Browsing by Subject "supernovae : general"

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Constraints on Circumstellar Material Around the Type Ia Supernova 2007af(1,2)
(2007-12) Simon, Joshua D.; Gal-Yam, Avishay; Penprase, Bryan E.; Li, Weidong; Quimby, Robert M.; Silverman, Jeffrey M.; Prieto, Carlos Allende; Wheeler, J. Craig; Filippenko, Alexei V.; Martinez, Irene T.; Beeler, Daniel J.; Patat, Ferdinando; Quimby, Robert M.; Prieto, Carlos Allende; Wheeler, J. Craig
Patat et al. recently inferred the existence of circumstellar material around a normal Type Ia supernova (SN Ia) for the first time, finding time-variable Na I D absorption lines in the spectrum of SN 2006X. We present high-resolution spectroscopy of the bright SN Ia 2007af at three epochs and search for variability in any of the Na D absorption components. Over the time range from 4 days before to 24 days after maximum light, we find that the host-galaxy Na D lines appear to be of interstellar rather than circumstellar origin and do not vary down to the level of 18 m angstrom (column density of 2 x 10(11) cm(-2)). We limit any circumstellar absorption lines to be weaker than similar to 10 m angstrom (6 x 10(10) cm(-2)). For the case of material distributed in spherically symmetric shells of radius similar to 10(16) cm surrounding the progenitor system, we place an upper limit on the shell mass of similar to(3 x 10(-8))/X M circle dot, where X is the Na ionization fraction. We also show that SN 2007af is a photometrically and spectroscopically normal SN Ia. Assuming that the variable Na D lines in SN 2006X came from circumstellar matter, we therefore conclude that either there is a preferred geometry for the detection of variable absorption components in SNe Ia, or SN 2007af and SN 2006X had different types of progenitor systems.
The Effect Of Turbulent Intermittency On The Deflagration To Detonation Transition In Supernova Ia Explosions
(2008-07) Pan, Lubin; Wheeler, J. Craig; Scalo, John; Pan, Lubin; Wheeler, J. Craig; Scalo, John
We examine the effects of turbulent intermittency on the deflagration to detonation transition (DDT) in Type Ia supernovae. The Zel'dovich mechanism for DDT requires the formation of a nearly isothermal region of mixed ash and fuel that is larger than a critical size. We primarily consider the hypothesis by Khokhlov et al. and Niemeyer and Woosley that the nearly isothermal, mixed region is produced when the flame makes the transition to the distributed regime. We use two models for the distribution of the turbulent velocity fluctuations to estimate the probability as a function of the density in the exploding white dwarf that a given region of critical size is in the distributed regime due to strong local turbulent stretching of the flame structure. We also estimate lower limits on the number of such regions as a function of density. We find that the distributed regime, and hence perhaps DDT, occurs in a local region of critical size at a density at least a factor of 2-3 larger than predicted for mean conditions that neglect intermittency. This factor makes the transition density much larger than the empirical value from observations in most situations. We also consider the intermittency effect on the more stringent conditions for DDT by Lisewski et al. and Woosley. We find that a turbulent velocity of 10(8) cm s(-1) in a region of size 10(6) cm, as required by Lisewski et al., is rare. We expect that intermittency has a weaker effect on the Woosley model with a stronger DDT criterion. The predicted transition density from this criterion remains below 10(7) g cm(-3) after accounting for intermittency using our intermittency models.
The First Supernova Explosions: Energetics, Feedback, And Chemical Enrichment
(2007-11) Greif, Thomas H.; Johnson, Jarrett L.; Bromm, Volker; Klessen, Ralf S.; Greif, Thomas H.; Johnson, Jarrett L.; Bromm, Volker
We perform three-dimensional smoothed particle hydrodynamics simulations in a realistic cosmological setting to investigate the expansion, feedback, and chemical enrichment properties of a 200M(circle dot) pair-instability supernova in the high-redshift universe. We find that the SN remnant propagates for a Hubble time at z similar or equal to 20 to a final mass-weighted mean shock radius of 2.5 kpc (proper), roughly half the size of the H II region, and in this process sweeps up a total gas mass of 2: 5; 10(5) M-circle dot. The morphology of the shock becomes highly anisotropic once it leaves the host halo and encounters filaments and neighboring minihalos, while the bulk of the shock propagates into the voids of the intergalactic medium. The SN entirely disrupts the host halo and terminates further star formation for at least 200 Myr, while in our specific case it exerts positive mechanical feedback on neighboring minihalos by shock-compressing their cores. In contrast, we do not observe secondary star formation in the dense shell via gravitational fragmentation, due to the previous photoheating by the progenitor star. We find that cooling by metal lines is unimportant for the entire evolution of the SN remnant, while the metal-enriched, interior bubble expands adiabatically into the cavities created by the shock, and ultimately into the voids with a maximum extent similar to the final mass-weighted mean shock radius. Finally, we conclude that dark matter halos of at least M-vir greater than or similar to 10(8) M-circle dot must be assembled to recollect all components of the swept-up gas.
