- ID:
- ivo://CDS.VizieR/J/MNRAS/430/1171
- Title:
- Sub-stellar birth rate from UKIDSS
- Short Name:
- J/MNRAS/430/1171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new sample of mid-L to mid-T dwarfs with effective temperatures of 1100-1700K selected from the UKIDSS Large Area Survey (LAS) and confirmed with infrared spectra from X-shooter/Very Large Telescope. This effective temperature range is especially sensitive to the formation history of Galactic brown dwarfs and allows us to constrain the form of the sub-stellar birth rate, with sensitivity to differentiate between a flat (stellar like) birth rate and an exponentially declining form. We present the discovery of 63 new L and T dwarfs from the UKIDSS LAS DR7, including the identification of 12 likely unresolved binaries, which form the first complete sub-set from our programme, covering 495 square degrees of sky, complete to J=18.1. We compare our results for this sub-sample with simulations of differing birth rates for objects of masses 0.10-0.03M_{sun}_ and ages 1-10Gyr. We find that the more extreme birth rates (e.g. a halo type form) can likely be excluded as the true form of the birth rate. In addition, we find that although there is substantial scatter we find a preference for a mass function, with a power-law index {alpha} in the range -1<{alpha}<0 that is consistent (within the errors) with the studies of late T dwarfs.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/610/1064
- Title:
- Substellar population of lambda Ori
- Short Name:
- J/ApJ/610/1064
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By collecting optical and infrared photometry and low-resolution spectroscopy, we have identified a large number of low-mass stars and brown dwarf candidates belonging to the young cluster (~5Myr) associated with the binary star {lambda} Orionis. The lowest mass object found is an M8.5 with an estimated mass of 0.02M_{Sun}_ (~0.01M_{Sun}_ for objects without spectroscopic confirmation). For those objects with spectroscopy, the measured strength of the H{alpha} emission line follows a distribution similar to other clusters with the same age range, with larger equivalent widths for cooler spectral types.
- ID:
- ivo://CDS.VizieR/J/ApJ/837/139
- Title:
- SUPER GOODS. I. Ultradeep SCUBA-2 survey
- Short Name:
- J/ApJ/837/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this first paper in the SUPER GOODS series on powerfully star-forming galaxies in the two GOODS fields, we present a deep SCUBA-2 survey of the GOODS-N at both 850 and 450{mu}m (central rms noise of 0.28mJy and 2.6mJy, respectively). In the central region, the 850{mu}m observations cover the GOODS-N to near the confusion limit of ~1.65mJy, while over a wider 450arcmin^2^ region-well complemented by Herschel far-infrared imaging-they have a median 4{sigma} limit of 3.5mJy. We present >=4{sigma} catalogs of 186 850{mu}m and 31 450{mu}m selected sources. We use interferometric observations from the Submillimeter Array (SMA) and the Karl G. Jansky Very Large Array (VLA) to obtain precise positions for 114 SCUBA-2 sources (28 from the SMA, all of which are also VLA sources). We present new spectroscopic redshifts and include all existing spectroscopic or photometric redshifts. We also compare redshifts estimated using the 20cm/850{mu}m and the 250cm/850{mu}m flux ratios. We show that the redshift distribution increases with increasing flux, and we parameterize the dependence. We compute the star formation history and the star formation rate (SFR) density distribution functions in various redshift intervals, finding that they reach a peak at z=2-3 before dropping to higher redshifts. We show that the number density per unit volume of SFR>~500M_{sun}_/yr galaxies measured from the SCUBA-2 sample does not change much relative to that of lower SFR galaxies from UV selected samples over z=2-5, suggesting that, apart from changes in the normalization, the shape in the number density as a function of SFR is invariant over this redshift interval.
