Metals in the outskirts of high-redshift galaxies Valentina D - - PowerPoint PPT Presentation

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Dec 26, 2022 48 likes •240 views

Metals in the outskirts of high-redshift galaxies Valentina D Odorico INAF Trieste Astronomical Observatory In collaboration with: G. Becker, F. Calura, R. Carswell, M. Centurion, S. Cristiani, G. Cupani, C. Mongardi, S. Perrotta,

SLIDE 1

Metals in the outskirts of high-redshift galaxies

Valentina D’Odorico

INAF – Trieste Astronomical Observatory

“What Matter(s) around Galaxies” July,19-23 2017

In collaboration with: G. Becker, F. Calura, R. Carswell, M. Centurion, S. Cristiani, G. Cupani, C. Mongardi, S. Perrotta, E. Pomante, M. Viel, et al.

SLIDE 2

Question driven outline

v What are the physical and chemical properties of the CGM?

Metal abundance and distribution
Ionization state

v How does the CGM evolve and what can we learn by comparing different epochs?

Redshift evolution of CDDF and Ω

v What are the physical processes that shape the CGM?

Feedback mechanisms
Epoch and sources of enrichment and ionization

SLIDE 3

What is the origin of the observed metals?

Enrichment scenarii

v Old metals from previous generations of galaxies è sprinkled in the IGM to low densities, metallicity floor at Z~10-3 Zo v Fresh metals expelled from coeval galaxies è clustered in the CGM EARLY ENRICHMENT

z~10 z~2-3

LATE ENRICHMENT

z~2-3

SLIDE 4

11.0 11.1 11.2 11.3 11.4 log N(CIV) 0.0 0.2 0.4 0.6 0.8 1.0 ∆z/∆ztot 11.0 11.5 12.0 12.5 13.0 13.5 14.0 14.5 15.0 15.5 log N(CIV) −17 −16 −15 −14 −13 −12 −11 −10 log dn/dNdX

This work Ellison et al. 2000 D’Odorico et al. 2010

Column density distribution functions

The UVES deep spectrum C IV

Number of lines per unit column density and per unit absorption path

CIV completeness limits

D’Odorico et al. 2016

QSO at zem~3.0 with V=16.9 Texp=64 h SNR ~300-600

SLIDE 5

12.5 13.0 13.5 14.0 14.5 15.0 15.5 16.0 16.5 17.0 log N(HI) 0.0 0.2 0.4 0.6 0.8 1.0 CIV detection rate

43 % 100 %

The UVES deep spectrum

CIV detection rates and connection with galaxies

Fraction of Lyman-α lines in the CGM of LBGs at 2 ≤ z ≤ 2.7, (KBSS, Rudie et al. 2012) C IV detection rate = # of C IV-H I absorber pairs / # of H I absorbers Metals are not found only in the CGM (<300 pkpc) of bright star-forming galaxies at z~2-3 (LBGs):

They could be present also at

larger distances (being produced at larger z);

They could lie also around smaller

galaxies. D’Odorico et al. 2016

SLIDE 6

11 12 13 14

log NCIV

Z = −4.0 Z = −3.0 Z = −2.0 Z = −1.0

13.0 13.5 14.0 14.5 15.0 15.5

log NHI

11 12 13 14

log NOV I

The UVES deep spectrum

(1+δ)=1 3

Cloudy models

HM background Solar relative abundances T=104 (1+δ)0.5 z=2.8

NCIV vs NHI NOVI vs NHI

The metallicity of the IGM

50 14.8 14.0 13.5

Assumption: the Jeans scale is the characteristic scale of the IGM. Used to transform NHI into (1+δ) Enriched volume to log Z/Zo ≥ −3: 14.0 ≤ log NHI <14.8 è 2.8 % extending the same Z distribution to 13.5 ≤ log NHI <14.0 è TOT 10.4 % Max volume from OVI è MAX 12.6 %

SLIDE 7

Where are the metals?

CGM of 20 isolated galaxies in two simulated boxes of 25 comoving Mpc with different prescriptions for star formation and feedback.

Mongardi et al. arXiv:1706.06123

Galaxies with M~1011-1012 Mo at z~2
Boxes pierced with 4000 lines of sight per galaxy with b< 800 kpc
Spectra of HI, CIV, SiIV, OVI built and fitted with

VPFIT

SLIDE 8

Where are the metals?

b < 1 Rvir 1 < b < 3 Rvir 3 < b < 5 Rvir b > 5 Rvir

N(CIV) vs N(HI) N(SiIV) vs N(HI)

b < 1 Rvir 1 < b < 3 Rvir

14 12

Mongardi et al. arXiv:1706.06123

SLIDE 9

How does the CGM evolve with time?

