72 research outputs found
On measuring the Tully-Fisher relation at
The evolution of the line width - luminosity relation for spiral galaxies,
the Tully-Fisher relation, strongly constrains galaxy formation and evolution
models. At this moment, the kinematics of z>1 spiral galaxies can only be
measured using rest frame optical emission lines associated with star
formation, such as Halpha and [OIII]5007/4959 and [OII]3727. This method has
intrinsic difficulties and uncertainties. Moreover, observations of these lines
are challenging for present day telescopes and techniques. Here, we present an
overview of the intrinsic and observational challenges and some ways way to
circumvent them. We illustrate our results with the HST/NICMOS grism sample
data of z ~ 1.5 starburst galaxies. The number of galaxies we can use in the
final Tully-Fisher analysis is only three. We find a ~2 mag offset from the
local rest frame B and R band Tully-Fisher relation for this sample. This
offset is partially explained by sample selection effects and sample specifics.
Uncertainties in inclination and extinction and the effects of star formation
on the luminosity can be accounted for. The largest remaining uncertainty is
the line width / rotation curve velocity measurement. We show that high
resolution, excellent seeing integral field spectroscopy will improve the
situation. However, we note that no flat rotation curves have been observed for
galaxies with z>1. This could be due to the described instrumental and
observational limitations, but it might also mean that galaxies at z>1 have not
reached the organised motions of the present day.Comment: 13 pages, 7 figures, A&A accepte
Dynamics of high redshift disk galaxies
This thesis discusses the dynamical properties of high redshift infrared selected and morphologically large disk selected galaxies at redshifts between 0.7 and 2.4 and their Tully-Fisher relations. Most observations were done using the near infrared integral field spectrograph SINFONI of the Very Large Telescope (VLT).UBL - phd migration 201
On measuring the Tully-Fisher relation at z > 1. A case study using strong Hα emitting galaxies at z > 1.5
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
Ultradeep Near-Infrared ISAAC Observations of the HDF-S: Observations, Reduction, Multicolor Catalog, and Photometric Redshifts
We present deep near-infrared (NIR) Js, H, and Ks-band ISAAC imaging of the
WFPC2 field of the HDF-S. The 2.5'x 2.5' high Galactic latitude field was
observed with the VLT under the best seeing conditions with integration times
amounting to 33.6 hours in Js, 32.3 hours in H, and 35.6 hours in Ks. We reach
total AB magnitudes for point sources of 26.8, 26.2, and 26.2 respectively (3
sigma), which make it the deepest ground-based NIR observations to date, and
the deepest Ks-band data in any field. The effective seeing of the coadded
images is ~0.45" in Js, ~0.48" in H, and ~0.46" in Ks. Using published WFPC2
optical data, we constructed a Ks-limited multicolor catalog containing 833
sources down to Ks,tot ~< 26 (AB), of which 624 have seven-band optical-to-NIR
photometry. These data allow us to select normal galaxies from their rest-frame
optical properties to high redshift (z ~< 4). The observations, data reduction
and properties of the final images are discussed, and we address the detection
and photometry procedures that were used in making the catalog. In addition, we
present deep number counts, color distributions and photometric redshifts of
the HDF-S galaxies. We find that our faint Ks-band number counts are flatter
than published counts in other deep fields, which might reflect cosmic
variations or different analysis techniques. Compared to the HDF-N, we find
many galaxies with very red V-H colors at photometric redshifts 1.95 < z < 3.5.
These galaxies are bright in Ks with infrared colors redder than Js-Ks > 2.3
(in Johnson magnitudes). Because they are extremely faint in the observed
optical, they would be missed by ultraviolet-optical selection techniques, such
as the U-dropout method.Comment: LaTeX, 24 pages, 15 figures, 3 tables. Accepted for publication in
the Astronomical Journal. The paper with full resolution images and figures
is available at http://www.strw.leidenuniv.nl/~fires/papers/2002Labbe.ps.gz .
The reduced data and catalogs can be found at
http://www.strw.leidenuniv.nl/~fires/data/hdfs
A Substantial Population of Red Galaxies at z > 2: Modeling of the Spectral Energy Distributions of an Extended Sample
We investigate the nature of the substantial population of high-z galaxies
with Js-Ks>2.3 discovered as part of our FIRES survey. This colour cut
efficiently isolates z>2 galaxies with red rest-frame optical colors ("Distant
Red Galaxies" or DRGs). We select objects in the 2.5'x2.5' HDF-South (HDF-S)
and 5'x5' field around the MS1054-03 cluster; the surface densities at Ks<21
are 1.6+-0.6 and 1.0+-0.2 arcmin^-2. We discuss the 34 DRGs at 2<z<3.5: 11 at
Ks<22.5 in HDF-S and 23 at Ks<21.7 in the MS1054-03 field. We analyze the SEDs
constructed from our deep near-infrared (NIR) and optical imaging from the ESO
VLT and HST. We develop diagnostics involving I-Js, Js-H, and H-Ks to argue
that the red NIR colors of DRGs cannot be attributed solely to extinction and
require for many an evolved stellar population with prominent Balmer/4000A
break. In the rest-frame, the optical colours of DRGs fall within the envelope
of normal nearby galaxies and the UV colours suggest a wide range in star
formation activity and/or extinction. This contrasts with the much bluer and
more uniform SEDs of Lyman break galaxies (LBGs). From evolutionary synthesis
models with constant star formation, solar metallicity, Salpeter IMF, and
Calzetti et al. extinction law, we derive for the HDF-S (MS1054-03 field) DRGs
median ages of 1.7(2.0) Gyr, A_V = 2.7(2.4) mag, stellar masses 0.8(1.6)x10^11
Msun, M/L_V = 1.2(2.3) Msun/LVsun, and SFR = 120(170) Msun/yr. Models assuming
declining SFRs with e-folding timescales of 10Myr-1Gyr generally imply younger
ages, lower A_V's and SFRs, but similar stellar masses within a factor of two.
