Iron Emission Research Articles

Spectral and timing properties of the accreting millisecond X-ray pulsar IGR J17498−2921 during its 2023 outburst

We present a comprehensive study of the spectral properties of the accreting millisecond X-ray pulsar IGR J17498−2921 during its 2023 outburst. Similar to other accreting millisecond X-ray pulsars, the broadband spectral emission observed quasi-simultaneously by NICER and NuSTAR is well described by an absorbed Comptonized emission with an electron temperature of ∼17 keV plus a disk reflection component. The broadening of the disk reflection spectral features, such as a prominent iron emission line at 6.4–6.7 keV, is consistent with the relativistic motion of matter in a disk truncated at ∼21 Rg from the source, near the Keplerian corotation radius. From the high-cadence monitoring data obtained with NICER, we observed that the evolution of the photon index and the temperature of seed photons tracks variations in the X-ray flux. This is particularly evident close to a sudden ∼–0.25 cycle jump in the pulse phase, which occurs immediately following an X-ray flux flare and a drop in the pulse amplitude below the 3σ detection threshold. We also report on the non-detection of optical pulsations with TNG/SiFAP2 from the highly absorbed optical counterpart.

Next-generation Accretion Disk Reflection Model: High-density Plasma Effects

Luminous accretion disks around black holes are expected to have densities of ∼1015−1022 cm−3, which are high enough that plasma physics effects become important. Many of these effects have been traditionally neglected in the calculation of atomic parameters, and therefore in photoionization models and ultimately also in X-ray reflection models. In this paper, we describe updates to the atomic rates used by the xstar code, which is in turn part of the xillver disk reflection model. We discuss the effect of adding necessary high-density corrections into the xillver code. Specifically, we find that the change of recombination rates plays an important role, dominating the differences between model versions. With synthetic spectra, we show that, even in a highly ionized state, high-density slabs can produce strong iron (∼6.5–9 keV) and oxygen (∼0.6–0.8 keV) resonance features. The significant iron emission could address the problem of the supersolar iron abundances found in some sources.

ESPRESSO reveals blueshifted neutral iron emission lines on the dayside of WASP-76 b

Context. Ultra hot Jupiters (gas giants with Teq > 2000 K) are intriguing exoplanets due to the extreme physics and chemistry present in their atmospheres. Their torrid daysides can be characterised using ground-based high-resolution emission spectroscopy. Aims. We search for signatures of neutral and singly ionised iron (Fe I and Fe II, respectively) in the dayside of the ultra hot Jupiter WASP-76 b, as these species were detected via transmission spectroscopy in this exoplanet. Furthermore, we aim to confirm the existence of a thermal inversion layer, which has been reported in previous studies, and attempt to constrain its properties. Methods. We observed WASP-76 b on four epochs with ESPRESSO at the VLT, at orbital phases shortly before and after the secondary transit, when the dayside is in view. We present the first analysis of high-resolution optical emission spectra for this exoplanet. We compare the data to synthetic templates created with petitRADTRANS, using cross-correlation function techniques. Results. We detect a blueshifted (−4.7 ± 0.3 km s−1) Fe I emission signature on the dayside of WASP-76 b at 6.0σ. The signal is detected independently both before and after the eclipse, and it is blueshifted in both cases. The presence of iron emission features confirms the existence of a thermal inversion layer. Fe II was not detected, possibly because this species is located in the upper layers of the atmosphere, which are more optically thin. Thus the Fe II signature on the dayside of WASP-76 b is too weak to be detected with emission spectroscopy. Conclusions. We propose that the blueshifted Fe I signature is created by material rising from the hot spot to the upper layers of the atmosphere, and discuss possible scenarios related to the position of the hotspot. This work unveils some of the dynamic processes ongoing on the dayside of the ultra hot Jupiter WASP-76 b through the analysis of the Fe I signature from its atmosphere, and complements previous knowledge obtained from transmission studies. It also highlights the ability of ESPRESSO to probe the dayside of this class of exoplanets.

