Chemical Evolution of the Milky Way

1
Chemical Evolution of the Milky Way

• Francesca Matteucci
• Astronomy Department
• Trieste University

2
How to model galactic chemical evolution

• Initial conditions (open or closed-box chemical
  composition of the gas)
• Birthrate function (SFRxIMF)
• Stellar yields (how elements are produced and
  restored into the ISM)
• Gas flows (infall, outflow, radial flow)
• Equations containing all of of this...

3
Initial Conditions

• a) Start from a gas cloud already present at t0
  (monolithic model). No flows allowed (closed-box)
• b) Assume that the gas accumulates either fastly
  or slowly and the system suffers outflows (open
  model)
• c) We assume that the gas at to is primordial
  (no metals)
• d) We assume that the gas at to is pre-enriched
  by Pop III stars

4
Star Formation History

• We define the stellar birthrate function as
• B(m,t) SFRxIMF
• The SFR is the star formation rate (how many
  solar masses go into stars per unit time)
• The IMF is the initial stellar mass function
  describing the distribution of stars as a
  function of stellar mass

5
Parametrization of the SFR

• The most common parametrization is the Schmidt
  (1959) law where the SFR is proportional to some
  power (k2) of the gas density
• Kennicutt (1998) suggested k1.5 from studying
  star forming galaxies, but also a law depending
  of the rotation angular speed of gas
• Other parameters such as gas temperature,
  viscosity and magnetic field are usually ignored

6
Kennicutts (1998) SFR
7
SFR accounting for feedback
8
The IMF
9
The IMF

• Upper panel different IMFs
• Lower panel normalization of the multi-slope
  IMFs to the Salpeter IMF
• Figure from Boissier Prantzos (1999)

10
The Infall law

• The infall rate can simply be constant in space
  and time
• Or described by an exponential law

11
The outflow law

• The rate of gas loss from a galaxy through a
  galactic wind can be expressed as

12
Stellar Yields

• We call stellar yield the newly produced and the
  already present mass of a given chemical element
  eventually ejected by a star of mass m
• Stellar yields depend upon the mass and the
  chemical composition of the parent star

13
Primary and Secondary elements

• We define primary element an element produced
  directly from H and He
• A typical primary element is carbon or oxygen
  which originate from the 3- alpha reaction
• We define secondary element an element produced
  starting from metals already present in the star
  at birth (e.g. Nitrogen produced in the CNO cycle)

14
Simple Model and Secondary Elements

• The solution of the Simple Model of chemical
  evolution (I.R.A.) for a secondary element Xs
  formed from a seed element Z
• Simple Model assumes I.R.A.
• Xs is proportional to Z(2)
• Xs/Z goes like Z

15
Primary versus secondary

• Figure from Pettini et al. (2002)
• Small dots are extragalactic HII regions
• Red triangles are Damped Lyman-alpha systems
  (DLA)
• Dashed lines mark the solution of the simple
  model for a primary and a secondary element

16
Stellar Yields

• Low and intermediate mass stars (0.8-8 Msun)
  produce He, N, C and heavy s-process elements.
  They die as C-O white dwarfs, when single, and
  can die as Type Ia SNe when binaries
• Massive stars (Mgt8-10 Msun) they produce mainly
  alpha-elements, some Fe, light s-process
  elements and r-process elements and explode as
  core-collapse SNe

17
Stellar Yields

• Yields for Fe in massive stars (Woosley Weaver
  1995 Thielemann et al. 1996 Nomoto et al. 1997
  Rauscher et al. 2002, Limongi Chieffi 2003)

18
Stellar Yields

• Mg yields from massive stars
• Big differences among different studies
• Mg yields are too low to reproduce the Mg
  abundances in stars

19
Stellar Yields

• Oxygen yields from massive stars
• Different studies agree on O yields
• Oxygen increases continuously with stellar mass
  from 10 to 40 Msun
• Not clear what happens for Mgt40 Msun

20
Stellar Yields

• New yield from Nomoto et al. (2007) for Oxygen in
  massive stars
• They are computed for 4 different metallicities

