J/MNRAS/481/894 Rapidly evolving transients in the DES (Pursiainen+, 2018)
Rapidly evolving transients in the Dark Energy Survey.
Pursiainen M., Childress M., Smith M., Prajs S., Sullivan M., Davis T.M.,
Foley R.J., Asorey J., Calcino J., Carollo D., Curtin C., D'Andrea C.B.,
Glazebrook K., Gutierrez C., Hinton S.R., Hoormann J.K., Inserra C.,
Kessler R., King A., Kuehn K., Lewis G.F., Lidman C., Macaulay E.,
Moller A., Nichol R.C., Sako M., Sommer N.E., Swann E., Tucker B.E.,
Uddin S.A., Wiseman P., Zhang B., Abbott T.M.C., Abdalla F.B., Allam S.,
Annis J., Avila S., Brooks D., Buckley-Geer E., Burke D.L.,
Carnero Rosell A., Carrasco Kind M., Carretero J., Castander F.J.,
Cunha C.E., Davis C., De Vicente J., Diehl H.T., Doel P., Eifler T.F.,
Flaugher B., Fosalba P., Frieman J., Garcia-Bellido J., Gruen D.,
Gruendl R.A., Gutierrez G., Hartley W.G., Hollowood D.L., Honscheid K.,
James D.J., Jeltema T., Kuropatkin N., Li T.S., Lima M., Maia M.A.G.,
Martini P., Menanteau F., Ogando R.L.C., Plazas A.A., Roodman A.,
Sanchez E., Scarpine V., Schindler R., Smith R.C., Soares-Santos M.,
Sobreira F., Suchyta E., Swanson M.E.C., Tarle G., Tucker D.L.,
Walker A.R., (the DES Collaboration)
<Mon. Not. R. Astron. Soc., 481, 894-917 (2018)>
=2018MNRAS.481..894P 2018MNRAS.481..894P (SIMBAD/NED BibCode)
ADC_Keywords: Supernovae
Keywords: supernovae: general
Abstract:
We present the results of a search for rapidly evolving transients in
the Dark Energy Survey Supernova Programme. These events are
characterized by fast light-curve evolution (rise to peak in ~<10d and
exponential decline in ~<30d after peak). We discovered 72 events,
including 37 transients with a spectroscopic redshift from host galaxy
spectral features. The 37 events increase the total number of rapid
optical transients by more than a factor of two. They are found at a
wide range of redshifts (0.05<z<1.56) and peak brightnesses
(-15.75>Mg>-22.25). The multiband photometry is well fit by a
blackbody up to few weeks after peak. The events appear to be hot
(T∼10000-30000K) and large (R∼1014-2x1015cm) at peak, and
generally expand and cool in time, though some events show evidence
for a receding photosphere with roughly constant temperature. Spectra
taken around peak are dominated by a blue featureless continuum
consistent with hot, optically thick ejecta. We compare our events
with a previously suggested physical scenario involving shock breakout
in an optically thick wind surrounding a core-collapse supernova, we
conclude that current models for such a scenario might need an
additional power source to describe the exponential decline. We find
that these transients tend to favour star-forming host galaxies, which
could be consistent with a core-collapse origin. However, more
detailed modelling of the light curves is necessary to determine their
physical origin.
Description:
The DES (Flaugher 2005, Int. J. Mod. Phys. A, 20, 3121) is an
international collaboration with a primary aim to study cosmic
acceleration, and thereby constrain the nature of the mysterious dark
energy that drives it. DES constructed the highly sensitive Dark
Energy Camera (DECam, Flaugher et al. 2015), which has a 3deg2 field
of view and is mounted on the 4m Victor M. Blanco telescope at Cerro
Tololo Inter-American Observatory (CTIO) in Chile. For providing the
camera, the DES collaboration was awarded 105 nights a year for 5yr,
starting from August 2013. DES recently concluded its fifth observing
year in February 2018.