Constraining Present‐Day Anthropogenic Total Iron Emissions Using Model and Observations

AbstractIron emissions from human activities, such as oil combustion and smelting, affect the Earth's climate and marine ecosystems. These emissions are difficult to quantify accurately due to a lack of observations, particularly in remote ocean regions. In this study, we used long‐term, near‐source observations in areas with a dominance of anthropogenic iron emissions in various parts of the world to better estimate the total amount of anthropogenic iron emissions. We also used a statistical source apportionment method to identify the anthropogenic components and their sub‐sources from bulk aerosol observations in the United States. We find that the estimates of anthropogenic iron emissions are within a factor of 3 in most regions compared to previous inventory estimates. Under‐ or overestimation varied by region and depended on the number of sites, interannual variability, and the statistical filter choice. Smelting‐related iron emissions are overestimated by a factor of 1.5 in East Asia compared to previous estimates. More long‐term iron observations and the consideration of the influence of dust and wildfires could help reduce the uncertainty in anthropogenic iron emissions estimates.

Accretion Properties of Soft X-Ray Transient XTE J1856+053 during Its 2023 Outburst

Soft X-ray transients (SXTs) are a subclass of the low-mass X-ray binaries that occasionally show a sudden rise in their soft X-ray luminosity; otherwise, they remain in an extremely faint state. We investigate the accretion properties of the SXT XTE J1856+053 during its 2023 outburst obtained by NICER and NuSTAR data in July. We present detailed results on the timing and spectral analysis of the X-ray emission during the outburst. The power spectral density shows no quasi-periodic oscillation features. The source’s spectrum on July 19 can be well fitted with a multicolor blackbody component, a power-law component, and a reflection component with a broadened iron emission line. NICER spectra can be well fitted by considering a combination of a blackbody and a power law. The source exhibits a transition within just 5 days from a soft state to an intermediate state during the outburst decline phase. The inner accretion disk has a low inclination angle (∼18°). The spectral analysis also suggests a high-spin (a > 0.9) black hole as the central accreting object.

Mathematical-model Analysis of the Potential Exposure to Lead, Zinc and Iron Emissions from Consumption of Premium Motor Spirit in Nigeria

Environmental pollution has been on the increase due to emission from vehicles using fossil fuels. This research investigated the exposure of air, soil and water bodies to trace metal emissions: Pb, Zn and Fe, as a result of the consumption of premium motor spirit (PMS) in Nigeria. The exposure of air, soil, and water bodies to these emissions also lead to exposure of humans, food and animals to the emissions. This was done to estimate the emission rates, emission rate per capita, and emission rates per land areas (or land distribution). The results showed that: the annual emission rates ranged between 4.66 kg/y for Pb in 2012 in Jigawa State and 5.050∙103 kg/y for Fe in 2015 in Lagos State; the emission rates per capita ranged between 0.52∙10−6 kg/(y∙person) for Pb in 2012 in Kwara State and 2.33∙10−3 kg/(y∙person) and this was recorded in Lagos State in the year 2015; while the rate per land area ranged between 0.093∙10−3 kg/(y∙km2) for Pb in 2012 in Taraba State and 1.38 kg/(y∙km2) for Fe in 2015 in Lagos State. Results showed that residents of Lagos are at the highest risk of trace metal poisoning because they had the highest emission rates per capita, followed by Abuja, Osun, and Ogun. The states at the lowest risk are Yobe and Taraba, with Yobe as the lowest. It is recommended that regulations concerning the trace metal contents of fuels imported and distributed in Nigeria should be created and implemented to curb these risks.

