ABSTRACT We present Atacama Large Millimeter/submillimeter Array (ALMA) 870 m (345 GHz) data for 49 high-redshift (0.47 < z < 2.85), luminous ( ) radio-powerful active galactic nuclei (AGNs), ...obtained to constrain cool dust emission from starbursts concurrent with highly obscured radiative-mode black hole (BH) accretion in massive galaxies that possess a small radio jet. The sample was selected from the Wide-field Infrared Survey Explorer with extremely steep (red) mid-infrared colors and with compact radio emission from NVSS/FIRST. Twenty-six sources are detected at 870 m, and we find that the sample has large mid- to far-infrared luminosity ratios, consistent with a dominant and highly obscured quasar. The rest-frame 3 GHz radio powers are and all sources are radio-intermediate or radio-loud. BH mass estimates are 7.7 < log(MBH/M ) < 10.2. The rest-frame 1-5 m spectral energy distributions are very similar to the "Hot DOGs" (hot dust-obscured galaxies), and steeper (redder) than almost any other known extragalactic sources. ISM masses estimated for the ALMA-detected sources are 9.9 < log (MISM/M ) < 11.75 assuming a dust temperature of 30 K. The cool dust emission is consistent with star formation rates reaching several thousand M yr−1, depending on the assumed dust temperature, but we cannot rule out the alternative that the AGN powers all the emission in some cases. Our best constrained source has radiative transfer solutions with approximately equal contributions from an obscured AGN and a young (10-15 Myr) compact starburst.
We present new subarcsecond-resolution Karl G. Jansky Very Large Array (VLA) imaging at 10 GHz of 155 ultraluminous (Lbol ∼ 1011.7-1014.2 L ) and heavily obscured quasars with redshifts z ∼ 0.4-3. ...The sample was selected to have extremely red mid-infrared-optical color ratios based on data from the Wide-Field Infrared Survey Explorer (WISE) along with a detection of bright, unresolved radio emission from the NRAO VLA Sky Survey (NVSS) or Faint Images of the Radio Sky at Twenty cm Survey. Our high-resolution VLA observations have revealed that the majority of the sources in our sample (93 out of 155) are compact on angular scales <0 2 (≤1.7 kpc at z ∼ 2). The radio luminosities, linear extents, and lobe pressures of our sources are similar to young radio active galactic nuclei (e.g., gigahertz-peaked spectrum GPS and compact steep-spectrum CSS sources), but their space density is considerably lower. Application of a simple adiabatic lobe expansion model suggests relatively young dynamical ages (∼104-7 yr), relatively high ambient ISM densities (∼1-104 cm−3), and modest lobe expansion speeds (∼30-10,000 km s−1). Thus, we find our sources to be consistent with a population of newly triggered, young jets caught in a unique evolutionary stage in which they still reside within the dense gas reservoirs of their hosts. Based on their radio luminosity function and dynamical ages, we estimate that only ∼20% of classical large-scale FR I/II radio galaxies could have evolved directly from these objects. We speculate that the WISE-NVSS sources might first become GPS or CSS sources, of which some might ultimately evolve into larger radio galaxies.
A snapshot imaging survey with the VLBA at 5 GHz of 90 of the reddest, most obscured quasars with Ultra Luminous InfraRed Galaxy‐level infrared luminosities reveals a range of small jet structures ...and also unresolved sources. The three highest frequency peakers in the sample show little evidence for any substantial radio emission on scales larger than about 100 pc, based on our VLA data and on archival survey data. These may be very young single‐epoch radio quasar events. Sources with lower peak frequencies, in the gigahertz peaked source (GPSs), tend to have VLBA fluxes that under‐predict the larger scale emission, indicating multiple structures and possibly multiple epochs of jet activity. One GPS source shows evidence for strong absorption at low frequencies, consistent with this hypothesis. Multifrequency and multiresolution imaging of a subset of 12 of the sample with VLA, VLBA, and eMerlin are under analysis.
We present 2 cm and 3.6 cm wavelength very long baseline interferometry images of the compact radio continuum sources in the nearby ultra-luminous infrared galaxy Arp220. Based on their radio spectra ...and variability properties, we confirm these sources to be a mixture of supernovae (SNe) and supernova remnants (SNRs). Of the 17 detected sources we resolve 7 at both wavelengths. The SNe generally only have upper size limits. In contrast all the SNRs are resolved with diameters >=0.27 pc. This size limit is consistent with them having just entered their Sedov phase while embedded in an interstellar medium (ISM) of density 104 cm--3. These objects lie on the diameter-luminosity correlation for SNRs (and so also on the diameter-surface brightness relation) and extend these correlations to very small sources. The data are consistent with the relation LD --9/4. Revised equipartition arguments adjusted to a magnetic field to a relativistic particle energy density ratio of 1% combined with a reasonable synchrotron-emitting volume filling factor of 10% give estimated magnetic field strengths in the SNR shells of ~15-50 mG. The SNR shell magnetic fields are unlikely to come from compression of ambient ISM fields and must instead be internally generated. We set an upper limit of 7 mG for the ISM magnetic field. The estimated energy in relativistic particles, 2%-20% of the explosion kinetic energy, is consistent with estimates from models that fit the IR-radio correlation in compact starburst galaxies.
