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An Intermediate Redshift Supernova Search at
ESO Preliminary Results G. Altavilla INAF-
Astronomical Observatory of Padua
M. Riello, E. Cappellaro, S. Benetti, A.
Pastorello, F. Patat, M. Prevedello, M. Turatto,
L. Zampieri
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
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WFI_at_2.2m Telescope aperture 2.2 m Field of view
34x 33 Pixel scale 0.238 arcsec/pix
Detector 4x2 mosaic of 2kx4k
CCDs Data size Raw 142 MB/file Reduced 268
MB/file
Effective surveyed area 5.1 square degrees
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
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Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
G. Altavilla
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• Subtraction steps
• geometric and photometric alignment
• best PSF image convolution
• subtraction
• (ISIS Alard Lupton 1998 ApJ 503, 325 )

Image to be searched Reference image
Subtracted image
SN 2000fc type Ia V22.4 z0.42 IAUC7537
Each image is the sum of three 15min exposures
Examples of spectra
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
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• Byproducts of the search
• AGN
• variables stars
• minor planets

AGN
Examples of spectra of AGN
Wait for Variable Sources data mining an
example by Marco Riello for details on the
observational strategy and data mining.
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
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SNe spectroscopically confirmed 21 Redshift
distribution
2001gg type II z0.61 2001ip type Ia z0.54
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Lampedusa (Italy) Sept. 16-20, 2002
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SNe spectroscopically confirmed Redshift
distribution
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Lampedusa (Italy) Sept. 16-20, 2002
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SNe spectroscopically confirmed Magnitude
distribution
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
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SNe spectroscopically confirmed Magnitude
distribution
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
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SN RATE

• Steps
• selection of the fields completely searched
• control time calculation (for type Ia only)
• luminosity L(B) (from Lilly et al. 1991)
• extraction of the confirmed SNe and of all the
  candidates found in the selected fields
• comparison between all candidates magnitude
  distribution and the confirmed SNe, and
  correction factors
• magnitude distribution redshift
  distribution
• type Ia rate
• core collapse rate from Ia Rate considering
• NII/NIa and tII/tIa

Galaxy counts (histogram) measured on our fields
and counts derived from the analysis of Lilly et
al. 1991, Maddox et al. 1990, Metcalfe et al.
1995 (from Shimasaku Fukugita 1998).
mm(max) mm(max)1 z mm(max)2
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
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11
Left magnitude distribution of all the
candidates found a convincing candidates, b
uncertain candidates Right magnitude
distribution of 13 SNe of the subsample, before
(double dashed histogram) and after the
correction obtained by the comparison with the
magnitude distribution of candidate ab (single
dashed histogram).
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
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Preliminary results and comparison with data in
literature
Rate (SNu, scaling
as (H0/75)2) z
N.SNe Ia Ib
II references local
83 0.25
0.28 Cappellaro et al. 1993 AA 268,
472 local 31 0.28
Hamuy Pinto 1999
AJ 117, 1185 local 137 0.20
0.08 0.40 Cappellaro et
al. 1999 AA 351, 459 0.10 4
0.25
Hardin et al. 2000 AA 362, 419 0.20
5 0.20 0.27
Present work 0.40 3
0.46
Pain et al. 1996 ApJ 473, 356 0.55
38 0.51
Pain et al. Astro-ph/0205476 a 3
Ia 2 II, considering the SNe of our subsample
(13 SNe) with redshift 0.15ltzlt0.25 b values
uncorrected for absorption c model E
b
b
0.40 -0.17
0.06 -0.06
0.04 -0.04
0.19 -0.19
0.27 -0.16
0.20 b -0.18
0.28 b -0.25
a
0.51 -0.35
0.15 c -0.13
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Lampedusa (Italy) Sept. 16-20, 2002
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II (tot)
II (S)
Ia (tot)
II (E)
Ia (S)
Ia (E)
Hamuy et al.1999
Cappellaro et al.1997
Pain et al.1999
Pain et al.1996
Present work
Pain et al.2000
Hardin et al. 2000
Reiss 2000
The cosmic SN rates (solid line) as the composite
of elliptical (short dashed line) and spirals
(long dashed line). The upper three lines show
SN II rates, the lower three lines show SN Ia
rates. Figure from Kobayashi, Nomoto, Tsujimoto
astro-ph/0102247
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Lampedusa (Italy) Sept. 16-20, 2002
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Work in progress Refine the value of the
rates, for both type Ia and Core Collapse SNe

consider the entire
sample
evaluate selection effects and
biases Possible synergies with other
intermediate z researches large fields
observations up to z0.5 V,R bands, good seeing
(1) time spacing 15 days
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
G. Altavilla
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Open questions...
always the same...
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
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Galaxy counts (histogram) measured on our fields
and counts derived from the analysis of Lilly et
al. 1991, Maddox et al. 1990, Metcalfe et al.
1995 (from Shimasaku Fukugita 1998).
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
G. Altavilla
17
Redshift distribution (after correction) of the
SNe observed and redshift distribution of the
expected SNe, obtained assuming an explosion rate
of 0.2 SNu.
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
G. Altavilla
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why SNe ?
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SN rates in spirals (left-hand scale, SNu)
Filled symbols are core collapse SNe, open
circle are SNe Ia. Cappellaro et al. 1999
AA 351,459 The line gives the SFR per unit B
luminosity (right-hand scale) from evolutionary
synthetis models (Kennicutt 1998 ARAA36,189)
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
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SN rate along redshift (solid line) as a
composite of those in spirals (long-dashed line)
and ellipticals (short- dashed line)
(a) in clusters (b) in the
field Kobayashi et al. 2000 ApJ 539,26 circle
Pain et al. 1996 square Pain et al. 1999
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
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Expected number of SNe
Number of SNe per square arcmin that can be
detected down to different limiting magnitudes.

x 900 arcmin2
DahlénFransson 1999AA,350 349
limiting magnitude 23.5
1 SNe / field (OmegaCAM_at_VST 10 SNe/Field)
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Lampedusa (Italy) Sept. 16-20, 2002
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Observational strategy
VST search follow up
VST search VLT follow up
spectroscopic
classification and light curve
Piggyback
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Lampedusa (Italy) Sept. 16-20, 2002
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The local SN rates
Cappellaro, Evans, Turatto 1999 AA 351, 459
(137 SNe)
1 SNu 1 SN (100 yr)-1(1010L?1B)-1

• errors include SN statisticsparametersbias
• scaling as (Ho/75)2

Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
G. Altavilla
24
Workshop on Variability with Wide Field Imagers
Lampedusa (Italy) Sept. 16-20, 2002
G. Altavilla