From haakon.andresen at astro.su.se Mon Jan 27 10:19:33 2025 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Mon, 27 Jan 2025 09:19:33 +0000 Subject: [Okc-wp4] No meeting this week Message-ID: Dear everyone, We had planed to start the EO seminars this week, but travel/lack of speakers resulted in us having to cancel this week's seminar. Sorry for the late announcement. - Haakon -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Mon Feb 24 09:50:08 2025 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Mon, 24 Feb 2025 08:50:08 +0000 Subject: [Okc-wp4] First EO meeting of 2025 (Thursday 27th in A5:1003) Message-ID: <4e2aed3b357b4c3f803520dc3c1eb157@astro.su.se> Hi everyone, We are finally ready to start up the EO meetings again, I am sure you have all missed them dearly. On Thursday, at 13:15 in A5:1003, Matthew Hayes will kick things off. Look forward to seeing you there. Best, Haakon (on behalf of the organisers) When and where: 13:15 in A5:1003 Speaker: Matthew Hayes Title: Massive (and not so massive) black holes in the reionization epoch (and nearby dwarf galaxies) -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Mon Mar 10 08:31:08 2025 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Mon, 10 Mar 2025 07:31:08 +0000 Subject: [Okc-wp4] EO speaker 13th March Message-ID: Dear everyone, Our speaker this week is Ricard Aguilera Miret who will present on magnetic fields in neutron start mergers. When: Thursday March 13th 13:15 Where: A5:1003 Best Haakon (on behalf of the organisers) Speaker: Aguilera Miret Title: Magnetic field dynamics in binary neutron star mergers. Abstract: When two neutron stars merge, their dynamics are governed by extreme physical conditions, including strong spacetime curvature, ultra-high matter densities, intense neutrino emission, and the rapid amplification of magnetic fields. In this talk, I will present the evolution of magnetic fields in a binary neutron star merger, from the inspiral phase to 250 milliseconds after the merger, using large eddy simulations. This technique enables us to achieve convergent results for the turbulent amplification of the magnetic field. I will also discuss the robustness of this amplification, demonstrating that it remains largely unaffected by the initial magnetic field topology, the total mass of the binary system, the mass ratio of its components, their stellar spins, and the equation of state. -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Thu Mar 13 13:02:20 2025 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Thu, 13 Mar 2025 12:02:20 +0000 Subject: [Okc-wp4] Seminar in 15, Magnetic field dynamics in binary neutron star mergers. Message-ID: Reminder of today's talk Aguilera Miret: Magnetic field dynamics in binary neutron star mergers. When two neutron stars merge, their dynamics are governed by extreme physical conditions, including strong spacetime curvature, ultra-high matter densities, intense neutrino emission, and the rapid amplification of magnetic fields. In this talk, I will present the evolution of magnetic fields in a binary neutron star merger, from the inspiral phase to 250 milliseconds after the merger, using large eddy simulations. This technique enables us to achieve convergent results for the turbulent amplification of the magnetic field. I will also discuss the robustness of this amplification, demonstrating that it remains largely unaffected by the initial magnetic field topology, the total mass of the binary system, the mass ratio of its components, their stellar spins, and the equation of state. -------------- next part -------------- An HTML attachment was scrubbed... URL: From smaranika.banerjee at astro.su.se Mon Mar 24 13:20:41 2025 From: smaranika.banerjee at astro.su.se (Smaranika Banerjee) Date: Mon, 24 Mar 2025 12:20:41 +0000 Subject: [Okc-wp4] OKC-EO seminar by Stan Barmentloo on Thursday 27th, 13:15 in A5:1003 Message-ID: <0eccbf69ce8b4373bdad6326182fd982@astro.su.se> Dear all, This week we will have the OKC-EO seminar by Stan Barmentloo. When and where: Thursday 27th, 13:15 in A5:1003 Title: The Mystery of the Missing Carbon: a detailed analysis of carbon emission in SESNe nebular spectra Abstract: Carbon is one of the most abundant elements in the universe, as well as the principal component for life as we know it. Galactic Chemical Evolution (GCE) models predict that carbon in the local universie originates primarily from processing in AGB stars and Core Collapse SNe (CCSNe). However, GCE models typically only use stellar evolution modeling as inputs, and not observations of CCSNe themselves. In