Multi-epoch X-ray spectral analysis of Centaurus A: Revealing new constraints on iron emission line origins

Abstract We conduct X-ray reverberation mapping and spectral analysis of the radio galaxy Centaurus A to uncover its central structure. We compare the light curve of the hard X-ray continuum from Swift Burst Alert Telescope observations with that of the Fe K$\alpha$ fluorescence line, derived from the Nuclear Spectroscopic Telescope Array (NuSTAR), Suzaku, XMM–Newton, and Swift X-ray Telescope observations. The analysis of the light curves suggests that a top-hat transfer function, commonly employed in reverberation mapping studies, is improbable. Instead, the relation between these light curves can be described by a transfer function featuring two components: one with a lag of $0.19_{- 0.02}^{+ 0.10} \,\, \mathrm{pc}/c$, and another originating at $r \\gt 1.7 \,\, \mathrm{pc}$ that produces an almost constant light curve. Further, we analyze the four-epoch NuSTAR and six-epoch Suzaku spectra, considering the time lag of the reflection component relative to the primary continuum. This spectral analysis supports that the reflecting material is Compton-thin, with $N_{\mathrm{H}} = 3.14_{-0.74}^{+0.44} \times 10^{23} \,\, \mathrm{cm}^{-2}$. These results suggest that the Fe K$\alpha$ emission may originate from Compton-thin circumnuclear material located at a sub-parsec scale, likely a dust torus, and materials at a greater distance.

Observational Evidence for Hot Wind Impact on Parsec Scales in Low-luminosity Active Galactic Nuclei

Supermassive black holes in galaxies spend the majority of their lifetime in the low-luminosity regime, powered by hot accretion flow. Strong winds launched from the hot accretion flow have the potential to play an important role in active galactic nuclei (AGN) feedback. Direct observational evidence for these hot winds with temperatures around 10 keV, has been obtained through the detection of highly ionized iron emission lines with Doppler shifts in two prototypical low-luminosity AGNs, namely M81* and NGC 7213. In this work, we further identify blueshifted H-like O/Ne emission lines in the soft X-ray spectra of these two sources. These lines are interpreted to be associated with additional outflowing components possessing velocity around several 103 km s−1 and lower temperature (∼0.2–0.4 keV). Blueshifted velocity and the X-ray intensity of these additional outflowing components are hard to explain by previously detected hot wind freely propagating to larger radii. Through detailed numerical simulations, we find the newly detected blueshifted emission lines would come from circumnuclear gas shock-heated by the hot wind instead. Hot wind can provide a larger ram pressure force on the clumpy circumnuclear gas than the gravitational force from the central black hole, effectively impeding the black hole accretion of gas. Our results provide strong evidence for the energy and momentum feedback by the hot AGN wind.

Temporal and spectral variations of the X-ray pulsar Cen X-3 observed by NuSTAR

We report a time-resolved analysis of the accreting X-ray pulsar Cen X-3 using observations carried out by NuSTAR, which cover approximately two binary orbits in different intensity states. The pulse profile is relatively stable over the orbital phase and shows energy dependence. It has an obvious double-peaked shape in the energy band below 15 keV –with the second pulse peak decreasing as energy increases– and is gradually dominated by a single peak in higher energy bands. We find that the pulse profile in the energy band of 3–5 keV at high-intensity states shows a subtle triple-peaked shape, with the main peak divided into two subpeaks. We also find a positive correlation between the pulse fraction and both energy and flux. Our spectral analysis reveals that the spectra can be well described by the continuum of Fermi-Dirac cutoff and NPEX models, and the cyclotron line is detected with the centroid energies varying from 26 keV to 29 keV, along with the iron emission line around 6.4 keV. We investigated the dependence between the cyclotron resonant scattering feature (CRSF) centroid energy and luminosity and discuss the theoretical critical luminosity. Although the variation of Ecyc − LX is not distinct, there is a possibility that the critical luminosity lies within the range of ∼(0.5 − 4)×1037 erg s−1 in the band of 4–78 keV. The photon index shows a strong positive correlation with luminosity. Our orbital-phase analysis reveals that the spectral parameters show orbital variability, and the highly variable photoelectric absorption may indicate the existence of clumpy stellar winds.

