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5501. [U]LIRGs - on the trail of AGN's types
ID:
ivo://CDS.VizieR/J/A+A/598/A1
Title:
[U]LIRGs - on the trail of AGN's types
Short Name:
J/A+A/598/A1
Date:
21 Oct 2021
Publisher:
CDS
Description:
The aim of this work is to characterize physical properties of Ultra Luminous Infrared Galaxies (ULIRGs) and Luminous Infrared Galaxies (LIRGs) detected in the far-infrared (FIR) 90um band in the AKARI Deep Field-South (ADF-S) survey. In particular, we want to estimate the active galactic nucleus (AGN) contribution to the LIRGs and ULIRGs' infrared emission and which types of AGNs are related to their activity. We examined 69 galaxies at redshift >=0.05 detected at 90um by the AKARI satellite in the AKARI Deep-Field South (ADF-S), with optical counterparts and spectral coverage from the ultraviolet to the FIR. We used two independent spectral energy distribution fitting codes: one fitting the SED from FIR to FUV (CIGALE) (we use the results from CIGALE as a reference) and gray-body + power spectrum fit for the infrared part of the spectra (CMCIRSED) in order to identify a subsample of ULIRGs and LIRGs, and to estimate their properties. A final catalog of 39 LIRGs and ULIRGs is used for our analysis.
5502. Ultra-compact dwarf candidates in Abell S0740
ID:
ivo://CDS.VizieR/J/AJ/136/2295
Title:
Ultra-compact dwarf candidates in Abell S0740
Short Name:
J/AJ/136/2295
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze three-band imaging data of the giant elliptical galaxy ESO 325-G004 from the Hubble Space Telescope Advanced Camera for Surveys (ACS). This is the nearest known strongly lensing galaxy, and it resides in the center of the poor cluster Abell S0740 at redshift z=0.034. Based on magnitude, color, and size selection criteria, we identify a sample of 15 ultra-compact dwarf (UCD) galaxy candidates within the ACS field.
5503. Ultracompact dwarf galaxies in Perseus
ID:
ivo://CDS.VizieR/J/MNRAS/422/885
Title:
Ultracompact dwarf galaxies in Perseus
Short Name:
J/MNRAS/422/885
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of the first search for ultracompact dwarfs (UCDs) in the Perseus cluster core, including the region of the cluster around the unusual brightest cluster galaxy NGC 1275. Utilizing Hubble Space Telescope Advanced Camera for Surveys imaging, we identify a sample of 84 UCD candidates with half-light radii 10<r_e_<57pc out to a distance of 250kpc from the cluster centre, covering a total survey area of ~70arcmin^2^.
5504. Ultra compact dwarfs and globulars in Hya I
ID:
ivo://CDS.VizieR/J/A+A/531/A4
Title:
Ultra compact dwarfs and globulars in Hya I
Short Name:
J/A+A/531/A4
Date:
21 Oct 2021
Publisher:
CDS
Description:
We performed a large spectroscopic survey of compact, unresolved objects in the core of the Hydra I galaxy cluster (Abell 1060), with the aim of identifying ultra-compact dwarf galaxies (UCDs) and investigating the properties of the globular cluster (GC) system around the central cD galaxy NGC 3311. We obtained VIMOS medium-resolution spectra of about 1200 candidate objects with apparent magnitudes 18.5<V<24.0mag, covering both the bright end of the GC luminosity function and the luminosity range of all known UCDs.
