188 research outputs found
Flat rotation curves and low velocity dispersions in KMOS star-forming galaxies at z ~ 1
The study of the evolution of star-forming galaxies requires the
determination of accurate kinematics and scaling relations out to high
redshift. In this paper we select a sample of 18 galaxies at z~1, observed in
the H-alpha emission-line with KMOS, to derive accurate kinematics using a
novel 3D analysis technique. We use the new code 3D-Barolo, that models the
galaxy emission directly in the 3D observational space, without the need to
extract kinematic maps. This technique's major advantage is that it is not
affected by beam smearing and thus it enables the determination of rotation
velocity and intrinsic velocity dispersion, even at low spatial resolution. We
find that: 1) the rotation curves of these z~1 galaxies rise very steeply
within few kiloparsecs and remain flat out to the outermost radius and 2) the
H-alpha velocity dispersions are low, ranging from 15 to 40 km/s, which leads
to V/sigma = 3-10. These characteristics are similar to those of disc galaxies
in the local Universe. Finally, we also report no significant evolution of the
stellar-mass Tully-Fisher relation. Our results show that disc galaxies are
kinematically mature and rotation-dominated already at z~1.Comment: Accepted for publication in A&A, 11 pages, 6 figures, 1 tabl
The angular momentum of disc galaxies at z=1
We investigate the relation between stellar mass and specific stellar angular
momentum, or `Fall relation', for a sample of 17 isolated, regularly rotating
disc galaxies at z=1. All galaxies have a) rotation curves determined from
Halpha emission-line data; b) HST imaging in optical and infrared filters; c)
robust determinations of their stellar masses. We use HST images in f814w and
f160w filters, roughly corresponding to rest-frames B and I bands, to extract
surface brightness profiles for our systems. We robustly bracket the specific
angular momentum by assuming that rotation curves beyond the outermost Halpha
rotation point stay either flat or follow a Keplerian fall-off. By comparing
our measurements with those determined for disc galaxies in the local Universe,
we find no evolution in the Fall relation in the redshift range 0<z<1,
regardless of the band used and despite the uncertainties in the stellar
rotation curves at large radii. This result holds unless stellar masses at z=1
are systematically underestimated by more than 50%. Our findings are compatible
with expectations based on a LCDM cosmological framework and support a scenario
where both the stellar Tully-Fisher and mass-size relations for spirals do not
evolve significantly in this redshift range.Comment: 11 pages, 4 figures, 1 table. Accepted by A&
The 3D Kinematics of Gas in the Small Magellanic Cloud
We investigate the kinematics of neutral gas in the Small Magellanic Cloud
(SMC) and test the hypothesis that it is rotating in a disk. To trace the 3D
motions of the neutral gas distribution, we identify a sample of young, massive
stars embedded within it. These are stars with radial velocity measurements
from spectroscopic surveys and proper motion measurements from Gaia, whose
radial velocities match with dominant HI components. We compare the observed
radial and tangential velocities of these stars with predictions from the
state-of-the-art rotating disk model based on high-resolution 21 cm
observations of the SMC from the Australian Square Kilometer Array Pathfinder
telescope. We find that the observed kinematics of gas-tracing stars are
inconsistent with disk rotation. We conclude that the kinematics of gas in the
SMC are more complex than can be inferred from the integrated radial velocity
field. As a result of violent tidal interactions with the LMC, non-rotational
motions are prevalent throughout the SMC, and it is likely composed of distinct
sub-structures overlapping along the line of sight.Comment: 9 pages, 5 figures, 1 Appendix; ApJ accepte
On the patchy appearance of the circum-Galactic medium and the influence of foreground absorption
Recent studies have demonstrated that the emission from the circumgalactic
medium of the Milky Way displays a relatively high degree of patchiness on
angular scales of . Taking advantage of the Spectrum Roentgen
Gamma eROSITA Final Equatorial Depth Survey (eFEDS), we aim to constrain any
variation in the soft X-ray surface brightness on scales going from sub-degree
to a hundred square degrees. We observe modulations of about % on scales of
several degrees and decreasing for higher energies. The observed patchiness is
stable over a period of two years, therefore excluding that it is induced by
Solar wind charge exchange. We also observe no correlation between such excess
and the density of galaxies in the Local Universe, suggesting no strong
contribution from the hot baryons in the filaments of the Cosmic web. Instead,
the soft X-ray emission is anti-correlated with the column density of absorbing
material. Indeed, we can reproduce the spectrum of the bright and dark regions
by simply varying the column density of the matter absorbing the emission
components located beyond the Local Hot Bubble, while no modulation of the
intrinsic emission is required. At high Galactic latitudes, the eROSITA all sky
map shows patchiness of the soft X-ray diffuse emission similar to the one
observed in the eFEDS field, it is therefore likely that the same
"absorption-modulation" is present over the entire sky. These results highlight
the importance of an accurate treatment of the absorption effects, to determine
the patchiness of the circumgalactic medium.Comment: Accepted for publication in Astronomy and Astrophysic
The PUMA project. III. Incidence and properties of ionised gas disks in ULIRGs, associated velocity dispersion and its dependence on starburstiness
A classical scenario suggests that ULIRGs transform colliding spiral galaxies
into a spheroid dominated early-type galaxy. Recent high-resolution simulations
have instead shown that, under some circumstances, rotation disks can be
preserved during the merging process or rapidly regrown after coalescence. Our
