-
E. Y. Hsiao,
G. H. Marion, M. M. Phillips,
C. R. Burns,
C. Winge,
N. Morrell,
C. Contreras,
W. L. Freedman,
M. Kromer,
E. E. E. Gall, [......],
M. Im,
Y. Jeon,
R. P. Kirshner,
P. E. Nugent,
S. E. Persson,
G. Pignata,
M. Roth,
V. Stanishev,
M. Stritzinger,
N. B. Suntzeff
[show abstract]
[hide abstract]
ABSTRACT: We present ten medium-resolution, high signal-to-noise ratio near-infrared
(NIR) spectra of SN 2011fe from SpeX on the NASA Infrared Telescope Facility
(IRTF) and Gemini Near-Infrared Spectrograph (GNIRS) on Gemini North, obtained
as part of the Carnegie Supernova Project. This data set constitutes the
earliest time-series NIR spectroscopy of a Type Ia supernova (SN Ia), with the
first spectrum obtained at 2.58 days past the explosion and covering -14.6 to
+17.3 days relative to B-band maximum. C I {\lambda}1.0693 {\mu}m is detected
in SN 2011fe with increasing strength up to maximum light. The delay in the
onset of the NIR C I line demonstrates its potential to be an effective tracer
of unprocessed material. For the first time in a SN Ia, the early rapid decline
of the Mg II {\lambda}1.0927 {\mu}m velocity was observed, and the subsequent
velocity is remarkably constant. The Mg II velocity during this constant phase
locates the inner edge of carbon burning and probes the conditions under which
the transition from deflagration to detonation occurs. We show that the Mg II
velocity does not correlate with the optical light-curve decline rate
{\Delta}m15. The prominent break at ~1.5 {\mu}m is the main source of concern
for NIR k-correction calculations. We demonstrate here that the feature has a
uniform time evolution among SNe Ia, with the flux ratio across the break
strongly correlated with {\Delta}m15. The predictability of the strength and
the onset of this feature suggests that the associated k-correction
uncertainties can be minimized with improved spectral templates.
01/2013;
-
Ryan J. Foley,
P. J. Challis,
R. Chornock,
M. Ganeshalingam,
W. Li,
G. H. Marion,
N. I. Morrell,
G. Pignata,
M. D. Stritzinger,
J. M. Silverman, [......],
A. V. Filippenko,
W. L. Freedman,
M. Hamuy,
S. W. Jha,
R. P. Kirshner,
C. McCully,
S. E. Persson, M. M. Phillips,
D. E. Reichart,
A. M. Soderberg
[show abstract]
[hide abstract]
ABSTRACT: We describe observed properties of the Type Iax class of supernovae (SNe
Iax), consisting of SNe observationally similar to its prototypical member, SN
2002cx. The class currently has 25 members, and we present optical photometry
and/or optical spectroscopy for most of them. SNe Iax are spectroscopically
similar to SNe Ia, but have lower maximum-light velocities (2000 < |v| < 8000
km/s), typically lower peak magnitudes (-14.2 > M_V,peak > -18.9 mag), and most
have hot photospheres. Relative to SNe Ia, SNe Iax have low luminosities for
their light-curve shape. There is a correlation between luminosity and
light-curve shape, similar to that of SNe Ia, but offset from that of SNe Ia
and with larger scatter. Despite a host-galaxy morphology distribution that is
highly skewed to late-type galaxies without any SNe Iax discovered in
elliptical galaxies, there are several indications that the progenitor stars
are white dwarfs (WDs): evidence of C/O burning in their maximum-light spectra,
low ejecta masses, strong Fe lines in their late-time spectra, a lack of X-ray
detections, and deep limits on massive stars and star formation at the SN
sites. However, two SNe Iax show strong He lines in their spectra. The
progenitor system and explosion model that best fits all of the data is a
binary system of a C/O WD that accretes matter from a He star and has a
significant deflagration. At least some of the time, this explosion will not
disrupt the WD. We estimate that in a given volume there are 31^+17_-13 SNe Iax
for every 100 SNe Ia, and for every 1 M_sun of iron generated by SNe Ia at z =
0, SNe Iax generate 0.052^+0.017_-0.014 M_sun. Being the largest class of
peculiar SNe, thousands of SNe Iax will be discovered by LSST. Future detailed
observations of SNe Iax should further our understanding of both their
progenitor systems and explosions as well as those of SNe Ia.