First-Year Spectroscopy For The Sloan Digital Sky Survey-II Supernova Survey
(2008-05) Zheng, Chen; Romani, Roger W.; Sako, Masao; Marriner, John; Bassett, Bruce; Becker, Andrew; Choi, Changsu; Cinabro, David; DeJongh, Fritz; Depoy, Darren L.; Dilday, Ben; Doi, Mamoru; Frieman, Joshua A.; Garnavich, Peter M.; Hogan, Craig J.; Holtzman, Jon; Im, Myungshin; Jha, Saurabh; Kessler, Richard; Konishi, Kohki; Lampeitl, Hubert; Marshall, Jennifer L.; McGinnis, David; Miknaitis, Gajus; Nichol, Robert C.; Prieto, Jose L.; Riess, Adam G.; Richmond, Michael W.; Schneider, Donald P.; Smith, Mathew; Takanashi, Naohiro; Tokita, Kouichi; Van der Heyden, Kurt; Yasuda, Naoki; Assef, Roberto J.; Barentine, John; Bender, Ralf; Blandford, Roger D.; Bremer, Malcolm; Brewington, Howard; Collins, Chris A.; Crotts, Arlin; Dembicky, Jack; Eastman, Jason; Edge, Alastair; Elson, Ed; Eyler, Michael E.; Filippenko, Alexi V.; Foley, Ryan J.; Frank, Stephan; Goobar, Ariel; Harvanek, Michael; Hopp, Ulrich; Ihara, Yutaka; Kahn, Steven; Ketzeback, William; Kleinman, Scott J.; Kollatschny, Wolfram; Krzesinski, Jurek; Leloudas, Giorgos; Long, Daniel C.; Lucey, John; Malanushenko, Elena; Malanushenko, Viktor; McMillan, Russet J.; Morgan, Christopher W.; Morokuma, Tomoki; Nitta, Atsuko; Ostman, Linda; Pan, Kaike; Romer, A. Kathy; Saurage, Gabrelle; Schlesinger, Katie; Snedden, Stephanie A.; Sollerman, Jasper; Stritzinger, Maximillian; Watson, Linda C.; Watters, Shannon; Wheeler, J. Craig; York, Donald; Barentine, John; Wheeler, J. Craig
This paper presents spectroscopy of supernovae (SNe) discovered in the first season of the Sloan Digital Sky Survey-II SN Survey. This program searches for and measures multi-band light curves of SNe in the redshift range z = 0.05-0.4, complementing existing surveys at lower and higher redshifts. Our goal is to better characterize the SN population, with a particular focus on SNe Ia, improving their utility as cosmological distance indicators and as probes of dark energy. Our SN spectroscopy program features rapid-response observations using telescopes of a range of apertures, and provides confirmation of the SN and host-galaxy types as well as precise redshifts. We describe here the target identification and prioritization, data reduction, redshift measurement, and classification of 129 SNe Ia, 16 spectroscopically probable SNe Ia, 7 SNe Ib/c, and 11 SNe II from the first season. We also describe our efforts to measure and remove the substantial host-galaxy contamination existing in the majority of our SN spectra.