21
Stellar Yields

• Yields of Fe from massive stars from Nomoto et
  al. (2007)
• The yields are computed for 4 different
  metallicities

22
Type Ia SN progenitors

• Single-degenerate scenario Whelan Iben 1974
  Han Podsiadlowsky 2004) a binary system with a
  C-O white dwarf plus a MS star. When the star
  becomes RG it starts accreting mass onto the WD
• When the WD reaches the Chandrasekhar mass it
  explodes by C-deflagration as Type Ia supernova

23
Type Ia SN progenitors

• Double-Degenerate scenario (Iben Tutukov,
  1984) two C-O WDs merge after loosing angular
  momentum due to gravitational wave radiation
• When the two WDs of 0.7 Msun merge, the
  Chandrasekhar mass is reached and C-deflagration
  occurs
• The nucleosynthesis is the same in the two
  scenarios

24
Single-Degenerate scenario
25
The clocks for the explosions of SNe Ia

• Single-Degenerate model the clock to the
  explosion is given by the lifetime of the
  secondary star, m2. The minimum time for the
  appearence of the first Type Ia SN is t_SNIa
  30Myr (the lifetime of a 8 Msun star)
• Double-Degenerate model the clock is given by
  the lifetime of the secondary plus the
  gravitational time-delay. T_SNIa 35 Myr
  Delta_grav 40 Myr
• The maximum timescale is 10 Gyr in the SD
• and several Hubble times in the DD

26
Type Ia SN nucleosynthesis

• A Chandrasekhar mass (1.44 Msun) explodes by
  C-deflagration
• C-deflagration produces 0.6 Msun of Fe plus
  traces of other elements from C to Si

27
Type II SNe

• Type II SNe arise from the core collapse of
  massive stars (M8-40 Msun) and produce mainly
  alpha-elements (O, Mg, Si, Ca...) and some Fe
• Stars more massive can end up as Type Ib/c SNe,
  they are also core collapse SNe (linked to
  gamma-ray bursts)

28
Basic Equations
29
Definitions of variables

• dGi/dt is the rate of time variation of the gas
  fraction in the form of an element i
• Xi(t) is the abundance by mass of a given element
  i
• Qmi is a term containing all the information
  about stellar evolution and nucleosynthesis

30
Definition of variables

• A 0.05-0.09 is the fraction in the IMF of binary
  systems of that particular type to give rise to
  Type Ia SNe. B1-A
• Tau_m is the lifetime of a star of mass m
• f(mu) is the distribution function of the mass
  ratio in binary systems
• A(t) and W(t) are the accretion and outflow rate,
  respectively

31
The formation of the Milky Way

• Eggen, Lynden-bell Sandage (1962) suggested a
  rapid collapse lasting 300 Myr
• Searle Zinn (1978) proposed a central collapse
  but that the outer halo formed by mergers

32
Different approaches in modelling the MW

• Serial approach halo, thick and thin disk form
  as a continuous process (Matteucci Francois
  1989)
• Parallel approach the different galactic
  component evolve at different rates but they are
  inter-connected (Pardi, Ferrini Matteucci 1995)

33
Different approaches in modelling the MW

• Two-infall approach halo and disk form out of
  two different infall episodes (e.g. Chiappini,
  Matteucci Gratton 1997 Alibes, Labay Canal
  2001)
• Stochastic approach mixing not efficient
  especially in the early halo phases (e.g.
  Tsujimoto et al. 1999 Argast et al. 2000 Oey
  2000)

34
The two-infall model for the formation of the MW

• The two-infall model of Chiappini, Matteucci
  Gratton (1997) predicts two main episodes of gas
  accretion
• During the first one the halo and bulge formed,
  the second gave rise to the disk

35
Another scenario

• The creation of the Milky way
• Hera, flowed when she realized she had been
  giving milk to Heracles and thrust him away her
  breast

36
Gas Infall at the present time
37
Recipes for the two-infall model

• SFR- Kennicutts law with a dependence on the
  surface gas density (exponent k1.5) plus a
  dependence on the total surface mass density
  (feedback). Threshold of 7 Msun/pc2
• IMF, Scalo (1986) normalized over a mass range of
  0.1-100 solar masses
• Exponential infall law with different timescales
  for inner halo (1-2 Gyr) and disk (inside-out
  formation with 7 Gyr at the S.N.)