Energetic feedback by active galactic nuclei (AGNs) plays an important evolutionary role in the regulation of star formation on galactic scales. However, the effects of this feedback as a function of ...redshift and galaxy properties such as mass, environment, and cold gas content remain poorly understood. The broad frequency coverage (1 to 116 GHz), high sensitivity (up to ten times higher than the Karl G. Jansky Very Large Array), and superb angular resolution (maximum baselines of at least a few hundred kilometers) of the proposed next-generation Very Large Array (ngVLA) are uniquely poised to revolutionize our understanding of AGNs and their role in galaxy evolution. Here, we provide an overview of the science related to AGN feedback that will be possible in the ngVLA era and present new continuum ngVLA imaging simulations of resolved radio jets spanning a wide range of intrinsic extents. We also consider key computational challenges and discuss exciting opportunities for multiwavelength synergy with other next-generation instruments, such as the Square Kilometer Array and the James Webb Space Telescope. The unique combination of high-resolution, large collecting area, and wide frequency range will enable significant advancements in our understanding of the effects of jet-driven feedback on sub-galactic scales, particularly for sources with extents of a few parsec to a few kiloparsec, such as young and/or lower-power radio AGNs, AGNs hosted by low-mass galaxies, radio jets that are interacting strongly with the interstellar medium of the host galaxy, and AGNs at high redshift.
We present optical to far-infrared photometry of 31 reddened QSOs that show evidence for radiatively driven outflows originating from active galactic nuclei (AGNs) in their rest-frame UV spectra. We ...use these data to study the relationships between the AGN-driven outflows, and the AGN and starburst infrared luminosities. We find that FeLoBAL QSOs are invariably IR-luminous, with IR luminosities exceeding 10 super(12) L sub(middot in circle) in all cases. The AGN supplies 76% of the total IR emission, on average, but with a range from 20% to 100%. We find no evidence that the absolute luminosity of obscured star formation is affected by the AGN-driven outflows. Conversely, we find an anticorrelation between the strength of AGN-driven outflows, as measured from the range of outflow velocities over which absorption exceeds a minimal threshold, and the contribution from star formation to the total IR luminosity, with a much higher chance of seeing a starburst contribution in excess of 25% in systems with weak outflows than in systems with strong outflows. Moreover, we find no convincing evidence that this effect is driven by the IR luminosity of the AGN. We conclude that radiatively driven outflows from AGNs can have a dramatic, negative impact on luminous star formation in their host galaxies. We find that such outflows act to curtail star formation such that star formation contributes less than ~25% of the total IR luminosity. We also propose that the degree to which termination of star formation takes place is not deducible from the IR luminosity of the AGN.
We present the first results from the Australia Telescope Large Area Survey, which consists of deep radio observations of a 3.7 deg2 field surrounding the Chandra Deep Field-South, largely coincident ...with the infrared Spitzer Wide-Area Infrared Extragalactic (SWIRE) Survey. We also list cross-identifications to infrared and optical photometry data from SWIRE, and ground-based optical spectroscopy. A total of 784 radio components are identified, corresponding to 726 distinct radio sources, nearly all of which are identified with SWIRE sources. Of the radio sources with measured redshifts, most lie in the redshift range 0.5-2 and include both star-forming galaxies and active galactic nuclei. We identify a rare population of infrared-faint radio sources that are bright at radio wavelengths but are not seen in the available optical, infrared, or X-ray data. Such rare classes of sources can only be discovered in wide, deep surveys such as this.
We have used a very long baseline interferometry (VLBI) array at 18 cm wavelength to image the nucleus of the luminous IR galaxy Arp 220 at 61 pc linear resolution, with very high sensitivity. The ...resulting map has an rms of 5.5 kJy beam super(-1), and careful image analysis results in 49 confirmed point sources ranging in flux density from 1.2 mJy down to 660 kJy. Comparison with high-sensitivity data from 12 months earlier reveals at least four new sources. The favored interpretation of these sources is that they are radio supernovae, and if all new supernovae are detectable at this sensitivity, a resulting estimate of the supernova rate in the Arp 220 system is 4 c 2 per year. The implied star formation rate is sufficient to power the entire observed far-infrared luminosity of the galaxy. The two nuclei of Arp 220 exhibit striking similarities in their radio properties, although the western nucleus is more compact, and appears to be 63 times more luminous than the eastern nucleus. There are also some puzzling differences, and differential free-free absorption, synchrotron aging, and expansion losses may all be playing a role. Comparison with the nearby starburst galaxy M82 supports the hypothesis that the activity in Arp 220 is essentially a scaled-up version of that in M82.
We present observations and analysis of an unusual C ii emission line in the very luminous quasi-stellar object (QSO) SDSS J155426.16+193703.0 at z ∼ 4.6. The line is extremely broad (full width at ...half-maximum 735 km s−1) and seems to have a flat-topped or double-peaked line profile. A velocity map of the line shows a gradient across the source that indicates large-scale rotation of star-forming gas. Together, the velocity map and line profile suggest the presence of a massive rotating disc with a dynamical mass
$M_\mathrm{dyn}\gtrsim 5\times 10^{10} \,\mathrm{M}_{\odot }$
. Using the assumption of a rotating disc origin, we employ an empirical relation between galaxy disc circular velocity and bulge velocity dispersion (σ) to estimate that σ > 310 km s−1, subject to a correction for the unknown disc inclination. This result implies that this source is consistent with the local M–σ relation, or offset at most by an order of magnitude in black hole mass. In contrast, the assumption of a bulge origin for the C ii emission line would lead to a conclusion that the black hole is nearly two orders of magnitude more massive than predicted by the M–σ relation, similar to previous findings for other high-redshift QSOs. As disc rotation may be a common origin for C ii emission at high redshifts, these results stress that careful consideration of dynamical origins is required when using observations of this line to derive properties of high-redshift galaxies.
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