12/2012;
-
F. Taddia,
M. D. Stritzinger, M. M. Phillips,
C. R. Burns,
E. Heinrich-Josties,
N. Morrell,
J. Sollerman,
S. Valenti,
J. P. Anderson,
L. Boldt, [......],
C. Contreras,
G. Folatelli,
W. L. Freedman,
M. Hamuy,
W. Krzeminski,
G. Leloudas,
K. Maeda,
S. E. Persson,
M. Roth,
N. B. Suntzeff
[show abstract]
[hide abstract]
ABSTRACT: We provide additional observational evidence that some Type Ia supernovae
(SNe Ia) show signatures of circumstellar interaction (CSI) with hydrogen-rich
material. Early phase optical and near-infrared (NIR) light curves and
spectroscopy of SN 2008J obtained by the Carnegie Supernova Project are studied
and compared to those of SNe 2002ic and 2005gj. Our NIR spectrum is the first
obtained for a 2002ic-like object extending up to 2.2 $\mu$m. A published
high-resolution spectrum is used to provide insight on the circumstellar
material (CSM). SN 2008J is found to be affected by $A_V\sim$ 1.9 mag of
extinction and to closely resemble SN 2002ic. Spectral and color comparison to
SNe 2002ic and 2005gj suggests $R_V$ $<$ 3.1. Spectral decomposition reveals
the underlying SN emission matches a 1991T-like event and, since SN 2008J is as
luminous as SN 2005gj ($V_{\rm max}$ $=$ $-$20.3 mag), we conclude that their
CSI emissions are similarly robust. The high-resolution spectrum reveals narrow
emission lines produced from un-shocked gas characterized by a wind velocity of
$\sim$ 50 km s$^{-1}$. We conclude that SN 2008J best matches an explosion of a
SN Ia that interacts with its CSM.
08/2012;
-
Maximilian Stritzinger,
Francesco Taddia,
Claes Fransson,
Ori D. Fox,
Nidia Morrell, M. M. Phillips,
Jesper Sollerman,
J. P. Anderson,
Luis Boldt,
Peter J. Brown, [......],
Carlos Contreras,
Gaston Folatelli,
S. M. Habergham,
Mario Hamuy,
Jens Hjorth,
Phil A. James,
Wojtek Krzeminski,
Seppo Mattila,
Sven E. Persson,
Miguel Roth
[show abstract]
[hide abstract]
ABSTRACT: We present an observational study of the Type IIn supernovae (SNe IIn) 2005ip
and 2006jd. Broad-band UV, optical and near-IR photometry, and
visual-wavelength spectroscopy of SN 2005ip complement and extend upon
published observations to 6.5 years past discovery. Our observations of SN
2006jd extend from UV to mid-infrared wavelengths, and like SN 2005ip, are
compared to reported X-ray measurements to understand the nature of the
progenitor. Both objects display a number of similarities with the 1988Z-like
subclass of SN IIn including: (i) remarkably similar early- and late-phase
optical spectra, (ii) a variety of high ionization coronal lines, (iii)
long-duration optical and near-IR emission and, (iv) evidence of cold and warm
dust components. However, diversity is apparent including an unprecedented
late-time r-band excess in SN 2006jd.The observed differences are attributed to
differences between the mass-loss history of the progenitor stars. We conclude
that the progenitor of SN 2006jd likely experienced a significant mass-loss
event during its pre-SN evolution akin to the great 19th century eruption of
\eta Carinae. Contrarily, as advocated by Smith et al. (2009), we find the
circumstellar environment of SN 2005ip to be more consistent with a clumpy wind
progenitor.
06/2012;
-
J. Mosher,
M. Sako,
L. Corlies,
G. Folatelli,
J. Frieman,
J. Holtzman,
S. W. Jha,
R. Kessler,
J. Marriner, M. M. Phillips,
M. Stritzinger,
N. Morrell,
D. P. Schneider
[show abstract]
[hide abstract]
ABSTRACT: Consistency between Carnegie Supernova Project (CSP) and SDSS-II supernova
(SN) survey ugri measurements has been evaluated by comparing SDSS and CSP
photometry for nine spectroscopically confirmed Type Ia supernova observed
contemporaneously by both programs. The CSP data were transformed into the SDSS
photometric system. Sources of systematic uncertainty have been identified,
quantified, and shown to be at or below the 0.023 magnitude level in all bands.
