# Presentation: 316972

## Supernova rates

- Osservatorio  Astronomico di Padova
- Istituto Nazionale di Astrofisica

*Enrico Cappellaro*

## SN discovery recordhttp://web.oapd.inaf.it/supern/snean.txt

**1987A**

- end of Palomar search

**1995at**
**z = 0.66**

**1988T   z = 0.28**

**Ω****λ****>0**

- Southern SN searches

**1998bw= GRB**

- SN discovery record**http://web.oapd.inaf.it/supern/snean.txt**

**Notes:**
SNe discovered in the new century outnumber those of the previous century.
For the local SN a major contribution is from Lotoss search

## SN and galaxy types

- Asiago SN catalogue
- RC3 galaxy sample

**Notes:**
number of SNe normalized to number of galaxies of given type.
II and Ib/c are linked to star formation 

## Rates vs. recent discovery recordrates from Cappellaro et al. 1999

*z < 0.01,  period 2000-2006, RC3 normalization *

| rate
 | from search |  |
| --- | --- | --- |
| 0.19 | 0.22 |  |
|  |  |  |
|  |  |  |
| 0.08 | 0.15 |  |
|  |  |  |
|  |  |  |
| 0.44 | 0.33 |  |

- Rates vs. recent discovery record*rates from Cappellaro et al. 1999*

**Notes:**
1 - high rate of Ia in I is strange
2 - compute rate from discovery record of the last 5 years
3 - difference are lost SNe
Conclusion: rate of Ib/c may be a factor 2 higher !

## where the difference come from ?

-  over-estimate of search efficiency
-  adopted SN luminosity function biased against faint objects
-  under-estimate of  extinction correction
-  for Ib/c:  bias in classification of ‘70-’80 Sne

## Apparent magnitude distribution of nearby (z<0.01) SNe

**Notes:**
Many new faint, nearby SNe. New luminosity function (eg. a new class of faint SNII)

## Core collapse from blue supergiants

*SN 1998A - **Pastorello et al. 2005 MNRAS 360, 950*

- SN 1987A is not unique

-   87A-like are likely ~10% of SNII

**Notes:**
87A temperature lower
symmetric P-cygni profile
Barium lines -> temperature effect

## SN and galaxy luminosity

***SN rate is proportional to luminosity***
- 80% of SNe in galaxies brighter than B -20

| All | 20% |
| --- | --- |
| B<-20 | 20% |
| B>-20 | 18% |

- LGRB occur in low luminosity galaxies
- They are associated to SN Ib/c

- Only a small fraction of SNIb/c are linked to LGRB

## SNIa progenitor population

*van den Bergh (1959) Ann.Ap. 22,123; Bertaud (1961) Ann.Ap. 24, 516*

- High rate of SN Ia in spirals

- progenitors are long lived, low mass stars

- most type Ia SNe come from short lived stars

*Oemler & Tinsley (1979)*

**Notes:**
single degenerate progenitor scenario. mass range of binaries component
8-3 Msun

## Cosmic evolution of SN Ia rate

- Strolger et al 2004 ApJ 613,200

- SN Ia progenitors are 4 Gyr old

## SN rate per unit massMannucci et al. 2005 A&A 433,807

-    SN rate in SNu from Cappellaro et al. 1999
-    B  K galaxy magnitude normalization (from 2MASS)
*   **log* (M/Lk)  B-K

## Two channels for  SN Ia evolution

- Hubble type of SN Ia host galaxies of the local Universe

- SNr(Ia) = 0.047+0.35 SNr(CC)

|  |   old | young |
| --- | --- | --- |
| E-S0 | 100 | 0 |
| Sa-Sb | 50 | 50 |
| Sbc-Sd | 20 | 80 |
| Irr | 0 | 100 |

- Half of the SNIa in the local Universe are from young progenitors

*see also Scannapieco & Bildsten 2005*

## Southern Intermediate Redshift ESO SN Search

- field of view: 34’x 33’
- pixel scale: 0.238 arcsec/pix  	effective search area  ~5.1sq.deg
- 25(+13) nights