goal is to analyze in detail the ionised gas kinematics in a sample of ULIRGs
to infer the incidence of gas rotational dynamics in late-stage interacting
galaxies and merger remnants. We analysed MUSE data of a sample of 20 nearby
(z<0.165) ULIRGs, as part of the "Physics of ULIRGs with MUSE and ALMA" (PUMA)
project. We found that 27% individual nuclei are associated with kpc-scale
disk-like gas motions. The rest of the sample displays a plethora of gas
kinematics, dominated by winds and merger-induced flows, which make the
detection of rotation signatures difficult. On the other hand, the incidence of
stellar disk-like motions is ~2 times larger than gaseous disks, as the former
are probably less affected by winds and streams. The eight galaxies with a
gaseous disk present relatively high intrinsic gas velocity dispersion (sigma =
30-85 km/s), rotationally-supported motions (with gas rotation velocity over
velocity dispersion vrot/sigma > 1-8), and dynamical masses in the range
(2-7)x1e10 Msun. By combining our results with those of local and high-z disk
galaxies from the literature, we found a significant correlation between sigma
and the offset from the main sequence (MS), after correcting for their
evolutionary trends. Our results confirm the presence of kpc-scale rotating
disks in interacting galaxies and merger remnants, with an incidence going from
27% (gas) to ~50% (stars). The ULIRGs gas velocity dispersion is up to a factor
of ~4 higher than in local normal MS galaxies, similar to high-z starbursts as
presented in the literature
Physics of ULIRGs with MUSE and ALMA: The PUMA project: III. Incidence and properties of ionised gas disks in ULIRGs, associated velocity dispersion, and its dependence on starburstiness
CONTEXT:
A classical scenario suggests that ultra-luminous infrared galaxies (ULIRGs) transform colliding spiral galaxies into a spheroid-dominated early-type galaxy. Recent high-resolution simulations have instead shown that, under some circumstances, rotation disks can be preserved during the merging process or rapidly regrown after coalescence. Our goal is to analyse in detail the ionised gas kinematics in a sample of ULIRGs to infer the incidence of gas rotational dynamics in late-stage interacting galaxies and merger remnants.
AIMS:
We analysed integral field spectrograph MUSE data of a sample of 20 nearby (z < 0.165) ULIRGs (with 29 individual nuclei) as part of the Physics of ULIRGs with MUSE and ALMA (PUMA) project. We used multi-Gaussian fitting techniques to identify gaseous disk motions and the 3D-Barolo tool to model them.
METHODS:
We found that 27% (8 out of 29) individual nuclei are associated with kiloparsec-scale disk-like gas motions. The rest of the sample displays a plethora of gas kinematics, dominated by winds and merger-induced flows, which makes the detection of rotation signatures difficult. On the other hand, the incidence of stellar disk-like motions is ∼2 times larger than gaseous disks, as the former are probably less affected by winds and streams. The eight galaxies with a gaseous disk present relatively high intrinsic gas velocity dispersion (σ0 ∈ [30 − 85] km s−1), rotationally supported motions (with gas rotation velocity over velocity dispersion vrot/σ0 ∼ 1 − 8), and dynamical masses in the range (2 − 7)×1010 M⊙. By combining our results with those of local and high-z disk galaxies (up to z ∼ 2) from the literature, we found a significant correlation between σ0 and the offset from the main sequence (δMS), after correcting for their evolutionary trends.
RESULTS:
Our results confirm the presence of kiloparsec-scale rotating disks in interacting galaxies and merger remnants in the PUMA sample, with an incidence going from 27% (gas) to ≲50% (stars). Their gas σ0 is up to a factor of ∼4 higher than in local normal main sequence galaxies, similar to high-z starbursts as presented in the literature; this suggests that interactions and mergers enhance the star formation rate while simultaneously increasing the velocity dispersion in the interstellar medium
Epidemiology, pathological aspects and genome heterogeneity of feline morbillivirus in Italy
Feline morbillivirus (FeMV) is an emerging morbillivirus first described in cats less than a decade ago. FeMV has been associated with chronic kidney disease of cats characterized by tubulointerstitial nephritis (TIN), although this aspect is still controversial and not demonstrated with certainty. To investigate FeMV prevalence and genomic characteristics, an epidemiological survey was conducted in a total number of 127 household cats originating from two Italian regions, Abruzzi and Emilia-Romagna. A total number of 69 cats originating from three feline colonies were also enrolled for the study. Correlation with TIN was investigated by employing a total number of 35 carcasses. Prevalence of FeMV RNA was higher in urine samples collected from cats of colonies (P = 31.8%, CI 95% 22.1–43.6) compared to household cats (P = 8.66%, CI 95% 4.9–14.9) and in young and middle-aged cats while prevalence of FeMV Abs was higher in old cats. Sequences obtained straight from infected biological samples, either partial or complete, cluster into two clades within FeMV genotype 1, distantly related to FeMV genotype 2. Immunohistochemistry analysis of kidney sections of FeMV RNA positive cats revealed immunoreactivity within epithelial cells of renal tubuli and inflammatory cells. However, statistically significant association between FeMV and renal damages, including TIN, was not demonstrated (p= 0.0695, Fisher exact test). By virus histochemistry performed with FeMV-negative feline tissues and a FeMV isolate, tropism for different cellular types such as inflammatory cells residing in blood vessels of kidney and brain, airway epithelial cells, alveolar macrophages and to a lesser extent, the central nervous system, was demonstrated. Additional studies are warranted in order to establish viral tropism and immune response during the early phases of infection and to disentangle the role of FeMV in co-infection processes
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