When all photometry for a given band is combined, we find average magnitude
differences of equal to or less than 0.011 magnitudes in ugri, with rms scatter
ranging from 0.043 to 0.077 magnitudes. The u band agreement is promising, with
the caveat that only four of the nine supernovae are well-observed in u and
these four exhibit an 0.038 magnitude supernova-to-supernova scatter in this
filter.
06/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: We present a study of the peculiar Type Ia supernova 2001ay (SN 2001ay). The
defining features of its peculiarity are: high velocity, broad lines, and a
fast rising light curve, combined with the slowest known rate of decline. It is
one magnitude dimmer than would be predicted from its observed value of
Delta-m15, and shows broad spectral features. We base our analysis on detailed
calculations for the explosion, light curves, and spectra. We demonstrate that
consistency is key for both validating the models and probing the underlying
physics. We show that this SN can be understood within the physics underlying
the Delta-m15 relation, and in the framework of pulsating delayed detonation
models originating from a Chandrasekhar mass, white dwarf, but with a
progenitor core composed of 80% carbon. We suggest a possible scenario for
stellar evolution which leads to such a progenitor. We show that the unusual
light curve decline can be understood with the same physics as has been used to
understand the Delta-m15 relation for normal SNe Ia. The decline relation can
be explained by a combination of the temperature dependence of the opacity and
excess or deficit of the peak luminosity, alpha, measured relative to the
instantaneous rate of radiative decay energy generation. What differentiates SN
2001ay from normal SNe Ia is a higher explosion energy which leads to a shift
of the Ni56 distribution towards higher velocity and alpha < 1. This result is
responsible for the fast rise and slow decline. We define a class of SN
2001ay-like SNe Ia, which will show an anti-Phillips relation.
05/2012;
-
M. Teodoro,
A. Damineli,
J. I. Arias,
F. X. de Araújo,
R. H. Barbá,
M. F. Corcoran,
M. Borges Fernandes,
E. Fernández-Lajús,
L. Fraga,
R. C. Gamen, [......],
E. R. Parkin,
C. B. Pereira, M. M. Phillips,
G. R. Solivella,
J. E. Steiner,
M. Stritzinger,
I. Thompson,
C. A. O. Torres,
M. A. P. Torres,
and M. I. Zevallos Herencia
[show abstract]
[hide abstract]
ABSTRACT: The periodic spectroscopic events in η Carinae are now well established and occur near the periastron passage of two massive stars in a very eccentric orbit. Several mechanisms have been proposed to explain the variations of different spectral features, such as an eclipse by the wind-wind collision (WWC) boundary, a shell ejection from the primary star or accretion of its wind onto the secondary. All of them have problems explaining all the observed phenomena. To better understand the nature of the cyclic events, we performed a dense monitoring of η Carinae with five Southern telescopes during the 2009 low-excitation event, resulting in a set of data of unprecedented quality and sampling. The intrinsic luminosity of the He II λ4686 emission line (L ~ 310 L ☉) just before periastron reveals the presence of a very luminous transient source of extreme UV radiation emitted in the WWC region. Clumps in the primary's wind probably explain the flare-like behavior of both the X-ray and He II λ4686 light curves. After a short-lived minimum, He II λ4686 emission rises again to a new maximum, when X-rays are still absent or very weak. We interpret this as a collapse of the WWC onto the "surface" of the secondary star, switching off the hard X-ray source and diminishing the WWC shock cone. The recovery from this state is controlled by the momentum balance between the secondary's wind and the clumps in the primary's wind.
