25 research outputs found
(Sub)millimetre-selected galaxies and the cosmic star-formation history
Understanding the time evolution of the star formation in the Universe is one
of the main aims of observational astronomy. Since a significant portion of the
UV starlight is being absorbed by dust and re-emitted in the IR, we need to
understand both of those regimes to properly describe the cosmic star formation
history. In UV, the depth and the resolution of the data permits calculations
of the star formation rate densities out to very high redshifts (z ∼ 8 − 9). In
IR however, the large beam sizes and the relatively shallow data limits these
calculations to z ∼ 2.
In this thesis, I explore the SMA and PdBI high-resolution follow-up of 30
bright sources originally selected by AzTEC and LABOCA instruments at 1.1
mm and 870 μm respectively in conjunction with the SCUBA-2 Cosmology
Legacy Survey (S2CLS) deep COSMOS and wide UDS maps, where 106 and
283 sources were detected, with the signal-to-noise ratio of > 5 and > 3.5 at
850 μm respectively. I find that the (sub)mm-selected galaxies reside and the
mean redshifts of ¯z ≃ 2.5±0.05 with the exception of the brightest sources which
seem to lie at higher redshifts (¯z ≃ 3.5 ± 0.2), most likely due to the apparent
correlation of the (sub)mm flux with redshift, where brighter sources tend to lie at
higher redshifts. Stellar masses, M⋆, and star formation rates, SFRs, were found
(M⋆ & 1010M⊙ and SFR & 100M⊙ yr−1) and used to calculate the specific SFRs.
I determine that the (sub)mm-selected sources mostly lie on the high-mass end
of the star formation ‘main-sequence’ which makes them a high-mass extension
of normal star forming galaxies. I also find that the specific SFR slightly evolves
at redshifts 2−4, suggesting that the efficiency of the star formation seems to be
increasing at these redshifts.
Using the S2CLS data, the bolometric IR luminosity functions (IR LFs) were
found for a range of redshifts z = 1.2 − 4.2 and the contribution of the SMGs to
the total star formation rate density (SFRD) was calculated. The IR LFs were
found to evolve out to redshift ∼ 2.5. The star formation activity in the Universe
was found to peak at z ≃ 2 followed by a slight decline. Assuming the IR to total
SFRD correction found in the literature the SFRD found in this work closely
follows the best-fitting function of Madau & Dickinson (2014)
First uses of HAART 300 rings for aortic valve repair in Poland – 4 case studies
Introduction: Aortic valve reconstructions using geometric an- nuloplasty rings HAART 300/200 open new era in aortic valve surgery. The HAART technology resizes, reshapes, stabilizes and simplifies aortic valve repair. The HAART aortic repair rings are designed to be implanted directly into aortic annulus (un- der aortic valve leaflets).
Aim: We present first in Poland 4 cases of aortic valve recon- structions using geometric annuloplasty rings HAART 300. Material and methods: Two patients had type IA aortic insuf- ficiency (due to El-Khoury classification) – they were treated by HAART 300 ring insertion and ascending aorta prosthesis implantation. Third patient, Marfan with type IB aortic insuf- ficiency was repaired by HAART 300 ring implantation followed by remodeling (Yacoub) procedure. Fourth patient with type II aortic insufficiency (due to RCC prolapse) was repaired by HAART 300 implantation and cusp plication.
Results: All patients shows good results on 6 months postop- erative 3D TTE examinations. Conclusions: Presented technique is reproducible and simplify aortic valve reconstructions
Mobile sailing robot for automatic estimation of fish density and monitoring water quality
Introduction: The paper presents the methodology and the algorithm developed to analyze sonar images focused on fish detection in small water bodies and measurement of their parameters: volume, depth and the GPS location. The final results are stored in a table and can be exported to any numerical environment for further analysis.Material and method: The measurement method for estimating the number of fish using the automatic robot is based on a sequential calculation of the number of occurrences of fish on the set trajectory. The data analysis from the sonar concerned automatic recognition of fish using the methods of image analysis and processing.Results: Image analysis algorithm, a mobile robot together with its control in the 2.4 GHz band and full cryptographic communication with the data archiving station was developed as part of this study. For the three model fish ponds where verification of fish catches was carried out (548, 171 and 226 individuals), the measurement error for the described method was not exceeded 8%.Summary: Created robot together with the developed software has features for remote work also in the variety of harsh weather and environmental conditions, is fully automated and can be remotely controlled using Internet. Designed system enables fish spatial location (GPS coordinates and the depth). The purpose of the robot is a non-invasive measurement of the number of fish in water reservoirs and a measurement of the quality of drinking water consumed by humans, especially in situations where local sources of pollution could have a significant impact on the quality of water collected for water treatment for people and when getting to these places is difficult. The systematically used robot equipped with the appropriate sensors, can be part of early warning system against the pollution of water used by humans (drinking water, natural swimming pools) which can be dangerous for their health
NGC 2770: high supernova rate due to interaction
Galaxies which hosted many core-collapse supernovae (SN) explosions can be
used to study the conditions necessary for the formation of massive stars. NGC
2770 was dubbed a SN factory, because it hosted four core-collapse SNe in 20
years (three type Ib and one type IIn). Its star formation rate (SFR) was
reported not to be enhanced and therefore not compatible with such a high SN
rate. We aim at explaining the high SN rate of NGC 2770. We used archival HI
line data for NGC 2770 and reinterpret the Halpha and optical continuum data.