38
Recipes for the model

• Type Ia SNe- Single degenerate model (WDRG or MS
  star), recipe from Greggio Renzini (1983) and
  Matteucci Recchi (2001)
• Minimum time for explosion 35 Myr (lifetime of a
  8 solar masses star), confirmed by recent
  findings (Mannucci et al. 2005, 2006)
• Time for restoring the bulk of Fe in the S.N. is
  1 Gyr (depends on the assumed SFR)

39
Solar Vicinity

• We study first the solar vicinity, namely the
  local ring at 8 kpc from the galactic center
• Then we study the properties of the entire disk
  from 4 to 22 Kpc
• Finally we discuss the properties of the Bulge
  

40
Stellar Lifetimes
41
The star formation rate (threshold effects)
42
Predicted SN rates

• Type II SN rate (blue) follows the SFR
• Type Ia SN rate (red) increases smoothly (small
  peak at 1 Gyr)

43
Time-delay model

• Blue line only Type II SNe produce Fe
• Red line only Type Ia SNe produce Fe
• Black line Type II SNe produce 1/3 of Fe and
  Type Ia SNe produce 2/3 of Fe

44
Specific prediction by the two-infall model

• The adoption of a threshold in the gas density
  for the SFR creates a gap in the SFR
• This gap occurs between the halo-thick disk and
  the thin-disk phase
• It is observed in the data

45
G-dwarf distribution (Chiappini et al.)
46
Different timescales for disk formation
47
G-dwarf distribution

• Chiappini et al. (1997) , Alibes et al. (2001)
  and Kotoneva et al. (2002) concluded that a good
  fit to the G-dwarf metallicity distribution can
  be obtained only with a time scale of disk
  formation at the solar distance of 7-8 Gyr

48
Evolution of the element abundances

• We follow the evolution in space and time of
  35 chemical species (H, D, He, Li, C, N, O, Ne,
  Mg, Si, S, Ca, Ti, K, Fe, Mn, Cr, Ni, Co, Sc,
  Zn, Cu, Ba, Eu, Y, La, Sr plus other isotopes)
  (Francois, FM et al.2004)
• We solve a system of 35 equations where SFR, IMF,
  nucleosynthesis and gas accretion are taken into
  account
• Basic yields from massive stars WW95, from
  low-intermediate stars van den Hoeck Groenewegen
  1997, from Type Ia SNe Iwamoto et al. 1999

49
Results from Francois et al. 2004
50
Results from Francois et al. 2004
51
Results from Francois et al. 2004
52
Corrected Yields
53
Corrected Yields
54
Corrected Yields
55
Suggestions for the Yields

• Yields from Woosley Weaver 1995 (WW95), Iwamoto
  et al. (1999)
• Major corrections for Fe-peak elements !
• O, Fe, Si and Ca are ok. Mg should be increased

56
C and N evolution

• Evolution of Carbon and Nitrogen as predicted by
  the two-infall model of Chiappini, Matteucci
  Gratton (1997)
• The green line in the N plot is an euristic model
  with primary N from massive stars

57
Last data on Nitrogen

• From Ballero, FM Chiappini (2005)
• It shows new data (filled circles and triangles)
  at low metallicity endorsing the suggestion that
  N should be primary in massive star
• Stellar rotation can produce such N (Meynet
  Maeder 2002)

58
Last data on N and C

• Primary nitrogen from rotating very metal poor
  massive stars
• Models from Chiappini et al. (2006) (dashed
  lines)
• Large squares from Israelian et al. 04 asterisks
  from Spite et al. 05 pentagons from Nissen 04