The Astrophysical Journal 01/2012; 746(1):73. · 6.02 Impact Factor
-
ShiAnne Kattner,
Douglas C. Leonard,
Christopher R. Burns, M. M. Phillips,
Gaston Folatelli,
Nidia Morrell,
Maximilian D. Stritzinger,
Mario Hamuy,
Wendy L. Freedman,
Sven E. Persson,
Miguel Roth,
Nicholas B. Suntzeff
[show abstract]
[hide abstract]
ABSTRACT: We analyze the standardizability of Type Ia supernovae (SNe Ia) in the
near-infrared (NIR) by investigating the correlation between observed peak NIR
absolute magnitude and post-maximum B-band decline rate. A sample of 27
low-redshift SNe Ia observed by the Carnegie Supernova Project between 2004 to
2007 is used. All 27 objects have pre-maximum coverage in optical bands, with a
subset of 13 having pre-maximum NIR observations as well. We describe the
methods used to derive absolute peak magnitudes and decline rates from both
spline- and template-fitting procedures, and confirm prior findings that
fitting templates to SNe Ia light curves in the NIR is problematic due to the
diversity of post-maximum behaviour of objects that are characterized by
similar decline rate values, especially at high decline rates. Nevertheless, we
show that NIR light curves can be reasonably fit with a template, especially if
the observations begin within 5 days after NIR maximum. For the subset of 13
objects in our dataset that excludes the highly reddened and fast declining SNe
Ia, and includes only those objects for which NIR observations began prior to
five days after maximum light, we find modest evidence for a peak
luminosity-decline rate relation in Y, and stronger evidence in J and H. Using
Rv values differing from the canonical value of 3.1 is shown to have little
effect on the results. A Hubble diagram is presented for the NIR bands and the
B band. The resulting scatter for the combined NIR bands is 0.13 mag, while the
B band produces a scatter of 0.22 mag. The data suggest that applying a
correction to SNe Ia peak luminosities for decline rate is likely to be
beneficial in the J and H bands to make SNe Ia more precise distance
indicators, but of only marginal importance in the Y band.
01/2012;
-
Gastón Folatelli, M. M. Phillips,
Nidia Morrell,
Masaomi Tanaka,
Keiichi Maeda,
Ken'ichi Nomoto,
Maximilian Stritzinger,
Christopher R. Burns,
Mario Hamuy,
Paolo Mazzali,
Luis Boldt,
Abdo Campillay,
Carlos Contreras,
Sergio González,
Miguel Roth,
Francisco Salgado,
W. L. Freedman,
Barry F Madore,
S. E. Persson,
and Nicholas B. Suntzeff
[show abstract]
[hide abstract]
ABSTRACT: The presence of unburned material in the ejecta of normal Type Ia supernovae (SNe Ia) is investigated using early-time spectroscopy obtained by the Carnegie Supernova Project. The tell-tale signature of pristine material from a C+O white dwarf progenitor star is the presence of carbon, as oxygen is also a product of carbon burning. The most prominent carbon lines in optical spectra of SNe Ia are expected to arise from C II. We find that at least 30% of the objects in the sample show an absorption at 6300 Å which is attributed to C II λ6580. An alternative identification of this absorption as Hα is considered to be unlikely. These findings imply a larger incidence of carbon in SNe Ia ejecta than previously noted. We show how observational biases and physical conditions may hide the presence of weak C II lines, and account for the scarcity of previous carbon detections in the literature. This relatively large frequency of carbon detections has crucial implications on our understanding of the explosive process. Furthermore, the identification of the 6300 Å absorptions as carbon would imply that unburned material is present at very low expansion velocities, merely 1000 km s–1 above the bulk of Si II. Based on spectral modeling, it is found that the detections are consistent with a mass of carbon of 10–3 to 10–2 M ☉. The presence of this material so deep in the ejecta would imply substantial mixing, which may be related to asymmetries of the flame propagation. Another possible explanation for the carbon absorptions may be the existence of clumps of unburned material along the line of sight. However, the uniformity of the relation between C II and Si II velocities is not consistent with such small-scale asymmetries. The spectroscopic and photometric properties of SNe Ia with and without carbon signatures are compared. A trend toward bluer color and lower luminosity at maximum light is found for objects which show carbon.
The Astrophysical Journal 12/2011; 745(1):74. · 6.02 Impact Factor
-
F. Taddia,
M. D. Stritzinger,
J. Sollerman, M. M. Phillips,
J. P. Anderson,
M. Ergon,
G. Folatelli,
C. Fransson,
W. Freedman,
M. Hamuy,
N. Morrell,
A. Pastorello,
S. E. Persson,
S Gonzalez
[show abstract]
[hide abstract]
ABSTRACT: Supernova 1987A revealed that a blue supergiant (BSG) star can end its life
as a core-collapse supernova (SN). SN 1987A and other similar objects exhibit
properties that distinguish them from ordinary Type II Plateau (IIP) SNe, whose
progenitors are believed to be red supergiants (RSGs). Similarities among
1987A-like events include a long rise to maximum, early luminosity fainter than
that of normal Type IIP SNe, and radioactivity acting as the primary source
powering the light curves. We present and analyze two SNe monitored by the
Carnegie Supernova Project that are reminiscent of SN 1987A. Optical and
near-infrared (NIR) light curves, and optical spectroscopy of SNe 2006V and
2006au are presented. These observations are compared to those of SN 1987A, and
are used to estimate properties of their progenitors. Both objects exhibit a
slow rise to maximum and light curve evolution similar to that of SN 1987A. At
the earliest epochs, SN 2006au also displays an initial dip which we interpret
as the signature of the adiabatic cooling phase that ensues shock break- out.
