- ID:
- ivo://CDS.VizieR/J/MNRAS/446/3478
- Title:
- Fornax A MWA 154MHz image
- Short Name:
- J/MNRAS/446/3478
- Date:
- 07 Feb 2022 14:41:00
- Publisher:
- CDS
- Description:
- We present new low-frequency observations of the nearby radio galaxy Fornax A at 154MHz with the Murchison Widefield Array, microwave flux-density measurements obtained from WMAP and Planck data, and {gamma}-ray flux densities obtained from Fermi data. We also compile a comprehensive list of previously published images and flux-density measurements at radio, microwave and X-ray energies. A detailed analysis of the spectrum of Fornax A between 154 and 1510MHz reveals that both radio lobes have a similar spatially averaged spectral index, and that there exists a steep-spectrum bridge of diffuse emission between the lobes. Taking the spectral index of both lobes to be the same, we model the spectral energy distribution of Fornax A across an energy range spanning 18 orders of magnitude, to investigate the origin of the X-ray and {gamma}-ray emission. A standard leptonic model for the production of both the X-rays and {gamma}-rays by inverse-Compton scattering does not fit the multiwavelength observations. Our results best support a scenario where the X-rays are produced by inverse-Compton scattering and the {gamma}-rays are produced primarily by hadronic processes confined to the filamentary structures of the Fornax A lobes.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/377/801
- Title:
- Fourth list of the Karachentsev catalog
- Short Name:
- J/A+A/377/801
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents HI observations of 165 dwarf galaxy candidates from the Karachentsev catalog of candidates for nearby dwarf galaxies prepared from film copies of POSSII and the ESO/SERC southern extension. Now a total of 601 galaxies from the published Karachentsev catalog have been searched for HI emission. Table 1 lists coordinates and general optical properties while Table 2 presents HI data and some global properties of these galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A1
- Title:
- FR0CAT. a FIRST catalog of FR 0 radio galaxies
- Short Name:
- J/A+A/609/A1
- Date:
- 04 Jan 2022 14:18:36
- Publisher:
- CDS
- Description:
- With the aim of exploring the properties of the class of FR 0 radio galaxies, we selected a sample of 108 compact radio sources, called FR0CAT, by combining observations from the NVSS, FIRST, and SDSS surveys. We included in the catalog sources with redshift <=0.05, with a radio size <=5kpc, and with an optical spectrum characteristic of low-excitation galaxies. Their radio luminosities at 1.4GHz are in the range 10^38^<={nu}L_1.4_<=10^40^erg/s. The FR0CAT hosts are mostly (86%) luminous (-21>=M_r_>=-23) red early-type galaxies with black hole masses 10^8^<=M_BH_<=10^9^M_{sun}_. These properties are similar to those seen for the hosts of FR I radio galaxies, but they are on average a factor ~1.6 less massive. The number density of FR0CAT sources is ~5 times higher than that of FR Is, and thus they represent the dominant population of radio sources in the local Universe. Different scenarios are considered to account for the smaller sizes and larger abundance of FR 0s with respect to FR Is. An age-size scenario that considers FR 0s as young radio galaxies that will all eventually evolve into extended radio sources cannot be reconciled with the large space density of FR 0s. However, the radio activity recurrence, with the duration of the active phase covering a wide range of values and with short active periods strongly favored with respect to longer ones, might account for their large density number. Alternatively, the jet properties of FR 0s might be intrinsically different from those of the FR Is, the former class having lower bulk Lorentz factors, possibly due to lower black hole spins. Our study indicates that FR 0s and FR I/IIs can be interpreted as two extremes of a continuous population of radio sources that is characterized by a broad distribution of sizes and luminosities of their extended radio emission, but shares a single class of host galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/598/A49
- Title:
- FRICAT. FIRST catalog of FR I radio galaxies
- Short Name:
- J/A+A/598/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We built a catalog of 219 FR I radio galaxies (FR Is), called FRICAT, selected from a published sample and obtained by combining observations from the NVSS, FIRST, and SDSS surveys. We included in the catalog the sources with an edge-darkened radio morphology, redshift >=0.15, and extending (at the sensitivity of the FIRST images) to a radius r larger than 30kpc from the center of the host. We also selected an additional sample (sFRICAT) of 14 smaller (10<r<30kpc) FR Is, limiting to z<0.05. The hosts of the FRICAT sources are all luminous (-21>=M_r_>=-24), red early-type galaxies with black hole masses in the range 10^8^<=M_BH_<=3x10^9^M_{sun}_; the spectroscopic classification based on the optical emission line ratios indicates that they are all low excitation galaxies. Sources in the FRICAT are then indistinguishable from the FR Is belonging to the Third Cambridge Catalogue of Radio Sources (3C) on the basis of their optical properties. Conversely, while the 3C-FR Is show a strong positive trend between radio and [O III] emission line luminosity, these two quantities are unrelated in the FRICAT sources; at a given line luminosity, they show radio luminosities spanning about two orders of magnitude and extending to much lower ratios between radio and line power than 3C-FR Is. Our main conclusion is that the 3C-FR Is just represent the tip of the iceberg of a much larger and diverse population of FR Is.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/116
