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251. Black hole masses in megamaser disk galaxies
ID:
ivo://CDS.VizieR/J/ApJ/826/L32
Title:
Black hole masses in megamaser disk galaxies
Short Name:
J/ApJ/826/L32
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use new precision measurements of black hole (BH) masses from water megamaser disks to investigate scaling relations between macroscopic galaxy properties and supermassive BH mass. The megamaser-derived BH masses span 10^6^-10^8^M_{sun}_, while all the galaxy properties that we examine (including total stellar mass, central mass density, and central velocity dispersion) lie within a narrower range. Thus, no galaxy property correlates tightly with M_BH_ in ~L* spiral galaxies as traced by megamaser disks. Of them all, stellar velocity dispersion provides the tightest relation, but at fixed {sigma}_*_ the mean megamaser M_BH_ are offset by -0.6+/-0.1dex relative to early-type galaxies. Spiral galaxies with non-maser dynamical BH masses do not appear to show this offset. At low mass, we do not yet know the full distribution of BH mass at fixed galaxy property; the non-maser dynamical measurements may miss the low-mass end of the BH distribution due to an inability to resolve their spheres of influence and/or megamasers may preferentially occur in lower-mass BHs.
252. Black hole masses of SDSS Seyfert 1 galaxies
ID:
ivo://CDS.VizieR/J/ApJ/881/L24
Title:
Black hole masses of SDSS Seyfert 1 galaxies
Short Name:
J/ApJ/881/L24
Date:
21 Oct 2021
Publisher:
CDS
Description:
Narrow-line Seyfert 1 galaxies (NLS1s) are believed to be powered by the accretion of matter onto low-mass black holes (BHs) in spiral host galaxies with BH masses M_BH_~10^6^-10^8^M_{sun}_. However, the broadband spectral energy distribution of the {gamma}-ray-emitting NLS1s are found to be similar to flat-spectrum radio quasars. This challenges our current notion of NLS1s having low M_BH_. To resolve this tension of low M_BH_ values in NLS1s, we fitted the observed optical spectrum of a sample of radio-loud NLS1s (RL-NLS1s), radio-quiet NLS1s (RQ-NLS1s), and radio-quiet broad-line Seyfert 1 galaxies (RQ-BLS1s) of ~500 each with the standard Shakura-Sunyaev accretion disk (AD) model. For RL-NLS1s we found a mean log(M_BH_^AD^/M_{sun}_) of 7.98+/-0.54. For RQ-NLS1s and RQ-BLS1s we found mean log(M_BH_^AD^/M_{sun}_) of 8.00+/-0.43 and 7.90+/-0.57, respectively. While the derived M_BH_^AD^ values of RQ-BLS1s are similar to their virial masses, for NLS1s the derived M_BH_^AD^ values are about an order of magnitude larger than their virial estimates. Our analysis thus indicates that NLS1s have M_BH_ similar to RQ-BLS1s and their available virial M_BH_ values are underestimated, influenced by their observed relatively small emission line widths. Considering Eddington ratio as an estimation of the accretion rate and using M_BH_^AD^, we found the mean accretion rate of our RQ-NLS1s, RL-NLS1s, and RQ-BLS1s as 0.06_-0.05_^+0.16^, 0.05_-0.04_^+0.18^ and 0.05_-0.04_^+0.15^, respectively. Our results therefore suggest that NLS1s have BH masses and accretion rates that are similar to BLS1s.
253. Black hole mass estimates
ID:
ivo://CDS.VizieR/J/ApJS/168/1
Title:
Black hole mass estimates
Short Name:
J/ApJS/168/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We describe the general problem of estimating black hole masses of active galactic nuclei (AGNs) by calculating the conditional probability distribution of M_BH_ given some set of observables. We estimated M_BH_ from both CIV and H{beta} for a sample of 100 sources, including new spectra of 29 quasars.