SNe 2006V and 2006au are both found to be bluer, hotter and brighter than SN
1987A. Spectra of SNe 2006V and 2006au are similar to those of SN 1987A and
other normal Type II objects, although both consistently exhibit expansion
velocities higher than SN 1987A. Semi-analytic models are fit to the UVOIR
light curve of each object from which physical properties of the progenitors
are estimated. This yields ejecta mass estimates of about 20 solar masses,
explosion energies of 2 - 3 x 10^51 erg, and progenitor radii of 75 - 100 solar
radii for both SNe. The progenitors of SNe 2006V and 2006au were most likely
BSGs with a larger explosion energy as compared to that of SN 1987A.
11/2011;
-
Maximilian D. Stritzinger, M. M. Phillips,
Luis N. Boldt,
Chris Burns,
Abdo Campillay,
Carlos Contreras,
Sergio Gonzalez,
Gastón Folatelli,
Nidia Morrell,
Wojtek Krzeminski, [......],
Mario Hamuy,
Wendy L. Freedman,
Barry F. Madore,
J. L. Marshall,
Sven E. Persson,
Jean-Philippe Rheault,
Nicholas B. Suntzeff,
Steven Villanueva,
Weidong Li,
and Alexei V. Filippenko
[show abstract]
[hide abstract]
ABSTRACT: The Carnegie Supernova Project (CSP) was a five-year observational survey conducted at Las Campanas Observatory that obtained, among other things, high-quality light curves of ~100 low-redshift Type Ia supernovae (SNe Ia). Presented here is the second data release of nearby SN Ia photometry consisting of 50 objects, with a subset of 45 having near-infrared follow-up observations. Thirty-three objects have optical pre-maximum coverage with a subset of 15 beginning at least five days before maximum light. In the near-infrared, 27 objects have coverage beginning before the epoch of B-band maximum, with a subset of 13 beginning at least five days before maximum. In addition, we present results of a photometric calibration program to measure the CSP optical (uBgVri) bandpasses with an accuracy of ~1%. Finally, we report the discovery of a second SN Ia, SN 2006ot, similar in its characteristics to the peculiar SN 2006bt.
The Astronomical Journal 10/2011; 142(5):156. · 4.03 Impact Factor
-
Maximilian Stritzinger, M. M. Phillips,
Luis Boldt S,
Chris Burns,
Abdo Campillay,
Carlos Contreras,
Sergio Gonzalez,
Gaston Folatelli,
Nidia Morrell,
Wojtek Krzeminski, [......],
Mario Hamuy,
Wendy L. Freedman,
Barry Madore,
Jennifer L. Marshall,
Sven E. Persson,
Jean-Philippe Rheault,
Nicholas Suntzeff,
Steven Villanueva,
Weidong Li,
Alexei V. Filippenko
[show abstract]
[hide abstract]
ABSTRACT: The Carnegie Supernova Project (CSP) was a five-year observational survey
conducted at Las Campanas Observatory that obtained, among other things,
high-quality light curves of ~100 low-redshift Type Ia supernovae (SNe Ia).
Presented here is the second data release of nearby SN Ia photometry consisting
of 50 objects, with a subset of 45 having near-infrared follow-up observations.
Thirty-three objects have optical pre-maximum coverage with a subset of 15
beginning at least 5 days before maximum light. In the near-infrared, 27
objects have coverage beginning before the epoch of B-band maximum, with a
subset of 13 beginning at least 5 days before maximum. In addition, we present
results of a photometric calibration program to measure the CSP optical
(uBgVri)bandpasses with an accuracy of ~1%. Finally, we report the discovery of
a second SN Ia, SN 2006ot, similar in its characteristics to the peculiar SN
2006bt.