this work, we aim to constrain the carbon production in CCSNe, more specifically in Stripped Envelope SNe, by studying their nebular spectra. In the optical, carbon emission can be anaylsed through the lines [C I] 8727, which is strongly blended with the Ca NIR triplet, and [C I] 9824, 9850, a doublet which lies in a spectral region with little coverage in nebular SESNe spectra. To study these lines, we use the SUMO code to create non-LTE spectral models for SESNe in the nebular (> 150d) phase, based on state-of-the-art helium star progenitor models. Furthermore, we create a new Monte Carlo script capable of deblending the individual elemental contributions to the Ca NIR triplet complex in SN spectra. Comparing carbon contributions in the spectral models to observations, we find that the spectral models strongly overproduce the carbon signatures. Potential explanations for this overproduction are discussed. Hope to see many of you there. Kind regards, Smaranika (on behalf of the organisers) =============================================================== Dr. Smaranika Banerjee Astronomy Department, Stockholm University Email: smaranika.banerjee at astro.su.se Old email: smaranikab at astr.tohoku.ac.jp Website: https://sites.google.com/view/smaranikabanerjee/welcome?authuser=0 Zoom: https://stockholmuniversity.zoom.us/j/3760189321 =============================================================== -------------- next part -------------- An HTML attachment was scrubbed... URL: From smaranika.banerjee at astro.su.se Thu Mar 27 09:30:42 2025 From: smaranika.banerjee at astro.su.se (Smaranika Banerjee) Date: Thu, 27 Mar 2025 08:30:42 +0000 Subject: [Okc-wp4] OKC-EO seminar by Stan Barmentloo on Thursday 27th, 13:15 in A5:1003 In-Reply-To: <0eccbf69ce8b4373bdad6326182fd982@astro.su.se> References: <0eccbf69ce8b4373bdad6326182fd982@astro.su.se> Message-ID: <4793b3e28f7c47d48fb281c12972f7ef@astro.su.se> Dear all, A gentle reminder of the OKC-EO seminar today at 13:15 by Stan. Thank you very much. Kind regards, Smaranika (on behalf of the organisers) =============================================================== Dr. Smaranika Banerjee Astronomy Department, Stockholm University Email: smaranika.banerjee at astro.su.se Old email: smaranikab at astr.tohoku.ac.jp Website: https://sites.google.com/view/smaranikabanerjee/welcome?authuser=0 Zoom: https://stockholmuniversity.zoom.us/j/3760189321 =============================================================== ________________________________ From: Okc-wp4-at-fysik.su.se on behalf of Smaranika Banerjee via Okc-wp4-at-fysik.su.se Sent: Monday, March 24, 2025 1:20:41 PM To: EO meeting email Subject: [Okc-wp4] OKC-EO seminar by Stan Barmentloo on Thursday 27th, 13:15 in A5:1003 Dear all, This week we will have the OKC-EO seminar by Stan Barmentloo. When and where: Thursday 27th, 13:15 in A5:1003 Title: The Mystery of the Missing Carbon: a detailed analysis of carbon emission in SESNe nebular spectra Abstract: Carbon is one of the most abundant elements in the universe, as well as the principal component for life as we know it. Galactic Chemical Evolution (GCE) models predict that carbon in the local universie originates primarily from processing in AGB stars and Core Collapse SNe (CCSNe). However, GCE models typically only use stellar evolution modeling as inputs, and not observations of CCSNe themselves. In this work, we aim to constrain the carbon production in CCSNe, more specifically in Stripped Envelope SNe, by studying their nebular spectra. In the optical, carbon emission can be anaylsed through the lines [C I] 8727, which is strongly blended with the Ca NIR triplet, and [C I] 9824, 9850, a doublet which lies in a spectral region with little coverage in nebular SESNe spectra. To study these lines, we use the SUMO code to create non-LTE spectral models for SESNe in the nebular (> 150d) phase, based on state-of-the-art helium star progenitor models. Furthermore, we create a new Monte Carlo script capable of deblending the individual elemental contributions to the Ca NIR triplet complex in SN spectra. Comparing carbon contributions in the spectral models to observations, we find that the spectral models strongly overproduce the carbon signatures. Potential explanations for this overproduction are discussed. Hope to see many of you there. Kind regards, Smaranika (on behalf of the organisers) =============================================================== Dr. Smaranika Banerjee Astronomy Department, Stockholm University Email: smaranika.banerjee at astro.su.se Old email: smaranikab at astr.tohoku.ac.jp