المؤلفون: Clocchiatti, Alejandro, Rodríguez, Ósmar, Morales, Ariel Órdenes, Cuevas-Tapia, Benjamín

مصطلحات موضوعية: Astrophysics - Cosmology and Nongalactic Astrophysics

الوصف: An analysis of the Cosmological Constant $\Omega_\Lambda$ fitted to subsamples of the Pantheon+ Type Ia SN sample spanning 2$\pi$ sterradians for a grid of 432 pole positions covering the whole sky reveals two large scale asymmetries. One of them is closely aligned with the Galactic North-South direction and the other points approximately towards RA$\sim 217.5^\circ$ Dec$\sim -26.4^\circ$, $\sim$50.9 degrees from the CMB dipole Apex. The signal to noise ratio (S/N) of the multiple $\Omega_\Lambda$ measurements in these directions is $3.2\lesssim $ S/N $\lesssim 8.4$. The first asymmetry is puzzling, and would indicate a systematic effect related with the distribution of Pantheon+ SNe on the sky and, probably, how the correction for reddening in the Galaxy is calculated. The second one, which entails a 2.8-$\sigma$ tension between $\Omega_\Lambda$ measure in opposite directions, bears strong implications on its interpretation as Dark Energy: It is consistent with the prediction for tilted observers located in a Friedmann-Robertson-Walker universe who could measure an acceleration or a deceleration with a dipolar asymmetry, irrespective of what the universe as a whole is doing. In this case, $\Omega_\Lambda$ would not be a physical entity, a real Dark Energy, but an apparent effect associated with the relativistic frame of reference transformation.
Comment: 13 pages, 8 figures

الوصول الحر: http://arxiv.org/abs/2406.00273Test

المؤلفون: Silva-Farfán, Javier, Förster, Francisco, Moriya, Takashi J., Hernández-García, L., Arancibia, A. M. Muñoz, Sánchez-Sáez, P., Anderson, Joseph P., Tonry, John L., Clocchiatti, Alejandro

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: We report an analysis of a sample of 186 spectroscopically confirmed Type II supernova (SN) light curves (LCs) obtained from a combination of Zwicky Transient Facility (ZTF) and Asteroid Terrestrial-impact Last Alert System (ATLAS) observations. We implement a method to infer physical parameters from these LCs using hydrodynamic models that take into account the progenitor mass, the explosion energy, and the presence of circumstellar matter (CSM). The CSM is modelled via the mass loss rate, wind acceleration at the surface of the progenitor star with a $\beta$ velocity law, and the CSM radius. We also infer the time of explosion, attenuation (A$_V$), and the redshift for each SN. Our results favor low-mass progenitor stars (M$_{ZAMS}$\,$<$14\,$M_\odot$) with a dense CSM ($\dot{M}$ $>$ 10$^{-3}$ [M$_\odot$ yr$^{-1}$], a CSM radius of $\sim$ 10$^{15}$ cm, and $\beta$ $>$ 2). Additionally, we find that the redshift inferred from the supernova LCs is significantly more accurate than that inferred using the host galaxy photometric redshift, suggesting that this method could be used to infer more accurate host galaxy redshifts from large samples of SNe II in the LSST era. Lastly, we compare our results with similar works from the literature.