08/2011;
-
A Sternberg,
A Gal-Yam,
J D Simon,
D C Leonard,
R M Quimby, M M Phillips,
N Morrell,
I B Thompson,
I Ivans,
J L Marshall,
A V Filippenko,
G W Marcy,
J S Bloom,
F Patat,
R J Foley,
D Yong,
B E Penprase,
D J Beeler,
C Allende Prieto,
G S Stringfellow
[show abstract]
[hide abstract]
ABSTRACT: Type Ia supernovae are key tools for measuring distances on a cosmic scale. They are generally thought to be the thermonuclear explosion of an accreting white dwarf in a close binary system. The nature of the mass donor is still uncertain. In the single-degenerate model it is a main-sequence star or an evolved star, whereas in the double-degenerate model it is another white dwarf. We show that the velocity structure of absorbing material along the line of sight to 35 type Ia supernovae tends to be blueshifted. These structures are likely signatures of gas outflows from the supernova progenitor systems. Thus, many type Ia supernovae in nearby spiral galaxies may originate in single-degenerate systems.
Science 08/2011; 333(6044):856-9. · 31.20 Impact Factor
-
M. Teodoro,
A. Damineli,
J. I. Arias,
F. X. de Araújo,
R. H. Barbá,
M. F. Corcoran,
M. Borges Fernandes,
E. Fernández Lajús,
L. Fraga,
R. C. Gamen, [......],
E. R. Parkin,
C. B. Pereira, M. M. Phillips,
G. R. Solivella,
J. E. Steiner,
M. Stritzinger,
I. Thompson,
C. A. O. Torres,
M. A. P. Torres,
M. I. Zevallos-Herencia
[show abstract]
[hide abstract]
ABSTRACT: The periodic spectroscopic events in eta Carinae are now well established and
occur near the periastron passage of two massive stars in a very eccentric
orbit. Several mechanisms have been proposed to explain the variations of
different spectral features, such as an eclipse by the wind-wind collision
boundary, a shell ejection from the primary star or accretion of its wind onto
the secondary. All of them have problems explaining all the observed phenomena.
To better understand the nature of the cyclic events, we performed a dense
monitoring of eta Carinae with 5 Southern telescopes during the 2009 low
excitation event, resulting in a set of data of unprecedented quality and
sampling. The intrinsic luminosity of the He II 4686 emission line (L~310 Lsun)
just before periastron reveals the presence of a very luminous transient source
of extreme UV radiation emitted in the wind-wind collision (WWC) region. Clumps
in the primary's wind probably explain the flare-like behavior of both the
X-ray and He II 4686 light-curves. After a short-lived minimum, He II 4686
emission rises again to a ne
04/2011;
-
Christopher R. Burns,
Maximilian Stritzinger, M. M. Phillips,
ShiAnne Kattner,
S. E. Persson,
Barry F. Madore,
Wendy L. Freedman,
Luis Boldt,
Abdo Campillay,
Carlos Contreras,
Gaston Folatelli,
Sergio Gonzalez,
Wojtek Krzeminski,
Nidia Morrell,
Francisco Salgado,
and Nicholas B. Suntzeff
[show abstract]
[hide abstract]
ABSTRACT: In providing an independent measure of the expansion history of the universe, the Carnegie Supernova Project (CSP) has observed 71 high-z Type Ia supernovae (SNe Ia) in the near-infrared bands Y and J. These can be used to construct rest-frame i-band light curves which, when compared to a low-z sample, yield distance moduli that are less sensitive to extinction and/or decline-rate corrections than in the optical. However, working with NIR observed and i-band rest-frame photometry presents unique challenges and has necessitated the development of a new set of observational tools in order to reduce and analyze both the low-z and high-z CSP sample. We present in this paper the methods used to generate uBVgriYJH light-curve templates based on a sample of 24 high-quality low-z CSP SNe. We also present two methods for determining the distances to the hosts of SN Ia events. A larger sample of 30 low-z SNe Ia in the Hubble flow is used to calibrate these methods. We then apply the method and derive distances to seven galaxies that are so nearby that their motions are not dominated by the Hubble flow.
