Article

# Constraints on core-collapse supernova progenitors from correlations with Halpha emission

• ##### P. A. James
Monthly Notices of the Royal Astronomical Society (Impact Factor: 5.52). 01/2008; 390:1527-1538. DOI: 10.1111/j.1365-2966.2008.13843.x
Source: arXiv

ABSTRACT We present observational constraints on the nature of the different core-collapse supernova (SN) types through an investigation of the association of their explosion sites with recent star formation (SF), as traced by Halpha + [NII] line emission. We discuss results on the analysed data of the positions of 168 core-collapse SNe with respect to the Halpha emission within their host galaxies. From our analysis we find that overall the type II progenitor population does not trace the underlying SF. Our results are consistent with a significant fraction of SNII arising from progenitor stars of less than 10Msolar. We find that the SNe of type Ib show a higher degree of association with HII regions than those of type II (without accurately tracing the emission), while the type Ic population accurately traces the Halpha emission. This implies that the main core-collapse SN types form a sequence of increasing progenitor mass, from the type II, to Ib and finally Ic. We find that the type IIn subclass display a similar degree of association with the line emission to the overall SNII population, implying that at least the majority of these SNe do not arise from the most massive stars. We also find that the small number of SN `impostors' within our sample do not trace the SF of their host galaxies, a result that would not be expected if these events arise from massive luminous blue variable star progenitors. Based on observations made with the Isaac Newton Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Institute de Astrofisica de Canarias, and on observations made with the Liverpool Telescope operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. E-mail: jxa@astro.livjm.ac.uk

