[Astronomy seminar] Reminder: Astronomy seminar Today at 10:30 in FC61

[Astronomy seminar announcements]

A kind reminder of today seminar.

Angela

> On 17 Sep 2018, at 21:25, Angela Adamo <angela.adamo at astro.su.se> wrote:
> 
> Dear all,
> welcome to our weekly seminar appointment Friday 21/09 at 10:30 am in FC61.
> The speaker is Anders Nyholm, from the astronomy department at SU. 
> 
> 
> Title: Circumstellar matters: Probing star death and AGN host history via supernova surroundings
> 
> Abstract: In my talk, I will discuss supernova (SN) research I have done for my PhD thesis. Type Ia (thermonuclear) SNe are sturdy rungs on the cosmic distance ladder, but no Type Ia progenitor system has yet been securely identified via observations. For nearby Type Ia SN 2014J we used the Nordic Optical Telescope to obtain a late spectrum of the SN, to search for hydrogen and helium ablated off a possible non-compact companion star. We put strong limits on the presence of such gas, making it plausible that the progenitor system was double-degenerate. Apart from this work, the rest of the thesis will be based on the intermediate Palomar Transient Factory (iPTF) survey. Using the iPTF SN catalogue, we examined the occurrence of SNe in active galactic nucleus (AGN) type 1 (broad Balmer lines) and type 2 (narrow Balmer lines) host galaxies. We found a larger number of SNe around AGN type 2 than around AGN type 1, and no core collapse (cc) SNe around AGN type 1. This result indicates that AGN type 2 hosts have younger stellar populations than AGN type 1 hosts. The main area of my PhD thesis work is SNe Type IIn, i.e. cc SNe happening in dense, hydrogen-rich circumstellar media. The interaction between SN ejecta and the circumstellar medium (CSM) can make SNe Type IIn luminous and long-lasting. In SNe IIn, as the ejecta sweeps up the CSM, the ejecta scans the late mass-loss history of the progenitor star. This offers rare glimpses of the last decades of supergiant stars. We studied Type IIn SN iPTF13z, with a long-lasting light curve showing several re-brightenings indicating that the SN ejecta ran into denser strata in the CSM. This, along with a clear detection of a pre-SN outburst, indicated that the iPTF13z progenitor star was restless before its demise. Such outbursts have been observed for a number of SNe Type IIn, offering clues about the progenitor stars. We currently work on a sample study of SNe IIn, using iPTF data, to improve our knowledge of this diverse class of transients.
> 
>> The agenda of our seminars is currently being updated on the www.astro.su.se webpage. 
>> We are experiencing difficulties in using the Albanova agenda, but it will be fixed soon.
> 
> Kind regards,
> Alexis and Angela
> 
> -------------------------------------------------------
> Angela Adamo  
> 
> Department of Astronomy
> Stockholm University and Oskar Klein Centre
> SE-10691 Stockholm - Sweden
> tel: +46 (0)8 5537 8556 
> email: angela.adamo at astro.su.se
> http://ttt.astro.su.se/~adamo
> -------------------------------------------------------
> 
>> On 29 Aug 2018, at 19:06, Angela Adamo <angela.adamo at astro.su.se> wrote:
>> 
>> Dear all,
>> thanks to the prompt reply of Prof. Erb we have actually managed to schedule an excellent seminar for this coming Friday.
>> Dr. Lluis Mas-Ribas has recently got his PhD in Oslo University and will move in a couple of weeks in California where he will start a post-doc a Caltech. 
>> He is visiting our Institute and will be around Thursday and Friday in case you are interested in talking to him.
>> 
>> We hope you can make it! Title and abstract will follow. 
>> The agenda of our seminars is currently being updated on the www.astro.su.se webpage. 
>> We are experiencing difficulties in using the Albanova agenda, but it will be fixed soon.
>> 
>> Kind regards,
>> Alexis and Angela
>> 
>> TITLE - Extended Diffuse Emission as a Probe of Galaxy and Reionization Physics
>> 
>> ABSTRACT
>> Two of the main questions for the Epoch or Reionzation are: (i) what sources reionized the Universe? and (ii) what is the escape fraction of ionizing 
>> photons from galaxies into the IGM? I will present our results demonstrating the use of the spatially extended Lya, Ha, and stellar continuum emission 
>> observed around star-forming galaxies from z~2 and up to z~7, and its comparison to future feasible JWST observations, to answer these two questions. 
>> Furthermore, I will show our recent calculations that indicate the JWST observability of the warm and hot CGM gas via the Thomson scattering of quasar 
>> radiation in massive galaxies, which appears to be redshift independent and thus enables measurements of the warm and hot halo gas properties, the 
>> baryonic content, and the impact of quasar feedback from z~0 to (at least) z~6.5 during Reionization.
>> 
>> 
>> -------------------------------------------------------
>> Angela Adamo  
>> 
>> Department of Astronomy
>> Stockholm University and Oskar Klein Centre
>> SE-10691 Stockholm - Sweden
>> tel: +46 (0)8 5537 8556 
>> email: angela.adamo at astro.su.se
>> http://ttt.astro.su.se/~adamo
>> -------------------------------------------------------
>> 
> 
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