الوصول الحر: http://arxiv.org/abs/2404.12620Test

المؤلفون: Siebert, Matthew R., Kwok, Lindsey A., Johansson, Joel, Jha, Saurabh W., Blondin, Stéphane, Dessart, Luc, Foley, Ryan J., Hillier, D. John, Larison, Conor, Pakmor, Rüdiger, Temim, Tea, Andrews, Jennifer E., Auchettl, Katie, Badenes, Carles, Barna, Barnabas, Bostroem, K. Azalee, Newman, Max J. Brenner, Brink, Thomas G., Bustamante-Rosell, María José, Camacho-Neves, Yssavo, Clocchiatti, Alejandro, Coulter, David A., Davis, Kyle W., Deckers, Maxime, Dimitriadis, Georgios, Dong, Yize, Farah, Joseph, Filippenko, Alexei V., Flörs, Andreas, Fox, Ori D., Garnavich, Peter, Gonzalez, Estefania Padilla, Graur, Or, Hambsch, Franz-Josef, Hosseinzadeh, Griffin, Howell, D. Andrew, Hughes, John P., Kerzendorf, Wolfgang E., Saux, Xavier K. Le, Maeda, Keiichi, Maguire, Kate, McCully, Curtis, Mihalenko, Cassidy, Newsome, Megan, O'Brien, John T., Pearson, Jeniveve, Pellegrino, Craig, Pierel, Justin D. R., Polin, Abigail, Rest, Armin, Rojas-Bravo, César, Sand, David J., Schwab, Michaela, Shahbandeh, Melissa, Shrestha, Manisha, Smith, Nathan, Strolger, Louis-Gregory, Szalai, Tamás, Taggart, Kirsty, Terreran, Giacomo, Terwel, Jacco H., Tinyanont, Samaporn, Valenti, Stefano, Vinkó, József, Wheeler, J. Craig, Yang, Yi, Zheng, Weikang, Ashall, Chris, Derkacy, James M., Galbany, Lluís, Hoeflich, Peter, Hsiao, Eric, De Jaeger, Thomas, Lu, Jing, Maund, Justyn, Medler, Kyle, Morrell, Nidia, Shappee, Benjamin J., Stritzinger, Maximilian, Suntzeff, Nicholas, Tucker, Michael, Wang, Lifan

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics

الوصف: Nebular-phase observations of peculiar Type Ia supernovae (SNe Ia) provide important constraints on progenitor scenarios and explosion dynamics for both these rare SNe and the more common, cosmologically useful SNe Ia. We present observations from an extensive ground-based and space-based follow-up campaign to characterize SN 2022pul, a "super-Chandrasekhar" mass SN Ia (alternatively "03fg-like" SN), from before peak brightness to well into the nebular phase across optical to mid-infrared (MIR) wavelengths. The early rise of the light curve is atypical, exhibiting two distinct components, consistent with SN Ia ejecta interacting with dense carbon-oxygen rich circumstellar material (CSM). In the optical, SN 2022pul is most similar to SN 2012dn, having a low estimated peak luminosity ($M_{B}=-18.9$ mag) and high photospheric velocity relative to other 03fg-like SNe. In the nebular phase, SN 2022pul adds to the increasing diversity of the 03fg-like subclass. From 168 to 336 days after peak $B$-band brightness, SN 2022pul exhibits asymmetric and narrow emission from [O I] $\lambda\lambda 6300,\ 6364$ (${\rm FWHM} \approx 2{,}000$ km s$^{-1}$), strong, broad emission from [Ca II] $\lambda\lambda 7291,\ 7323$ (${\rm FWHM} \approx 7{,}300$ km s$^{-1}$), and a rapid Fe III to Fe II ionization change. Finally, we present the first-ever optical-to-mid-infrared (MIR) nebular spectrum of an 03fg-like SN Ia using data from JWST. In the MIR, strong lines of neon and argon, weak emission from stable nickel, and strong thermal dust emission (with $T \approx 500$ K), combined with prominent [O I] in the optical, suggest that SN 2022pul was produced by a white dwarf merger within carbon/oxygen-rich CSM.
Comment: 23 pages, 11 figures, submitted to ApJ