The extreme coronal line emitter AT 2022fpx: varying optical polarization properties and late-time X-ray flare

ABSTRACT Supermassive black holes disrupt passing stars, producing outbursts called tidal disruption events (TDEs). TDEs have recently gained attention due to their unique dynamics and emission processes, which are still not fully understood. Especially, the so-called optical TDEs are of interest as they often exhibit delayed or obscured X-ray emission from the accretion disc, making the origin of the prompt emission unclear. In this paper, we present multiband optical polarization observations and optical spectrometry of a recent TDE candidate AT 2022fpx, alongside monitoring observations in optical, ultraviolet, and X-rays. The optical spectra of AT 2022fpx show Bowen fluorescence as well as highly ionized iron emission lines, which are characteristic of extreme coronal line emitters. Additionally, the source exhibits variable but low-polarized continuum emission at the outburst peak, with a clear rotation of the polarization angle. X-ray emission observed approximately 250 d after the outburst peak in the decay appear flare-like but is consistent with constant temperature blackbody emission. The overall outburst decay is slower than for typical TDEs, and resembles more the ones seen from Bowen fluorescence flares. These observations suggest that AT 2022fpx could be a key source in linking different long-lived TDE scenarios. Its unique characteristics, such as extreme coronal line emission, variable polarization, and delayed X-ray flare, can be attributed to the outer shock scenario or a clumpy torus surrounding the supermassive black hole. Further studies, especially in the context of multiwavelength observations, are crucial to fully understand the dynamics and emission mechanisms of these intriguing astrophysical events.

Suzaku observation of an iron K-shell line in the spiral galaxy NGC 6946

Abstract An emission line at ∼6.7 keV is attributable to an He-like iron K-shell transition, which indicates existence of a thin thermal plasma with a temperature of several keV. Using Suzaku archival data, we searched for the iron K-line from the spiral galaxy NGC 6946, and found it at 6.68 ± 0.07 keV at the 3.1σ level in the central $r\le {2.^{\prime }5}$ region. The iron line luminosity from the central region was estimated to be (2.3 ± 1.2) × 1037 erg s−1 at a distance of 5.5 Mpc. The origin of the iron emission line is discussed.

Water-saving irrigation mitigates methane emissions from paddy fields: The role of iron

Iron (Fe) and methane (CH4) emissions play crucial roles in the carbon cycling of paddy field ecosystems. However, little is known about the effect and mechanism of Fe transformation on the CH4 emission from paddy fields, especially with different water management methods. In this study, the dynamic changes in CH4 emissions and different forms of Fe and soil organic carbon content were observed in paddy fields under flooded irrigation (FI) and water-saving irrigation (WSI) (including intermittent irrigation (II) and controlled irrigation (CI)). In addition, the structural equation model was used to clarify the response relationship between CH4 emissions and Fe ions in paddy fields. The results indicate that the cumulative CH4 emissions under WSI were reduced by 29.03–61.29%. The reasons are as follows (i) WSI increased the oxidation ability of Fe to CH4 by increasing the soil ferric iron (Fe3+) content in paddy fields; (ii) WSI could reduce the substrate utilization by methanogens by transforming the Fe oxide forms to increase the binding capacity of Fe to dissolved organic carbon, which reduced the CH4 production. In addition, compared with II, CI had higher soil Fe3+ content, Fe-bound organic carbon content, and lower acetate content, so it had lower CH4 production capacity. In summary, WSI promotes the direct oxidation of CH4 by Fe3+ in paddy fields and indirectly reduces CH4 production by facilitating the combination of Fe oxides with the substrates. These findings deepen our understanding of the mechanisms of CH4 emission in paddy fields and provide new insights for research on carbon sequestration and emission reduction in paddy field ecosystems.