The DES main survey observes a wide area of about 5000deg2 (roughly
1/8 of the sky), and at the conclusion of its fourth year of
observations DES has visited each 3deg2 field within this footprint
at least six times.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 62 72 Basic information of the host galaxies of the
whole sample
table4.dat 62 72 The sample of 72 rapidly evolving transients
including 37 with spectroscopic redshift
table5.dat 74 37 Light-curve parameters of gold and silver sample
transients in g band
table6.dat 82 37 The best-fitting parameters for a blackbody at
peak
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Sample Sample name (G1)
15- 25 A11 --- Name Transient DES name (DESYYANaaaa)
27 A1 --- f_Name [*] Flag on Name (1)
29- 34 A6 --- Survey Observing survey
36- 40 F5.3 arcsec AOffset ? Angular offset
42- 46 F5.2 kpc POffset ? Physical transient offset
48- 52 F5.3 --- DLR ? Directional Light Radius (2)
54- 57 F4.2 --- zspec ? Spectroscopic redshift of the host galaxy (3)
59- 62 F4.2 --- zphot ? Photometric redshift of the host galaxy
(Bonnett et al. 2016PhRvD..94d2005B 2016PhRvD..94d2005B)
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Note (1): Flag as follows:
* = host galaxy candidates that are 'quasi-stellar': objects classified as
stars based on their apparent shape and as such were not initially
targetted for spectroscopic followup (but are now in the spectroscopy
queue)
Note (2): DLR is the ratio of the distance of the transient from the galaxy
centre and the half-light radius of that galaxy (for more details see
e.g. Gupta et al. 2016AJ....152..154G 2016AJ....152..154G)
Note (3): zspec for DES16E1bir was obtained from host galaxy spectral features
present in the spectrum of the transient
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Sample Sample name (G1)
15- 25 A11 --- Name Transient DES name (DESYYANaaaa)
27- 28 I2 h RAh Right ascension (J2000)
30- 31 I2 min RAm Right ascension (J2000)
33- 37 F5.2 s RAs Right ascension (J2000)
39 A1 --- DE- Declination sign (J2000)
40- 41 I2 deg DEd Declination (J2000)
43- 44 I2 arcmin DEm Declination (J2000)
46- 50 F5.2 arcsec DEs Declination (J2000)
52- 55 F4.2 --- zspec ? Spectroscopic resdshift (1)
57- 62 F6.4 mag E(B-V) Milky way colour excesses from
Schlafly & Finkbeiner (2011ApJ...737..103S 2011ApJ...737..103S)
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Note (1): Given redshifts are from the spectra of the host galaxies except for
DES15C3opk and DES16E1bir for which they were obtained from host
galaxy spectral features present in spectra of the events
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Sample Sample name (G1)
15- 25 A11 --- Name Transient DES name (DESYYANaaaa)
27- 31 I5 d tpeak Date of the maximum observed g band flux
33- 38 F6.2 mag Gmagpeak Peak magnitude on the g band
40- 43 F4.2 mag e_Gmagpeak Error on Mpeak
45- 48 F4.1 d trise ? Time between last non-detection and observed
peak (1)
50- 54 F5.2 d tdecline ? Time exponential fit takes to decline to one
tenth of the observed peak flux (1)
56- 61 F6.3 d E_tdecline ? Upper error on tdecline (1)
63- 68 F6.3 d e_tdecline ? Lower error on tdecline (1)
70- 74 F5.2 d t1/2 ? Time above half maximum (1)
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Note (1): trise, tdecline, and t1/2 are given in rest frame.
Errors for tdecline are given in 1σ confidence, but no errors
are given for trise (and t1/2) as the values are effectively upper
limits.
tdecline and t1/2 have not been given for DES13C1tgd and DES13X3pby
as they have only one detection in g band.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Sample Sample name (G1)
15- 25 A11 --- Name Transient DES name (DESYYANaaaa)
27- 32 F6.2 10+3K Tpeak Temperature from best blackbody fit (1)
34- 38 F5.2 10+3K E_Tpeak Upper error on Tpeak
40- 44 F5.2 10+3K e_Tpeak Lower error on Tpeak
46- 50 F5.2 10+14cm rpeak Radius of the transient from best blackbody fit
52- 55 F4.2 10+14cm E_rpeak Upper error on rpeak
57- 60 F4.2 10+14cm e_rpeak Lower error on rpeak
62- 67 F6.2 10-7W Lpeak Luminosity from best blackbody fit
69- 73 F5.2 10-7W E_Lpeak Upper error on Lpeak
75- 80 F6.2 10-7W e_Lpeak Lower error on Lpeak
82 I1 --- Ndata Number of data points the fit was based on
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Note (1): For DES13C3bcok best-fitting temperature is found at the upper
boundary for fitting
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Global notes:
Note (G1): We split our sample into three groups based on the quality of the
light curves and availability of a redshift. These groups will be
referred to as 'gold', 'silver', and 'bronze'.
Our gold sample consists of 20 transients. These objects have known
host galaxy redshifts, allowing us to constrain their true
luminosities, but they also had to pass cuts based on the quality of
the photometric data.
We define the silver sample as those objects with redshifts but which
do not fulfill the photometric requirements for the gold sample -
this silver sample consists of a total of 17 objects. They have
either less than three epochs altogether or have several epochs but
less than three with data in more than two bands.
Our bronze sample consists of the 35 transients currently without
redshifts. These events have light curves similar in shape to the
ones in the gold and silver samples, but lack a spectroscopic
redshift allowing a precise determination of the absolute brightness.
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 07-Jun-2022