Website: https://sites.google.com/view/smaranikabanerjee/welcome?authuser=0 Zoom: https://stockholmuniversity.zoom.us/j/3760189321 =============================================================== -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Fri Mar 28 14:54:34 2025 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Fri, 28 Mar 2025 13:54:34 +0000 Subject: [Okc-wp4] EO seminar next week: April 3rd Chad Finley Message-ID: Dear everyone, To account for the Easter holiday, we shifted the seminars in April around. That means that we will not have our usual two week break and there will be a seminar next week. As you might remember, there were some very intriguing neutrino events from both IceCube and KM3NeT earlier this year. Chad has gratuitously agreed to give us the details, I am very much looking forward to the seminar. There will be a reminder next week, but I wanted to announce it early due to the irregular timing. Best, Haakon (on behalf of the organisers) Thursday April 3rd, 13:15 A5:1003. Chad Finley: Nu News: neutrino alerts (IceCube) and the first EHE neutrino (KM3NeT) Zoom Meeting: https://stockholmuniversity.zoom.us/j/3575421837 -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Thu Apr 3 09:44:55 2025 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Thu, 3 Apr 2025 07:44:55 +0000 Subject: [Okc-wp4] Todays seminar: Chad Finley Nu News: neutrino alerts (IceCube) and the first EHE neutrino (KM3NeT) Message-ID: <9aee66a9ef044cd1b09a5040b3f15f3d@astro.su.se> A reminder of today's EO seminar, where Chad will talk about recent neutrino events. As usual in A5:1003 at 13:15. Best, Haakon (on behalf of the organisers) -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Tue Apr 8 13:12:29 2025 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Tue, 8 Apr 2025 11:12:29 +0000 Subject: [Okc-wp4] Talk/speaker suggetions for OKC day Message-ID: <7b6948de7650460394b5158b058fb48f@astro.su.se> Dear everyone, as mentioned at last weeks seminar, we should come up with suggestions for talks for the OKC day. The talk does not need to be summary talks of the groups activity, but can be talks on topics that would be of interest to the wider OKC. I think last weeks talk was a good example of that. We have been asked to come up with suggestions before the end of the month. If you have any suggestions or want to volunteer, you can talk to me or contact Ariel directly. Best, Haakon -------------- next part -------------- An HTML attachment was scrubbed... URL: From smaranika.banerjee at astro.su.se Fri Apr 18 17:40:14 2025 From: smaranika.banerjee at astro.su.se (Smaranika Banerjee) Date: Fri, 18 Apr 2025 15:40:14 +0000 Subject: [Okc-wp4] OKC EO seminar on 24th by Yang Hu Message-ID: <7d223851def249c48a90b0499dd7c705@astro.su.se> Dear all, Next week we will have EO seminar byYang Hu. When and where: Thursday 24th, 13:15 in A5:1003 Title: When CSM Outmasses Ejecta: the Case of Hydrogen-Rich Superluminous Supernovae 2021aaev Abstract Hydrogen-rich superluminous supernovae (SLSNe-II), characterised by their extreme peak luminosity (�� -20 mag in optical), represent a rare subclass of supernovae (SNe). While a handful have been observed with medium- or high-resolution spectroscopy (most showing narrow H lines; SLSNe-IIn), two key questions persist: (1) Are SLSNe-IIn simply the luminous extreme of the SN IIn population? (2) What are the characteristic circumstellar medium (CSM) parameters that power SLSNe-IIn? Here, we present extensive photometric and spectroscopic observations of SN 2021aaev, a SLSN-IIn at z = 0.1557 with a rise time of 32.5 �� 1.0 days and a peak luminosity of -21.35 �� 0.03 mag (ATLAS o-band). Its early spectra resemble SNe IIn but reveal persistent flash-ionisation features lasting >1 week, marking it as the first SLSN-II flasher. Its late photospheric spectra diverge from typical SNe IIn and show similarity to SN 2017hcc (a SLSN-IIn), with the persistent narrow H�� up to +96 days since first light. Our analysis indicates interaction between 2-5 M�� of ejecta and an extensive (��10^16 cm), heavy (��2 Mej) CSM. This makes SN 2021aaev a compelling case for understanding the diversity within SLSNe-II and the connection (or lack thereof) between SLSNe-IIn and SNe IIn. See you all there. Kind regards, Smaranika (on behalf of organizers) =============================================================== Dr. Smaranika Banerjee Astronomy Department, Stockholm University Email: smaranika.banerjee at astro.su.se Old email: smaranikab at astr.tohoku.ac.jp Website: https://sites.google.com/view/smaranikabanerjee/welcome?authuser=0 