Ground-based and JWST Observations of SN 2022pul. II. Evidence from Nebular Spectroscopy for a Violent Merger in a Peculiar Type Ia Supernova

We present an analysis of ground-based and JWST observations of SN 2022pul, a peculiar “03fg-like” (or “super-Chandrasekhar”) Type Ia supernova (SN Ia), in the nebular phase at 338 days postexplosion. Our combined spectrum continuously covers 0.4–14 μm and includes the first mid-infrared spectrum of a 03fg-like SN Ia. Compared to normal SN Ia 2021aefx, SN 2022pul exhibits a lower mean ionization state, asymmetric emission-line profiles, stronger emission from the intermediate-mass elements (IMEs) argon and calcium, weaker emission from iron-group elements (IGEs), and the first unambiguous detection of neon in a SN Ia. A strong, broad, centrally peaked [Ne ii] line at 12.81 μm was previously predicted as a hallmark of “violent merger” SN Ia models, where dynamical interaction between two sub-M Ch white dwarfs (WDs) causes disruption of the lower-mass WD and detonation of the other. The violent merger scenario was already a leading hypothesis for 03fg-like SNe Ia; in SN 2022pul it can explain the large-scale ejecta asymmetries seen between the IMEs and IGEs and the central location of narrow oxygen and broad neon. We modify extant models to add clumping of the ejecta to reproduce the optical iron emission better, and add mass in the innermost region (<2000 km s−1) to account for the observed narrow [O i] λ λ6300, 6364 emission. A violent WD–WD merger explains many of the observations of SN 2022pul, and our results favor this model interpretation for the subclass of 03fg-like SNe Ia.

Evaluating the potential of iron-based interventions in methane reduction and climate mitigation

Keeping global surface temperatures below international climate targets will require substantial measures to control atmospheric CO2 and CH4 concentrations. Recent studies have focused on interventions to decrease CH4 through enhanced atmospheric oxidation. Here for the first time using a set of models, we evaluate the effect of adding iron aerosols to the atmosphere to enhance molecular chlorine production, and thus enhance the atmospheric oxidation of methane and reduce its concentration. Using different iron emission sensitivity scenarios, we examine the potential role and impact of enhanced iron emissions on direct interactions with solar radiation, and on the chemical and radiative response of methane. Our results show that the impact of iron emissions on CH4 depends sensitively on the location of the iron emissions. In all emission regions there is a threshold in the amount of iron that must be added to remove methane. Below this threshold CH4 increases. Even once that threshold is reached, the iron-aerosol driven chlorine-enhanced impacts on climate are complex. The radiative forcing of both methane and ozone are decreased in the most efficient regions but the direct effect due to the addition of absorbing iron aerosols tends to warm the planet. Adding any anthropogenic aerosol may also cool the planet due to aerosol cloud interactions, although these are very uncertain, and here we focus on the unique properties of adding iron aerosols. If the added emissions have a similar distribution as current shipping emissions, our study shows that the amount of iron aerosols that must be added before methane decreases is 2.5 times the current shipping emissions of iron aerosols, or 6 Tg Fe yr−1 in the most ideal case examined here. Our study suggests that the photoactive fraction of iron aerosols is a key variable controlling the impact of iron additions and poorly understood. More studies of the sensitivity of when, where and how iron aerosols are added should be conducted. Before seriously considering this method, additional impacts on the atmospheric chemistry, climate, environmental impacts and air pollution should be carefully assessed in future studies since they are likely to be important.

The impact of the EU's Carbon Border Adjustment Mechanism on the global iron and steel trade and emission reduction.

The European Council completed the legislative procedure to establish the Carbon Border Adjustment Mechanism (CBAM) on April 25, 2023, which will be launched in 2027. The iron and steel sector is the main target of the forthcoming CBAM due to the industry's energy-intensive consumption with high carbon dioxide (CO2) emissions. However, minimal existing research has been conducted in this regard. This study employs GTAP-e 11.0 and TOPSIS models to estimate the effects of CBAM implementation on the major nations around the world from 2027 to 2030, examining countries' GDP, social welfare, iron and steel production, trade balance, and CO2 emissions to the global environment. This study concludes: (1) The GDP and social welfare of important iron and steel trade partners throughout the world will be significantly impacted by the application of CBAM. Most nations, including those in the EU, will experience negative GDP effects, with China undergoing the most pronounced social welfare declines followed by India. In contrast, the EU27 will benefit the most in terms of social welfare, followed by the US, Japan, and Russia. (2) Iron and steel production will decrease in all countries outside the EU, but it will have a positive impact on the trade balance of most countries. (3) The CO2 emissions of all countries except for the EU and Japan will decrease, with a positive impact on preventing carbon leakage in the international iron and steel trade. (4) Comprehensive analysis demonstrates that the EU will benefit the most, and China will suffer the most from CBAM application. Based on the above conclusions, this study proposes corresponding policy recommendations.