A Measurement Of The Rate Of Type Ia Supernovae At Redshift Z Approximate To 0.1 From The First Season Of The SDSS-II Supernova Survey
(2008-07) Dilday, Benjamin; Kessler, Richard; Frieman, Joshua A.; Holtzman, Jon; Marriner, John; Miknaitis, Gajus; Nichol, Robert C.; Romani, Roger; Sako, Masao; Bassett, Bruce; Becker, Andrew; Cinabro, David; DeJongh, Fritz; Depoy, Darren L.; Doi, Mamoru; Garnavich, Peter M.; Hogan, Craig J.; Jha, Saurabh; Konishi, Kohki; Lampeitl, Hubert; Marshall, Jennifer L.; McGinnis, David; Prieto, Jose Luis; Riess, Adam G.; Richmond, Michael W.; Schneider, Donald P.; Smith, Mathew; Takanashi, Naohiro; Tokita, Kouichi; van der Heyden, Kurt; Yasuda, Naoki; Zheng, Chen; Barentine, John; Brewington, Howard; Choi, Changsu; Crotts, Arlin; Dembicky, Jack; Harvanek, Michael; Im, Myunshin; Ketzeback, William; Kleinman, Scott J.; Krzesinski, Jurek; Long, Daniel C.; Malanushenko, Elena; Malanushenko, Viktor; McMillan, Russet J.; Nitta, Atsuko; Pan, Kaike; Saurage, Gabrelle; Snedden, Stephanie A.; Watters, Shannon; Wheeler, J. Craig; York, Donald; Wheeler, J. Craig
The Shape Of Cas A
(2008-04) Wheeler, J. Craig; Maund, Justyn R.; Couch, Sean M.; Wheeler, J. Craig; Maund, Justyn R.; Couch, Sean M.
On the basis of optical, IR, and X-ray studies of CasA, we propose a geometry for the remnant based on a " jet-induced'' scenario with significant systematic departures from axial symmetry. In this model, the main jet axis is oriented in the direction of strong blueshifted motion at an angle of 110 degrees-120 degrees east of north and about 40 degrees-50 degrees to the east of the line of sight. Normal to this axis would be an expanding torus as predicted by jet-induced models. In the proposed geometry, iron-peak elements in the main jetlike flow could appear " beyond'' the portions of the remnant rich in silicon by projection effects, not the effect of mixing. In the context of the proposed geometry, the displacement of the compact object from the kinematic center of the remnant at a position angle of similar to 169 degrees can be accommodated if the motion of the compact object is near to, but slightly off from, the direction of the main " jet'' axis by of order 30 degrees. In this model, the classical NE " jet,'' the SW " counterjet,'' and other protrusions, particularly the " hole'' in the north, are nonaxisymmetric flows approximately in the equatorial plane, e. g., out through the perimeter of the expanding torus, rather than being associated with the main jet. We explore the spokelike flow in the equatorial plane in terms of Rayleigh-Taylor, Richtmyer-Meshkov, and Kelvin-Helmholz instabilities and illustrate these instabilities with a jet-induced simulation.
The Sloan Digital Sky Survey-II Supernova Survey: Technical Summary
(2008-01) Frieman, Joshua A.; Bassett, Bruce; Becker, Andrew; Choi, Changsu; Cinabro, David; DeJongh, Fritz; Depoy, Darren L.; Dilday, Ben; Doi, Mamoru; Garnavich, Peter M.; Hogan, Craig J.; Holtzman, Jon; Im, Myungshin; Jha, Saurabh; Kessler, Richard; Konishi, Kohki; Lampeitl, Hubert; Marriner, John; Marshall, Jennifer L.; McGinnis, David; Miknaitis, Gajus; Nichol, Robert C.; Prieto, Jose Luis; Riess, Adam G.; Richmond, Michael W.; Romani, Roger; Sako, Masao; Schneider, Donald P.; Smith, Mathew; Takanashi, Naohiro; Tokita, Kouichi; van der Heyden, Kurt; Yasuda, Naoki; Zheng, Chen; Adelman-McCarthy, Jennifer; Annis, James; Assef, Roberto J.; Barentine, John; Bender, Ralf; Blandford, Roger D.; Boroski, William N.; Bremer, Malcolm; Brewington, Howard; Collins, Chris A.; Crotts, Arlin; Dembicky, Jack; Eastman, Jason; Edge, Alastair; Edmondson, Edmond; Elson, Edward; Eyler, Michael E.; Filippenko, Alexei V.; Foley, Ryan J.; Frank, Stephan; Goobar, Ariel; Gueth, Tina; Gunn, James E.; Harvanek, Michael; Hopp, Ulrich; Ihara, Yutaka; Ivezić, Želko; Kahn, Steven; Kaplan, Jared; Kent, Stephen; Ketzeback, William; Kleinman, Scott J.; Kollatschny, Wolfram; Kron, Richard