59
s- and r-process elements

• Data from Francois et al. (2007) with UVES on VLT
• Models Cescutti et al. (2006) red line, best
  model, with Ba_s from 1-3 solar masses (Busso et
  al. 01) and Ba_r from 10-30 solar masses

60
s- and r- process elements

• Data from Francois et al. (200)
• Models from Cescutti et al. (2006) red line,
  best model with Eu only r-process from 10-30
  solar masses

61
Abundance Gradients

• The abundances of heavy elements decrease with
  galactocentric distance
• in the disk
• Gradients of different elements are slightly
  different (depending on their nucleosynthesis and
  timescales of production)
• Gradients are measured from HII regions, PNe, B
  stars, open clusters and Cepheids

62
How does the gradient form?

• If one assumes the disk to form inside-out,
  namely that first collapses the gas which forms
  the inner parts and then the gas which forms the
  outer parts
• Namely, if one assumes a timescale for the
  formation of the disk increasing with
  galactocentric distance, the gradients are well
  reproduced

63
Abundance gradients

• Predicted and observed abundance gradients from
  Chiappini, Matteucci Romano (2001)
• Data from HII regions, PNe and B stars, red dot
  is the Sun
• The gradients steepen with time (from blue to red)

64
Abundance gradients

• Predictions from Boissier Prantzos (1999), no
  threshold density in the SF
• They predict the gradient to flatten in time
• The difference is due to the effect of the
  threshold

65
Abundance Gradients

• New data on Cepheids from Andrievsky al.(02,04)
  (open blue circles)
• Red triangles-OB stars from Daflon Cunha (2004)
• Blue filled hexagons are Cepheids from Yong et
  al.(2006), blue open triangles are open clusters
  from Young et al. 05, cian data from Carraro et
  al.(2004)

66
Abundance Gradients

• Blue filled hexagons from Andrievsky al.(02,04)
  
• Red squares are the average values
• For Barium there are not yet enough data to
  compare

67
Scenarios for Bulge formation

• Accretion of extant stellar systems which
  eventually settle in the Galactic center
• Accumulation either slow or rapid at the center
  of the Galaxy of gas from the halo, or thick disk
  or thin disk, and subsequent evolution slow or
  fast

68
The Galactic Bulge

• The first model for the chemical evolution of the
  Bulge from Matteucci Brocato (1990)
• Fast formation (lt1 Gyr) from halo gas and
  subsequent fast evolution (high SF efficiency)

69
The Galactic Bulge

• A more recent version of the Matteucci Brocato
  (1990) figure
• Different alpha/Fe patterns are expected for
  different SF histories
• Good tool to interpret high-redshift objects

70
The Galactic Bulge

• A model for the Bulge (green line) from Ballero ,
  FM, Origlia Rich (2007)
• Yields from Francois et al. (04), SF efficiency
  of 20 Gyr(-1), timescale of accretion 0.1 Gyr
• Data from Zoccali et al. 06, Fulbright et al. 06,
  Origlia Rich (04, 05)

71
The Galactic Bulge

• Model (red, Ballero et al. 2007)
• Predicts large Mg to Fe for a large Fe interval
• Turning point at larger than solar Fe. Mg flatter
  than O
• Data from Zoccali et al. 06 Fulbright et al. 06,
  Origlia Rich (04, 05)

72
The Galactic Bulge

• Metallicity Distribution of Bulge stars, data
  from Zoccali et al. (2003) and Fulbright et al.
  (2006) (dot-dashed)
• Models from Ballero et al. 07, with different SF
  eff.