الوصول الحر: http://arxiv.org/abs/2308.12449Test

المؤلفون: Kwok, Lindsey A., Siebert, Matthew R., Johansson, Joel, Jha, Saurabh W., Blondin, Stephane, Dessart, Luc, Foley, Ryan J., Hillier, D. John, Larison, Conor, Pakmor, Ruediger, Temim, Tea, Andrews, Jennifer E., Auchettl, Katie, Badenes, Carles, Barna, Barnabas, Bostroem, K. Azalee, Newman, Max J. Brenner, Brink, Thomas G., Bustamante-Rosell, Maria Jose, Camacho-Neves, Yssavo, Clocchiatti, Alejandro, Coulter, David A., Davis, Kyle W., Deckers, Maxime, Dimitriadis, Georgios, Dong, Yize, Farah, Joseph, Filippenko, Alexei V., Flors, Andreas, Fox, Ori D., Garnavich, Peter, Gonzalez, Estefania Padilla, Graur, Or, Hambsch, Franz-Josef, Hosseinzadeh, Griffin, Howell, D. Andrew, Hughes, John P., Kerzendorf, Wolfgang E., Saux, Xavier K. Le, Maeda, Keiichi, Maguire, Kate, McCully, Curtis, Mihalenko, Cassidy, Newsome, Megan, O'Brien, John T., Pearson, Jeniveve, Pellegrino, Craig, Pierel, Justin D. R., Polin, Abigail, Rest, Armin, Rojas-Bravo, Cesar, Sand, David J., Schwab, Michaela, Shahbandeh, Melissa, Shrestha, Manisha, Smith, Nathan, Strolger, Louis-Gregory, Szalai, Tamas, Taggart, Kirsty, Terreran, Giacomo, Terwel, Jacco H., Tinyanont, Samaporn, Valenti, Stefano, Vinko, Jozsef, Wheeler, J. Craig, Yang, Yi, Zheng, WeiKang, Ashall, Chris, DerKacy, James M., Galbany, Lluis, Hoeflich, Peter, de Jaeger, Thomas, Lu, Jing, Maund, Justyn, Medler, Kyle, Morrell, Nidia, Shappee, Benjamin J., Stritzinger, Maximilian, Suntzeff, Nicholas, Tucker, Michael, Wang, Lifan

المصدر: The Astrophysical Journal, Volume 966, Issue 1, id.135, 18 pp., May 2024

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics

الوصف: We present an analysis of ground-based and JWST observations of SN~2022pul, a peculiar "03fg-like" (or "super-Chandrasekhar") Type Ia supernova (SN Ia), in the nebular phase at 338d post explosion. Our combined spectrum continuously covers 0.4--14 $\mu$m and includes the first mid-infrared spectrum of an 03fg-like SN Ia. Compared to normal SN Ia 2021aefx, SN 2022pul exhibits a lower mean ionization state, asymmetric emission-line profiles, stronger emission from the intermediate-mass elements (IMEs) argon and calcium, weaker emission from iron-group elements (IGEs), and the first unambiguous detection of neon in a SN Ia. Strong, broad, centrally peaked [Ne II] line at 12.81 $\mu$m was previously predicted as a hallmark of "violent merger'' SN Ia models, where dynamical interaction between two sub-$M_{ch}$ white dwarfs (WDs) causes disruption of the lower mass WD and detonation of the other. The violent merger scenario was already a leading hypothesis for 03fg-like SNe Ia; in SN 2022pul it can explain the large-scale ejecta asymmetries seen between the IMEs and IGEs and the central location of narrow oxygen and broad neon. We modify extant models to add clumping of the ejecta to better reproduce the optical iron emission, and add mass in the innermost region ($< 2000$ km s$^{-1}$) to account for the observed narrow [O I]~$\lambda\lambda6300$, 6364 emission. A violent WD-WD merger explains many of the observations of SN 2022pul, and our results favor this model interpretation for the subclass of 03fg-like SN Ia.
Comment: 20 pages, 10 figures, published in ApJ

الوصول الحر: http://arxiv.org/abs/2308.12450Test

المؤلفون: Zenati, Yossef, Wang, Qinan, Bobrick, Alexey, DeMarchi, Lindsay, Glanz, Hila, Rozner, Mor, Rest, Armin, Metzger, Brian D., Margutti, Raffaella, Gomez, Sebastian, Smith, Nathan, Toonen, Silvia, Bright, Joe S., Norman, Colin, Foley, Ryan J., Gagliano, Alexander, Krolik, Julian H., Smartt, Stephen J., Villar, Ashley V., Narayan, Gautham, Fox, Ori, Auchettl, Katie, Brethauer, Daniel, Clocchiatti, Alejandro, Coelln, Sophie V., Coppejans, Deanne L., Dimitriadis, Georgios, Doroszmai, Andris, Drout, Maria, Jacobson-Galan, Wynn, Gao, Bore, Ridden-Harper, Ryan, Kilpatrick, Charles Donald, Laskar, Tanmoy, Matthews, David, Rest, Sofia, Smith, Ken W., Stauffer, Candice McKenzie, Stroh, Michael C., Strolger, Louis-Gregory, Terreran, Giacomo, Pierel, Justin D. R., Piro, Anthony L.