- Title:
- FR II radio galaxies from MaxBCG
- Short Name:
- J/ApJ/756/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified and studied a sample of 151 FR IIs found in brightest cluster galaxies (BCGs) in the MaxBCG cluster catalog with data from FIRST and NVSS. We have compared the radio luminosities and projected lengths of these FR IIs to the projected length distribution of a range of mock catalogs generated by an FR II model and estimate the FR II lifetime to be 1.9x10^8^yr. The uncertainty in the lifetime calculation is a factor of two, primarily due to uncertainties in the intracluster medium (ICM) density and the FR II axial ratio. We furthermore measure the jet power distribution of FR IIs in BCGs and find that it is well described by a log-normal distribution with a median power of 1.1x10^37^W and a coefficient of variation of 2.2. These jet powers are nearly linearly related to the observed luminosities, and this relation is steeper than many other estimates, although it is dependent on the jet model. We investigate correlations between FR II and cluster properties and find that galaxy luminosity is correlated with jet power. This implies that jet power is also correlated with black hole mass, as the stellar luminosity of a BCG should be a good proxy for its spheroid mass and therefore the black hole mass. Jet power, however, is not correlated with cluster richness, nor is FR II lifetime strongly correlated with any cluster properties. We calculate the enthalpy of the lobes to examine the impact of the FR IIs on the ICM and find that heating due to adiabatic expansion is too small to offset radiative cooling by a factor of at least six. In contrast, the jet power is approximately an order of magnitude larger than required to counteract cooling. We conclude that if feedback from FR IIs offsets cooling of the ICM, then heating must be primarily due to another mechanism associated with FR II expansion.
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/1013
- Title:
- FR II radio galaxies in SDSS
- Short Name:
- J/MNRAS/415/1013
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Starting from the Cambridge Catalogues of radio sources, we have created a sample of 401 Fanaroff-Riley type II (FR II) radio sources that have counterparts in the main galaxy sample of the seventh Data release of the Sloan Digital Sky Survey (SDSS) and analyse their radio and optical properties.
- ID:
- ivo://CDS.VizieR/J/A+A/648/A102
- Title:
- FR-type radio sources at 3GHz VLA-COSMOS
- Short Name:
- J/A+A/648/A102
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Radio active galactic nuclei (AGN) are traditionally separated into two Fanaro-Riley (FR) type classes, edge-brightened FRII sources or edge-darkened FRI sources. With the discovery of a plethora of radio AGN of different radio shapes, this dichotomy is becoming too simplistic in linking the radio structure to the physical properties of radio AGN, their hosts, and their environment. We probe the physical properties and large-scale environment of radio AGN in the faintest FR population to date, and link them to their radio structure. We use the VLA-COSMOS Large Project at 3GHz (3GHz VLA-COSMOS), with a resolution and sensitivity of 0.75" and 2.3Jy/beam to explore the FR dichotomy down to Jy levels. We classified objects as FRIs, FRIIs, or hybrid FRI/FRII based on the surface-brightness distribution along their radio structure. Our control sample was the jet-less/compact radio AGN objects (COM AGN), which show excess radio emission at 3GHz VLA-COSMOS exceeding what is coming from star-formation alone; this sample excludes FRs. The largest angular projected sizes of FR objects were measured by a machine-learning algorithm and also by hand, following a parametric approach to the FR classification. Eddington ratios were calculated using scaling relations from the X-rays, and we included the jet power by using radio luminosity as a probe. Furthermore, we investigated their host properties (star-formation ratio, stellar mass, morphology), and we explore their incidence within X-ray galaxy groups in COSMOS, and in the density fields and cosmic-web probes in COSMOS. Our sample is composed of 59 FRIIs, 32 FRI/FRIIs, 39 FRIs, and 1818 COM AGN at 0.03<=z<=6. On average, FR objects have similar radio luminosities (L_3GHz_~10^23^W/Hz/sr), spanning a range of 10^21-26^W/Hz/sr, and they lie at a median redshift of z~1. The median linear projected size of FRIIs is 106.6^238.2^_36.9_kpc, larger than that of FRI/FRIIs and FRIs by a factor of 2-3. The COM AGN have sizes smaller than 30kpc, with a median value of 1.7^4.7^_1.5_kpc. The median Eddington ratio of FRIIs is 0.006^0.007^_0.005_, a factor of 2.5 less than in FRIs and a factor of 2 higher than in FRI/FRII. When the jet power is included, the median Eddington ratios of FRII and FRI/FRII increase by a factor of 12 and 15, respectively. FRs reside in their majority in massive quenched hosts (M*>10^10.5^M_{sun}_), with older episodes of star-formation linked to lower X-ray galaxy group temperatures, suggesting radio-mode AGN quenching. Regardless of their radio structure, FRs and COM AGN are found in all types and density environments (group or cluster, filaments, field). By relating the radio structure to radio luminosity, size, Eddington ratio, and large-scale environment, we find a broad distribution and overlap of FR and COM AGN populations. We discuss the need for a different classification scheme, that expands the classic FR classification by taking into consideration the physical properties of the objects rather than their projected radio structure which is frequency-, sensitivity- and resolution-dependent. This point is crucial in the advent of current and future all-sky radio surveys.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A68