Zoom: https://stockholmuniversity.zoom.us/j/3760189321 =============================================================== -------------- next part -------------- An HTML attachment was scrubbed... URL: From smaranika.banerjee at astro.su.se Thu Apr 24 10:33:36 2025 From: smaranika.banerjee at astro.su.se (Smaranika Banerjee) Date: Thu, 24 Apr 2025 08:33:36 +0000 Subject: [Okc-wp4] OKC EO seminar on 24th by Yang Hu In-Reply-To: <7d223851def249c48a90b0499dd7c705@astro.su.se> References: <7d223851def249c48a90b0499dd7c705@astro.su.se> Message-ID: <2f2648d61a024247ba5a2b9cbaf75c36@astro.su.se> Dear all, Reminder of the talk today. Thank you very much. Kind regards, Smaranika (on behalf of organizers) =============================================================== Dr. Smaranika Banerjee Astronomy Department, Stockholm University Email: smaranika.banerjee at astro.su.se Old email: smaranikab at astr.tohoku.ac.jp Website: https://sites.google.com/view/smaranikabanerjee/welcome?authuser=0 Zoom: https://stockholmuniversity.zoom.us/j/3760189321 =============================================================== ________________________________ From: Okc-wp4-at-fysik.su.se on behalf of Smaranika Banerjee via Okc-wp4-at-fysik.su.se Sent: Friday, April 18, 2025 5:40:14 PM To: EO meeting email Subject: [Okc-wp4] OKC EO seminar on 24th by Yang Hu Dear all, Next week we will have EO seminar byYang Hu. When and where: Thursday 24th, 13:15 in A5:1003 Title: When CSM Outmasses Ejecta: the Case of Hydrogen-Rich Superluminous Supernovae 2021aaev Abstract Hydrogen-rich superluminous supernovae (SLSNe-II), characterised by their extreme peak luminosity (�� -20 mag in optical), represent a rare subclass of supernovae (SNe). While a handful have been observed with medium- or high-resolution spectroscopy (most showing narrow H lines; SLSNe-IIn), two key questions persist: (1) Are SLSNe-IIn simply the luminous extreme of the SN IIn population? (2) What are the characteristic circumstellar medium (CSM) parameters that power SLSNe-IIn? Here, we present extensive photometric and spectroscopic observations of SN 2021aaev, a SLSN-IIn at z = 0.1557 with a rise time of 32.5 �� 1.0 days and a peak luminosity of -21.35 �� 0.03 mag (ATLAS o-band). Its early spectra resemble SNe IIn but reveal persistent flash-ionisation features lasting >1 week, marking it as the first SLSN-II flasher. Its late photospheric spectra diverge from typical SNe IIn and show similarity to SN 2017hcc (a SLSN-IIn), with the persistent narrow H�� up to +96 days since first light. Our analysis indicates interaction between 2-5 M�� of ejecta and an extensive (��10^16 cm), heavy (��2 Mej) CSM. This makes SN 2021aaev a compelling case for understanding the diversity within SLSNe-II and the connection (or lack thereof) between SLSNe-IIn and SNe IIn. See you all there. Kind regards, Smaranika (on behalf of organizers) =============================================================== Dr. Smaranika Banerjee Astronomy Department, Stockholm University Email: smaranika.banerjee at astro.su.se Old email: smaranikab at astr.tohoku.ac.jp Website: https://sites.google.com/view/smaranikabanerjee/welcome?authuser=0 Zoom: https://stockholmuniversity.zoom.us/j/3760189321 =============================================================== -------------- next part -------------- An HTML attachment was scrubbed... URL: From smaranika.banerjee at astro.su.se Tue May 6 17:01:40 2025 From: smaranika.banerjee at astro.su.se (Smaranika Banerjee) Date: Tue, 6 May 2025 15:01:40 +0000 Subject: [Okc-wp4] OKC EO talk by Bhaskar Biswas on Thursday 8th, 13:15 in A5:1003 Message-ID: <91b0306658b147889b5cfbc15957b2aa@astro.su.se> Dear all, This week Bhaskar Biswas (who used to be an OKC member) is visiting us from Hamburg. He will talk about the following : When and where: Thursday 8th, 13:15 in A5:1003 Title: One Framework to Rule Them All: EoS, Populations, H₀, and Gravity from Multimessenger DataAbstract: Multimessenger observations of neutron star mergers offer a powerful way to study dense matter, stellar populations, cosmic expansion, and gravity itself. In this talk, I will present a single, unified framework that allows us to infer the neutron star equation of state, the population properties of merging systems, the Hubble constant (H₀), and possible deviations from general relativity—all at the same time. This method combines gravitational wave data, electromagnetic observations, and theoretical inputs from nuclear physics in a consistent Bayesian approach. I will show how this framework works in practice, what