Ca II Absorbers in the Sloan Digital Sky Survey Data Release 9 · Ca II Absorbers in the Sloan...

Ca II Absorbers in the Sloan Digital Sky Survey Data Release 9

Gendith Sardane Department of Physics & Astronomy

PITTsburgh Particle Physics Astrophysics and Cosmology Center

University of Pittsburgh, PA December 2, 2013

Outline

I.  Introduction/Motivation II.  Survey Details III.  Statistics IV.  Imaging V.  Summary

I. Search for Ca II in the SDSS

HI Ly−a CIV OVI MgII CaII0

2

4

6

8

10

12Lo

ok B

ack

Tim

e, G

Yr

0.00

0.16

0.37

0.65

1.07

1.86

4.11

Reds

hift

In an SDSS spectrum :

Motivation •  Ca II λλ 3934,3969 ÅÅ gives access to the very low

redshift Universe. •  It is a rare class of absorber— under-utilized, under

represented and under-studied. •  Strong Ca II systems preferentially reside in dense,

dusty, neutral, metal-rich, molecular H2-bearing environments – the reservoirs for SF (Wild & Hewett, 2005, Wild et al 2006, Wild et al 2007, Nestor et al 2008, Zych et al 2007, Zych et al 2009)

•  Ca II absorber regions exhibit higher SFRs than other absorber regions (Zych et al 2008, Zhu & Menard 2013)

•  Host galaxies as faint as ~0.01L* can be studied with SDSS images

Search for Ca II in SDSS

1.  SDSS DR9 spectroscopic QSOs brighter than i = 20.

2.  zQSO > 0.1

3.  Exclude BAL QSOs (Paris et al. 2012, Shen et al. 2011 )

4.  Searched a total of roughly 95, 000 QSOs

5.  Search excludes the Ly-alpha forest

0 1 2 3 4 5 6QSO Redshift

0

5.0•103

1.0•104

1.5•104

QSO

Num

ber

0 1 2 3 4 5 6

Num

ber o

f QSO

s

Search for Ca II in SDSS : Data Reduction Pipeline

Spectrum: wavelength, flux, error

Fit Continuum: Splines and Gaussians

Linefinder to find candidate CaII absorbers, separated zQSO & z =0 by at

least 6,000 km/s

Visual inspection to remove spurious systems. Apply significance &doublet ratio cuts

= 441 candidates

zQSO ≈ 1.7199

5040 5060 5080 5100Observed Wavelength, Angstroms

0.0

0.1

0.2

0.3

0.4

0.5No

rmali

zed Fl

ux


0.0

0.1

0.2

0.3

0.4

0.5

Norm

alized

Flux

<zABS > ≈ 0.819 7160 7180 7200 72200.7

0.8

0.9

1.0

1.1

4000 5000 6000 7000 8000 9000Observed Wavelength, Angstroms

0

100

200

300

400

Flux

[ 10

ï17 e

rgs/

s/cm

2 /Ang

] CIV

C III ]

Mg II

0 1 2 3W0

h3934 [Å]

0

20

40

60

80

Num

ber o

f Det

ectio

ns

Observed Redshift and Rest Equivalent Width Distributions

Stats: Cuts : W0

λ3934 ≥ 5σ , W0λ3969 ≥ 2.5σ,

1-σDR ≤ DR ≤ 2+σDR Number of systems= 441

DR =W0λ3934

W0λ3969

0.0 0.5 1.0 1.5Redshift, zabs

0

20

40

60

80

Num

ber

< zabs > ≈ 0.58 < W0λ3934 > ≈ 0.77

1.5 0

Å

0.0 0.5 1.0 1.5Redshift, z

0

2•104

4•104

6•104

8•104

1•105

Sigh

tline

Cov

erag

e

4000 5000 6000 7000 8000 9000Wavelength, Angstroms

W0min = 0.3Å

W0min = 0.6Å

W0min = 1.0Å

W0min = 2.0Å

W0min = 4.0Å

0 1 2 3 4 5 6W0

min, Angstroms

0

2•104

4•104

6•104

8•104

1•105

Cum

ulat

ive

Pathïl

engt

h, g

(W)

Survey Sensitivity Function

Ca II Absorbers in the Sloan Digital Sky Survey Data Release 9

Gendith Sardane1, David A. Turnshek1, Sandhya M. Rao1

[email protected]