254. Blanco survey of the lens BCS J2352-5452
ID:
ivo://CDS.VizieR/J/ApJ/742/48
Title:
Blanco survey of the lens BCS J2352-5452
Short Name:
J/ApJ/742/48
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on the serendipitous discovery in the Blanco Cosmology Survey (BCS) imaging data of a z=0.9057 galaxy that is being strongly lensed by a massive galaxy cluster at a redshift of z=0.3838. The lens (BCS J2352-5452) was discovered while examining i- and z-band images being acquired in 2006 October during a BCS observing run. Follow-up spectroscopic observations with the Gemini Multi-Object Spectrograph instrument on the Gemini-South 8m telescope confirmed the lensing nature of this system. Using weak-plus-strong lensing, velocity dispersion, cluster richness N_200_, and fitting to a Navarro-Frenk-White (NFW) cluster mass density profile, we have made three independent estimates of the mass M_200_ which are all very consistent with each other. The combination of the results from the three methods gives M_200_=(5.1+/-1.3)x10^14^M_{sun}_, which is fully consistent with the individual measurements. The final NFW concentration c_200_ from the combined fit is c_200_=5.4^+1.4^_-1.1_. We have compared our measurements of M_200_ and c_200_ with predictions for (1) clusters from {Lambda}CDM simulations, (2) lensing-selected clusters from simulations, and (3) a real sample of cluster lenses.
255. BLAST: the redshift survey
ID:
ivo://CDS.VizieR/J/ApJ/707/1779
Title:
BLAST: the redshift survey
Short Name:
J/ApJ/707/1779
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) has recently surveyed ~8.7deg^2^ centered on Great Observatories Origins Deep Survey-South at 250, 350, and 500um. In Dye et al. (2009, Cat. J/ApJ/703/285), we presented the catalog of sources detected at 5{sigma} in at least one band in this field and the probable counterparts to these sources in other wavebands. In this paper, we present the results of a redshift survey in which we succeeded in measuring redshifts for 82 of these counterparts. The spectra show that the BLAST counterparts are mostly star-forming galaxies but not extreme ones when compared to those found in the Sloan Digital Sky Survey. Roughly one quarter of the BLAST counterparts contain an active nucleus. We have also investigated the cases where there are two possible counterparts to the BLAST source, finding that in at least half of these there is evidence that the two galaxies are physically associated, either because they are interacting or because they are in the same large-scale structure. Finally, we have made the first direct measurements of the luminosity function in the three BLAST bands.
256. BL Lac objects GTC low resolution spectroscopy
ID:
ivo://CDS.VizieR/J/ApJ/861/130
Title:
BL Lac objects GTC low resolution spectroscopy
Short Name:
J/ApJ/861/130
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on 16 BL Lacertae objects that were proposed to be at z>1. We present spectroscopic observations secured at the 10.4m GTC that allowed us to assess the redshift of these sources. In particular, for five objects, we disprove the previous value of the redshift reported in the literature and found that they lie at z<1. Moreover, two of them exhibit broad emission lines that are not characteristic of BL Lacertae objects. On the other hand, for eight targets, we improve the tentative value of z, previously based on only one feature, by detecting a number of emission lines. Finally, in three cases, we detect the onset of the Ly{alpha} forest at z>2.50. Based on the new high quality spectra, we found that only half of the observed objects can be classified as bona-fide BL Lacs.
257. Blue and red spectra of {omega} Cen HB stars
ID:
ivo://CDS.VizieR/J/MNRAS/399/195
Title:
Blue and red spectra of {omega} Cen HB stars
Short Name:
J/MNRAS/399/195
Date:
21 Oct 2021
Publisher:
CDS
Description:
The multiphase interstellar medium (ISM) is highly structured, on scales from the size of the Solar System to that of a galaxy. In particular, small-scale structures are difficult to study and hence are poorly understood. We used the multiplex capabilities of the AAOmega spectrograph at the Anglo-Australian Telescope to create a half-square-degree map of the neutral and low-ionized ISM in front of the nearby (~5kpc), most massive Galactic globular cluster, {omega} Centauri. Its redshifted, metal-poor and hot horizontal branch stars probe the medium-strong CaII K and NaI D2 line absorption, and weak absorption in the {lambda}5780 and {lambda}5797 diffuse interstellar bands (DIBs), on scales around a parsec. The kinematical and thermodynamical picture emerging from these data is that we predominantly probe the warm neutral medium and weakly ionized medium of the Galactic Disc-Halo interface, ~0.3-1kpc above the mid-plane. A comparison with Spitzer Space Telescope 24um and DIRBE/IRAS maps of the warm and cold dust emission confirms that both NaI and CaII trace the overall column density of the warm neutral and weakly ionized medium. Clear signatures are seen of the depletion of calcium atoms from the gas phase into dust grains.