- Title:
- Full-Stokes polarimetry of 5 radio sources
- Short Name:
- J/A+A/609/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis pipeline that enables the recovery of reliable information for all four Stokes parameters with high accuracy. Its novelty relies on the effective treatment of the instrumental effects even before the computation of the Stokes parameters, contrary to conventionally used methods such as that based on the Mueller matrix. For instance, instrumental linear polarization is corrected across the whole telescope beam and significant Stokes Q and U can be recovered even when the recorded signals are severely corrupted by instrumental effects. The accuracy we reach in terms of polarization degree is of the order of 0.1-0.2%. The polarization angles are determined with an accuracy of almost 1{def}. The presented methodology was applied to recover the linear and circular polarization of around 150 active galactic nuclei, which were monitored between July 2010 and April 2016 with the Effelsberg 100-m telescope at 4.85GHz and 8.35GHz with a median cadence of 1.2 months. The polarized emission of the Moon was used to calibrate the polarization angle measurements. Our analysis showed a small system-induced rotation of about 1{deg} at both observing frequencies. Over the examined period, five sources have significant and stable linear polarization; three sources remain constantly linearly unpolarized; and a total of 11 sources have stable circular polarization degree m_c_, four of them with non-zero m_c_. We also identify eight sources that maintain a stable polarization angle. All this is provided to the community for future polarization observations reference. We finally show that our analysis method is conceptually different from those traditionally used and performs better than the Mueller matrix method. Although it has been developed for a system equipped with circularly polarized feeds, it can easily be generalized to systems with linearly polarized feeds as well.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1194
- Title:
- FUV/HI relations in nearby galaxies
- Short Name:
- J/AJ/140/1194
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine data from The HI Nearby Galaxy Survey and the GALEX Nearby Galaxy Survey to study the relationship between atomic hydrogen (HI) and far-ultraviolet (FUV) emission outside the optical radius (r25) in 17 spiral and 5 dwarf galaxies. In this regime, HI is likely to represent most of the interstellar medium (ISM) and FUV emission to trace recent star formation with little bias due to extinction, so that the two quantities closely trace the underlying relationship between gas and star formation rate (SFR).
- ID:
- ivo://CDS.VizieR/J/A+A/573/A93
- Title:
- Galaxies optical emission-line diagnostic diagrams
- Short Name:
- J/A+A/573/A93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The discovery of the M-{sigma} relation, the local galaxy bimodality, and the link between black-hole and host-galaxy properties have raised the question of whether active galactic nuclei (AGN) play a role in galaxy evolution. AGN feedback is one of the biggest observational challenges of modern extragalactic astrophysics. Several theoretical models implement AGN feedback to explain the observed galaxy luminosity function and, possibly, the color and morphological transformation of spiral galaxies into passive ellipticals. For understanding the importance of AGN feedback, a study of the AGN populations in the radio-optical domain is crucial. A mass sequence linking star-forming galaxies and AGN has already been noted in previous works, and it is now investigated as a possible evolutionary sequence. We observed a sample of 119 intermediate-redshift (0.04<=z<0.4) SDSS-FIRST radio emitters with the Effelsberg 100-m telescope at 4.85 and 10.45GHz and obtained spectral indices. The sample includes star-forming galaxies, composite galaxies (with mixed contribution to line emission from star formation and AGN activity), Seyferts, and low ionization narrow emission region (LINER) galaxies. With these sources we search for possible evidence of spectral evolution and a link between optical and radio emission in intermediate-redshift galaxies. We find indications of spectral index flattening in high-metallicity star-forming galaxies, composite galaxies, and Seyferts. This "flattening sequence" along the [NII]-based emission-line diagnostic diagram is consistent with the hardening of galaxy ionizing field, thanks to nuclear activity. After combining our data with FIRST measurements at 1.4GHz, we find that the three-point radio spectra of Seyferts and LINERs show substantial differences, which are attributable to small radio core components and larger (arcsecond sized) jet/lobe components, respectively. A visual inspection of FIRST images seems to confirm this hypothesis. Galaxies along this sequence are hypothesized to be transitioning from the active star-forming galaxies (blue cloud) to the passive elliptical galaxies (red sequence). This supports the suggestion that AGN both play a role in shutting down star formation and allow the transition from one galaxy class to the other.