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena

الوصف: We present multi-band ATLAS photometry for SN 2019tsf, a stripped-envelope Type Ib supernova (SESN). The SN shows a triple-peaked light curve and a late (re-)brightening, making it unique among stripped-envelope systems. The re-brightening observations represent the latest photometric measurements of a multi-peaked Type Ib SN to date. As late-time photometry and spectroscopy suggest no hydrogen, the potential circumstellar material (CSM) must be H-poor. Moreover, late (>150 days) spectra show no signs of narrow emission lines, further disfavouring CSM interaction. On the contrary, an extended CSM structure is seen through a follow-up radio campaign with Karl G. Jansky Very Large Array (VLA), indicating a source of bright optically thick radio emission at late times, which is highly unusual among H-poor SESNe. We attribute this phenomenology to an interaction of the supernova ejecta with spherically-asymmetric CSM, potentially disk-like, and we present several models that can potentially explain the origin of this rare Type Ib supernova. The warped disc model paints a novel picture, where the tertiary companion perturbs the progenitors CSM, that can explain the multi-peaked light curves of SNe, and here we apply it to SN 2019tsf. This SN 2019tsf is likely a member of a new sub-class of Type Ib SNe and among the recently discovered class of SNe that undergo mass transfer at the moment of explosion
Comment: 23 pages, Comments are welcome, Submitted to ApJ

الوصول الحر: http://arxiv.org/abs/2207.07146Test

المؤلفون: Cartier, Régis, Hamuy, Mario, Contreras, Carlos, Anderson, Joseph P., Phillips, Mark M., Morrell, Nidia, Stritzinger, Maximilian D., Hueichapan, Emilio D., Clocchiatti, Alejandro, Roth, Miguel, Thomas-Osip, Joanna, González, Luis E.

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Solar and Stellar Astrophysics

الوصف: We present optical photometry and spectroscopy of the superluminous SN 2002gh from maximum light to $+204$ days, obtained as part of the Carnegie Type II Supernova (CATS) project. SN 2002gh is among the most luminous discovered supernovae ever, yet it remained unnoticed for nearly two decades. Using Dark Energy Camera archival images we identify the potential SN host galaxy as a faint dwarf galaxy, presumably having low metallicity, and in an apparent merging process with other nearby dwarf galaxies. We show that SN 2002gh is among the brightest hydrogen-poor SLSNe with $M_{V} = -22.40 \pm 0.02$, with an estimated peak bolometric luminosity of $2.6 \pm 0.1 \times 10^{44}$ erg s$^{-1}$. We discount the decay of radioactive nickel as the main SN power mechanism, and assuming that the SN is powered by the spin down of a magnetar we obtain two alternative solutions. The first case, is characterized by significant magnetar power leakage, and $M_{\mathrm{ej}}$ between 0.6 and 3.2 $M_{\odot}$, $P_{\mathrm{spin}} = 3.2$ ms, and $B = 5 \times 10^{13}$ G. The second case does not require power leakage, resulting in a huge ejecta mass of about 30 $M_{\odot}$, a fast spin period of $P_{\mathrm{spin}} \sim 1$ ms, and $B\sim 1.6 \times 10^{14}$ G. We estimate a zero-age main-sequence mass between 14 and 25 $M_{\odot}$ for the first case and of about 135 $M_{\odot}$ for the second case. The latter case would place the SN progenitor among the most massive stars observed to explode as a SN.
Comment: 25 pages, 18 figures, accepted for publication in MNRAS