- ID:
- ivo://CDS.VizieR/J/ApJ/887/23
- Title:
- SUPER GOODS. IV. 850um data of CDFS X-ray sources
- Short Name:
- J/ApJ/887/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Chandra Deep Field (CDF)-S is the deepest X-ray image available and will remain so for the near future. We provide a spectroscopic (64.5%; 64% with spectral classifications) and photometric redshift catalog for the full 7Ms sample, but much of our analysis focuses on the central (off-axis angles <5.7') region, which contains a large, faint ALMA sample of 75 >4.5{sigma} 850{mu}m sources. We measure the 850{mu}m fluxes at the X-ray positions using the ALMA images, where available, or an ultradeep SCUBA-2 map. We find that the full X-ray sample produces ~10% of the 850{mu}m extragalactic background light. We separate the submillimeter-detected X-ray sources into star-forming galaxies and active galactic nuclei (AGNs) using a star formation rate (SFR) versus X-ray luminosity calibration for high-SFR galaxies. We confirm this separation using the X-ray photon indices. We measure the X-ray fluxes at the accurate positions of the 75 ALMA sources and detect 70% at >3{sigma} in either the 0.5-2 or 2-7keV bands. However, many of these may produce both their X-ray and submillimeter emission by star formation. Indeed, we find that only 20% of the ALMA sources have intermediate X-ray luminosities (rest-frame 8-28 keV luminosities of 10^42.5^-10^44^erg/s), and none has a high X-ray luminosity (>10^44^erg/s). Conversely, after combining the CDF-S with the CDF-N, we find extreme star formation (SFR>300M_{sun}_/yr) in some intermediate X-ray luminosity sources but not in any high X-ray luminosity sources. We argue that the quenching of star formation in the most luminous AGNs may be a consequence of the clearing of gas in these sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/901/133
- Title:
- Supermassive BH masses of reverberation-mapped AGNs
- Short Name:
- J/ApJ/901/133
- Date:
- 21 Feb 2022 08:57:26
- Publisher:
- CDS
- Description:
- Using different kinds of velocity tracers derived from the broad H{beta} profile (in the mean or rms spectrum) and the corresponding virial factors f, the central supermassive black hole masses (M_BH_) are calculated for a compiled sample of 120 reverberation-mapped (RM) active galactic nuclei (AGNs). For its subsample of RM AGNs with measured stellar velocity dispersion ({sigma}_*_), the multivariate linear regression technique is used to calibrate the mean value f, as well as the variable FWHM-based f. It is found that, whether excluding the pseudobulges or not, the M_BH_ from the H{beta} line dispersion in the mean spectrum ({sigma}_H{beta},mean_) has the smallest offset rms with respect to the M_BH_-{sigma}_*_ relation. For the total sample excluding SDSS-RM AGNs, with respect to M_BH_ from {sigma}_*_ or that from the H{beta} line dispersion in the rms spectrum ({sigma}_H{beta},rms_), it is found that we can obtain M_BH_ from the {sigma}_H{beta},mean_ with the smallest offset rms of 0.38 or 0.23dex, respectively. It implies that, with respect to the H{beta} FWHM, we prefer {sigma}_H{beta},mean_ to calculate M_BH_ from the single-epoch spectrum. Using the FWHM-based f, we can improve the M_BH_ calculation from FWHM(H{beta}) and the mean f, with a decreased offset rms from 0.52 to 0.39 dex with respect to M_BH_ from {sigma}_*_ for the subsample of 36 AGNs with {sigma}_*_. The value of 0.39dex is almost the same as that from {sigma}_H{beta},mean_ and the mean f.
- ID:
- ivo://CDS.VizieR/J/A+A/657/A64
- Title:
- Supernovae ZTF light curves
- Short Name:
- J/A+A/657/A64
- Date:
- 16 Mar 2022 13:01:07
- Publisher:
- CDS
- Description:
- Stripped-envelope supernovae (SE SNe) of Type Ib and Type Ic are thought to result from explosions of massive stars having lost their outer envelopes. The favoured explosion mechanism is by core-collapse, with the shock later revived by neutrino heating. However, there is an upper limit to the amount of radioactive ^56^Ni that such models can accomplish. Recent literature point to a tension between the maximum luminosity from such simulations and observations. We use a well characterized sample of SE SNe from the Zwicky Transient Facility (ZTF) Bright Transient Survey (BTS). We scrutinize the observational caveats regarding estimating the maximum luminosity (and thus the amount of ejected radioactive nickel) for the members of this sample. We employ the strict selection criteria for the BTS to collect a sample of spectroscopically classified normal Type Ibc SNe for which we use the ZTF light curves to determine the maximum luminosity. We cull the sample further based on data quality, light-curve shape, distance and colors, and examine uncertainties that may affect the numbers. The methodology of the sample construction from this BTS sample can be used for many other future investigations. We analyze observational data, consisting of optical light curves and spectra, for the selected sub-samples. In total we use 129 Type Ib or Type Ic BTS SNe with an initial rough luminosity distribution peaked at M_r_=-17.61+/-0.72, and where 36% are apparently brighter than the theoretically predicted maximum brightness of M_r_=-17.8. When we further cull this sample to ensure that the SNe are normal Type Ibc with good LC data within the Hubble flow, the sample of 94 objects has M_r_=-17.64+/-0.54. A main uncertainty in absolute magnitude determinations for SNe is the host galaxy extinction correction, but the reddened objects only get more luminous after corrections. If we simply exclude objects with red, unusual or uncertain colors, we are left with 14 objects at M_r_=-17.90+/-0.73, whereof a handful are most certainly brighter than the suggested theoretical limit. The main result of this study is thus that normal SNe Ibc do indeed reach luminosities above 10^42.6^erg/s, apparently in conflict with existing explosion models.