it tells us about the physics of neutron stars and the universe, and how it can help address open questions like the Hubble tension or the nature of gravity. By connecting nuclear physics, astrophysics, and cosmology in one analysis, this approach opens a path to deeper understanding through multimessenger data. See many of you there. Thank you very much. Kind regards, Smaranika (on behalf of the organisers) =============================================================== Dr. Smaranika Banerjee Astronomy Department, Stockholm University Email: smaranika.banerjee at astro.su.se Old email: smaranikab at astr.tohoku.ac.jp Website: https://sites.google.com/view/smaranikabanerjee/welcome?authuser=0 Zoom: https://stockholmuniversity.zoom.us/j/3760189321 =============================================================== -------------- next part -------------- An HTML attachment was scrubbed... URL: From smaranika.banerjee at astro.su.se Thu May 8 10:12:50 2025 From: smaranika.banerjee at astro.su.se (Smaranika Banerjee) Date: Thu, 8 May 2025 08:12:50 +0000 Subject: [Okc-wp4] OKC EO talk by Bhaskar Biswas on Thursday 8th, 13:15 in A5:1003 In-Reply-To: <91b0306658b147889b5cfbc15957b2aa@astro.su.se> References: <91b0306658b147889b5cfbc15957b2aa@astro.su.se> Message-ID: Dear all, Reminder of the talk today. Thank you very much. Kind regards, Smaranika =============================================================== Dr. Smaranika Banerjee Astronomy Department, Stockholm University Email: smaranika.banerjee at astro.su.se Old email: smaranikab at astr.tohoku.ac.jp Website: https://sites.google.com/view/smaranikabanerjee/welcome?authuser=0 Zoom: https://stockholmuniversity.zoom.us/j/3760189321 =============================================================== ________________________________ From: Smaranika Banerjee Sent: Tuesday, May 6, 2025 5:01:40 PM To: EO meeting email Cc: Haakon Andresen; bhaskar.biswas at uni-hamburg.de Subject: OKC EO talk by Bhaskar Biswas on Thursday 8th, 13:15 in A5:1003 Dear all, This week Bhaskar Biswas (who used to be an OKC member) is visiting us from Hamburg. He will talk about the following : When and where: Thursday 8th, 13:15 in A5:1003 Title: One Framework to Rule Them All: EoS, Populations, H₀, and Gravity from Multimessenger DataAbstract: Multimessenger observations of neutron star mergers offer a powerful way to study dense matter, stellar populations, cosmic expansion, and gravity itself. In this talk, I will present a single, unified framework that allows us to infer the neutron star equation of state, the population properties of merging systems, the Hubble constant (H₀), and possible deviations from general relativity—all at the same time. This method combines gravitational wave data, electromagnetic observations, and theoretical inputs from nuclear physics in a consistent Bayesian approach. I will show how this framework works in practice, what it tells us about the physics of neutron stars and the universe, and how it can help address open questions like the Hubble tension or the nature of gravity. By connecting nuclear physics, astrophysics, and cosmology in one analysis, this approach opens a path to deeper understanding through multimessenger data. See many of you there. Thank you very much. Kind regards, Smaranika (on behalf of the organisers) =============================================================== Dr. Smaranika Banerjee Astronomy Department, Stockholm University Email: smaranika.banerjee at astro.su.se Old email: smaranikab at astr.tohoku.ac.jp Website: https://sites.google.com/view/smaranikabanerjee/welcome?authuser=0 Zoom: https://stockholmuniversity.zoom.us/j/3760189321 =============================================================== -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Fri May 16 08:54:57 2025 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Fri, 16 May 2025 06:54:57 +0000 Subject: [Okc-wp4] EO seminar on the 22nd of May Message-ID: Dear Everyone, Mark Pearce will present recent XL-Calibur results in week's EO seminar, I highly recommend the seminar to all crab, x-ray, and balloon enthusiasts. Where: A5:1003 When: Thursday 22nd of May at 13:15 Best, Haakon (on behalf of the organisers) Speaker: Mark Pearce Hard X-ray polarimetry of the Crab with XL-Calibur In summer 2024, the linear polarisation of hard X-ray emission from the Crab pulsar and wind nebula was measured by XL-Calibur. Observations were made during a week-long stratospheric balloon flight between Sweden and Canada. The addition of polarimetry to the standard high-energy measurement techniques of