Even though the continuum-based SFR indicators do not yield high values, the
dust-corrected Halpha luminosity implies a high SFR, consistent with the high
SN rate. Such disparity between the SFR estimators is an indication of recently
enhanced star formation activity, because the continuum indicators trace long
timescale of the order of 100 Myr, unlike the line indicators, which trace
timescales of the order of 10 Myr. Hence, the unique feature of NGC 2770
compared to other galaxies is the fact that it is observed very recently after
the enhancement of the SFR. It also has high dust extinction, E(B-V) above 1
mag. We provide support for the hypothesis that the increased SFR in NGC 2770
is due to the interaction with its companion galaxies. We report an HI bridge
between NGC 2770 and its closest companion and the existence of a total of four
companions within 100 kpc (one identified for the first time). There are no
clear HI concentrations close to the positions of SNe in NGC 2770 such as those
detected for hosts of gamma-ray bursts (GRBs) and broad-lined SNe type Ic
(IcBL). This suggests that the progenitors of type Ib SNe are not born out of
recently accreted atomic gas, as was suggested for GRB and IcBL SN progenitors.Comment: Astronomy & Astrophysics, in press, 8 pages, 3 figures, 1 tabl
Investigating the Impact of Metallicity on Star Formation in the Outer Galaxy. I. VLT/KMOS Survey of Young Stellar Objects in Canis Major
The effects of metallicity on the evolution of protoplanetary disks may be
studied in the outer Galaxy where the metallicity is lower than in the solar
neighbourhood. We present the VLT/KMOS integral field spectroscopy in the
near-infrared of 120 candidate young stellar objects (YSOs) in the
CMa-224 star-forming region located at a Galactocentric distance of 9.1
kpc. We characterise the YSO accretion luminosities and accretion rates using
the hydrogen Br emission and find the median accretion luminosity of
. Based on the measured
accretion luminosities, we investigate the hypothesis of star formation history
in the CMa-224. Their median values suggest that Cluster C, where most of
YSO candidates have been identified, might be the most evolved part of the
region. The accretion luminosities are similar to those observed toward
low-mass YSOs in the Perseus and Orion molecular clouds, and do not reveal the
impact of lower metallicity. Similar studies in other outer Galaxy clouds
covering a wide range of metallicities are critical to gain a complete picture
of star formation in the Galaxy.Comment: Accepted for publication in APJS, 51 pages, 37 figures, 6 table
A large population of strongly lensed faint submillimetre galaxies in future dark energy surveys inferred from JWST imaging
Bright galaxies at sub-millimetre wavelengths from Herschel are now well
known to be predominantly strongly gravitationally lensed. The same models that
successfully predicted this strongly lensed population also predict about one
percent of faint m-selected galaxies from deep JCMT surveys will also
be strongly lensed. Follow-up ALMA campaigns have so far found one potential
lens candidate, but without clear compelling evidence e.g. from lensing arcs.