73
The Galactic Bulge

• Models with different IMF
• The best IMF for the Bulge is flatter than in the
  S.N and flatter than Salpeter
• Best IMF x0.95 for Mgt 1 solar mass and x0.33
  below

74
Bulge vs. Thick and Thin Disk Stars

• Zoccali et al. (2006) compared new high
  resolution data for the Bulge (green dots and red
  crosses) with data for thick disk (yellow
  triangles) and thin disk (blue crosses)
• The Bulge stars are systematically more
  overabundant in O

75
Comparison with data

• Comparison between models of Immeli et al. (2004)
  with data from Zoccali et al. (2006)
• The best model (green line) predicts a very fast
  Bulge formation
• However, Immelis models have a fixed delay for
  Type Ia SNe

76
Conclusions on the Bulge

• The best model for the Bulge suggests that it is
  very old and formed by means of a strong
  starburst
• The efficiency of SF was 20 times higher than in
  the rest of the Galaxy
• The IMF was very flat, as it is suggested for
  starbursts
• The timescale for the Bulge formation was 0.1 Gyr
  and not longer than 0.5 Gyr

77
Conclusions on the Milky Way

• The Disk at the solar ring formed on a time scale
  not shorter than 7 Gyr
• The whole Disk formed inside-out with timescales
  of the order of 2 Gyr in the inner regions and 10
  Gyr in the outer regions
• The inner halo formed on a timescale not longer
  than 2 Gyr, the outer halo formed on longer
  timescales perhaps from accretion
• Abundance gradients arise from the inside-out
  Disk formation

78
Dwarf Spheroidals of the Local Group
79
SF and Hubble Sequence from Sandage
80
SF and HS from Kennicutt
81
Models for the Hubble Sequence
82
Type Ia SN rate in galaxies
83
Timescales for Type Ia SNe enrichment

• The typical timescale for the Type Ia SN
  enrichment is the maximum in the Type Ia SN rate
  (Matteucci Recchi 2001)
• It depends on the star formation history of a
  specific galaxy, IMF and stellar lifetimes

84
Typical timescales for SNIa

• In ellipticals and bulges the timescale for the
  maximum enrichment from Type Ia SNe is 0.3-0.5
  Gyr
• In the solar vicinity there is a first peak at 1
  Gyr, then it decreases slightly (gap in the SF)
  and increases again till 3 Gyr
• In irregulars the peak is for a time gt 4 Gyr

85
Time-delay model in different galaxies
86
Interpretation of time-delay model

• Galaxies with intense SF (ellipticals and bulges)
  show overabundance of alpha-elements for a large
  Fe/H range
• Galaxies with slow SF (irregulars) show instead
  low alpha/Fe ratios at low Fe/H
• The SFR determines the shape of the alpha/Fe
  vs. Fe/H relations

87
Identifying high-z objects

• Lyman-break galaxy cB58, data from Pettini et al.
  2002
• The model predictions are for an elliptical
  galaxy of 10(10) Msun (Matteucci Pipino 2002)

88
Dating high-z objects

• The Lyman-break galaxy cB58
• Predicted abundance ratios versus redshift
• The estimated age is 35 Myr

89
Conclusions on high-z objects

• Comparison between data and abundance ratios of
  high-z objects suggests
• DLA are probably dwarf irregulars or at most
  external parts of disks
• Lyman-break galaxies are probably small
  ellipticals in the phase of galactic wind

90
How do dSphs form?

• CDM models for galaxy formation predict dSph
  systems (107 Msun) to be the first to form stars
  (all stars should form lt 1Gyr)
• Then heating and gas loss due to reionization
  must have halted soon SF
• Observationally, all dSph satellites of the MW
  contain old stars indistinguishable from those of
  Galactic globular clusters and they have
  experienced SF for long periods (gt2 Gyr, Grebel
  Gallagher, 04)

91
Chemical Evolution of Dwarf Spheroidals

• Lanfranchi Matteucci (2003, 2004) proposed a
  model which assumes the SF as derived by the CMDs
• Initial baryonic masses 5x10(8)Msun
• A strong galactic wind occurs when the gas
  thermal energy equates the gas potential energy.
  DM ten times LM but diffuse (M/L today of the
  order of 100)
• The wind rate is assumed to be several times the
  SFR

92
Standard Model of LM03

• LM03 computed a standard models for dwarf
  spheroidals
• They assumed 1 long star formation episode (8
  Gyr), a low star formation efficiency lt1
  Gyr(-1)
• They assumed that galactic winds are triggered by
  SN explosions at rates gt 5 times the SFR . The
  final mass is 10(7)Msun
• The IMF is that of Salpeter (1955)

