- 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.
Number of results to display per page
Search Results
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJS/191/222
- Title:
- BLAST observations of the SEP field
- Short Name:
- J/ApJS/191/222
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a survey carried out by the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) on a 9deg^2^ field near the South Ecliptic Pole at 250, 350, and 500um. The median 1{sigma} depths of the maps are 36.0, 26.4, and 18.4mJy, respectively. We apply a statistical method to estimate submillimeter galaxy number counts and find that they are in agreement with other measurements made with the same instrument and with the more recent results from Herschel/SPIRE. Thanks to the large field observed, the new measurements give additional constraints on the bright end of the counts. We identify 132, 89, and 61 sources with S/N>=4 at 250, 350, 500um, respectively and provide a multi-wavelength combined catalog of 232 sources with a significance >=4{sigma} in at least one BLAST band.
- ID:
- ivo://CDS.VizieR/J/PASJ/55/947
- Title:
- Blazars and Seyfert galaxies accretion rates
- Short Name:
- J/PASJ/55/947
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accretion rates and their correlation with cosmological redshifts for a sample of blazars and Seyfert galaxies are presented. The sample includes 77 blazars (28 FSRQs, 26 LBLs, and 23 HBLs) and 60 Seyfert galaxies, of which the extended spectral energy distribution information and redshifts are available. Within the framework of accreting black holes, the accretion rates for these sources were estimated based on their bolometric luminosities.
- ID:
- ivo://CDS.VizieR/J/ApJ/900/L34
- Title:
- BL Lac objects and radio galaxies comparison
- Short Name:
- J/ApJ/900/L34
- Date:
- 15 Feb 2022 00:20:41
- Publisher:
- CDS
- Description:
- The most elusive and extreme subclass of active galactic nuclei (AGNs), known as BL Lac objects, shows features that can only be explained as the result of relativistic effects occurring in jets pointing at a small angle with respect to the line of sight. A longstanding issue is the identification of the BL Lac parent population with jets oriented at larger angles. According to the "unification scenario" of AGNs, radio galaxies with low luminosity and an edge-darkened radio morphology are the most promising candidate parent population of BL Lacs. Here we compare the large-scale environment, an orientation-independent property, of well-defined samples of BL Lacs with samples of radio galaxies all lying in the local universe. Our study reveals that BL Lacs and radio galaxies live in significantly different environments, challenging predictions of the unification scenario. We propose a solution to this problem proving that large-scale environments of BL Lacs are statistically consistent with those of compact radio sources, known as FR 0s, and share similar properties. This implies that highly relativistic jets are ubiquitous and are the natural outcome of the accretion of gas into the deep gravitational potential well produced by supermassive black holes.
- ID:
- ivo://CDS.VizieR/J/A+A/600/A65
- Title:
- B2 0924+30 LOFAR HBA and WSRT maps
- Short Name:
- J/A+A/600/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using LOFAR (LOw Frequency ARray), Westerbork telescope and survey data, we map the spectral index and age of the remnant radio galaxy by using different ageing models.
- 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.
- ID:
- ivo://CDS.VizieR/J/other/RAA/19.81
- Title:
- Blue-core galaxies properties
- Short Name:
- J/other/RAA/19.8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We select 107 blue-core galaxies from the MaNGA survey, studying their morphology, kinematics as well as the gas-phase metallicity. Our results are as follows: (i) In our sample, 26% of blue-core galaxies have decoupled gas-star kinematics, indicating external gas accretion; 15% have bar-like structure and 8% show post-merger features, such as tidal tails and irregular gas/star velocity field. All these processes/features, such as accreting external misaligned gas, interaction and bar, can trigger gas inflow. Thus the central star-forming activities lead to bluer colors in their centers (blue-core galaxies). (ii) By comparing with the SDSS DR7 star-forming galaxy sample, we find that the blue-core galaxies have higher central gas-phase metallicity than what is predicted by the local mass-metallicity relation. We explore the origin of the higher metallicity, finding that not only the blue-core galaxies, but also the flat-gradient and red-core galaxies all have higher metallicity. This can be explained by the combined effect of redshift and galaxy color.
- 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.
- 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.
