Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.stsci.edu/~marel/abstracts/psdir/IAU184_2.ps Äàòà èçìåíåíèÿ: Mon Oct 13 23:30:31 1997 Äàòà èíäåêñèðîâàíèÿ: Sat Dec 22 11:30:40 2007 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: ngc 6251

NUCLEAR GAS KINEMATICS OF NGC 7052 AND IC 1459
FROM HST/FOS SPECTRA
To appear in `The Central Regions of the Galaxy and Galaxies', Proc. IAU
Symp. 184, Kyoto, August 1997, Y. Sofue, ed., Kluwer Academic Publishers.
ROELAND P. VAN DER MAREL
STScI, 3700 San Martin Drive, Baltimore, MD 21218, USA
Abstract. We have obtained HST/FOS measurements of the nuclear kine­
matics of the gas disks in NGC 7052 and IC 1459. The spectra show steeper
rotation curves and broader emission lines than ground­based data. De­
tailed modeling is in progress to constrain the mass of possible black holes.
Kinematical studies with HST of optical emission lines in galaxies with
nuclear disks of gas and dust are a powerful tool to search for massive black
holes. Detections have been reported for, e.g., M87 (Harms et al. 1994; Mar­
coni et al. 1997), NGC 4261 (Ferrarese et al. 1996), M84 (Bower et al. 1997)
and NGC 6251 (Ferrarese et al. 1998). Here I present preliminary results
from HST/FOS observations of NGC 7052 and IC 1459 that I obtained in
collaboration with van den Bosch, de Zeeuw, Carollo and Franx. NGC 7052
is an E4 galaxy with a rapidly rotating nuclear disk of dust and gas (van
den Bosch & van der Marel 1995). IC 1459 is an E3 galaxy with a large
scale gas disk that counter­rotates with respect to the stars in the central
region (Franx & Illingworth 1988). The disks have inclinations of ¸ 70 and
¸ 60 degrees, respectively. We obtained spectra with the FOS/RD detector
in the optical region of the spectrum (4500--6800 š A) through small apertures
placed at various positions along the major axis. Figure 1 shows the gas
kinematics inferred from fits to the Hff+[NII] emission lines, as well as lower
spatial resolution ground­based measurements. For both galaxies, the HST
data show a steeper rotation curve and broader emission lines than the
ground­based data. This may indicate the presence of massive black holes.
Detailed modeling is in progress, taking into account also the broad­band
and narrow­band WFPC2 images that were obtained in the context of these
projects. The resulting BH mass determinations and/or limits will be pre­
sented in two forthcoming papers (van der Marel & van den Bosch 1998;
van der Marel, de Zeeuw, Carollo & Franx 1998).

2 ROELAND P. VAN DER MAREL
Figure 1. Gas kinematics for NGC 7052 and IC 1459, as function of major axis distance.
Top panels: rotation velocities; bottom panels: Gaussian velocity dispersions (both in
km/s). The data points with error bars are the new HST/FOS measurements. The NGC
7052 data were obtained with the circular 0:26 00 diameter aperture (open circles), and the
IC 1459 data were obtained with the 0:08 00 (solid squares) and 0:21 00 (open squares) square
apertures. Crosses connected by lines are ground­based measurements. The ground­based
NGC 7052 data were obtained with the William Herschel Telescope in 0:6 00 FWHM seeing
(van den Bosch & van der Marel 1995). The ground­based IC 1459 data were obtained
with the CTIO 4m Telescope in 1:5 00 FWHM seeing (van der Marel & Franx 1993). All
quantities were obtained from fits to the Hff+[NII] lines, except for the ground­based IC
1459 measurements, which were obtained from fits to the [OIII]5007 line.
This work is based on observations with the NASA/ESA HST, obtained
at STScI, and was supported by grants HF­1065.01­94A, GO­5848.01­94A,
GO­6537.01­95A and an STScI Fellowship. STScI is operated by AURA
Inc., under NASA contract NAS5­26555.
References
Bower G.A. et al., 1997, ApJL, in press
Ferrarese L., Ford, H.C., Jaffe, W., 1996, ApJ, 470, 444
Ferrarese L. et al., 1998, in preparation
Franx M., Illingworth G.D., 1988, ApJ, 327, L55
Harms R.J. et al., 1994, ApJ, 435, L35
Marconi A., Axon D.J., Macchetto F.D., Capetti A., et al. 1997, MNRAS, 289, 21
van den Bosch F., van der Marel R.P., 1995, MNRAS, 274, 884
van der Marel R.P., Franx M., 1993, ApJ, 407, 525