Rand (2000)

• NGC 5775 Hα map.

• D = 24.8 Mpc

• It is an interacting galaxy

Rand (2000)

• DIG detected out to 13 kpc

• Gas approaches the systemic velocity of the galaxy.

• Implies that the gas is decreasing in rotational velocity and have no rotational above several kpcs.

Swaters et al. (1997)

• D = 9.5 Mpc

• Neutral hydrogen map from WSRT

• Presence of an H I halo extending up to at least 5 kpc from the plane

Swaters et al. (1997)

Halo gas appears to rotate 25 to 100 km s-1 more slowly than the gas in the plane.     

 

Disk gas

Halo gas

Swaters et al. (1997)

The channel radial velocities run in steps of 33 km/s from systemic (528 km/s

heliocentric) at the top to near rotational (299 km/s heliocentric) at the bottom.

The total mass of the anomalous gas is 3×108 Msun (of which just 6−7×106 Msunforbidden), which corresponds to 10% of the total H I mass of NGC 2403.

Fraternali et al. (2002)

Halos of nine galaxies (with redshifts cz < 6000 kms−1) were probed at large galactocentric radii using background quasars. The projected quasar-galaxy separations range from 55 to 387 h−1

75 kpc.

Lyα absorption lines were successfully detected in the spectra of five quasars and in each case at wavelengths consistent with the galaxy’s redshift.

HI velocity fields were obtained at the VLA for three of the galaxies in our sample to derive their rotation curves.

Coté et al. (Astroph 410288)

DSS overlaid column densities

Lyα

Coté et al. (Astroph 410288)

Lyα

It is very difficult to explain the observed Lyα velocity as due to gas in an extended rotating disk.

In most cases one would need to invoke large warps in the outer gas disks and also thick gas disks in order to reconcile the observed velocities with the predicted ones.

The cosmic web is the most likely origin for the detected Ly lines.

Observations confirm the Bowen et al. (2002) correlation of equivalent widths with the local volume density of galaxies around the sightline, and the observed equivalent widths of the lines are consistent with expectations of the cosmic web.

Coté et al. (Astroph 410288)

How far can we measure the kinematics of haloes?

How do the kinematics of the stellar component reflect that of the halokinematics?

What role does morphology and star formation history play?

Do disturbed galaxies have more enriched haloes?

• Study Mg II quasar absorption line systems in order to understand the kinematics of halos probing distances out to 70 kpcs from the galaxies.

Therefore the galaxies in our sample are selected by the known

presence of Mg II absorption

• Determine whether the galaxy kinematics and/or morphologies are coupled to the halo kinematics

• Our main goal is to determine how early epoch galaxy halos are built and sustained.

Mg II 2796, 2803

2796 2803

Mg II 2796, 2803

Velocity km s-1

Sample includes absorbers with W(2796) < 1

Steidel et al. (2002)

Selected 5 edge-on galaxies

4 of the 5 showed the trend for the halo gas kinematics follows that of the galaxies

What is needed is a larger sample which represents a broad range of orientations with respect to the quasar line of sight

z = 0.550 z = 0.551

z = 0.640 z = 0.661

z = 0.374

z = 0.525

z = 0.787

z = 0.346

z = 0.442

z = 0.553

z = 0.888

z = 0.729

z = 0.418 z = 0.494

z = 0.591

z = 0.298

z = 0.888

z = 0.472

z = 0.368z = 0.317

z = 0.437

z = 0.891z = 0.797

z = 0.656

z = 0.851

Orientated such that the QSO is down5”

5”

QSO

Velocity

Inte

nsi

ty

PA = 45o i = 0o PA = 45o i = 30o PA = 0o i = 0o PA = N/A i = 90o

cos(PA)cos(i) = 0.61 cos(PA)cos(i) = 1.0 cos(PA)cos(i) = 0.0

“Normal” Absorbers Wind Dominate & DLA Systems

z = 0.550 z = 0.551

z = 0.640 z = 0.661

z = 0.374

z = 0.525

z = 0.787

z = 0.346

z = 0.442

z = 0.553

z = 0.888

z = 0.729

z = 0.418 z = 0.494

z = 0.591

z = 0.298

z = 0.888

z = 0.472

z = 0.368z = 0.317

z = 0.437

z = 0.891z = 0.797

z = 0.656

z = 0.851

Simard et al. (2002)

NE

Barred Spiral Structure!

If more than 5% of the galaxies total residual flux is due to asymmetries then these galaxies are considered to not be “normal”; they are “asymmetric”.

Schade et al. (1995)

HST Image Model Model Residual

RA33 RT

> 0.05

“Normal” Absorbers Wind Dominate & DLA Systems “Nor

mal

” G

alax

ies

Asy

mm

etric

Gal

axie

s

• Halo gas is “aware” of the kinematics of the galaxy (pilot study 5 galaxies).

• There are no clear trends between absorption strength and orientation of the galaxy. More detailed models are needed.

• Minor morphological perturbations are correlated to absorption strength. This may suggest that most Mg II absorption selected galaxies have had some previous minor interactions or harassments.

• 21 of 25 Keck HIRES spectra are in hand and are currently being analyzed. The remaining quasar spectra will be obtained in the near future.

• Obtain redshifts of remaining candidates in order to increase sample size to over 50.

• Obtain rotation curves of the galaxy using Gemini and Keck.

Forbidden Gas Lagging Halo

Ellison et al. (2003)

MC 1331+170 zabs = 0.7

Swaters et al. (1997)Schaap et al. (2000)Sancisi et al. (2001)

Fraternali et al. (Yesterday)

Observed spectra contain an admixture of both models

Asymmetric Blended Line Morphology

Symmetric Resolved Line Morphology