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##### Article: Paired galaxies with different activity levels and their supernovae
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ABSTRACT: We investigate the influence of close neighbor galaxies on the properties of supernovae (SNe) and their host galaxies using 56 SNe located in pairs of galaxies with different levels of star formation (SF) and nuclear activity. The statistical study of SN hosts shows that there is no significant difference between morphologies of hosts in our sample and the larger general sample of SN hosts in the Sloan Digital Sky Survey (SDSS) Data Release 8 (DR8). The mean distance of type II SNe from nuclei of hosts is greater by about a factor of 2 than that of type Ibc SNe. The distributions and mean distances of SNe are consistent with previous results compiled with the larger sample. For the first time it is shown that SNe Ibc are located in pairs with significantly smaller difference of radial velocities between components than pairs containing SNe Ia and II. We consider this as a result of higher star formation rate (SFR) of these closer systems of galaxies. SN types are not correlated with the luminosity ratio of host and neighbor galaxies in pairs. The orientation of SNe with respect to the preferred direction toward neighbor galaxy is found to be isotropic and independent of kinematical properties of the galaxy pair.
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##### Article: Spatial distributions of core-collapse supernovae in infrared-bright galaxies
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ABSTRACT: We have measured the correlation between the locations of core-collapse supernovae (CCSNe) and host galaxy light in the Ha line, near ultraviolet (NUV), R-band and Ks-band to constrain the progenitors of CCSNe using pixel statistics. Our sample consists of 86 CCSNe in 57 infrared (IR)-bright galaxies, of which many are starbursts and ten are luminous infrared galaxies (LIRGs). We also analyse the radial distribution of CCSNe in these galaxies, and determine power-law and exponential fits to CCSN surface density profiles. To probe differences between the SNe of these galaxies and normal spiral galaxies, our results were compared to previous studies with samples dominated by normal spiral galaxies where possible. We obtained a normalised scale length of 0.23^{+0.03}_{-0.02} R_25 for the CCSN surface density in IR-bright galaxies; less than that derived for CCSNe in a sample dominated by normal spiral galaxies (0.29 \pm 0.01). This reflects a more centrally concentrated population of massive stars in IR-bright galaxies. Furthermore, this centralisation is dominated by a central excess of type Ibc/IIb SNe. This may be due to a top-heavy initial mass function and/or an enhanced close binary fraction in regions of enhanced star formation. Type Ic SNe are most strongly correlated with Ha light and NUV-bright regions, reflecting the shortest lifetime and thus highest mass for type Ic progenitors. Previous studies with samples dominated by normal spiral galaxies have indicated a lower Ibc-Ha correlation than our results do, which may be due to the central excess of type Ibc/IIb SNe in our sample. The difference between types II and Ib is minimal, suggesting that progenitor mass is not the dominant factor in determining if a SN is of type Ib or II. Similar differences in correlation can be seen in the Ks-band, with type Ibc/IIb SNe tracing the Ks-band light better than type II in our sample.
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• ##### Thesis: The statistical investigation of the First and Second Byurakan survey galaxies and their neighbors
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ABSTRACT: In the thesis we study close pairs of galaxies with the aim of understanding the influence of gravitational interaction on nuclear activity and star formation of paired galaxies. For this purpose we investigate dependencies of integral parameters of galaxies, their star formation and properties of nuclei on kinematic parameters of systems and their large-scale environment. The thesis has an introduction, three main chapters, a summary, lists of abbreviations and references, and three appendices. In the first chapter, the methods of selection of sample of pairs of galaxies and measurements of physical parameters of the First Byurakan Survey (Markarian) galaxies and their neighbors are presented, and the databases in appendices A and B are described, which contain parameters of neighbors of Markarian galaxies measured by us, and the parameters of pairs having Markarian galaxies, based on the Sloan Digital Sky Survey (SDSS) data. The selection effects of sample of pairs are discussed, and the statistical comparison of Markarian galaxies and their neighbors is done. The results of statistical study of star formation and activity of nuclei in pairs having Markarian galaxies are presented, as well as the correlations between properties of galaxies in pairs and the physical mechanisms behind them. In the second chapter, the results of statistical study of the Second Byurakan Survey (SBS) galaxies and their neighbors, and star formation and activity of nuclei in those pairs are presented and discussed. In the third chapter, possibilities of using supernovae as indicators of star formation are discussed, the sample of supernovae in pairs of galaxies is presented, and study of star formation in pairs of interacting galaxies by means of that sample of supernovae is done. Also а conclusion about the nature of progenitors of different types of supernovae is made. The short summary of main results of the study concludes the thesis. The thesis has 158 pages. The main results are the following. 1. The linear distance between members of pairs of galaxies and the degree of their morphological disturbance reflect the strength of interaction better than the difference of line-of-sight velocities of pair members. The latter correlates with the density of large-scale environment of a pair and with morphologies of paired galaxies. 2. Close neighbors of Markarian galaxies mostly do not differ in their properties from that of Markarian galaxies. Close neighbors of SBS galaxies mostly do not differ in their properties from that of SBS galaxies. The SBS galaxies in pairs do not differ from isolated SBS galaxies in their properties. 3. The interactions between galaxies enhance their star formation, particularly, the mass normalized specific star formation rate in paired galaxies increases by an order of 0.5 averagely. This effect is revealed when studying both pairs with smaller differences of line-of–sight velocities and pairs with smaller linear separations between components. The effect is revealed for galaxies of any morphological type, in environments with almost any density, for both high- and low-mass galaxies. 4. The interaction with neighbors of the same or later morphological types enhances star formation. The interactions with neighbor galaxies of comparable masses increases star formation rate and activity of nuclei more effectively than interaction with less-massive neighbors. 5. The fraction of active nuclei among more disturbed and stronger interacting pairs is the highest. Galaxies with active nuclei usually are located in stronger interacting pairs and/or in pairs with later stages of interaction, in comparison with star-forming and passive galaxies. 6. Star formation rates and nuclear activity of paired galaxies are correlated. For a galaxy with a certain activity type of the nucleus, the probability of having a neighbor with the same type of activity is higher. 7. Due to the effect of interaction-enhanced star formation, the supernovae of type Ibc are located in pairs with smaller differences of line-of-sight velocities than supernovae Ia and II. The full thesis is available only in Armenian.
05/2014, Degree: PhD, Supervisor: Artashes R. Petrosian