The Astronomical Journal 12/2010; 141(1):19. · 4.03 Impact Factor
-
Giuliano Pignata,
Maximilian Stritzinger,
Alicia Soderberg,
Paolo Mazzali, M. M. Phillips,
Nidia Morrell,
J. P. Anderson,
Luis Boldt,
Abdo Campillay,
Carlos Contreras, [......],
Miguel Roth,
Francisco Salgado Emily M. Levesque,
Armin Rest,
J. Adam Crain,
Andrew C. Foster,
Joshua B. Haislip,
Kevin M. Ivarsen,
Aaron P. LaCluyze,
Melissa C. Nysewander,
Daniel E. Reichart
[show abstract]
[hide abstract]
ABSTRACT: Ultraviolet, optical, and near-infrared photometry and optical spectroscopy of the broad-lined Type Ic supernova (SN) 2009bb are presented, following the flux evolution from -10 to +285 days past B-band maximum. Thanks to the very early discovery, it is possible to place tight constraints on the SN explosion epoch. The expansion velocities measured from near maximum spectra are found to be only slightly smaller than those measured from spectra of the prototype broad-lined SN 1998bw associated with GRB 980425. Fitting an analytical model to the pseudo-bolometric light curve of SN 2009bb suggests that 4.1+-1.9 Msun of material was ejected with 0.22 +-0.06 Msun of it being 56Ni. The resulting kinetic energy is 1.8+-0.7x10^52 erg. This, together with an absolute peak magnitude of MB=-18.36+-0.44, places SN 2009bb on the energetic and luminous end of the broad-lined Type Ic (SN Ic) sequence. Detection of helium in the early time optical spectra accompanied with strong radio emission, and high metallicity of its environment makes SN 2009bb a peculiar object. Similar to the case for GRBs, we find that the bulk explosion parameters of SN 2009bb cannot account for the copious energy coupled to relativistic ejecta, and conclude that another energy reservoir (a central engine) is required to power the radio emission. Nevertheless, the analysis of the SN 2009bb nebular spectrum suggests that the failed GRB detection is not imputable to a large angle between the line-of-sight and the GRB beamed radiation. Therefore, if a GRB was produced during the SN 2009bb explosion, it was below the threshold of the current generation of gamma-ray instruments. Comment: Accepted for publication in ApJ
11/2010;
-
Carlos Contreras,
Mario Hamuy, M. M. Phillips,
Gastón Folatelli,
Nicholas B. Suntzeff,
S. E. Persson,
Maximilian Stritzinger,
Luis Boldt,
Sergio González,
Wojtek Krzeminski, [......],
Miguel Roth,
Francisco Salgado,
María José Maureira,
Christopher R. Burns,
W. L. Freedman,
Barry F. Madore,
David Murphy,
Pamela Wyatt,
Weidong Li,
and Alexei V. Filippenko
[show abstract]
[hide abstract]
ABSTRACT: The Carnegie Supernova Project (CSP) is a five-year survey being carried out at the Las Campanas Observatory to obtain high-quality light curves of ~100 low-redshift Type Ia supernovae (SNe Ia) in a well-defined photometric system. Here we present the first release of photometric data that contains the optical light curves of 35 SNe Ia, and near-infrared light curves for a subset of 25 events. The data comprise 5559 optical (ugriBV) and 1043 near-infrared (Y JHKs ) data points in the natural system of the Swope telescope. Twenty-eight SNe have pre-maximum data, and for 15 of these, the observations begin at least 5 days before B maximum. This is one of the most accurate data sets of low-redshift SNe Ia published to date. When completed, the CSP data set will constitute a fundamental reference for precise determinations of cosmological parameters, and serve as a rich resource for comparison with models of SNe Ia.