G; Krzesiński, Jurek; Lamenti, Dennis; Leloudas, Giorgos; Lin, Huan; Long, Daniel C.; Lucey, John; Lupton, Robert H.; Malanushenko, Elena; Malanushenko, Viktor; McMillan, Russet J.; Mendez, Javier; Morgan, Christopher W.; Morokuma, Tomoki; Nitta, Atsuko; Ostman, Linda; Pan, Kaike; Rockosi, Constance M.; Romer, A. Kathy; Ruiz-Lapuente, Pilar; Saurage, Gabrelle; Schlesinger, Katie; Snedden, Stephanie A.; Sollerman, Jesper; Stoughton, Chris; Stritzinger, Maximilian; SubbaRao, Mark; Tucker, Douglas; Vaisanen, Petri; Watson, Linda C.; Watters, Shannon; Wheeler, J. Craig; Yanny, Brian; York, Donald; Barentine, John; Wheeler, J. Craig
The Sloan Digital Sky Survey-II (SDSS-II) has embarked on a multi-year project to identify and measure light curves for intermediate-redshift (0.05 < z < 0.35) Type la supernovae (SNe Ia) using repeated five-band (ugriz) imaging over an area of 300 sq. deg. The survey region is a stripe 2.5 degrees wide centered on the celestial equator in the Southern Galactic Cap that has been imaged numerous times in earlier years, enabling construction of a deep reference image for the discovery of new objects. Supernova imaging observations are being acquired between September I and November 30 of 2005-7. During the first two seasons, each region was imaged on average every five nights. Spectroscopic follow-up observations to determine supernova type and redshift are carried out on a large number of telescopes. In its first two three-month seasons, the survey has discovered and measured light curves for 327 spectroscopically confirmed SNe Ia, 30 probable SNe Ia, 14 confirmed SNe Ib/c, 32 confirmed SNe 11, plus a large number of photometrically identified SNe la, 94 of which have host-galaxy spectra taken so far. This paper provides an overview of the project and briefly describes the observations completed during the first two seasons of operation.
Spectropolarimetry Of The Type IIb Supernova 2001Ig(1)
(2007-12) Maund, Justyn R.; Wheeler, J. Craig; Patat, Ferdinando; Wang, Lifan; Baade, Dietrich; Hoflich, Peter A.; Maund, Justyn R., J. Craig Wheeler, Ferdinando Patat, Lifan Wang, Dietrich Baade, and A. H. Peter. "Spectropolarimetry of the Type IIb Supernova 2001ig." The Astrophysical Journal, Vol. 671, No. 2 (Dec., 2007): 1944.
We present spectropolarimetric observations of the Type IIb SN 2001ig in NGC 7424; conducted with the ESO VLT FORS1 on 2001 December 16, 2002 January 3, and 2002 August 16, or 13, 31, and 256 days postexplosion. These observations are at three different stages of the SN evolution: (1) the hydrogen-rich photospheric phase, (2) the Type II to Type Ib transitional phase, and (3) the nebular phase. At each of these stages, the observations show remarkably different polarization properties as a function of wavelength. We show that the degree of interstellar polarization is 0.17%. The low intrinsic polarization (similar to 0.2%) at the first epoch is consistent with an almost spherical (<10% deviation from spherical symmetry) hydrogen-dominated ejecta. Similar to SN 1987A and to Type IIP SNe, a sharp increase in the degree of the polarization (similar to 1%) is observed when the outer hydrogen layer becomes optically thin by day 31; only at this epoch is the polarization well described by a "dominant axis.'' The polarization angle of the data shows a rotation through similar to 40 degrees between the first and second epochs, indicating that the asymmetries of the first epoch were not directly coupled with those observed at the second epoch. For the most polarized lines, we observe wavelength-dependent loop structures in addition to the dominant axis on the Q-U plane. We show that the polarization properties of Type IIb SNe are roughly similar to one another, but with significant differences arising due to line blending effects especially with the high velocities observed for SN 2001ig. This suggests that the geometry of SN 2001ig is related to SN 1993J and that these events may have arisen from a similar binary progenitor system.