Context. Several issues regarding the nature of dust at high redshift remain unresolved: its composition, its production and growth mechanisms, and its effect on background sources. Aims. We provide ...a more accurate relation between dust depletion levels and dust-to-metals ratio (DTM), and to use the DTM to investigate the origin and evolution of dust in the high-redshift Universe via gamma-ray burst damped Lyman-alpha absorbers (GRB-DLAs). Methods. We use absorption-line measured metal column densities for a total of 19 GRB-DLAs, including five new GRB afterglow spectra from VLT/X-Shooter. We use the latest linear models to calculate the dust depletion strength factor in each DLA. Using these values we calculate total dust and metal column densities to determine a DTM. We explore the evolution of DTM with metallicity, and compare it to previous trends in DTM measured with different methods. Results. We find significant dust depletion in 16 of our 19 GRB-DLAs, yet 18 of the 19 have a DTM significantly lower than the Milky Way. We find that DTM is positively correlated with metallicity, which supports a dominant ISM grain-growth mode of dust formation. We find a substantial discrepancy between the dust content measured from depletion and that derived from the total V-band extinction, AV, measured by fitting the afterglow SED. We advise against using a measurement from one method to estimate that from the other until the discrepancy can be resolved.
A radical reexamination of the textual and archaeological evidence about Augustus and the Palatine Caesar Augustus (63 BC–AD 14), who is usually thought of as the first Roman emperor, lived on the ...Palatine Hill, the place from which the word "palace" originates. A startling reassessment of textual and archaeological evidence, The House of Augustus demonstrates that Augustus was never an emperor in any meaningful sense of the word, that he never had a palace, and that the so-called "Casa di Augusto" excavated on the Palatine was a lavish aristocratic house destroyed by the young Caesar in order to build the temple of Apollo. Exploring the Palatine from its first occupation to the present, T. P. Wiseman proposes a reexamination of the "Augustan Age, " including much of its literature.Wiseman shows how the political and ideological background of Augustus' rise to power offers a radically different interpretation of the ancient evidence about the Augustan Palatine. Taking a long historical perspective in order to better understand the topography, Wiseman considers the legendary stories of Rome's origins—in particular Romulus' foundation and inauguration of the city on the summit of the Palatine. He examines the new temple of Apollo and the piazza it overlooked, as well as the portico around it with its library used as a hall for Senate meetings, and he illustrates how Commander Caesar, who became Caesar Augustus, was the champion of the Roman people against an oppressive oligarchy corrupting the Republic.A decisive intervention in a critical debate among ancient historians and archaeologists, The House of Augustus recalibrates our views of a crucially important period and a revered public space.
ABSTRACT
Type Ia supernovae (SNe Ia) are explosions of white dwarf stars that facilitate exquisite measurements of cosmological expansion history, but improvements in accuracy and precision are ...hindered by observational biases. Of particular concern is the apparent difference in the corrected brightnesses of SNe Ia in different host galaxy environments. SNe Ia in more massive, passive, older environments appear brighter after having been standardized by their light-curve properties. The luminosity difference commonly takes the form of a step function. Recent works imply that environmental characteristics that trace the age of the stellar population in the vicinity of SNe show the largest steps. Here, we use simulations of SN Ia populations to test the impact of using different tracers and investigate promising new models of the step. We test models with a total-to-selective dust extinction ratio RV that changes between young and old SN Ia host galaxies, as well as an intrinsic luminosity difference between SNe from young and old progenitors. The data are well replicated by a model driven by a galaxy-age varying RV and no intrinsic SN luminosity difference, and we find that specific star formation rate measured locally to the SN is a relatively pure tracer of this galaxy-age difference. We cannot rule out an intrinsic difference causing part of the observed step and show that if luminosity differences are caused by multiple drivers then no single environmental measurement is able to accurately trace them. We encourage the use of multiple tracers in luminosity corrections to negate this issue.
Aims.
We investigate electron temperature (
T
e
) and gas-phase oxygen abundance (
Z
Te
) measurements for galaxies in the local Universe (
z
< 0.25). Our sample comprises spectra from a total of ...264 emission-line systems, ranging from individual H
II
regions to whole galaxies, including 23 composite H
II
regions from star-forming main sequence galaxies in the MaNGA survey.
Methods.
We utilise 130 of these systems with directly measurable
T
e
(O
II
) to calibrate a new metallicity-dependent
T
e
(O
III
)–
T
e
(O
II
) relation that provides a better representation of our varied dataset than existing relations from the literature. We also provide an alternative
T
e
(O
III
)–
T
e
(N
II
) calibration. This new
T
e
method is then used to obtain accurate
Z
Te
estimates and form the mass – metallicity relation (MZR) for a sample of 118 local galaxies.
