Bibcode
Lípari, S.; Mediavilla, E.; Garcia-Lorenzo, B.; Díaz, R. J.; Acosta-Pulido, J.; Agüero, M. P.; Taniguchi, Y.; Dottori, H.; Terlevich, R.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 355, Issue 3, pp. 641-681.
Fecha de publicación:
12
2004
Número de citas
29
Número de citas referidas
29
Descripción
A study of the morphology, kinematics and ionization structure of the
infrared (IR) merger NGC5514 is presented. This study is based mainly on
INTEGRAL two-dimensional (2D) spectroscopy (obtained at the 4.2-m
William Herschel Telescope, WHT), plus optical and near-IR images. Clear
evidence of two extranuclear starbursts with young outflows (OFs) and
low-ionization nuclear emission region (LINER) activity are reported.
One of these OFs has generated a supergiant bubble and the other is
associated with an extended complex of HII regions.
In the galactic bubble it was found that: (i) the [SII], Hα,
[NII], [OI] and [OIII] emission-line maps show a bubble with a distorted
ellipsoidal shape, with major and minor axes of ~6.5 kpc [13.6 arcsec;
at position angle (PA) = 120°+/- 10°] and ~4.5 kpc (9.6 arcsec);
(ii) these maps depict four main knots, a very strong one and three
others more compact and located at the border; (iii) the centre of the
bubble is located at ~4.1 kpc (8.5 arcsec) to the west of the main
nucleus; (iv) the WHT spectra show, in this area, two strong components:
blue and red emission-line systems, probably associated with emission
from the near and far side of the external shell, for which the mean OF
velocities were measured as VOFblue= (-320 +/- 20)
kms-1 and VOFred= (+265 +/- 25) kms-1
(v) these two components depict LINER properties, probably associated
with large-scale OF + shocks; (vi) at the east border, the kinematics of
the ionized gas and the [SII] emission-line maps show an extended
ejection of 4 kpc aligned with the PA of the major axis; (vii) three
other ejections were found, two of them perpendicular to the extended
one. Each ejection starts in one of the knots. These results suggest
that the bubble is in the rupture phase.
For the complex of giant HII regions it was found that: (i) the
Hα, [NII] and [SII] emission-line maps show a compact strong
emission area (peaking at ~810 pc ~1.7 arcsec, to the east of the second
nucleus) and faint extended emission with an elongated shape, and major
and minor axes of ~5.1 kpc (10.8 arcsec; at PA ~20°) and ~2.9 kpc
(6.0 arcsec); (ii) inside this complex, the spectra show HII region and
transition LINER/HII characteristics; (iii) at the border of this
extended HII area the spectra have outflow components and LINER
properties.
INTEGRAL 2D [NII], Hα, [SII] and [OIII] velocity fields (VFs) are
presented. These VF maps show results consistent with an expansion of
the bubble, plus four ejections of ionized gas. The U, B, V, I, J, H and
KS images show a pre-merger morphology, from which faint
filaments of emission emerge, centred on the bubble. The ionization
structure and the physical conditions were analysed using the following
2D emission-line ratio and width maps: [SII]/Hα, [NII]/Hα,
[OI]/Hα, [OIII]/Hβ and FWHM-[NII]. In the region of the
bubble, 100 per cent of the [NII]/Hα and [SII]/Hα ratios
show very high values (>0.8) consistent with LINER processes
associated with high-velocity shocks. These new results support the
previous proposition that extreme nuclear and `extranuclear' starbursts
with galactic winds + shocks play an important role in the evolution of
IR mergers/quasi-stellar objects.