5505. Ultracool dwarf K2 light curves
ID:
ivo://CDS.VizieR/J/A+A/641/A170
Title:
Ultracool dwarf K2 light curves
Short Name:
J/A+A/641/A170
Date:
21 Oct 2021
Publisher:
CDS
Description:
With the discovery of a planetary system around the ultracool dwarf TRAPPIST-1, there has been a surge of interest in such stars as potential planet hosts. Planetary systems around ultracool dwarfs represent our best chance of characterising temperate rocky-planet atmospheres with the James Webb Space Telescope. However, TRAPPIST-1 remains the only known system of its kind and the occurrence rate of planets around ultracool dwarfs is still poorly constrained. We seek to perform a complete transit search on the ultracool dwarfs observed by NASA's K2 mission, and use the results to constrain the occurrence rate of planets around these stars. We filter and characterise the sample of ultracool dwarfs observed by K2 by fitting their spectral energy distributions and using parallaxes from Gaia. We build an automatic pipeline to perform photometry, detrend the light curves, and search for transit signals. Using extensive injection-recovery tests of our pipeline, we compute the detection sensitivity of our search, and thus the completeness of our sample. We infer the planetary occurrence rates within a hierarchical Bayesian model (HBM) to treat uncertain planetary parameters.With the occurrence rate parametrised by a step-wise function, we present a convenient way to directly marginalise over the second level of our HBM (the planetary parameters). Our method is applicable generally and can greatly speed up inference with larger catalogues of detected planets. We detect one planet in our sample of 702 ultracool dwarfs: a previously validated mini-Neptune. We thus infer a mini-Neptune (2-4R_{Earth}_) occurrence rate of {eta}=0.20^+0.16^_0.11_ within orbital periods of 1-20 days. For super-Earths (1-2R_{Earth}_) and ice or gas giants (4-6R_{Earth}_) within 1-20 days, we place 95% credible intervals of {eta}<1.14 and {eta}<0.29, respectively. If TRAPPIST-1-like systems were ubiquitous, we would have a 96% chance of finding at least one.
5506. Ultra-cool dwarfs at low Galactic latitudes
ID:
ivo://CDS.VizieR/J/MNRAS/427/3280
Title:
Ultra-cool dwarfs at low Galactic latitudes
Short Name:
J/MNRAS/427/3280
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an ultra-cool dwarf (UCD) catalogue compiled from low southern Galactic latitudes and mid-plane, from a cross-correlation of the Two Micron All-Sky Survey (2MASS) and the SuperCOSMOS survey. The catalogue contains 246 members identified from 5042deg^2^ within 220{deg}<=l<=360{deg} and 0{deg}<l<=30{deg}, for |b|<=15{deg}. Sixteen candidates are spectroscopically confirmed in the near-infrared as UCDs with spectral types from M7.5V to L9, the latest being the unusual blue L dwarf 2MASSJ11263991-5003550. Our catalogue selection method is presented enabling UCDs from ~M8V to the L-T transition to be selected down to a 2MASS limiting magnitude of Ks=~14.5mag (for S/N>=10).
5507. Ultracool dwarfs from the 2MASS
ID:
ivo://CDS.VizieR/J/AJ/136/1290
Title:
Ultracool dwarfs from the 2MASS
Short Name:
J/AJ/136/1290
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using data from the 2 Micron All Sky Survey All-Sky Point Source Catalogue, we have extended our census of nearby ultracool dwarfs to cover the full celestial sphere above Galactic latitude of 15{deg}. Starting with an initial catalog of 2139484 sources, we have winnowed the sample to 467 candidate late-type M or L dwarfs within 20pc of the Sun. Fifty-four of those sources already have spectroscopic observations confirming them as late-type dwarfs. We present optical spectroscopy of 376 of the remaining 413 sources, and identify 44 as ultracool dwarfs with spectroscopic distances less than 20pc. Twenty-five of the 37 sources that lack optical data have near-infrared spectroscopy. Combining the present sample with our previous results and data from the literature, we catalog 94 L dwarf systems within 2pc. We discuss the distribution of activity, as measured by H{alpha} emission, in this volume-limited sample. We have coupled the present ultracool catalog with data for stars in the northern 8pc sample and recent (incomplete) statistics for T dwarfs to provide a snapshot of the current 20pc census as a function of spectral type.