93
Galactic winds

• LM03 included the energetics from SNe and stellar
  winds to study the occurrence of galactic winds,
  the condition for the wind being
• Dark matter halos 10 times more massive than the
  initial luminous mass (5x10(8) Msun) but not
  very concentrated (see later)

94
The binding energy of gas
95
The binding energy of gas
96
Binding energy of gas

• S is the ratio between the effective radius of
  the galaxy and the radius of the dark matter core
• We assume S0.10 in dSphs

97
DM in Dwarf Spheroidals

• Mass to light ratios vs. Galaxy absolute V
  magnitude (Gilmore et al. 2006)
• The solid curve shows the relation expected if
  all the dSphs contain about 4x10(7) Msun of DM
  interior to their stellar distributions
• No galaxy has a DM halo lt 5x10(7)Msun

98
DM in dSphs

• Mass to light ratios in dSphs from Mateo et al.
  (1998)
• In the bottom panel the visual absolute magnitude
  has been corrected for stellar evolution effects
• The Sgr point is an upper limit

99
Galactic Winds

• The energy feedback from SNe and stellar winds in
  LM03 is
• SNe II inject 0.03 Eo (Eo is the initial blast
  wave energy of 10(51) erg )
• SNe Ia inject Eo since they explode when the gas
  is already hot and with low density (Recchi et
  al. 2001)
• Stellar winds inject 0.03 Ew (Ew is 10(49) erg)

100
Gas Infall and Galaxy Formation

• LM03 assumed that each galaxy forms by infall of
  gas of primordial chemical composition
• The formation occurs on a short timescale of 0.5
  Gyr

101
Standard Model of LM03

• Standard Model SF lasts for 8 Gyr, strong wind
  removes all the gas
• Different SF eff. and wind eff. are tested, from
  0.005 to 5 Gyr(-1) for SF and from (6 to 15)
  xSF for the winds

102
Abundance patterns

• It is evident that the alpha/Fe ratios in
  dSphs show a steeper decline with Fe/H than in
  the stars in the Milky Way
• This is the effect of the time-delay model,
  namely of a low SF efficiency coupled with a
  strong galactic wind
• After the wind SF continues for a while

103
Individual galaxies

• Then LM03,04 computed the evolution of 6 dSphs
  Carina, Sextan, Draco, Sculptor, Sagittarius and
  Ursa Minor
• They assumed the SF histories as measured by the
  Color-Magnitude diagrams (Mateo, 1998Dolphin
  2002 Hernandez et al. 2000 Rizzi et al. 2003)

104
Star Formation Historiesin LM03
105
SF histories of dSphs (Mateo et al. 1998)
106
Individual galaxies
107
Dwarf Spheroidals Carina

• Model Lanfranchi Matteucci (04,06)
• SF history from Rizzi et al. 03. Four bursts of 2
  Gyr, SF efficiency 0.15 Gyr(-1) lt 1- 2 Gyr(-1)
  (S.N.), wind7xSFR
• Salpeter IMF

108
Predicted C and N in Carina

• Predicted evolution of C and N for Carinas best
  model
• The continuous line is for secondary N in massive
  stars
• The dashed line assumes primary N from massive
  stars

109
Metallicity distribution in Carina

• Data from Koch et al. (2005)
• Best model from Lanfranchi al. (2006)
• This model well reproduces also the alpha/Fe
  ratios in Carina

110
Dwarf Spheroidals Draco

• Model and data for Draco
• SF history, 1 burst of 4 Gyr, SF efficiency of
  0.03 Gyr(-1)
• Wind6xSFR
• Salpeter IMF

111
Dracos metallicity distribution

• Predicted metallicity distribution for Draco
  compared with the predicted metallicity
  distribution for the Solar Vicinity

112
Dwarf Spheroidals Sextans

• Best Model 1 burst of 8 Gyr
• SF efficiency 0.08 Gyr(-1)
• Wind9xSFR
• Salpeter IMF