الوصول الحر: http://arxiv.org/abs/2108.09828Test

المؤلفون: Kwok, Lindsey A., Siebert, Matthew R., Johansson, Joel, Jha, Saurabh W., Blondin, Stéphane, Dessart, Luc, Foley, Ryan J., Hillier, D. John, Larison, Conor, Pakmor, Rüdiger, Temim, Tea, Andrews, Jennifer E., Auchettl, Katie, Badenes, Carles, Barnabas, Barna, Bostroem, K. Azalee, Brenner Newman, Max J., Brink, Thomas G., Bustamante-Rosell, María José, Camacho-Neves, Yssavo, Clocchiatti, Alejandro, Coulter, David A., Davis, Kyle W., Deckers, Maxime, Dimitriadis, Georgios, Dong, Yize, Farah, Joseph, Filippenko, Alexei V., Flörs, Andreas, Fox, Ori D., Garnavich, Peter, Padilla Gonzalez, Estefania, Graur, Or, Hambsch, Franz-Josef, Hosseinzadeh, Griffin, Howell, D. Andrew, Hughes, John P., Kerzendorf, Wolfgang E., Saux, Xavier K., Maeda, Keiichi, Maguire, Kate, McCully, Curtis, Mihalenko, Cassidy, Newsome, Megan, O'Brien, John T., Pearson, Jeniveve, Pellegrino, Craig, Pierel, Justin D. R., Polin, Abigail, Rest, Armin, Rojas-Bravo, César, Sand, David J., Schwab, Michaela, Shahbandeh, Melissa, Shrestha, Manisha, Smith, Nathan, Strolger, Louis-Gregory, Szalai, Tamás, Taggart, Kirsty, Terreran, Giacomo, Terwel, Jacco H., Tinyanont, Samaporn, Valenti, Stefano, Vinkó, József, Wheeler, J. Craig, Yang, Yi, Zheng, WeiKang, Ashall, Chris, DerKacy, James M., Galbany, Lluís, Hoeflich, Peter, de Jaeger, Thomas, Lu, Jing, Maund, Justyn, Medler, Kyle, Morell, Nidia, Shappee, Benjamin J., Stritzinger, Maximilian, Suntzeff, Nicholas, Tucker, Michael, Wang, Lifan

المصدر: Astrophysical Journal, 966(1), 135, (2024-05-01)

الوصف: We present an analysis of ground-based and JWST observations of SN 2022pul, a peculiar "03fg-like" (or "super-Chandrasekhar") Type Ia supernova (SN Ia), in the nebular phase at 338 days postexplosion. Our combined spectrum continuously covers 0.4–14μm and includes the first mid-infrared spectrum of a 03fg-like SN Ia. Compared to normal SN Ia 2021aefx, SN 2022pul exhibits a lower mean ionization state, asymmetric emission-line profiles, stronger emission from the intermediate-mass elements (IMEs) argon and calcium, weaker emission from iron-group elements (IGEs), and the first unambiguous detection of neon in a SN Ia. A strong, broad, centrally peaked [Neii] line at 12.81μm was previously predicted as a hallmark of "violent merger" SN Ia models, where dynamical interaction between two sub-MChwhite dwarfs (WDs) causes disruption of the lower-mass WD and detonation of the other. The violent merger scenario was already a leading hypothesis for 03fg-like SNe Ia; in SN 2022pul it can explain the large-scale ejecta asymmetries seen between the IMEs and IGEs and the central location of narrow oxygen and broad neon. We modify extant models to add clumping of the ejecta to reproduce the optical iron emission better, and add mass in the innermost region (<2000 km s−1) to account for the observed narrow [Oi]λλ6300, 6364 emission. A violent WD–WD merger explains many of the observations of SN 2022pul, and our results favor this model interpretation for the subclass of 03fg-like SNe Ia. ; © 2024. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of theCreative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. ; This work is based on observations made with the NASA/ESA/CSA JWST as part of program #02072. We thank Shelly Meyett for her consistently excellent work scheduling the JWST observations, Sarah Kendrew for assistance with the MIRI ...

