Joint Infrared & X-ray Investigation of LINER Galaxies Rachel Dudik, John McNulty & Mona Sanei

Study of LINER galaxies in the far infrared Mona Sanei

LINERs What 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

Definition 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

ISO *Sixty cm telescope made up of four instruments(2 spectrometers): Spectrometer that allows you to gather specta from the wavelength range of micrometers. LWS:(far infrared) SWS: (near infrared) ISOPHOT: ISOCAM: um um

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.

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

Histogram: Comparison with LINERs

Histogram: NGs and LINERs

H 1 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 – eV CII 158  m – eV  The 63 line corresponds to a higher energy level transition Higher density region = more 63 lines [OI]/[CII] is a density indicator

Histogram Comparison:

Plot One: No apparent trend

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 WardWilliam Arthur Ward