Here we report the discovery of a compelling gravitational lens system
confirming the lensing population predictions, with a
submm source lensed by a foreground galaxy within the COSMOS
field, identified through public JWST imaging of a m source in the
SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES) catalogue. These systems will
typically be well within the detectable range of future wide-field surveys such
as Euclid and Roman, and since sub-millimetre galaxies are predominantly very
red at optical/near-infrared wavelengths, they will tend to appear in
near-infrared channels only. Extrapolating to the Euclid-Wide survey, we
predict tens of thousands of strongly lensed near-infrared galaxies. This will
be transformative for the study of dusty star-forming galaxies at cosmic noon,
but will be a contaminant population in searches for strongly lensed
ultra-high-redshift galaxies in Euclid and Roman.Comment: 8 pages; 4 figures; 4 tables; submitted to MNRA
Revisiting the Color-Color Selection: Submillimeter and AGN Properties of NUV-r-J Selected Quiescent Galaxies
We examine the robustness of the color-color selection of quiescent galaxies
(QGs) against contamination of dusty star-forming galaxies using the latest
submillimeter data. We selected 18,304 QG candidates out to 3 using the
commonly adopted selection based on the high-quality multi-wavelength
COSMOS2015 catalog. Using extremely deep 450 and 850 m catalogs from the
latest JCMT SCUBA-2 Large Programs, S2COSMOS, and STUDIES, as well as ALMA
submillimeter, VLA 3 GHz, and MIPS 24 m catalogs, we identified
luminous dusty star-forming galaxies among the QG candidates. We also conducted
stacking analyses in the SCUBA-2 450 and 850 m images to look for
less-luminous dusty galaxies among the QG candidates. By cross-matching to the
24 m and 3 GHz data, we were able to identify a sub-group of
"IR-radio-bright" QGs who possess a strong 450 and 850 m stacking signal.
The potential contamination of these luminous and less-luminous dusty galaxies
accounts for approximately 10% of the color-selected QG candidates. In
addition, there exists a spatial correlation between the luminous star-forming
galaxies and the QGs at a kpc scale. Finally, we found a high QG
fraction among radio AGNs at 1.5. Our data show a strong correlation
between QGs and radio AGNs, which may suggest a connection between the
quenching process and the radio-mode AGN feedback.Comment: This paper is accepted for publication on Ap
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NEPSC2, the North Ecliptic Pole SCUBA-2 survey: 850-<i>μ</i>m map and catalogue of 850-<i>μ</i>m selected sources over 2 deg<sup>2</sup>
Abstract We present an 850-μm mosaic map and extracted catalogue of submillimetre sources in the extended North Ecliptic Pole (NEP) region over about 2 deg2. The 850-μm map is constructed using newly obtained observations by SCUBA-2 at the East Asian Observatory’s James Clerk Maxwell Telescope, carried out using the observatory’s large programme opportunities. The recent 850-μm survey has extended the submillimetre data coverage by almost a factor of 4 compared to previous surveys, with a depth of σrms = 1.0–2.3 mJy beam−1. The catalogue contains 549 sources selected above a significance level of 4σ, where the false-detection rate is 10 per cent; a higher threshold of 4.5σ is required in order to achieve a false-detection rate below 3 per cent, which results in 342 sources being selected. Despite the large spatial variation of the noise, the deboosted flux density of sources is comparable to results from the SCUBA-2 Cosmology Legacy Survey (S2CLS), which covered the central 0.6 deg2 of our survey area with better sensitivity. We construct the source counts at 850 μm, finding results in agreement with other 850-μm surveys in cosmological blank fields over S850 = 4–15 mJy. We find a slight excess of bright galaxies (S850 > 15 mJy), which can be considered to be at ɀphot = 2–4. The 850-μm data adds valuable long-wavelength information to mid-infrared-selected sources from the AKARI NEP-deep and NEP-wide surveys, which will be helpful in preparing for future near-infrared to millimetre wavelength observations in the NEP region. Our 850-μm mosaic map and source catalogue will be made publicly available
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A large population of strongly lensed faint submillimetre galaxies in future dark energy surveys inferred from <i>JWST</i> imaging
Bright galaxies at sub-millimetre wavelengths from Herschel are now well known to be predominantly strongly gravitationally lensed. The same models that successfully predicted this strongly lensed population also predict about one percent of faint 450μm-selected galaxies from deep JCMT surveys will also be strongly lensed. Follow-up ALMA campaigns have so far found one potential lens candidate, but without clear compelling evidence e.g. from lensing arcs. Here we report the discovery of a compelling gravitational lens system confirming the lensing population predictions, with a zs = 3.4 ± 0.4 submm source lensed by a zspec = 0.360 foreground galaxy within the COSMOS field, identified through public JWST imaging of a 450μm source in the SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES) catalogue. These systems will typically be well within the detectable range of future wide-field surveys such as Euclid and Roman, and since sub-millimetre galaxies are predominantly very red at optical/near-infrared wavelengths, they will tend to appear in near-infrared channels only. Extrapolating to the Euclid-Wide survey, we predict tens of thousands of strongly lensed near-infrared galaxies. This will be transformative for the study of dusty star-forming galaxies at cosmic noon, but will be a contaminant population in searches for strongly lensed ultra-high-redshift galaxies in Euclid and Roman