160 research outputs found
The host galaxies of FeLoBAL quasars at z ∼ 0.9 are not dominated by recent major mergers
Theoretical models have suggested an evolutionary model for quasars, in which most of luminous quasars are triggered by major mergers. It is also postulated that reddening as well as powerful outflows indicate an early phase of activity, close to the merger event. We test this model on a sample of quasars with powerful low-ionization outflows seen in broad iron absorption lines (FeLoBAL). This sample of objects show strong reddening in the optical and fast (∼0.1c) high-column density outflows. We present HSTWFC3/IR F160W imaging of 10 FeLoBAL host galaxies at redshifts z ∼ 0.9 (λ rest ∼ 8500 Å). We compare the host galaxy morphologies and merger signatures of FeLoBALs to luminous blue non-BAL quasars from Villforth et al. (2017) of comparable luminosity, which show no excess of merger features compared to inactive control samples. If FeLoBAL quasars are indeed in a young evolutionary state, close in time to the initial merging event, they should have strong merger features. We find that the host galaxies of FeLoBAL quasars are of comparable luminosity to the host galaxies of optical quasars and show no enhanced merger rates. When looking only at quasars without strong point spread function residuals, an enhancement in disturbed and merger rates is seen. While FeLoBAL hosts show weak enhancements over a control of blue quasars, their host galaxies are not dominated by recent major mergers. </p
Comparison of Howland and General Impedance Converter (GIC) circuit based current sources for bio-impedance measurements
The current source is a key component in bio-impedance measurement systems. The accuracy of the current source can be measured in terms of its output impedance together with other parameters, with certain applications demanding extremely high output impedance. This paper presents an investigation and comparison of different current source designs based on the Enhanced Howland circuit combined with a General Impedance Converter (GIC) circuit using both ideal and non-ideal operational amplifiers. Under differing load conditions two different settings of the GIC are evaluated and the results are compared to show its performance settings. Whilst the study has shown that over a wide bandwidth (i.e. 100Hz-100MHz) the output impedance is limited, operation over a more limited range offers output impedance in the Giga-ohm range, which can be considered as being infinite
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MASCOT: an ESO-ARO legacy survey of molecular gas in nearby SDSS-MaNGA galaxies - I. First data release, and global and resolved relations between H<inf>2</inf>and stellar content
We present the first data release of the MaNGA-ARO Survey of CO Targets
(MASCOT), an ESO Public Spectroscopic Survey conducted at the Arizona Radio
Observatory (ARO). We measure the CO(1-0) line emission in a sample of 187
nearby galaxies selected from the Mapping Nearby Galaxies at Apache Point
Observatory (MaNGA) survey that has obtained integral field unit (IFU)
spectroscopy for a sample of ~ 10,000 galaxies at low redshift. The main goal
of MASCOT is to probe the molecular gas content of star-forming galaxies with
stellar masses > 10^9.5 M_solar and with associated MaNGA IFU observations and
well-constrained quantities like stellar masses, star formation rates and
metallicities. In this paper we present the first results of the MASCOT survey,
providing integrated CO(1-0) measurements that cover several effective radii of
the galaxy and present CO luminosities, CO kinematics, and estimated H2 gas
masses. We observe that the decline of galaxy star formation rate with respect
to the star formation main sequence (SFMS) increases with the decrease of
molecular gas and with a reduced star formation efficiency, in agreement with
results of other integrated studies. Relating the molecular gas mass fractions
with the slope of the stellar age gradients inferred from the MaNGA
observations, we find that galaxies with lower molecular gas mass fractions
tend to show older stellar populations close to the galactic center, while the
opposite is true for galaxies with higher molecular gas mass fractions,
providing tentative evidence for inside-out quenching
The host galaxies of FeLoBAL quasars at z ∼ 0.9 are not dominated by recent major mergers
Theoretical models have suggested an evolutionary model for quasars, in which
most of luminous quasars are triggered by major mergers. It is also postulated
that reddening as well as powerful outflows indicate an early phase of
activity, close to the merger event. We test this model on a sample of quasars
with powerful low ionization outflows seen in broad Iron absorption lines
(FeLoBAL). This sample of objects show strong reddening in the optical and fast
(0.1c) high column density outflows. We present HST WFC3/IR F160W imaging
of 10 FeLoBAL host galaxies at redshifts z0.9
(). We compare the host galaxy morphologies and
merger signatures of FeLoBALs to luminous blue non-BAL quasars from Villforth
et al. 2017 of comparable luminosity, which show no excess of merger features
compared to inactive control samples. If FeLoBAL quasars are indeed in a young
evolutionary state, close in time to the initial merging event, they should
have strong merger features. We find that the host galaxies of FeLoBAL quasars
are of comparable luminosity to the host galaxies of optical quasars and show
no enhanced merger rates. When looking only at quasars without strong PSF
residuals, an enhancement in disturbed and merger rates is seen. While FeLoBAL
hosts show weak enhancements over a control of blue quasars, their host
galaxies are not dominated by recent major mergers.Comment: accepted for publication in MNRA
VODKA-JWST: A 3.8 kpc dual quasar at cosmic noon in a powerful starburst galaxy with JWST/MIRI IFU
Dual quasars, two active supermassive black holes at galactic scales,
represent crucial objects for studying the impact of galaxy mergers and quasar
activity on the star formation rate (SFR) within their host galaxies,
particularly at cosmic noon when SFR peaks. We present JWST/MIRI mid-infrared
integral field spectroscopy of J074922.96+225511.7, a dual quasar with a
projected separation of 3.8 kilo-parsec at a redshift of 2.17. We detect
spatially extended [Fe II] 5.34m and polycyclic aromatic hydrocarbon
(PAH) 3.3m emissions from the star formation activity in its host galaxy.