ABSTRACT

We present the results of a Ca II��3934, 3969 absorption-line survey culled

from ⇠ 95, 000 QSO spectra from the Sloan Digital Sky Survey Data Release

9. With ⇠ 470 doublets, the catalog is the Ca IIcatalog ever compiled to date,

spanning redshifts z < 1.34. We find that the �3934 equivalent width distribu-

tion cannot be su�ciently described by a single exponential fucntion. A double

exponential function is required to satisfactorily describe the distribution. The

fuction is written as a sum of weak and strong components.... say the parame-

ters. This suggests that Ca IIis composed of two distinct populations of absorbing

clouds. The number density per unit redshift does not show evidence for evolu-

tion. In comparison to the Mg II, we found that only 3% of the Mg IIhave Ca II,

suggesting that it is rare!

Subject headings:

1. Introduction

The sensitivity matrix.

g(W �39340 , z) =

NLOSX

i=1

H(z � zmin(i))H(z

max(i) � z)H[W �39340 � 5�0]H[W �3969

0 � 2.5�0] (1)

Now this is the cumulative path as a function of redshift:

g(W0) =

Z 1

0

g(W0, z)dz (2)

Now this is the distribution in equivalent width corrected by the path:

1Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260

The Corrected Equivalent Width Distribution

0 1 2 3 4 5 6W0

min, Angstroms

0

2•104

4•104

6•104

8•104

1•105

Cum

ulat

ive

Pathïl

engt

h, g

(W)

Maximize Likelihood of the distribution:

– 2 –

dN

dW=

X

Wi2(W,W+dW )

1

g(Wi

)dW(3)

Now this is the model fuction for my corrected equivalent width distribution dn/dW :

dn

dW=

N⇤weak

W ⇤weak

exp

� W0

W ⇤weak

!+

N⇤strong

W ⇤strong

exp

� W0

W ⇤strong

!(4)

To calculate dn/dz I used :

dn

dz

��W>Wmin

=X

Wi>Wminzi2(z,z+dz)

1

g(Wi

, zi

)dz(5)

p(Wi

; ✓) =g(W

i

)f(Wi

; ✓)WmaxZ

Wmin

g(W )f(W ; ✓)dW

(6)

2. Observations

3. Results

3.1. UV Spectra

3.1.1. COS-NUV Spectra

Gen to write paragraphs describing Figure 3.

3.1.2. COS-FUV Spectra

Dan vanden Berk to write this section.

0.5 1.0 1.5 2.0 2.5 3.0W0

h3934 [Å]

ï12

ï10

ï8

ï6

ï4

ï2

0

ln(,

N/,

W0h3

934 )

– 2 –

dN

dW=

X

Wi2(W,W+dW )

1

g(Wi

)dW(3)


dn

dW �39340

=N⇤

weak

W ⇤weak

exp

� W �3934

0

W ⇤weak

!+

N⇤strong

W ⇤strong

exp

� W �3934

0

W ⇤strong

!(4)


dn

dz

��W>Wmin

=X

Wi>Wminzi2(z,z+dz)

1

g(Wi

, zi

)dz(5)

var =X

Wi>Wminzi2(z,z+dz)

✓1

g(Wi

, zi

)dz

◆2

(6)

p(Wi

; ✓) =g(W

i

)f(Wi

; ✓)WmaxZ

Wmin

g(W )f(W ; ✓)dW

(7)

dn

dz= �(z)⇢(z)

dl

dz(8)

dn

dz=

c

Ho

�(z)⇢(z)

(1 + z)p

⌦M

(1 + z)3 + ⌦⇤

(9)

2. Observations

3. Results

3.1. UV Spectra



W0min [ Å ]

0 1 2 3 4W0

h3934 [Å]

0

20

40

60

80N

umbe

r of D

etec

tions

Observed W0λ3934 [ Å ]

0.5 1.0 1.5 2.0 2.5 3.0W0 [Å]

ï6

ï5

ï4

ï3

ï2

ï1

0

1

log 1

0(,N

/,W

0)

Corrected Rest Equivalent Width Distributions

MLE Parameters :

Parameter! Weak! Strong!N*! 0.229 ± 0.032 0.022 ± 0.014

W*[A]! 0.146 ± 0.017 0.359 ± 0.055

– 2 –

dN

dW=

X

Wi2(W,W+dW )

1

g(Wi

)dW(3)


dn

dW �39340

=N⇤

weak

W ⇤weak

exp

� W �3934

0

W ⇤weak

!+

N⇤strong

W ⇤strong

exp

� W �3934

0

W ⇤strong

!(4)


dn

dz

��W>Wmin

=X

Wi>Wminzi2(z,z+dz)