The Astronomical Journal 01/2010; 139(2):519. · 4.03 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: High-quality observations of $B$ and $V$ light curves obtained at Las Campanas Observatory for local Type Ia Supernovae (SNe Ia) show clear evidence that SNe Ia with the same brightness decline or stretch may have systematic and independent deviations at times < 5 days before and at times > 30 days after maximum light. This suggests the existence of two independent secondary parameters which control the shape of SN Ia light curves in addition to the brightness decline relation. stretch. The differences are consistent in morphology of the time dependence and size with predictions by models within the delayed detonation scenario. The secondary parameters may reflect two independent physical effects caused by variations in the progenitor and accretion rates, and link the LC variations in shape with the intrinsic, absolute brightness. Comment: 32 pages, 9 Figures, ApJ accepted
12/2009;
-
Gastón Folatelli, M. M. Phillips,
Christopher R. Burns,
Carlos Contreras,
Mario Hamuy,
W. L. Freedman,
S. E. Persson,
Maximilian Stritzinger,
Nicholas B. Suntzeff,
Kevin Krisciunas, [......],
Wojtek Krzeminski,
Nidia Morrell,
Miguel Roth,
Francisco Salgado,
Barry F. Madore,
David Murphy,
Pamela Wyatt,
Weidong Li,
Alexei V. Filippenko,
and Nicole Miller
[show abstract]
[hide abstract]
ABSTRACT: An analysis of the first set of low-redshift (z < 0.08) Type Ia supernovae (SNe Ia) monitored by the Carnegie Supernova Project between 2004 and 2006 is presented. The data consist of well-sampled, high-precision optical (ugriBV) and near-infrared (NIR; YJHKs ) light curves in a well-understood photometric system. Methods are described for deriving light-curve parameters, and for building template light curves which are used to fit SN Ia data in the ugriBVYJH bands. The intrinsic colors at maximum light are calibrated using a subsample of supernovae (SNe) assumed to have suffered little or no reddening, enabling color excesses to be estimated for the full sample. The optical-NIR color excesses allow the properties of the reddening law in the host galaxies to be studied. A low average value of the total-to-selective absorption coefficient, RV 1.7, is derived when using the entire sample of SNe. However, when the two highly reddened SNe (SN 2005A and SN 2006X) in the sample are excluded, a value RV 3.2 is obtained, similar to the standard value for the Galaxy. The red colors of these two events are well matched by a model where multiple scattering of photons by circumstellar dust steepens the effective extinction law. The absolute peak magnitudes of the SNe are studied in all bands using a two-parameter linear fit to the decline rates and the colors at maximum light, or alternatively, the color excesses. In both cases, similar results are obtained with dispersions in absolute magnitudes of 0.12-0.16 mag, depending on the specific filter-color combination. In contrast to the results obtained from the comparison of the color excesses, these fits of absolute magnitude give RV 1-2 when the dispersion is minimized, even when the two highly reddened SNe are excluded. This discrepancy suggests that, beyond the "normal" interstellar reddening produced in the host galaxies, there is an intrinsic dispersion in the colors of SNe Ia which is correlated with luminosity but independent of the decline rate. Finally, a Hubble diagram for the best-observed subsample of SNe is produced by combining the results of the fits of absolute magnitude versus decline rate and color excess for each filter. The resulting scatter of 0.12 mag appears to be limited by the peculiar velocities of the host galaxies as evidenced by the strong correlation between the distance-modulus residuals observed in the individual filters. The implication is that the actual precision of SNe Ia distances is 3%-4%.
The Astronomical Journal 12/2009; 139(1):120. · 4.03 Impact Factor
-
G. Leloudas,
M. D. Stritzinger,
J. Sollerman,
C. R. Burns,
C. Kozma,
K. Krisciunas,
J. R. Maund,
P. Milne,
A. V. Filippenko,
C. Fransson, [......],
W Li, M. M. Phillips,
B. P. Schmidt,
J. Skottfelt,
S. Taubenberger,
L. Boldt,
J. P. U. Fynbo,
L. Gonzalez,
M. Salvo,
J. Thomas-Osip
[show abstract]
[hide abstract]
ABSTRACT: An extensive dataset for SN 2003hv that covers the flux evolution from maximum light to day +786 is presented. The data are combined with published nebular-phase infrared spectra, and the observations are compared to model light curves and synthetic nebular spectra. SN 2003hv is a normal Type Ia supernova (SN Ia) with photometric and spectroscopic properties consistent with its rarely observed B-band decline-rate parameter, Delta m_15 = 1.61 +- 0.02. The blueshift of the most isolated [Fe II] lines in the nebular-phase optical spectrum appears consistent with those observed in the infrared at similar epochs. At late times there is a prevalent color evolution from the optical toward the near-infrared bands. We present the latest-ever detection of a SN Ia in the near-infrared in Hubble Space Telescope images. The study of the ultraviolet/optical/infrared (UVOIR) light curve reveals that a substantial fraction of the flux is "missing" at late times. Between 300-700 days past maximum brightness, the UVOIR light curve declines linearly following the decay of radioactive Co56, assuming full and instantaneous positron trapping. At 700 days we detect a possible slowdown of the decline in optical bands, mainly in the V band. The data are incompatible with a dramatic infrared catastrophe. However, the idea that an infrared catastrophe occurred in the densest regions before 350 days can explain the missing flux from the UVOIR wavelengths and the flat-topped profiles in the near-infrared. We argue that such a scenario is possible if the ejecta are clumpy. The observations suggest that positrons are most likely trapped in the ejecta. Comment: 20 pages, 9 figures. Fixed typos found during proofs to match published version
08/2009;