We derive the SFR of 10 M yr using PAH
3.3m, which is five times higher than that derived from the cutoff
luminosity of the infrared luminosity function for galaxies at . While
the SFR of J0749+2255 agrees with that of star-forming galaxies of comparable
stellar mass at the same redshifts, its molecular gas content falls short of
expectations based on the molecular Kennicutt-Schmidt law. This discrepancy may
result from molecular gas depletion due to the longer elevated stage of star
formation, even after the molecular gas reservoir is depleted. We do not
observe any quasar-driven outflow that impacts PAH and [Fe II] in the host
galaxy based on the spatially resolved maps. From the expected flux in
PAH-based star formation, the [Fe II] line likely originates from the
star-forming regions in the host galaxy. Our study highlights the stardust
nature of J0749+2255, indicating a potential connection between the dual quasar
phase and intense star formation activities.Comment: 12 pages, 7 figures, 1 table, submitted to ApJ, comments are welcom
MASCOT: molecular gas depletion times and metallicity gradients – evidence for feedback in quenching active galaxies
We present results from the first public data release of the MaNGA-ARO Survey of CO Targets (MASCOT), focusing our study on galaxies whose star formation rates and stellar masses place them below the ridge of the star-forming main sequence. In optically selected type 2 AGN/low-ionization nuclear emission regions (LINERs)/Composites, we find an empirical relation between gas-phase metallicity gradients ∇Z and global molecular gas depletion times tdep=MH2/SFR with ‘more quenched’ systems showing flatter/positive gradients. Our results are based on the O3N2 metallicity diagnostic (applied to star-forming regions within a given galaxy), which was recently suggested to also be robust against emission by diffuse ionized gas (DIG) and LINERs. We conduct a systematic investigation into possible drivers of the observed ∇Z − tdep relation (ouflows, gas accretion, in situ star formation, mergers, and morphology). We find a strong relation between ∇Z or tdep and centralized outflow strength traced by the [O III] velocity broadening. We also find signatures of suppressed star formation in the outskirts in AGN-like galaxies with long depletion times and an enhancement of metals in the outer regions. We find no evidence of inflows impacting the metallicity gradients, and none of our results are found to be significantly affected by merger activity or morphology. We thus conclude that the observed ∇Z–tdep relation may stem from a combination of metal redistribution via weak feedback, and a connection to in situ star formation via a resolved mass-metallicity–SFR relation. © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.DW and CB are supported through the Emmy Noether Programme of the German Research Foundation. MA acknowledges support from FONDECYT grant 1211951, CONICYT + PCI + INSTITUTO MAX PLANCK DE ASTRONOMIA MPG190030, CONICYT+PCI + REDES 190194, and ANID BASAL project FB210003. WB acknowledges support from the ERC Advanced Grant 695671, ‘QUENCH’ and from the Science and Technology Facilities Council (STFC). Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High Performance Computing at the University of Utah.With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).Peer reviewe
Cross-calibration of CO- versus dust-based gas masses and assessment of the dynamical mass budget in Herschel-SDSS Stripe82 galaxies
We present a cross-calibration of CO- and dust-based molecular gas masses at z ≤ 0.2. Our results are based on a survey with the IRAM 30-m telescope collecting CO(1–0) measurements of 78 massive (logM⋆/M⊙> 10) galaxies with known gas-phase metallicities and with IR photometric coverage from Wide-field Infrared Survey Explorer(WISE; 22 μm) and Herschel Spectral and Photometric Imaging Receiver (SPIRE; 250, 350, 500μm). We find a tight relation (∼0.17 dex scatter) between the gas masses inferred from CO and dust continuum emission, with a minor systematic offset of 0.05 dex. The two methods can be brought into agreement by applying a metallicity-dependent adjustment factor (∼0.13 dex scatter). We illustrate that the observed offset is consistent with a scenario in which dust traces not only molecular gas but also part of the HI reservoir, residing in the H2-dominated region of the galaxy. Observations of the CO(2–1) to CO(1–0) line ratio for two-thirds of the sample indicate a narrow range in excitation properties, with a median ratio of luminosities ⟨R21⟩ ∼ 0.64. Finally, we find dynamical mass constraints from spectral line profile fitting to agree well with the anticipated mass budget enclosed within an effective radius, once all mass components (stars, gas, and dark matter) are accounted for