The 2022 Outburst of IGR J17091–3624: Connecting the Exotic GRS 1915+105 to Standard Black Hole X-Ray Binaries

While the standard X-ray variability of black hole X-ray binaries (BHXBs) is stochastic and noisy, there are two known BHXBs that exhibit exotic “heartbeat”-like variability in their lightcurves: GRS 1915+105 and IGR J17091–3624. In 2022, IGR J17091–3624 went into outburst for the first time in the NICER/NuSTAR era. These exquisite data allow us to simultaneously track the exotic variability and the corresponding spectral features with unprecedented detail. We find that as in typical BHXBs, the outburst began in the hard state, then continued in the intermediate state, but then transitioned to an exotic soft state, where we identify two types of heartbeat-like variability (Class V and a new Class X). The flux energy spectra show a broad iron emission line due to relativistic reflection when there is no exotic variability, and absorption features from highly ionized iron when the source exhibits exotic variability. Whether absorption lines from highly ionized iron are detected in IGR J17091–3624 is not determined by the spectral state alone, but rather is determined by the presence of exotic variability; in a soft spectral state, absorption lines are only detected along with exotic variability. Our finding indicates that IGR J17091–3624 can be seen as a bridge between the most peculiar BHXB GRS 1915+105 and “normal” BHXBs, because it alternates between the conventional and exotic behaviors of BHXBs. We discuss the physical nature of the absorbing material and exotic variability in light of this new legacy data set.

Probing the accretion geometry of the atoll source 4U 1702−429 in different spectral states with NICER, NuSTAR, and AstroSat

ABSTRACT We perform a comprehensive spectral study of a carefully selected sample (total exposure ∼50.5 ks) of NICER observations of the atoll neutron star low-mass X-ray binary 4U 1702−429. Our sample encompasses nearly all classical spectral states found within the NICER data set. We require two thermal emission components, originating from the accretion disc and the boundary layer, to describe the soft state spectra in the energy band 0.3–10.0 keV. In contrast, in our model, only the disc component directly contributes to the intermediate/hard state. Additionally, we use a thermally Comptonized component (or a power law with pegged normalization) to represent the hard coronal emission in the soft and intermediate/hard state spectra. The boundary layer emerges as the principal source providing soft seed photons for Comptonization across all spectral states. In contrast to a previously held assertion regarding this source, our analyses reveal a decrease in the inner disc temperature coupled with the retreat of the inner disc from the neutron star surface as the source evolves from the soft to the intermediate/hard state. The reflection features are either absent or weak (∼3σ–4σ) in all these observations. Further investigation using broad-band NuSTAR (3.0–50.0 keV) and AstroSat spectra (1.3–25.0 keV) shows a slightly stronger iron emission line (∼5.8σ) in the NuSTAR spectra. However, this feature is not significantly detected in the AstroSat observation. The AstroSat data suggest a highly ionized disc, explaining the absence of reflection features. In the case of NuSTAR, a truncated disc is likely responsible for the weak reflection features.