العلاقة: https://doi.org/10.3847/1538-4357/ad2c0dTest; oai:authors.library.caltech.edu:8fhzj-t9331

الإتاحة: https://doi.org/10.3847/1538-4357/ad2c0dTest

المؤلفون: Siebert, Matthew R., Kwok, Lindsey A., Johansson, Joel, Jha, Saurabh W., Blondin, Stéphane, Dessart, Luc, Foley, Ryan J., Hillier, D. John, Larison, Conor, Pakmor, Rüdiger, Temim, Tea, Andrews, Jennifer E., Auchettl, Katie, Badenes, Carles, Barna, Barnabas, Bostroem, K. Azalee, Brenner Newman, Max J., Brink, Thomas G., Bustamante-Rosell, María José, Camacho-Neves, Yssavo, Clocchiatti, Alejandro, Coulter, David A., Davis, Kyle W., Deckers, Maxime, Dimitriadis, Georgios, Dong, Yize, Farah, Joseph, Filippenko, Alexei V., Flörs, Andreas, Fox, Ori D., Garnavich, Peter, Gonzalez, Estefania Padilla, Graur, Or, Hambsch, Franz Josef, Hosseinzadeh, Griffin, Howell, D. Andrew, Hughes, John P., Kerzendorf, Wolfgang E., Le Saux, Xavier K., Maeda, Keiichi, Maguire, Kate, McCully, Curtis, Mihalenko, Cassidy, Newsome, Megan, O'Brien, John T., Pearson, Jeniveve, Pellegrino, Craig, Pierel, Justin D.R., Polin, Abigail, Rest, Armin, Rojas-Bravo, César, Sand, David J., Schwab, Michaela, Shahbandeh, Melissa, Shrestha, Manisha, Strolger, Louis Gregory, Szalai, Tamás, Taggart, Kirsty, Terreran, Giacomo, Terwel, Jacco H., Tinyanont, Samaporn, Valenti, Stefano, Vinkó, József, Wheeler, J. Craig, Yang, Yi, Zheng, Wei Kang, Ashall, Chris, DerKacy, James M., Galbany, Lluís, Hoeflich, Peter, Hsiao, Eric, de Jaeger, Thomas, Lu, Jing, Maund, Justyn, Medler, Kyle, Morrell, Nidia, Shappee, Benjamin J., Stritzinger, Maximilian, Suntzeff, Nicholas, Tucker, Michael, Wang, Lifan

المصدر: Siebert , M R , Kwok , L A , Johansson , J , Jha , S W , Blondin , S , Dessart , L , Foley , R J , Hillier , D J , Larison , C , Pakmor , R , Temim , T , Andrews , J E , Auchettl , K , Badenes , C , Barna , B , Bostroem , K A , Brenner Newman , M J , Brink , T G , Bustamante-Rosell , M J , Camacho-Neves , Y , Clocchiatti , A , Coulter , D A ....

الوصف: Nebular-phase observations of peculiar Type Ia supernovae (SNe Ia) provide important constraints on progenitor scenarios and explosion dynamics for both these rare SNe and the more common, cosmologically useful SNe Ia. We present observations from an extensive ground- and space-based follow-up campaign to characterize SN 2022pul, a super-Chandrasekhar mass SN Ia (alternatively “03fg-like” SN), from before peak brightness to well into the nebular phase across optical to mid-infrared (MIR) wavelengths. The early rise of the light curve is atypical, exhibiting two distinct components, consistent with SN Ia ejecta interacting with dense carbon-oxygen (C/O)-rich circumstellar material (CSM). In the optical, SN 2022pul is most similar to SN 2012dn, having a low estimated peak luminosity (M B = −18.9 mag) and high photospheric velocity relative to other 03fg-like SNe. In the nebular phase, SN 2022pul adds to the increasing diversity of the 03fg-like subclass. From 168 to 336 days after peak B-band brightness, SN 2022pul exhibits asymmetric and narrow emission from [O I] λλ6300, 6364 (FWHM ≈ 2000 km s −1 ), strong, broad emission from [Ca II] λλ7291, 7323 (FWHM ≈ 7300 km s −1 ), and a rapid Fe III to Fe II ionization change. Finally, we present the first ever optical-to-MIR nebular spectrum of an 03fg-like SN Ia using data from JWST. In the MIR, strong lines of neon and argon, weak emission from stable nickel, and strong thermal dust emission (with T ≈ 500 K), combined with prominent [O I] in the optical, suggest that SN 2022pul was produced by a white dwarf merger within C/O-rich CSM.