An introductory view on archaeoastronomy
Archaeoastronomy is still a marginalised topic in academia and is described by the Sophia Centre, the only UK institution offering a broader MA containing this field, as ‘the study of the incorporation of celestial orientation, alignments or symbolism in human monuments and architecture’. By many it is associated with investigating prehistoric monuments such as Stonehenge and combining astronomy and archaeology. The following will show that archaeoastronomy is far more than just an interdisciplinary field linking archaeology and astronomy. It merges aspects of anthropology, ethno-astronomy and even educational research, and is possibly better described as cultural astronomy. In the past decades it has stepped away from its quite speculative beginnings that have led to its complete rejection by the archaeology community. Overcoming these challenges it embraced full heartedly solid scientific and statistical methodology and achieved more credibility. However, in recent times the humanistic influences of a cultural context motivate a new generation of archaeoastronomers that are modernising this subject; and humanists might find it better described as post-modern archaeoastronomy embracing the pluralism of today’s academic approach to landscape and ancient people
First results from the JWST Early Release Science Program Q3D: Benchmark Comparison of Optical and Mid-IR Tracers of a Dusty, Ionized Red Quasar Wind at z=0.435
The [OIII] 5007 A emission line is the most common tracer of warm, ionized
outflows in active galactic nuclei across cosmic time. JWST newly allows us to
use mid-infrared spectral features at both high spatial and spectral resolution
to probe these same winds. Here we present a comparison of ground-based,
seeing-limited [OIII] and space-based, diffraction-limited [SIV] 10.51 micron
maps of the powerful, kpc-scale outflow in the Type 1 red quasar SDSS
J110648.32+480712.3. The JWST data are from the Mid-InfraRed Instrument (MIRI).
There is a close match in resolution between the datasets (0."4--0."6), in
ionization potential of the O+2 and S+3 ions (35 eV), and in line sensitivity
(1e-17 to 2e-17 erg/s/cm2/arcsec2). The [OIII] and [SIV] line shapes match in
velocity and linewidth over much of the 20 kpc outflowing nebula, and [SIV] is
the brightest line in the rest-frame 3.5--19.5 micron range, demonstrating its
usefulness as a mid-IR probe of quasar outflows. [OIII] is nevertheless
intriniscally brighter and provides better contrast with the point-source
continuum, which is strong in the mid-IR. There is a strong anticorrelation of
[OIII]/[SIV] with average velocity, which is consistent with a scenario of
differential obscuration between the approaching (blueshifted) and receding
(redshifted) sides of the flow. The dust in the wind may also obscure the
central quasar, consistent with models that attribute red quasar extinction to
dusty winds.Comment: Submitted to ApJ
Belle II Executive Summary
Belle II is a Super Factory experiment, expected to record 50 ab
of collisions at the SuperKEKB accelerator over the next decade. The
large samples of mesons, charm hadrons, and tau leptons produced in the
clean experimental environment of collisions will provide the basis of
a broad and unique flavor-physics program. Belle II will pursue physics beyond
the Standard Model in many ways, for example: improving the precision of weak
interaction parameters, particularly Cabibbo-Kobayashi-Maskawa (CKM) matrix
elements and phases, and thus more rigorously test the CKM paradigm, measuring
lepton-flavor-violating parameters, and performing unique searches for
missing-mass dark matter events. Many key measurements will be made with
world-leading precision.Comment: 7 pages, to be submitted to the "Rare and Precision Measurements
Frontier" of the APS DPF Community Planning Exercise Snowmass 202
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