5508. 827 ultracool dwarfs with K2
ID:
ivo://CDS.VizieR/J/AJ/160/19
Title:
827 ultracool dwarfs with K2
Short Name:
J/AJ/160/19
Date:
21 Oct 2021
Publisher:
CDS
Description:
The occurrence of planets orbiting ultracool dwarfs is poorly constrained. We present results from a guest observer program on NASA's K2 spacecraft to search for transiting planets orbiting a sample of 827 ultracool dwarfs. Having found no transiting planets in our sample, we determined an upper limit on the occurrence of planets. We simulated planets orbiting our sample for a range of orbital periods and sizes. For the simulated planets that transit their host, we injected the transit light curve into the real K2 light curves, then attempted to recover the injected planets. For a given occurrence rate, we calculated the probability of seeing no planets, and use the results to place an upper limit on planet occurrence as a function of planet radius and orbital period. We find that short-period, mini-Neptune and Jupiter-sized planets are rare around ultracool dwarfs, consistent with results for early and mid-type M dwarf stars. We constrain the occurrence rate {eta} for planets between 0.5 and 10 R{earth} with orbital periods between 1 and 26.3days.
5509. Ultracool white dwarfs
ID:
ivo://CDS.VizieR/J/MNRAS/449/3966
Title:
Ultracool white dwarfs
Short Name:
J/MNRAS/449/3966
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present parallax observations and a detailed model atmosphere analysis of 54 cool and ultracool (Teff<4000K) white dwarfs (WDs) in the solar neighbourhood. For the first time, a large number of cool and ultracool WDs have distance and tangential velocities measurements available. Our targets have distances ranging from 21pc to >100pc, and include five stars within 30pc. Contrary to expectations, all but two of them have tangential velocities smaller than 150km/s thus suggesting Galactic disc membership. The oldest WDs in this sample have WD cooling ages of 10Gyr, providing a firm lower limit to the age of the thick disc population. Many of our targets have uncharacteristically large radii, indicating that they are low-mass WDs. It appears that we have detected the brighter population of cool and ultracool WDs near the Sun. The fainter population of ultracool CO-core WDs remain to be discovered in large numbers. The Large Synoptic Survey Telescope should find these elusive, more massive ultracool WDs in the solar neighbourhood.
5510. Ultradeep Ks imaging in the GOODS-N
ID:
ivo://CDS.VizieR/J/ApJS/187/251
Title:
Ultradeep Ks imaging in the GOODS-N
Short Name:
J/ApJS/187/251
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an ultradeep K_s_-band image that covers 0.5x0.5deg^2^ centered on the Great Observatories Origins Deep Survey-North (GOODS-N). The image reaches a 5{sigma} depth of K_s,AB_=24.45 in the GOODS-N region, which is as deep as the GOODS-N Spitzer Infrared Array Camera (IRAC) 3.6um image. We present a new method of constructing IRAC catalogs that uses the higher spatial resolution K_s_ image and catalog as priors and iteratively subtracts fluxes from the IRAC images to estimate the IRAC fluxes. Our iterative method is different from the {chi}^2^ approach adopted by other groups. We verified our results using data taken in two different epochs of observations, as well as by comparing our colors with the colors of stars and with the colors derived from model spectral energy distributions of galaxies at various redshifts. We make available to the community our WIRCam K_s_-band image and catalog (94951 objects in 0.25deg^2^), the Interactive Data Language pipeline used for reducing the WIRCam images, and our IRAC 3.6-8.0um catalog (16950 objects in 0.06deg^2^ at 3.6um). With this improved K_s_ and IRAC catalog and a large spectroscopic sample from our previous work (Cat. <J/ApJ/689/687>), we study the color-magnitude and color-color diagrams of galaxies. We compare the effectiveness of using K_s_ and IRAC colors to select active galactic nuclei and galaxies at various redshifts. We also study a color selection of z=0.65-1.2 galaxies using the K_s_, 3.6um, and 4.5um bands.