العلاقة: https://pure.au.dk/portal/en/publications/218346b7-6dcb-4eb6-9dea-01d2238a229dTest

الإتاحة: https://doi.org/10.3847/1538-4357/ad0975Test
https://pure.au.dk/portal/en/publications/218346b7-6dcb-4eb6-9dea-01d2238a229dTest

المؤلفون: Farias, Diego, Clocchiatti, Alejandro, Woods, Tyrone, Rest, Armin

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics

الوصف: Supersoft X-rays sources (SSSs) have been proposed as potential Type Ia supernova (SN Ia) progenitors. If such objects are indeed persistently X-ray luminous and embedded in sufficiently dense ISM, they will be surrounded by extended nebular emission. These nebulae should persist even long after a SN Ia explosion, due to the long recombination and cooling times involved. With this in mind, we searched for nebular [O III] emission around four SSSs and three SNRs in the Large Magellanic Cloud, using the 6.5m Baade telescope at Las Campanas Observatory and the IMACS camera. We confirm that, out of the four SSS candidates, only CAL 83 can be associated with an [O III] nebula. The [O III] luminosity for the other objects are constrained to $\lesssim 17\%$ of that of CAL 83 at 6.8 pc from the central source. Models computed with the photoionization code CLOUDY indicate that either the ISM densities in the environments of CAL 87, RX J0550.0-7151 and RX J0513.9-6951 must be significantly lower than surrounding CAL 83, or the average X-ray luminosities of these sources over the last $\lesssim 10,000$ years must be significantly lower than presently observed, in order to be consistent with the observed luminosity upper limits. For the three SNRs we consider (all with ages $< 1000$ years), our [O III] flux measurements together with the known surrounding ISM densities strongly constrain the ionizing luminosity of their progenitors in the last several thousand years, independent of the progenitor channel.
Comment: 18 pages, 17 figures, accepted for publication in MNRAS

الوصول الحر: http://arxiv.org/abs/2007.12316Test

المؤلفون: Cikota, Aleksandar, Patat, Ferdinando, Wang, Lifan, Wheeler, J. Craig, Bulla, Mattia, Baade, Dietrich, Höflich, Peter, Cikota, Stefan, Clocchiatti, Alejandro, Maund, Justyn R., Stevance, Heloise F., Yang, Yi

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics

الوصف: Spectropolarimetry enables us to measure the geometry and chemical structure of the ejecta in supernova explosions, which is fundamental for the understanding of their explosion mechanism(s) and progenitor systems. We collected archival data of 35 Type Ia Supernovae (SNe Ia), observed with FORS on the Very Large Telescope at 127 epochs in total. We examined the polarization of the Si II $\lambda$6355 $\AA$ line (p$_{\rm Si II}$) as a function of time which is seen to peak at a range of various polarization degrees and epochs relative to maximum brightness. We reproduced the $\Delta$m$_{15}$-p$_{\rm Si II}$ relationship identified in a previous study, and show that subluminous and transitional objects display polarization values below the $\Delta$m$_{15}$-p$_{\rm Si II}$ relationship for normal SNe Ia. We found a statistically significant linear relationship between the polarization of the Si II $\lambda$6355 $\AA$ line before maximum brightness and the Si II line velocity and suggest that this, along with the $\Delta$m$_{15}$-p$_{\rm Si II}$ relationship, may be explained in the context of a delayed-detonation model. In contrast, we compared our observations to numerical predictions in the $\Delta$m$_{15}$-v$_{\rm Si II}$ plane and found a dichotomy in the polarization properties between Chandrasekhar and sub-Chandrasekhar mass explosions, which supports the possibility of two distinct explosion mechanisms. A subsample of SNe display evolution of loops in the $q$-$u$ plane that suggests a more complex Si structure with depth. This insight, which could not be gleaned from total flux spectra, presents a new constraint on explosion models. Finally, we compared our statistical sample of the Si II polarization to quantitative predictions of the polarization levels for the double-detonation, delayed-detonation, and violent-merger models.
Comment: 22 pages, accepted for publication in MNRAS

الوصول الحر: http://arxiv.org/abs/1908.07526Test