- ID:
- ivo://CDS.VizieR/II/135
- Title:
- Suppl. to Diffuse Interstellar Band Measurements
- Short Name:
- II/135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This bibliographic search has been undertaken in order to gather all data concerning four diffuse interstellar bands (DIB) published since the Snow, York, and Welty (1977) catalogue, and up to 1987.0. These four DIB are : 4430, 5780, 5797, and 6284 Angstrom. In the present set of data, no statistical reduction to a unique system has been made because most of the lists contain only few data.
- ID:
- ivo://CDS.VizieR/J/MNRAS/423/725
- Title:
- Survey of diffuse interstellar bands
- Short Name:
- J/MNRAS/423/725
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents an atlas of diffuse interstellar bands together with tables with measurements of their parameters: central wavelengths, full widths at half-maximum and equivalent widths. For this goal the spectra of ten reddened, early-type stars have been selected. The spectra are of high resolution, ~100000, and reasonable signal-to-noise ratio, S/N>300; they cover a wide spectral range 3500-10000{AA} and show a lack of evident Doppler splitting in the interstellar KI line. The measurement technique has allowed a homogeneous set of data to be achieved. As a result, the identity of 336 DIBs from previous surveys has been confirmed and 21 new bands have been found.
- ID:
- ivo://CDS.VizieR/J/MNRAS/253/686
- Title:
- Survey of faint compact objects
- Short Name:
- J/MNRAS/253/686
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a low-resolution (73A) spectroscopic survey of faint compact objects conducted with the Low Dispersion Survey Spectrograph at the Anglo-Australian Telescope. The sample is a random subset of all compact sources with 22.5<=b_j_<=23.5 in three high-latitude fields. Additional data on compact sources with 21<=b_j_<=22.5 have been selected from the higher resolution (13A) survey previously published by Colless et al. (1990), and a subset of these brighter objects has been studied at both dispersions.
- ID:
- ivo://CDS.VizieR/J/ApJS/177/39
- Title:
- Survey of low-redshift OVI absorbers
- Short Name:
- J/ApJS/177/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using high-resolution ultraviolet spectra of 16 low-z QSOs obtained with the E140M echelle mode of the Space Telescope Imaging Spectrograph, we study the physical conditions and statistics of OVI absorption in the intergalactic medium (IGM) at z<0.5. We identify 51 intervening (z_abs_<z_QSO_) OVI systems comprising 77 individual components, and we find 14 "proximate" systems (z_abs_~z_QSO_) containing 34 components. For intervening systems (components) with rest-frame equivalent width W_r_>30m{AA}, the number of OVI absorbers per unit redshift dN/dz=15.6^+2.9^_-2.4_(21.0^+3.2^_-2.8_), and this decreases to dN/dz=0.9^+1.0^_-0.5_(0.3^+0.7^_-0.3_) for W_r_>300m{AA}. The number per redshift increases steeply as z_abs_ approaches z_QSO_; we find that dN/dz is ~3-10 times higher within 2500km/s of z_QSO_. The most striking difference between intervening and proximate systems is that some proximate absorbers have substantially lower HI/OVI ratios.