spectroscopy, timing and imaging, allows systematically new tests of source emission models. XL-Calibur is the most sensitive hard X-ray polarimetry mission to date, offering an order-of-magnitude improvement in signal-to-background performance compared to preceding missions. The energy range (15-80 keV) complements the NASA/ASI IXPE mission (2-8 keV), allowing broadband studies. I will introduce the XL-Calibur mission, explain how the linear polarisation of hard X-rays is measured, and summarise results from Crab observations. Plans for further hard X-ray polarimetry missions will be briefly described. -------------- next part -------------- An HTML attachment was scrubbed... URL: From smaranika.banerjee at astro.su.se Tue Jun 3 17:28:08 2025 From: smaranika.banerjee at astro.su.se (Smaranika Banerjee) Date: Tue, 3 Jun 2025 15:28:08 +0000 Subject: [Okc-wp4] OKC-EO talk this week Message-ID: Dear all, I posted on Slack before, here is the reminder of the OKC-EO talk this week by Seiji Toshikage, who is visiting us from Japan from June 3rd - 11th. Also, we will go to dinner this Friday, please feel free to join. Title: The First Search for Optical Transient as a Counterpart of a Month-timescale IceCube Neutrino Multiplet Event Abstract: Optical transients with timescale of months, such as supernovae (SNe) and tidal disruption events (TDEs), are candidates of high-energy neutrino sources. Multiple neutrino detections from the same direction within a month timescale provide a unique opportunity to identify such optical counterparts in the local Universe. In this work, we conduct archival search for the optical counterpart of an IceCube triplet event using the data of Zwicky Transient Facility. We develop a dedicated alert filtering system and validate the performance by following a blind analysis method. Applying this filtering system to the data after the detections of the IceCube triplet event, we find no transient candidates within the localization area. Assuming that the IceCube triplet event originates from an astrophysical source, we constrain parameters of optical light curve, a peak luminosity and a decay timescale, using a simple signal model that is motivated by TDEs and superluminous SNe (SLSNe). Assuming the case with no time lag between neutrino detections and optical peak, almost entire parameter space of the known TDEs and SLSNe would be constrained. To give constraints on transients with a rapidly evolving light curve, immediate, realtime follow-up observations for future neutrino multiplet events are crucial. Thank you very much. Kind regards, Smaranika =============================================================== Dr. Smaranika Banerjee Astronomy Department, Stockholm University Email: smaranika.banerjee at astro.su.se Old email: smaranikab at astr.tohoku.ac.jp Website: https://sites.google.com/view/smaranikabanerjee/welcome?authuser=0 Zoom: https://stockholmuniversity.zoom.us/j/3760189321 =============================================================== -------------- next part -------------- An HTML attachment was scrubbed... URL: From smaranika.banerjee at astro.su.se Thu Jun 5 09:12:55 2025 From: smaranika.banerjee at astro.su.se (Smaranika Banerjee) Date: Thu, 5 Jun 2025 07:12:55 +0000 Subject: [Okc-wp4] OKC-EO talk this week In-Reply-To: References: Message-ID: Dear all, A gentle reminder of the talk today. Thank you very much. Kind regards, Smaranika (on behalf of organisers) =============================================================== Dr. Smaranika Banerjee Astronomy Department, Stockholm University Email: smaranika.banerjee at astro.su.se Old email: smaranikab at astr.tohoku.ac.jp Website: https://sites.google.com/view/smaranikabanerjee/welcome?authuser=0 Zoom: https://stockholmuniversity.zoom.us/j/3760189321 =============================================================== ________________________________ From: Okc-wp4-at-fysik.su.se on behalf of Smaranika Banerjee via Okc-wp4-at-fysik.su.se Sent: Tuesday, June 3, 2025 5:28:08 PM To: EO meeting email Subject: [Okc-wp4] OKC-EO talk this week Dear all, I posted on Slack before, here is the reminder of the OKC-EO talk this week by Seiji Toshikage, who is visiting us from Japan from June 3rd - 11th. Also, we will go to dinner this Friday, please feel free to join. Title: The First Search for Optical Transient as a Counterpart of a Month-timescale IceCube Neutrino Multiplet Event Abstract: Optical transients with timescale of months, such as supernovae (SNe) and tidal disruption events (TDEs), are candidates of high-energy neutrino sources. Multiple neutrino