Compared to LBGs at similar redshifts and rest-frame L_V's, DRGs are older,
more massive, and more obscured for any given star formation history.
[ABRIDGED]Comment: Accepted for publication in the Astrophysical Journal. 27 pages, 14
b/w figure
Spectroscopic confirmation of a substantial population of luminous red galaxies at redshifts z ≳ 2
We confirm spectroscopically the existence of a population of galaxies at z greater than or similar to 2 with rest-frame optical colors similar to normal nearby galaxies. The galaxies were identified by their red near-infrared colors in deep images obtained with the Infrared Spectrometer and Array Camera on the Very Large Telescope of the field around the foreground cluster MS 1054-03. Redshifts of six galaxies with J(s)-K-s > 2.3 were measured from optical spectra obtained with the W. M. Keck telescope. Five out of six are in the range, demonstrating that the 2.43 = z = 3.52 J(s)-K-s color selection is quite efficient. The rest-frame ultraviolet spectra of confirmed z > 2 galaxies display a range of properties, with two galaxies showing emission lines characteristic of active galactic nuclei, two having Lyalpha in emission, and one showing interstellar absorption lines only. Their full spectral energy distributions are well described by constant star formation models with ages 1.4-2.6 Gyr, except for one galaxy whose colors indicate a dusty starburst. The confirmed z > 2 galaxies are very luminous: their K-s magnitudes are in the range 19.2-19.9, corresponding to rest-frame absolute V magnitudes from -24.8 to -23.2. Assuming that our bright spectroscopic sample is representative for the general population of J(s)-K-s selected objects, we find that the surface density of red z greater than or similar to 2 galaxies is approximate to0.9 arcmin(-2) to K-s = 21. The surface density is comparable to that of Lyman break-selected galaxies with K-s < 21, when corrections are made for the different redshift distributions of the two samples. Although there will be some overlap between the two populations, most "optical-break" galaxies are too faint in the rest-frame ultraviolet to be selected as Lyman break galaxies. The most straightforward interpretation is that star formation in typical optical-break galaxies started earlier than in typical Lyman break galaxies. Optical-break galaxies may be the oldest and most massive galaxies yet identified at, and they z 1 2 could evolve into early-type galaxies and bulges
Spectroscopic Confirmation of a Substantial Population of Luminous Red Galaxies at Redshifts z>2
We confirm spectroscopically the existence of a population of galaxies at z>~2 with rest-frame optical colors similar to normal nearby galaxies. The galaxies were identified by their red near-infrared colors in deep images obtained with ISAAC on the Very Large Telescope. Redshifts of six galaxies with Js-Ks>2.3 were measured from optical spectra obtained with the Keck Telescope. Five out of six are in the range 2.432 galaxies display a range of properties, with two galaxies showing emission lines characteristic of AGN, two having Ly-alpha in emission, and one showing interstellar absorption lines only. Their full spectral energy distributions are well described by constant star formation models with ages 1.4-2.6 Gyr, except for one galaxy whose colors indicate a dusty starburst. The confirmed z>2 galaxies are very luminous, with Ks=19.2-19.9. Assuming that our bright spectroscopic sample is representative for the general population of Js-Ks selected objects, we find that the surface density of red z>~2 galaxies is ~0.9/arcmin^2 to Ks=21. The surface density is comparable to that of Lyman-break selected galaxies with Ks2, and could evolve into early-type galaxies and bulges
Dynamical properties of a large young disk galaxy at z=2.03
Context. The study of high redshift Tully-Fisher relations (TFRs) is limited
by the use of long slit spectrographs, rest frame B band and star formation
selected galaxies. Aims. We try to circumvent these issues by using integral
field spectroscopy (SINFONI), by studying the rest frame K band and stellar
mass TFR, and by selecting targets without a bias to strongly star forming
galaxies. In this paper, we demonstrate our methods on our best case. This
galaxy, F257, at z=2.03, was selecte from a sample of candidate high redshift
large disk galaxies in the Hubble Deep Field South that were selected with
photometric and morphological criteria. Methods. We used SINFONI at the VLT to
obtain an integral field spectrum of the Halpha line and hence a velocity field
and rotation curve. We also use UBVIJHK+IRAC band photometry to determine a
stellar photometric mass. Results. We find that F257 is indistinguishable from
local late type galaxies in many respects: it has a regular velocity field,
increasing velocity disperion towards its center, its rotation curve flattens
at 1-2 disk scale lengths, it has the same specific angular momentum as local
disks, its properties are consistent with the local K band TFR. Although mainly
rotationally supported, its gas component is dynamically heated with respect to
local galaxies (V/sigma_z ~ 4) and it is offset from the local stellar mass TFR
at the 2sigma level. But, this offset depends on the SED modeling parameters.
In particular, for a 2-component star formation history (SFH), F257 is in
agreement with the local stellar mass TFR. F257 is then a nearly (~75%) maximum
disk. The dynamical properties of F257 are more like those of local galaxies
than those of any other galaxy at similar redshift observed to date. However,
the gas-to-stellar mass ratio is unusally large: 2.5.Comment: Accepted for publication in A&A, 15 pages, 14 figure
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