1

g(Wi

, zi

)dz(5)

var =X

Wi>Wminzi2(z,z+dz)

✓1

g(Wi

, zi

)dz

◆2

(6)

p(Wi

; ✓) =g(W

i

)f(Wi

; ✓)WmaxZ

Wmin

g(W )f(W ; ✓)dW

(7)

dn

dz= �(z)⇢(z)

dl

dz(8)

dn

dz=

c

Ho

�(z)⇢(z)

(1 + z)p

⌦M

(1 + z)3 + ⌦⇤

(9)

2. Observations

3. Results

3.1. UV Spectra



TWO Populations!

Ca II Equivalent Width Distribution vs Mg II & C IV

1 2 3 4 5 6W0 [Å]

ï6

ï5

ï4

ï3

ï2

ï1

0

1

log 1

0(,N

/,W

0)

Mg II

C IV Ca II

Evolution?

W0h3934 [Å]

Num

ber

0.0 0.5 1.0 1.5 2.0 2.5 3.005

10

15

20

2530

zBIN = [ 0.03,0.41 ]

0.0 0.5 1.0 1.5 2.0 2.5 3.0

zBIN = [ 0.42,0.72 ]

0.0 0.5 1.0 1.5 2.0 2.5 3.0

zBIN = [ 0.72,1.34 ]

W0h3934 [Å]

Num

ber

0.0 0.5 1.0 1.5 2.0 2.5 3.005

10

15

20

2530

zBIN = [ 0.03,0.41 ]

0.0 0.5 1.0 1.5 2.0 2.5 3.0

zBIN = [ 0.42,0.72 ]

0.0 0.5 1.0 1.5 2.0 2.5 3.0

zBIN = [ 0.72,1.34 ]

W0h3934 [Å]

Num

ber

0.0 0.5 1.0 1.5 2.0 2.5 3.005

10

15

20

2530

zBIN = [ 0.03,0.41 ]

0.0 0.5 1.0 1.5 2.0 2.5 3.0

zBIN = [ 0.42,0.72 ]

0.0 0.5 1.0 1.5 2.0 2.5 3.0

zBIN = [ 0.72,1.34 ]

W0h3934 [Å]

ln(,

N/,

W0h3

934 )

0.0 0.5 1.0 1.5 2.0 2.5ï12ï10

ï8

ï6

ï4

ï2

0 zBIN = [ 0.03,0.41 ]

0.0 0.5 1.0 1.5 2.0 2.5

zBIN = [ 0.42,0.72 ]

0.0 0.5 1.0 1.5 2.0 2.5

zBIN = [ 0.72,1.34 ]

zrange = [0.03, 0.42)

zrange = [0.03, 0.42)

zrange = [0.42, 0.72)

zrange = [0.42, 0.72)

zrange = [0.72, 1.34]

zrange = [0.72, 1.34]

1 2 3 4 5 6W0 [Å]

ï6

ï5

ï4

ï3

ï2

ï1

0

1lo

g 10(,

N/,

W0)

