Joint Infrared & X-ray Investigation of

LINER Galaxies

Rachel Dudik, John McNulty & Mona Sanei

Study of LINER galaxies in the far infrared

Mona Sanei

LINERsWhat are they?

Heckman, T.M. (1980) – optical spectroscopy

Low-Ionization Nuclear Emission-line Regions

Why are they important?

Very common – 30-50% of all galaxies are LINERs

No explanation the difference in location of LINERs

LINERs Continued …Questions

Are LINERs AGNs or …

Are LINERs stars in an unusual environment?Evolutionary Change!!!

Very few near by galaxies are standard AGNs (Seyferts)

If LINERs = Black hole = AGNs [ >50% of galaxies]

For AGNs to be so common could imply that They are an evolutionary phase in the

life of a galaxy

The following graphs: represent the far infrared study of liners

Normal Galaxy – Malhotra et al. (2001)ULIGs, SBs, and AGNs – Satyapal et al. (2002).

Goal: Do liners distinguish themselves from other galaxies in the far infrared.

There are 500 LINER galaxies;

69 have been observed by ISO

                                                         

The far infrared wavelength range contains several fine structure emission lines.

The lines we find and their line ratios, allow us to probe the physical conditions of the galaxy and the underlying ionizing

radiation field.

-4.5 -4.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.00

5

10

15

20

Normal Galaxies

LINERs and Normal Galaxies

LINERs have lower [CII]/FIR ratios than normal galaxies.

Num

ber o

f Ga

laxi

es

log([CII]/FIR)

LINERs

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0

2

4

6

8N

um

ber o

f Ga

laxi

es

log([CII]/FIR)

LINERs

Starbursts

AGNs

ULIGs

Histogram: Comparison with LINERs

0.0 0.5 1.0 1.5 2.0 2.5 3.00

2

4

6

8

10

12

14

16N

um

ber o

f Ga

laxi

es

[OI]/[CII]

Normal Galaxies

.

LINERs

Histogram: NGs and LINERs

H1 is bombarded by radiation/light; electrons are ionized

kinetic energy

Collisionally excite the electrons of oxygen and carbon out of the ground state

OI 63 m – 0.0197 eV

CII 158 m – 0.00787 eV

The 63 line corresponds to a higher energy level transition

Higher density region = more 63 lines

[OI]/[CII] is a density indicator

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

0

1

2

3

4

5

Num

ber o

f Ga

laxi

es

[OI]/[CII]

LINERs

.

.

ULIGs

.

.

Starbursts

.

.

AGNs

Histogram Comparison:

                               

Plot One:Plot One:

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-4.5

-4.0

-3.5

-3.0

-2.5

-2.0

-1.5

-1.0

6 7 8 9 10 11 12

log(Lfir)

log

([C

II]/F

IR)

LINERs

No apparent trend

-0.600

-0.100

0.400

0.900

1.400

1.900

2.400

2.900

8.000 8.500 9.000 9.500 10.000 10.500 11.000 11.500

log(Lfir)

[OI]/[

CII]

y = 0.1252x - 0.2444

R2 = 0.1796

-0.600

-0.100

0.400

0.900

1.400

1.900

2.400

2.900

8.000 8.500 9.000 9.500 10.000 10.500 11.000 11.500

log(Lfir)

[OI]/[

CII]

Plot One:Plot One: Do you see a trend?!?

Liners have a weak [CII] emission compared to normal galaxies, starbursts, and standard AGNs. (They seem to resemble ULIGs)

Liners have higher [OI]/[CII] ratios than normal galaxies, this may imply denser gas. Further analysis is required.

Conclusions :

For the future:1. We will model the observed

infrared emission lines to infer the properties of the gas and possible AGNs in these galaxies.

2. More observations!? Space infrared telescope facility SIRTF (launched January 2003)

The mediocre teacher tells. The good teacher explains. The superior teacher demonstrates. The great teacher inspires.

William Arthur Ward