broad band imaging. The line emission and time evolution are discussed in the context of the interaction between the ejecta and the ring. The evolution of the radiative shocks resulting from this interaction can from these observations be studied in real time.



Marco Muccino, Sapienza University of Rome

co-authors: Carlo Luciano Bianco, Luca Izzo, Ana Virginia Penacchioni, Giovanni Battista Pisani, Remo Ruffini

GRB 090227B, a genuine short burst, and GRB 090510, a disguised short burst in the highest CircumBurst Medium ever inferred

GRB 090227B and GRB 090510, both detected by Fermi satellite, are two Gamma-Ray Bursts (GRBs) classified as short bursts. The major outcome of our analysis is that they originate from different systems. The clear detection of their thermal components and the determination of the corresponding energetics have allowed us to infer the main theoretical parameters of the Fireshell model: the energy of e+e- plasma, Ee+e-, the amount of baryons engulfed, B, as well as the density profile of the CircumBurst Medium (CBM). In the case of GRB 090227B, from the inferred values of Ee+e-=(2.83±0.15)x10^53 erg and of B=(4.13±0.05)x10(-5), as well as of the average density of the CircumBurst Medium (CBM), =(1.90±0.20)x10(-5) cm^(-3), we assume the progenitor of this burst to be a symmetric binary neutron stars with masses m=1.34 Msun, radii R=12.24 km, and thickness of their crusts 0.47 km. For GRB 090510, the plasma energy Ee+e-= (1.10±0.06)x10^53 erg is constrained by the isotropic energy Eiso, and we derive a Baryon load B=(1.45±0.28)x10^(-3) and a Lorentz factor at transparency Gamma=(6.7±1.7)x10^2, which are characteristic of the long GRB class, and a very high CBM density, =(1.85±0.14)x10^3 cm^(-3). The joint effect of the high values of Gamma and of compresses in time and “inflates” in intensity the extended afterglow, making appear GRB 090510 as a short burst, which we here define as “disguised short GRB by excess” occurring in an overdense region with 10^3 cm^(-3).



Tuulia Pennanen, University of Oulu

co-authors: Indrek Vurm, Juri Poutanen

Simulations of gamma-ray burst afterglows

Gamma-ray burst (GRB) afterglows are the result of the interaction between the relativistic jet emanating from the central object and the surrounding medium. We have developed a numerical code to simulate the afterglow radiation, which is emitted mainly via the synchrotron and inverse Compton mechanisms by shock-accelerated electrons. The code solves the full kinetic equations describing the temporal evolution of the photon and electron distributions in the emission region. Our simulations suggest that a luminous high-energy component may arise in the GRB spectrum due to the scattering of the prompt GRB photons against the afterglow-emitting electrons. We have also compared the difference between the afterglow in a wind environment and a constant-density medium, and found that the low-energy end of a power-law electron distribution can be thermalized by synchrotron self-absorption heating in a wind-type medium.



Remo Ruffini, Sapienza University of Rome and ICRANet

co-authors: Bianco, C. L.; Izzo, L.; Muccino, M.; Penacchioni, A. V.; Pisani, G. B.; Rueda, J. A.; Wang, Y.

The Induced Gravitational Collapse paradigm in GRB-SN events

It has been proposed that the temporal coincidence of a gamma-ray burst (GRB) and a type Ib/c supernova (SN) can be explained with the concept of induced gravitational collapse (IGC), induced by the matter ejected from an SN Ib/c accreting onto a companion neutron star (NS) in a binary system. The NS is expected to reach the critical mass necessary for it to collapse to a black hole (BH) and emit a GRB. We will present the theoretical framework of this scenario, the application to the prototype GRB-SN 090618, which presents the characteristic four distinct emission episodes. The presence of GRB 060729 and GRB 130427A will be also presented.



Eda Sonbas, University of Adiyaman

co-authors: A. Akyuz, S. Topal, U. Temiz

A search for gamma-ray burst remnant candidate in spiral galaxy M101

Gamma Ray Bursts (GRBs) are expected to leave behind GRB remnants, similar to how standard supernovae (SNe) leave behind SN remnants. The identification of these remnants in nearby galaxies would allow having knowledge about their birth sides and progenitors. It would also provide independent constraints on GRB rates and energetics (Perna et al. 2000). In this work, we present the preliminary results of an optical search for Gamma Ray Burst Remnants (GRBR) in the spiral galaxy M101. Photometrical and spectroscopical observations were performed with the 1.5m Russian-Turkish and 6-m BTA Telescopes. According to high line flux ratio (like as; OIII/Hbeta, HeII/Hbeta ve OIII/OII) in photoinozied regions, we identified 15 emission nebulae as GRBR. Knowing the positions of the GRBRs, we can compare their distributions relative to other emission nebulae ( e.g. Supernova Remnants, Planetary Nebulae, HII regions).



Ari Takalo, University of Turku

co-authors: Seppo Mattila, Jens Melinder, Erkki Kankare

Supernova detection efficiency inside starburst and luminous infrared galaxies

We have developed methods for estimating supernova detection efficiencies inside starburst and luminous infrared galaxies (LIRGs). These methods were developed for estimating completeness corrected supernova rates from near-infrared supernova searches. We have carried-out both under natural seeing conditions and using adaptive optics correction. The method is based on simulating artificial supernovae on observed images of the target galaxies and utilising a detection algorhitm to search for these simulated sources in subtracted images. The search method uses optimal image subtraction from the ISIS 2.2 package to find variability in the observed images and combines SExtractor and aperture photometry statistics for finding objects in the subtracted images. We show initial result for data obtained using the NACO instrument on the ESO VLT.