News from the Past:
2019 Updates on Metal-Poor Stars

Tilman Hartwig
初代星・初代銀河研究会2019 @名古屋
Introduction

2 / 102019

The first stars set the scene
dN/dM

Radiative Feedback

Metal Enrichment
Galaxy Formation
First Black Holes
Chemical Evolution?
Initial Mass Function (IMF)
M/Msun
0.1

1

10

100

1000
energetic photons
SN metal production

Motivation

Tilman Hartwig

A Brief History of TimeFirst generation
massive, already dead?

"Stellar Archaeology"

ESO

Second generation
survive as "extremely metal-poor" (EMP)
stars in the Milky Way
Motivation

Tilman Hartwig

Metal-Poor Stars are a Time Machine"cosmic time"
Saga database,Suda-sanMotivation[X/Y] = log10(NX/NY) - log10(NX,sun/NY,sun)Tilman Hartwig

Observing the First Stars
first stars

mixingmetals

MilkyWay

2nd generationstars

Ishigaki+18
Hartwig+18a

SN
explosion

JWST

Hartwig+18b
Moriya+19<0.8MsunHartwig+15
Magg+19

stellarbinaryKinugawa+16
black hole Hartwig+16

binaryMotivation

gravitational
waves

aLIGO

Tilman Hartwig

[Fe/H] (photometry)

Aguado et al., arXiv:1909.08138[Fe/H] (spectroscopy)
707 new very metal-poor stars with [Fe/H] < −2.0
95 new extremely metal-poor stars with [Fe/H] < −3.0
News from the Past

Tilman Hartwig

Nordlander et al.
arXiv:1904.07471

Lowest ever detected
abundance of iron in a star:[Fe/H] = −6.2 ± 0.2 with nosignificant s-/r-processenhancement
News from the Past

Tilman Hartwig

Norris & Yong,arXiv:1905.04810

3D non-LTE corrections
decrease [C/Fe] andtherefore the CEMP
fraction of EMP stars.
News from the Past

Tilman Hartwig

Magg et al., arXiv:1903.08661

Probability of metal-free stars
with <0.8Msun: <1%News from the Past

Probability of not detecting
metal-free stars until today,
as function of halo mass.
Tilman Hartwig

Arentsen et al., 2019, A&A, 621,108

There are:- CEMP-s stars that are
not in a binary- CEMP-no stars that are
in a binary
Binary fraction
increases with [C/Fe]News from the Past

Tilman Hartwig

Ji et al., arXiv:1905.01814

XLa = Mc / (MA + MB + Mc)
News from the Past

If NSMs are the dominant
r-process source, future
NSM should have higher
lanthanide fractions thanGW170817

Tilman Hartwig

Ezzeddine et al., arXiv:1904.03211

Bipolar PopIII SN explosion
can explain high [Zn/H]:
external enrichment?

News from the Past

Tilman Hartwig

multiple supernovae

one supernova

My Research: Multiplicity of the First Stars
first stars

mixing

2nd generation stars

mono-enriched

multi-enrichede.g. Greif+10

News from the Past

Tilman Hartwig

Multiplicity of the First Stars
80% mono
10% multi[Fe/H]
Poisson Statistics: p(1)=0.8, p(2)=0.1
0.3 supernovae per minihalo. In contradiction to Susa 2019?

News from the Past

Tilman Hartwig

Only 0.3 supernovae?
Observation

1 SNaverage: 2 SNe3 SNe

EMP stars:
Interpretation: 1 SN

average: 0.5 SNe
NO EMP stars:
Interpretation: No SN?

We obtain Information about supernova explosion energies
instead of number of supernovae? (Chiaki+18)

News from the Past

Tilman Hartwig

Salvadori et al., arXiv:1906.00994

Chemical signature of PISN
hidden behind normal CCSN
signature? Under-abundanceof [(N, Cu, Zn)/Fe]< 0 are key
elements. One candidate:
BD+80 245

News from the Past

223Msun Pair-Instability SN+
Metals from 30Myr oldstellar population

Tilman Hartwig

Welsh et al., arXiv:1906.00009

11 most metal-poor DLAs:
their chemical diversity
indicates that they wereenriched by ~20 PopIII SNe20

News from the Past

Tilman Hartwig

2019 Updates on Metal-Poor Stars-100 new extremely metal-poor stars with [Fe/H] < −3.0
Record detection of [Fe/H] = −6.2
3D non-LTE corrections decrease [C/Fe]
Probability to find metal-free stars with <0.8Msun is <1%
Some CEMP-no stars may have experienced binary
mass transfer
Lanthanide fraction of future NS merger will help toidentify r-process sources.
Bipolar PopIII explosions can explain high [Zn/Fe]
Observational hints that the first stars form in multiples:
Abundance pattern of PISN+X identified.
DLAs are enriched by ~20 PopIII supernovae.

News from the Past

Tilman Hartwig