Redshift Number Density

0.0 0.5 1.0 1.5zABS

0.0001

0.0010

0.0100

dn/d

z

W0lim > 1.0Å

0.0 0.5 1.0 1.5zABS

W0lim > 1.5Å

0.0001

0.0010

0.0100

NEC

0.0 0.5 1.0 1.5zABS

W0lim > 1.5Å

0.0001

0.0010

0.0100

NEC

0.0 0.5 1.0 1.5zABS

0.0001

0.0010

0.0100

dn/d

z

W0lim > 1.0Å

0.0 0.5 1.0 1.5zABS

W0lim > 1.5Å

0.0001

0.0010

0.0100

NEC

0.0 0.5 1.0 1.5zABS

W0lim > 0.6Å

0.001

0.010

0.100

0.0 0.5 1.0 1.5zABS

0.01

0.10

1.00

dn/d

z

W0lim > 0.3Å

0.0 0.5 1.0 1.5zABS

0.01

0.10

1.00

dn/d

z

W0lim > 0.3Å

0.0 0.5 1.0 1.5zABS

W0lim > 0.6Å

0.001

0.010

0.100

0.0 0.5 1.0 1.5zABS

0.0001

0.0010

0.0100

dn/d

z

W0lim > 1.0Å

≥ ≥

≥ ≥

Redshift Number Density : CaII vs MgII

0 2 4 6 8 10 12Lookback Time, Gyr

0.01

0.10

1.00

dn/d

z

W0h3934 * 0.3 Å

W0h2796 * 0.3 Å Mg II NEC

Ca II NEC

0.00 0.16 0.37 0.65 1.07 1.86 4.11Redshift


0.001

0.010

0.100

1.000

dn/d

z

W0h3934 * 0.6 Å


Ca II NEC

0.00 0.16 0.37 0.65 1.07 1.86 4.11Redshift

0


0.001

0.010

0.100

1.000

dn/d

z

W0h3934 * 0.6 Å


Ca II NEC

0.00 0.16 0.37 0.65 1.07 1.86 4.11Redshift 0

Absorber – Galaxy Connection

1.  Find the average number density of galaxies around Ca II-absorbing QSOs from SDSS images as a function of angular distance, redshift and limiting magnitude

2.  At z = 0.15, the limiting magnitude of SDSS corresponds to L ~ 0.03L*

3.  Background is determined from non-CaII absorbing QSOs

Lines of Sight with Absorbers

radius, arcsec

log

[Ave

rage

Num

ber p

er a

rcm

in2 p

er L

OS] z = [ 0.02, 0.05)

Brighter than rSDSS < 19.3z = [ 0.05, 0.08)

Brighter than rSDSS < 20.6z = [ 0.08, 0.11)

Brighter than rSDSS < 21.3

z = [ 0.11, 0.12)Brighter than rSDSS < 21.5



Some Ca II absorbers are Associated with very Luminous, Low-Impact Parameter Galaxies

b = 8 kpc b = 21 kpc b = 5 kpc b = 25 kpc

L = 1.3L* L = 1.3L* L =1.4L* L = 9.5L*

zabs = 0.047 zabs = 0.114 zabs = 0.113 zabs = 0.242

Are all Ca II absorbers associated with moderately luminous, low-impact

parameter galaxies?

No.

Cases with the Lowest Redshifts : zabs < 0.08

Brighter than 0.01L*

0 10 20 30 40 50 60Minimum Impact Parameter [Arcsec]

0

1

2

3

4

Num

ber

of D

etec

tions

<Impact Parameter > = 24.7[arcsec]


0 10 20 30 40 50 60Minimum Impact Parameter [Arcsec]

0

1

2

3

4

Num

ber

of D

etec

tions

<Impact Parameter > = 24.7[arcsec]


0.00 0.05 0.10 0.15 0.20 0.25 0.30Nearest Neighbor Luminosity [L*]

0

2

4

6

Num

ber o

f Det

ectio

ns

Mean Luminosity = 0.15L*

Median Luminosity = 0.04L*

Minimum Luminosity = 0.01L*

Maximum Luminosity = 1.35L*


0 20 40 60 80 100Minimum Impact Parameter [kpc]

0

1

2

3

4

Num

ber o

f Det

ectio

ns

Ca II at zabs = 0.0655: Where is the absorbing galaxy?


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Nor

mal

ized

Flu

x

At minimum b: bmin ~ 43” r (bmin )= 21.0 bmin ~ 53 kpc L(bmin)~ 0.03 L*

S

S

S

S

S

Spectrum: W0

3934 = 1.1 ± 0.2 W0

3969 = 0.5 ± 0.2

CaII Absorption Spectrum SDSS r-band image

S : star-like Arrows: Blue – QSO Red – “Galaxy”

z = 0.0655

At minimum b: bmin ~ 74.6 ” r (bmin) = 20.7 bmin ~ 90.2 kpc L(bmin) ~ 0.04L*

Spectrum: W0

3934 = 0.25 ± 0.05 W0

3969 = 0.26 ± 0.05

Ca II at zabs = 0.0636: Where is the absorbing galaxy?

4180 4200 4220 4240Observed Wavelength

0.6

0.8

1.0

1.2

Nor

mal

ized

Flu

x

z = 0.0636

CaII Absorption Spectrum SDSS r-band image

Summary

•  Conducted a search of Ca II λλ 3934,3969 AA doublet from ~95, 000 quasars in SDSS DR9.

•  Rest equivalent width distribution is fit very well by a double power-law model, with little or no evolution with redshift.

•  The redshift number density is consistent with the no evolution curve at > 99%, and at least an order of magnitude smaller than Mg II.

•  Very few Ca II absorbers are associated with bright, low-impact parameter galaxies.

•  In some cases, there is no evidence for “plausible” absorbing galaxies.

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