From Sub-Solar to Super-Solar Chemical Abundances along the Quasar Main Sequence

The 4D (four-dimensional) eigenvector 1 (E1) sequence has proven to be a highly effective tool for organizing observational and physical properties of type-1 active galactic nuclei (AGNs). In this paper, we present multiple measurements of metallicity for the broad line region gas, from new and previously-published data. We demonstrate a consistent trend along the optical plane of the E1 (also known as the quasar main sequence), defined by the line width of Balmer hydrogen Hβ profile and by a parameter measuring the prominence of singly-ionized iron emission. The trend involves an increase from sub-solar metallicity in correspondence with extreme Population B (weak Feii emission, large Hβ FWHM (full width at half maximum)) to metallicity several tens the solar value in correspondence with extreme Population A (strongest Feii optical emission, narrower Hβ profiles). The data establish the metallicity as a correlate of the 4DE1/main sequence. If the considerably high metallicity (Z≳10Z⊙, solar metallicity) gas is expelled from the sphere of influence of the central black hole, as indicated by the widespread evidence of nuclear outflows and disk wind in the case of sources radiating at a high Eddington ratio, then it is possible that the outflows from quasars played a role in chemically enriching the host galaxy.

Determining the nutritional values of new corn varieties on pigs and broilers.

The objective of this study was to evaluate the nutritional values of three new corn varieties (high-iron corn, cadmium-resistant corn, low-phytate phosphorus corn) cultivated with molecular marker-assisted selection breeding technique fed to growing pigs and broilers. Exp. 1 was conducted to compare the nutritional values of high-iron corn, high-chromium corn, low-phytate phosphorus corn and conventional corn fed to growing pigs based on a 15 × 2 Youden square design. Exp.2 was conducted to compare the nutritional values of high-iron corn, low-phytate phosphorus corn and conventional corn fed to broilers based on a completely randomized design. Parameters including nutrient digestibility, available energy and amino acids, and mineral deposition were measured. The results shows that the iron content in the high-iron corn and the cadmium content in the cadmium-resistant corn were 29.608 mg/kg and 0.0057 mg/kg, respectively, both were greater than those in the other three kinds of corns. When fed to growing pigs, the neutral detergent fiber digestibility of the high-iron corn group was lower than that of the conventional corn group (p < 0.05), and the acid detergent fiber digestibility of the high-iron group and the low-phytate phosphorus corn group was lower than that of the conventional corn group (p < 0.01). In addition, the digestible energy value of the high-iron corn in growing pigs was lower than that of the conventional corn (p < 0.05). When fed to broilers, it was observed that the tibia length of the low-phytate phosphorus corn group and the high-iron corn group was lower than that of the conventional corn group (p < 0.05). Moreover, the iron emission in feces of broilers fed the low-phytate phosphorus corn was lower than those fed the conventional corn and the high-iron corn (p < 0.05). In conclusion, modern breeding techniques could provide new plant ingredients which have potential benefits to pig and broiler production, but the comprehensive effects may be better when applied to growing pigs considering growth performance and environment effects. The breeding techniques related to the current study rarely changed the available energy values of the corn in growing pigs and broilers.

Joint Analysis of the Iron Emission in the Optical and Near-Infrared Spectrum of I Zw 1

Constraining the physical conditions of the ionized media in the vicinity of an active supermassive black hole (SMBH) is crucial to understanding how these complex systems operate. Metal emission lines such as iron (Fe) are useful probes to trace the gaseous media’s abundance, activity, and evolution in these accreting systems. Among these, the Feii emission has been the focus of many prior studies to investigate the energetics, kinematics, and composition of the broad-emission line region (BELR) from where these emission lines are produced. In this paper, we present the first simultaneous Feii modeling in the optical and near-infrared (NIR) regions. We use cloudy photoionization code to simulate both spectral regions in the wavelength interval 4000–12,000 Å. We compare our model predictions with the observed line flux ratios for I Zw (Zwicky) 1—a prototypical strong Feii-emitting active galactic nuclei (AGNs). This allows setting constraints on the BLR cloud density and metal content that is optimal for the production of the Feii emission, which can be extended to I Zw 1-like sources by examining a broad parameter space. We demonstrate the salient and distinct features of the Feii pseudo-continuum in the optical and NIR, giving special attention to the effect of micro-turbulence on the intensity of the Feii emission.