*Cappellaro et al. 2005, Botticella et al. in preparation*

- SN 2000fc Ia  z=0.42

- ESO VLT+FORS1/2
- spectroscopic follow-up
- 13 nights

## Pros

- Cons

-  unbiased candidate selection
-  both Ia and CC rates
-  well defined galaxy sample
-  detailed error analysis
-  improved treatment of  extinction correction

-  only 35% SN spectroscopic
- classification
-  U band not available
-  limited redshift range

## ~200 candidates

- 41 direct spectroscopy

- 15 Ia   14  II   5  Ib/c
-                     7  AGN

- 22 AGN

- 44 host galaxy spectra

- ~60 long term variability AGN

- Southern Intermediate Redshift SN search
*Botticella et al. 2007*

- Photometric redshifts for ~40000  galaxies

## Extinction correction

- Riello & Patat 2005

- 2002bo

- I band

- AV = 9 mag

- AV = 1.1 mag

- 2002cv

## what is not accounted for:SN in the nucleus of starburst galaxies

- M82
- radio remnants indicate 1 SN / 20yr
- only SN 2004am  observed (5 mag abs)

*wait for the talk of Filippo Mannucci*

## SN rates are derived from maximum likelihood fit of the observed SN redshift distribution

- SNu

- SNu

## Core collapse rate evolution

**Notes:**
dahlen SFR too shallow at low redshift

## SN Ia  rate evolution

**Notes:**
1 - What was available 5 yr ago.
2 - Many new measurements are changing the picture: problem of modeling at low z (too long delay time, SFR too high ?)
3 - latest measurements (Neill SN Legacy Survey- large dispersion at z~0.5.)
4 - extinction correction is important

## SN Ia  rate evolution

- Delay time distribution

- Star formation rate evolution

- Greggio 2005 A&A

**Notes:**
minimo tau corresponds to the evolutive time of 8 Msun. Second break corresponds to evolutive time of 2.5 Msun

## Neill et al. 2007 (astro-ph/0701161)

- Blanc & Greggio in prep.

- SFR from
- Cole et al. 2001
- Hopkins & Beacom 2006

## Star formation rate evolution

- SFR from
- Cole et al. 2001
- Hopkins & Beacom 2006

- SFR from
- Chary & Elbaz 2001

## SN progenitor age with redshift

- Most local SN Ia are from old progenitors
- High-z SN Ia are from young progenitors

## SN Ia  rate evolution

- Sullivan et al. 2007

- 0.2<z<0.75

- local and medium redshift SNIa show the same
- dependence on galaxy mass and SFR

## SN Ia diversity vs. parent population		

**Notes:**
dispersion is larger when age dispersion is smaller 

## Howell et al. 2007 astro-ph/0701912

- PREDICTED AND OBSERVED EVOLUTION IN THE MEAN PROPERTIES OF TYPE IA SUPERNOVAE  WITH REDSHIFT

## z

- 0

- 0.1

- 0.5

- 0.75

- 1.0

- 1.5

- Age distribution of exploding SN Ia at different redshift

-    age [Gyr]
-   a      b     c
- 4.2   7.3  3.5
- 3.7   6.2  3.2
- 1.8   2.8  1.8
- 1.2   1.7  1.2
- 0.9   1.0  0.8
- 0.7   0.6  0.5

- a)

- b)

- c)

## Conclusions

- Possible inconsistency in the calibration of SFR and CC SN rates. From SN side problem may be extinction correction.

- For rate determination systematics is now more important than statistics

- Star formation history causes uncertainties in the
- SNIa rate prediction as large as the delay time function

- Most of SN Ia in the local and low-z Universe are from
- middle age progenitors.

- All current scenarios predict that at high-z SN Ia progenitor
- are young (~0.5 Gy at z~1.5)