SLIDE 10

Shull et al. 2014

CIV cosmic mass density

Absorption path length interval: approximated as: Evolution of ΩCIV = metal enrichment X ionisation state of metal-enriched gas C IV becomes a preferred ionisation state at lower overdensities towards higher redshifts (e.g. Oppenheimer & Davé 2006)

SLIDE 11

Shull et al. 2014

CIV cosmic mass density

Absorption path length interval: approximated as: Evolution of ΩCIV = metal enrichment X ionisation state of metal-enriched gas C IV becomes a preferred ionisation state at lower overdensities towards higher redshifts (e.g. Oppenheimer & Davé 2006)

Extension to z~7 by Bosman, Becker et al. (2017)

SLIDE 12

Comparison with simulations

Finlator et al. (2015): spatially resolved UVB (galaxies + AGNs)

Observational point from D’Odorico et al. 2013

Overproduction of CIV attributed to the shape of the adopted UVB at the HeII edge.

Small volume è shortage of strong CIV systems

SLIDE 13

Comparison with simulations

Rahmati et al. (2016): EAGLE simulations, homogeneous HM01 UVB Keating et al. (2015): comparison of different simulations/ feedback implementations

SLIDE 14

SiIV abundance and redshift evolution

Rahmati et al. 2016

SiIII SiIIV

SiIV could be a simpler element to simulate, weak dependence on UVB shape

Adapted from Keating et al. 2015

SLIDE 15

Three samples: v UVES/HIRES 27 QSOs 1.74 < z < 3.7 ΔX~40 (D’Odorico+10, Calura+12) v XQ-100 100 QSOs (45 analysed) 3.2 < z < 4.5 ΔX=99 (Perrotta+16) v Xshooter 7 QSOs 4.95 < z < 6.19 ΔX=27 (D’Odorico+13 plus 1 obj)

SiIV abundance and redshift evolution

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

Redshift

5 10 15 20 25 30

Number of spectra

XQ-100 45 obj. UVES/HIRES 27 obj. Xshooter 7 obj.

No of spectra per redshift bin (Δz=0.2)

Absorption path length ΔX

D’Odorico+ in prep.

2 3 4 5 6

Redshift

10 20 30 40 50 60

∆ X

Boksenberg & Sargent 2015

50 20 30 10

SLIDE 16

Three samples: v UVES/HIRES 27 QSOs 1.74 < z < 3.7 ΔX~40 v XQ-100 100 QSOs (45 analysed) 3.2 < z < 4.5 ΔX=99 v Xshooter 7 QSOs 4.95 < z < 6.19 ΔX=27

SiIV abundance and redshift evolution

Column density distribution function

12.0 12.5 13.0 13.5 14.0 14.5 15.0 log N(SiIV) −17 −16 −15 −14 −13 −12 −11 log dn/dNdX

XQ-100 3.2 < z < 3.8 XQ-100 3.8 < z < 4.5 Xshooter 4.95 < z < 6.19

D’Odorico+ in prep.

SLIDE 17

SiIV abundance and redshift evolution

SiIV cosmic mass density (log N(SiIV) > 12.5)

1 2 3 4 5 6

Redshift

10−1 100 101

log Ω (SiIV) (x 10−8)

1 2 3 4 5 6

Redshift

10−1 100 101

log Ω (SiIV) (x 10−8)

Shull et al. (2014) Cooksey et al. (2011) Boksenberg & Sargent (2015) Xshooter 7 obj. XQ100 45 obj. UVES/HIRES 27 obj.

No sub/DLAs Contribution of DLAs should be included or not?

D’Odorico+ in prep.

SLIDE 18

Redshift evolution of CGM metals

The mass density of CIV evolves significantly towards lower redshift while SiIV seems to have a jump at high redshift. Effect of different environment or UVB, or…?

1 2 3 4 5 6 7

Redshift

10−1 100 101

log Ω (SiIV) (x 10−8)

Xshooter 7 obj. XQ100 45 obj. UVES/HIRES 27 obj.

Log N (CIV) > 13.4 Log N (SiIV) > 12.5

SLIDE 19

Final thoughts & future perspectives

ü Metals are not confined to the CGM of bright star forming galaxies: should we change the definition of CGM or maybe define a metallicity threshold between CGM and IGM? ü Data suggest pre-enrichment; ü Present simulations have problems in reproducing the redshift evolution of ΩCIV and the properties of CIV at z~6; ü SiIV could be a simpler element to simulate, its behaviour with time is different wrt CIV.

Medium/High-resolution spectroscopy with 8-10m class telescopes has reached the “photon starving” regime for many of the IGM hot topics è z~2-3 ESPRESSO@VLT online in 2018 z~6 and beyond HIRES@ELT in 2025-2030