113
Sextans metallicity distribution

• Predicted metallicity distribution for Sextans by
  LM04
• The predicted G-dwarf metallicity distribution
  for Solar Vicinity stars is shown for comparison

114
Dwarf Spheroidals Ursa Minor

• Best Model 1 burst of 3 Gyr
• SF efficiency 0.2 Gyr(-1)
• Wind10xSFR
• Salpeter IMF

115
Ursa Minors metallicity distribution

• Predicted metallicity distribution for Ursa Minor
  by LM04
• The predicted G-dwarf metallicity distribution
  for the solar vicinity is shown for comparison

116
Dwarf spheroidals Sagittarius

• Best modelone long episode of SF of duration 13
  Gyr (Dolphin et al 2002)
• SF eff. Like the S.N., but very strong wind 9XSFR

117
Metallicity distribution in Sagittarius

• Predicted metallicity distribution by LM04 for
  Sagittarius continuous line (Salpeter IMF),
  dashed line (Scalo IMF)
• The predicted G-dwarf metallicity distribution
  for the solar vicinity is shown by the dotted line

118
Dwarf Spheroidals Sculptor

• Model and data for Sculptor
• SF efficiency 0.05-0.5 Gyr(-1), wind 7 XSFR
• One long SF episide lasting 7 Gyr
• Salpeter IMF

119
Sculptors metallicity distribution

• Predicted metallicity distribution in Sculptor
  (LM04)
• The predicted G-dwarf metallicity distribution
  for the solar vicinity is shown for comparison

120
s- and r- process elements in dSphs

• Lanfranchi et al. 2006 adopted the
  nucleosynthesis prescriptions for the s- and r-
  process elements as in the S.N.
• They calculated the evolution of the s/Fe and
  r/Fe ratios in dSphs
• They predicted that s-process elements, which are
  produced on long timescales are higher for the
  same Fe/H in dSphs

121
Model and data for Carina
122
Model and data for Draco
123
Model and data for Sextans
124
Model and data for Sculptor
125
Model and data for Sagittarius
126
Sagittarius more data

• Best model is continuous line. Dotted lines are
  different SF efficiencies
• Dashed line is the best model with no wind
• The strong wind compensate the high SF efficiency
• Data from Bonifacio et al. 02,04 Monaco et al.
  05 (open squares)

127
C and N in Sagittarius predictions
128
Other Models for dSphs

• Carigi, Hernandez Gilmore (2002) computed
  models for 4 dSphs by assuming SF histories
  derived by Hernandez et al. (2000)
• They assumed gas infall and computed the gas
  thermal energy to study galactic winds
• They assumed a Kroupa et al.(1993) IMF

129
Carigi et al. (2002)

• They assumed only a sudden wind which devoids the
  galaxy from gas instantaneously (LM03 have a
  continuous wind)
• They predicted a too high metallicity for dSphs
  and not the correct slope for alpha/ Fe ratios

130
Carigi et als predictions for Ursa Minor
131
Model of Ikuta Arimoto (2002)

• They adopted a closed model (no infall, no
  outflow)
• They suggested a very low SFR such as that of
  LM03, 04
• No wind considered. They had to invoke external
  mechanisms to stop the SF
• They assumed different IMFs

132
Ikuta Arimoto (2002)
133
Model of Fenner et al. 2006

• Very similar to the model of LM03, 04 with
  galactic winds for Sculptor
• They suggest 0.05 Gyr(-1) as SF efficiency
• Their galactic wind is not as strong as the winds
  of LM03, 04
• They conclude that chemical evolution in dSphs is
  inconsistent with SF being truncated after
  reionization epoch (z 8)

134
Comparison between dSphs and MW

• Blue line and blue data refer to Sculptor
• Red line and red data refer to the Milky Way
• The effect of the time-delay model is to shift
  towards left the model for Sculptor with a lower
  SF efficiency than in the MW

135
Comparison dSph and MW

• Eu/Fe in Sculptor and the MW
• Model and data for Sculptor are in blue
• Model and data for the MW are in red

136
Conclusions on dSphs

• By comparing the alpha/Fe ratios in the MW and
  dSphs one concludes that they had different SF
  histories
• The alpha/Fe ratios in dSphs are always lower
  than in the MW at the same Fe/H, as a
  consequence of the time delay model and strong
  galactic wind

137
Conclusions on dSphs

• Good agreement both for s/Fe and r/Fe ratios
  is obtained . These ratios are generally higher,
  for a given Fe/H, than the corresponding ratios
  in S.N.
• This is again a consequence of the time-delay
  model
• It is unlikely that the dSphs are the building
  blocks of the MW

138
Other spirals
139
Results for M101 (Chiappini et al. 03)
140
Results for M101
141
Properties of spirals (Boissier et al. 01)
142
Conclusions on Spirals
143
Type Ia SN rate

• Time delay distribution for the single-degenerate
  scenario (Matteucci Recchi2001 Greggio
  Renzini 1983)
• Prompt Type Ia SNe are 13 of total

144
Bimodal Type Ia SN rates

• Mannucci et al. (05, 06) suggested that 50 of
  all Type Ia Sne should explode from 40 to 100
  Myr from the beginning of star formation
• The other 50 comes from long living systems

145
Type Ia SN rates in the solar vicinity

• Mannucci et al. DTD in the two-infall model for
  the solar vicinity (dotted line)
• Compared with the Type Ia SN rate with the DTD of
  Matteucci Recchi

146
Predictions for the solar vicinity

• Predictions for O/Fe with the DTD of Mannucci
  et al. And for the DTD of Matteucci Recchi
• Long-dashed line is the prediction for the
  Mannucci DTD

147
Predictions for ellipticals

• The dotted line represents the predicted Type Ia
  SN rate in an elliptical of 10(11)Msun with the
  DTD of Mannucci et al.

148
Cosmic SN rates
149
Cosmic SN rates

• The DTD of Matteucci Recchi
• Preditions for the cosmic Type Ia SN rate
  (including all galaxies)
• Predictions of Type Ia SN rate per unit mass
  versus color and for radio-galaxies

150
Cosmic SN rates

• The DTD of Mannucci
• Predictions for the cosmic Type Ia SN rate
• Predictions for Type Ia SN rate per unit mass
  versus B-K color
• Predictions of Type Ia SN rate for radio-galaxies

151
Conclusions on SN rates

• Cosmic Type Ia SN rates are predicted to be in
  good agreement with data except for the highest
  redshift point which is very uncertain
• Both DTDs give similar results
• Prompt Type Ia SNe should be there
• The main differences between the two DTDs are
  expected at very high redshift

152
THANKS EVA BEN!
153
N132D in LMC oxygen rich SN remnant
SII red, OIII green, OI blue
154
How to search
SN 1998dh

• Compare images taken at different epochs
• few days lt time interval lt 1-2 month
• 14 lt limiting magnitude lt 24
• 0.01 lt target redshift lt 1
• 5 arcmin lt field of view lt 1 deg
• B-V lt band lt R-I

155
SN search
156
SN distribution in galactic
coordinates
157
SN rate with redshift
Madau, Della Valle Panagia 1998 On the
evolution of the cosmic supernova rate Sadat et
al. 1998 AA 331, L69 Cosmic star formation and
Type Ia/II supernova rates at high Z Yungelson
Livio 2000 ApJ 528, 108 Supernova Rates A
Cosmic History Kobayashi et al. 2000 ApJ 539, 26
The History of the Cosmic Supernova Rate Derived
from the Evolution of the Host Galaxies Sullivan
et al. 2000 MNRAS 319, 549 A strategy for finding
gravitationally lensed distant supernovae Dahlèn
Fransson 1999 AA 350, 349 Rates and redshift
distributions of high-z supernovae Calura
Matteucci 2003 ApJ 596, 734
158
Astrophysics massive star evolution
GRBs
NS
BH
Zampieri et al. (2003) MNRAS 338, 711