258. Blue compact galaxies from SBS
ID:
ivo://CDS.VizieR/J/A+A/373/24
Title:
Blue compact galaxies from SBS
Short Name:
J/A+A/373/24
Date:
21 Oct 2021
Publisher:
CDS
Description:
The work studies of the environment of low-mass galaxies with active star formation (SF) and a possible trigger of SF bursts due to gravitational interaction. Following the study by Taylor et al. (1995ApJS...99..427T), we extend the search for possible disturbing galaxies of various masses to a much larger sample of 86 BCGs from the sky region of the Second Byurakan survey (SBS). The BCG magnitudes and radial velocities are revised and up-dated. The sample under study is separated by the criteria: EW([O III]5007)>45{AA} and V_h_<6000km/s nd should be representative of all low-mass galaxies which experience SF bursts.
259. Blue diffuse dwarf galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/465/3977
Title:
Blue diffuse dwarf galaxies
Short Name:
J/MNRAS/465/3977
Date:
21 Oct 2021
Publisher:
CDS
Description:
The search for chemically unevolved galaxies remains prevalent in the nearby Universe, mostly because these systems provide excellent proxies for exploring in detail the physics of high-z systems. The most promising candidates are extremely metal-poor galaxies (XMPs), i.e. galaxies with <1/10 solar metallicity. However, due to the bright emission-line-based search criteria traditionally used to find XMPs, we may not be sampling the full XMP population. In 2014, we reoriented this search using only morphological properties and uncovered a population of ~150 'blue diffuse dwarf (BDD) galaxies', and published a sub-sample of 12 BDD spectra. Here, we present optical spectroscopic observations of a larger sample of 51 BDDs, along with their Sloan Digital Sky Survey (SDSS) photometric properties. With our improved statistics, we use direct-method abundances to confirm that BDDs are chemically unevolved (7.43<12+log(O/H)<8.01), with ~20 per cent of our sample classified as being XMP galaxies, and find that they are actively forming stars at rates of ~1-33x10^-2^M_{sun}_/yr in HII regions randomly embedded in a blue, low-surface-brightness continuum. Stellar masses are calculated from population synthesis models and estimated to be in the range log (M_*_/M_{sun}_)~=5-9. Unlike other low-metallicity star-forming galaxies, BDDs are in agreement with the mass-metallicity relation at low masses, suggesting that they are not accreting large amounts of pristine gas relative to their stellar mass. BDD galaxies appear to be a population of actively star-forming dwarf irregular (dIrr) galaxies which fall within the class of low-surface-brightness dIrr galaxies. Their ongoing star formation and irregular morphology make them excellent analogues for galaxies in the early Universe.
260. Blue diffuse dwarf galaxies spectroscopic data
ID:
ivo://CDS.VizieR/J/MNRAS/448/2687
Title:
Blue diffuse dwarf galaxies spectroscopic data
Short Name:
J/MNRAS/448/2687
Date:
21 Oct 2021
Publisher:
CDS
Description:
Extremely metal poor (XMP) galaxies are known to be very rare, despite the large numbers of low-mass galaxies predicted by the local galaxy luminosity function. This paper presents a subsample of galaxies that were selected via a morphology-based search on Sloan Digital Sky Survey images with the aim of finding these elusive XMP galaxies. By using the recently discovered XMP galaxy, Leo P, as a guide, we obtained a collection of faint, blue systems, each with isolated H II regions embedded in a diffuse continuum, that have remained optically undetected until now. Here we show the first results from optical spectroscopic follow-up observations of 12 of ~100 of these blue diffuse dwarf (BDD) galaxies yielded by our search algorithm. Oxygen abundances were obtained via the direct method for eight galaxies, and found to be in the range 7.45<12+log(O/H)<8.0, with two galaxies being classified as XMPs. All BDDs were found to currently have a young star-forming population (<10 Myr) and relatively high ionization parameters of their H II regions. Despite their low luminosities (-11<~M_B_<~-18) and low surface brightnesses (~23-25 mag/arcsec^2^), the galaxies were found to be actively star forming, with current star formation rates between 0.0003 and 0.078 M_{sun}_/yr. From our current subsample, BDD galaxies appear to be a population of non-quiescent dwarf irregular galaxies, or the diffuse counterparts to blue compact galaxies and as such may bridge the gap between these two populations. Our search algorithm demonstrates that morphology-based searches are successful in uncovering more diffuse metal-poor star-forming galaxies, which traditional emission-line-based searches overlook.

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