detections from the same direction within a month timescale provide a unique opportunity to identify such optical counterparts in the local Universe. In this work, we conduct archival search for the optical counterpart of an IceCube triplet event using the data of Zwicky Transient Facility. We develop a dedicated alert filtering system and validate the performance by following a blind analysis method. Applying this filtering system to the data after the detections of the IceCube triplet event, we find no transient candidates within the localization area. Assuming that the IceCube triplet event originates from an astrophysical source, we constrain parameters of optical light curve, a peak luminosity and a decay timescale, using a simple signal model that is motivated by TDEs and superluminous SNe (SLSNe). Assuming the case with no time lag between neutrino detections and optical peak, almost entire parameter space of the known TDEs and SLSNe would be constrained. To give constraints on transients with a rapidly evolving light curve, immediate, realtime follow-up observations for future neutrino multiplet events are crucial. Thank you very much. Kind regards, Smaranika =============================================================== Dr. Smaranika Banerjee Astronomy Department, Stockholm University Email: smaranika.banerjee at astro.su.se Old email: smaranikab at astr.tohoku.ac.jp Website: https://sites.google.com/view/smaranikabanerjee/welcome?authuser=0 Zoom: https://stockholmuniversity.zoom.us/j/3760189321 =============================================================== -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Mon Jun 16 09:53:32 2025 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Mon, 16 Jun 2025 07:53:32 +0000 Subject: [Okc-wp4] Seminar on Thursday the 19th Message-ID: <111ce69b3c114bd58dc6764eacb74e42@astro.su.se> Dear Everyone, This week's seminar will be about Type Ia supernovae, join us in A5:1003 at 13:15 for an explosive event. Best, Haakon (on behalf of the organisers) Konstantinos Tsalapatas A thermonuclear supernova interacting with hydrogen- and helium-deficient circumstellar material It is widely accepted that SNe Ia are the thermonuclear runaway explosion of a White Dwarf (WD), yet no consensus has been reached regarding their progenitor systems. The growing diversity of observed Type Ia that deviate from their normal behaviour could hold crucial insights into the progenitor pathways. The emerging Type Ia-CSM is a family of explosions that strongly interact with their ambient medium. This particular sub-type is better explained within the context of the Single Degenerate channel. There exists only a single outlier, SN 2020eyj, which lacks strong H lines but exhibits clear He features. SN 2020eyj connected Sne Ia with a He-donor companion. In our study, we present a Type Ia-CSM interacting with a H- and He-poor medium. Our object shares a lot of common photometric and spectroscopic characteristics with SN 2020eyj and other bona fide SNe Ia-CSM. However, the unique composition of its circumstellar medium challenges the Single Degenerate channel. -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Thu Jun 19 08:02:29 2025 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Thu, 19 Jun 2025 06:02:29 +0000 Subject: [Okc-wp4] Reminder EO meeting today, 13:15 in A5:1003 Message-ID: Dear Everyone, A quick reminder of today's seminar. - Haakon Konstantinos Tsalapatas A thermonuclear supernova interacting with hydrogen- and helium-deficient circumstellar material It is widely accepted that SNe Ia are the thermonuclear runaway explosion of a White Dwarf (WD), yet no consensus has been reached regarding their progenitor systems. The growing diversity of observed Type Ia that deviate from their normal behaviour could hold crucial insights into the progenitor pathways. The emerging Type Ia-CSM is a family of explosions that strongly interact with their ambient medium. This particular sub-type is better explained within the context of the Single Degenerate channel. There exists only a single outlier, SN 2020eyj, which lacks strong H lines but exhibits clear He features. SN 2020eyj connected Sne Ia with a He-donor companion. In our study, we present a Type Ia-CSM interacting with a H- and He-poor medium. Our object shares a lot of common photometric and spectroscopic characteristics with SN 2020eyj and other bona fide SNe Ia-CSM. However, the unique composition of its circumstellar medium challenges the Single Degenerate channel. -------------- next part -------------- An HTML attachment was scrubbed... URL: