Browsing by Author "Mattila, S."

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    Delayed appearance and evolution of coronal lines in the TDE AT2019qiz
    (Oxford University Press, 2023) Short, P.; Lawrence, A.; Nicholl, M.; Ward, M.; Reynolds, T. M.; Mattila, S.; Yin, C.; Arcavi, I; Carnall, A.; Charalampopoulos, P.; Gromadzki, M.; Jonker, P. G.; Kim, Sam; Leloudas, G.; Mandel, I; Onori, F.; Pursiainen, M.; Schulze, S.; Villforth, C.; Wevers, T.
    Tidal disruption events (TDEs) occur when a star gets torn apart by a supermassive black hole as it crosses its tidal radius. We present late-time optical and X-ray observations of the nuclear transient AT2019qiz, which showed the typical signs of an optical-UV transient class commonly believed to be TDEs. Optical spectra were obtained 428, 481, and 828 rest-frame days after optical light-curve peak, and a UV/X-ray observation coincided with the later spectrum. The optical spectra show strong coronal emission lines, including [Fe vii], [Fe x], [Fe xi], and [Fe xiv]. The Fe lines rise and then fall, except [Fe xiv] that appears late and rises. We observe increasing flux of narrow H & alpha; and H & beta; and a decrease in broad H & alpha; flux. The coronal lines have full width at half-maximum ranging from & SIM;150-300 km s(-1), suggesting they originate from a region between the broad- and narrow-line emitting gas. Between the optical flare and late-time observation, the X-ray spectrum softens dramatically. The 0.3-1 keV X-ray flux increases by a factor of & SIM;50, while the hard X-ray flux decreases by a factor of & SIM;6. Wide-field Infrared Survey Explorer fluxes also rose over the same period, indicating the presence of an infrared echo. With AT2017gge, AT2019qiz is one of two examples of a spectroscopically confirmed optical-UV TDE showing delayed coronal line emission, supporting speculations that Extreme Coronal Line Emitters in quiescent galaxies can be echos of unobserved past TDEs. We argue that the coronal lines, narrow lines, and infrared emission arise from the illumination of pre-existing material likely related to either a previous TDE or active galactic nucleus activity.
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    PESSTO : survey description and products from the first data release by the Public ESO Spectroscopic Survey of Transient Objects
    (2015) Smartt, S. J.; Valenti, S.; Fraser, M.; Inserra, C.; Young, D. R.; Sullivan, M.; Bauer, Franz Erik; Clocchiatti, Alejandro; Romero Cañizales, Cristina; Schulze, S.; Pastorello, A.; Benetti, S.; Gal-Yam, A.; Knapic, C.; Molinaro, M.; Smareglia, R.; Smith, K. W.; Taubenberger, S.; Yaron, O.; Anderson, J. P.; Ashall, C.; Balland, C.; Baltay, C.; Barbarino, C.; Baumont, S.; Bersier, D.; Blagorodnova, N.; Bongard, S.; Botticella, M. T.; Bufano, F.; Bulla, M.; Cappellaro, E.; Campbell, H.; Cellier-Holzem, F.; Chen, T. W.; Childress, M. J.; Contreras, C.; Dall’Ora, M.; Danziger, J.; de Jaeger, T.; De Cia, A.; Della Valle, M.; Dennefeld, M.; Elias Rosa, N.; Elman, N.; Feindt, U.; Fleury, M.; Gall, E.; González Gaitan, S.; Galbany, L.; Morales Garoffolo, A.; Greggio, L.; Guillou, L. L.; Hachinger, S.; Hadjiyska, E.; Hage, P. E.; Hillebrandt, W.; Hodgkin, S.; Hsiao, E. Y.; James, P. A.; Jerkstrand, A.; Kangas, T.; Kankare, E.; Kotak, R.; Kromer, M.; Kuncarayakti, H.; Leloudas, G.; Lundqvist, P.; Lyman, J. D.; Hook, I. M.; Maguire, K.; Manulis, I.; Margheim, S. J.; Mattila, S.; Maund, J. R.; Mazzali, P. A.; McCrum, M.; McKinnon, R.; Moreno Raya, M. E.; Nicholl, M.; Nugent, P.; Pain, R.; Pignata, Giuliano; Phillips, M. M.; Polshaw, J.; Pumo, M. L.; Rabinowitz, D.; Reilly, E.; Scalzo, R.; Schmidt, B.; Sim, S.; Sollerman, J.; Taddia, F.; Tartaglia, L.; Terreran, G.; Tomasella, L.; Turatto, M.; Walker, E.; Walton, N. A.; Wyrzykowski, L.; Yuan, F.; Zampieri, L.
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    SN 2005at - A neglected type Ic supernova at 10 Mpc
    (2014) Romero Cañizales, Cristina; Kankare, E.; Fraser, M.; Ryder, S.; Mattila, S.; Kotak, R.; Laursen, P.; Monard, L.; Salvo, M.; Vaisanen, P.
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    Supernova 2011jb
    (2011) Drake, A. J.; Djorgovski, S. G.; Graham, M. J.; Mahabal, A.; Williams, R.; Prieto, J. L.; Catelan, Marcio; Beshore, E. C.; Larson, S. M.; Christensen, E.; Kankare, E.; Mattila, S.; Pastorello, A.
    Report the discovery of an apparent supernova in unfiltered Catalina Sky Survey (CSS) images: SN 2011 UT R.A. (2000.0) Decl. Mag. 2011jb Nov. 28.45 11 37 04.80 +15 28 14.2 17.8 Nothing is visible at this position on a CSS image from June 12.19 UT (limiting mag 19.2). E. Kankare and S. Mattila, Tuorla Observatory, University of Turku; and A. Pastorello, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, report that a spectrum of SN 2011jb was obtained on Dec. 19.3 UT with the Nordic Optical Telescope (+ ALFOSC; range 320-910 nm). Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) and "GELATO" code (Harutyunyan et al. 2008, A.Ap. 488, 383; available at https://gelato.tng.iac.es/login.cgi) suggest that 2011jb is a type-IIn supernova like SN 2002ic and SN 2005gj (see, e.g., Trundle et al. 2008, A.Ap. 483, L47), roughly 40-50 days after peak at z = 0.084. The authors further report that an image obtained with the NOT on the same date (Dec. 19) provides an R-band magnitude of about 17.6, corresponding to an absolute magnitude of about -20.3 (after correction for foreground extinction of A_R about 0.1, from NED) for SN 2011jb (assuming H_o = 70 km/s/Mpc)....
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    Supernova 2011jc = Psn J03383439+2232595
    (2011) Drake, A. J.; Djorgovski, S. G.; Graham, M. J.; Mahabal, A.; Williams, R.; Prieto, J. L.; Catelan, Marcio; Beshore, E. C.; Larson, S. M.; Christensen, E.; Elenin, L.; Foglia, S.; Galli, G.; Wright, D.; Fraser, M.; Tomasella, L.; Pastorello, A.; Benetti, S.; Kankare, E.; Mattila, S.
    Report the discovery of an apparent supernova in unfiltered Mount Lemmon Survey (MLS) images: SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011jc Nov. 30.26 3 38 34.39 +22 32 59.5 18.9 1".1 E, 16".7 N The variable was designated PSN J03383439+2232595 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2011jc based on the spectroscopic confirmation reported below. Additional reported CCD magnitudes for 2011jc (unfiltered unless noted otherwise): Sept. 29.48 UT, [21.0 (MLS); Oct. 18.49, 19.6 (MLS); Dec. 4.336, 18.4 (L. Elenin, Lyubertsy, Russia; 0.45-m f/2.8 telescope + KAF09000 chip, remotely taken at the ISON-NM Observatory near Mayhill, NM, USA; position end figures 34s.39 +/- 0".1, 58".9 +/- 0".1; NOMAD reference stars; limiting mag about 19.8; image posted at website URL http://spaceobs.org/images/TOCP/PSNJ03383439+2232595-20111204.png); 10.961, R = 18.2 (Federica Luppi, Varese, Italy; 0.35-m f/7.9 reflector + Bessell R filter; position end figures 34s.37, 59".4; reference stars from CMC-14 catalogue); 19.900, 19.0 (S. Foglia and G. Galli, Pogliano Milanese, Italy; 0.28-m f/6.8 Schmidt-Cassegrain reflector + ST8-XME camera; position end figures 34s.38, 59".6; UCAC 2.0 reference stars). D. Wright and M. Fraser, Queen's University, Belfast; L. Tomasella, A. Pastorello, and S. Benetti, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova; and E. Kankare and S. Mattila, University of Turku; on behalf of a larger collaboration, report that low-S/N spectrograms of PSN J03383439+2232595 = SN 2011jc, obtained on Dec. 16.01 and 18.92 UT with the Asiago 1.82-m Copernico Telescope (+ AFOSC; range 350-820 nm; resolution 2.4 nm), on Dec. 19.0 with the Nordic Optical Telescope (+ ALFOSC; range 320-910 nm; resolution 1.6 nm), and on Dec. 19.05 with the William Herschel Telescope (+ ISIS; range 300-975 nm; resolution 1.2 nm) show that 2011jc is a type-IIn supernova. The best fits to these spectra found by GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383; available at URL https://gelato.tng.iac.es/login.cgi) suggest that 2011jc is similar to SN 2005gj (comparison spectra are from Padova-Asiago Supernova Archive) a few days after explosion, if a redshift of 0.087 is assumed for the host galaxy....
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    Supernova 2013fc in a circumnuclear ring of a luminous infrared galaxy : the big brother of SN. 1998S
    (2016) Kangas, T.; Mattila, S.; Kankare, E.; Lundqvist, P.; Vaisanen, P.; Childress, M.; Pignata, Giuliano; Mccully, C.; Valenti, S.; Romero Cañizales, Cristina
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    The nature of supernovae 2010O and 2010P in Arp 299-I. Near-infrared and optical evolution
    (OXFORD UNIV PRESS, 2014) Kankare, E.; Mattila, S.; Ryder, S.; Fraser, M.; Pastorello, A.; Elias Rosa, N.; Romero Canizales, C.; Alberdi, A.; Hentunen, V. P.; Herrero Illana, R.; Kotilainen, J.; Perez Torres, M. A.; Vaeisaenen, P.
    We present near-infrared and optical photometry, plus optical spectroscopy of two stripped-envelope supernovae (SNe) 2010O and 2010P that exploded in two different components of an interacting luminous infrared galaxy Arp 299 within only a few days of one another. SN 2010O is found to be photometrically and spectroscopically similar to many normal Type Ib SNe and our multiwavelength observations of SN 2010P suggest it to be a Type IIb SN. No signs of clear hydrogen features or interaction with the circumstellar medium are evident in the optical spectrum of SN 2010P. We derive estimates for the host galaxy line-of-sight extinctions for both SNe, based on both light curve and spectroscopic comparison finding consistent results. These methods are also found to provide much more robust estimates of the SN host galaxy reddening than the commonly used empirical relations between extinction and equivalent width of Na i D absorption features. The SN observations also suggest that different extinction laws are present in different components of Arp 299. For completeness, we study high-resolution pre-explosion images of Arp 299 and find both SNe to be close to, but not coincident with, extended sources that are likely massive clusters. A very simple model applied to the bolometric light curve of SN 2010O implies a rough estimate for the explosion parameters of E-k approximate to 3 x 10(51) erg, M-ej approximate to 2.9 M-circle dot and M-Ni approximate to 0.16 M-circle dot.
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    The nature of supernovae 2010O and 2010P in Arp 299-II. Radio emission
    (OXFORD UNIV PRESS, 2014) Romero Canizales, C.; Herrero Illana, R.; Perez Torres, M. A.; Alberdi, A.; Kankare, E.; Bauer, F. E.; Ryder, S. D.; Mattila, S.; Conway, J. E.; Beswick, R. J.; Muxlow, T. W. B.
    We report radio observations of two stripped-envelope supernovae (SNe), 2010O and 2010P, which exploded within a few days of each other in the luminous infrared galaxy Arp 299. Whilst SN 2010O remains undetected at radio frequencies, SN 2010P was detected (with an astrometric accuracy better than 1 milli arcsec in position) in its optically thin phase in epochs ranging from similar to 1 to similar to 3 yr after its explosion date, indicating a very slow radio evolution and a strong interaction of the SN ejecta with the circumstellar medium. Our late-time radio observations towards SN 2010P probe the dense circumstellar envelope of this SN, and imply M [M-circle dot yr(-1)]/upsilon(wind) [10 km s(-1)] = (3.0 - 5.1) x 10(-5), with a 5 GHz peak luminosity of similar to 1.2 x 10(27) erg s(- 1) Hz(- 1) on day similar to 464 after explosion. This is consistent with a Type IIb classification for SN 2010P, making it the most distant and most slowly evolving Type IIb radio SN detected to date.