Results.
We find that all the
T
e
(O
III
)–
T
e
(O
II
) relations considered here systematically under-estimate
Z
Te
for low-ionisation systems by up to 0.6 dex. We determine that this is due to such systems having an intrinsically higher O
+
abundance than O
++
abundance, rendering
Z
Te
estimates based only on O
III
lines inaccurate. We therefore provide an empirical correction based on strong emission lines to account for this bias when using our new
T
e
(O
III
)–
T
e
(O
III
) and
T
e
(O
III
)–
T
e
(N
II
) relations. This allows for accurate metallicities (1
σ
= 0.08 dex) to be derived for any low-redshift system with an O
III
λ
4363 detection, regardless of its physical size or ionisation state. The MZR formed from our dataset is in very good agreement with those formed from direct measurements of metal recombination lines and blue supergiant absorption lines, in contrast to most other
T
e
-based and strong-line-based MZRs. Our new
T
e
method therefore provides an accurate and precise way of obtaining
Z
Te
for a large and diverse range of star-forming systems in the local Universe.
All disc-accreting astrophysical objects produce powerful disc winds. In compact binaries containing neutron stars or black holes, accretion often takes place during violent outbursts. The main disc ...wind signatures during these eruptions are blue-shifted X-ray absorption lines, which are preferentially seen in disc-dominated 'soft states'
. By contrast, optical wind-formed lines have recently been detected in 'hard states', when a hot corona dominates the luminosity
. The relationship between these signatures is unknown, and no erupting system has as yet revealed wind-formed lines between the X-ray and optical bands, despite the many strong resonance transitions in this ultraviolet (UV) region
. Here we report that the transient neutron star binary Swift J1858.6-0814 exhibits wind-formed, blue-shifted absorption lines associated with C IV, N V and He II in time-resolved UV spectroscopy during a luminous hard state, which we interpret as a warm, moderately ionized outflow component in this state. Simultaneously observed optical lines also display transient blue-shifted absorption. Decomposing the UV data into constant and variable components, the blue-shifted absorption is associated with the former. This implies that the outflow is not associated with the luminous flares in the data. The joint presence of UV and optical wind features reveals a multi-phase and/or spatially stratified evaporative outflow from the outer disc
. This type of persistent mass loss across all accretion states has been predicted by radiation-hydrodynamic simulations
and helps to explain the shorter-than-expected duration of outbursts
.
We present and analyse an extensive dataset of the superluminous supernova (SLSN) LSQ14mo (z = 0.256), consisting of a multi-colour light curve from −30 d to +70 d in the rest-frame (relative to ...maximum light) and a series of six spectra from PESSTO covering −7 d to +50 d. This is among the densest spectroscopic coverage, and best-constrained rising light curve, for a fast-declining hydrogen-poor SLSN. The bolometric light curve can be reproduced with a millisecond magnetar model with ~ 4 M⊙ ejecta mass, and the temperature and velocity evolution is also suggestive of a magnetar as the power source. Spectral modelling indicates that the SN ejected ~ 6 M⊙ of CO-rich material with a kinetic energy of ~7 × 1051 erg, and suggests a partially thermalised additional source of luminosity between −2 d and +22 d. This may be due to interaction with a shell of material originating from pre-explosion mass loss. We further present a detailed analysis of the host galaxy system of LSQ14mo. PESSTO and GROND imaging show three spatially resolved bright regions, and we used the VLT and FORS2 to obtain a deep (five-hour exposure) spectra of the SN position and the three star-forming regions, which are at a similar redshift. The FORS2 spectrum at + 300 days shows no trace of SN emission lines and we place limits on the strength of O i from comparisons with other Ic supernovae. The deep spectra provides a unique chance to investigate spatial variations in the host star-formation activity and metallicity. The specific star-formation rate is similar in all three components,as is the presence of a young stellar population. However, the position of LSQ14mo exhibits a lower metallicity, with 12 + log (O/H) = 8.2 in both the R23 and N2 scales (corresponding to ~0.3 Z⊙ ). We propose that the three bright regions in the host system are interacting, which could induce gas flows triggering star formation in low-metallicity regions.
We present the results of a search for rapidly evolving transients in the Dark Energy Survey Supernova Programme. These events are characterized by fast light-curve evolution (rise to peak in ≲10 d ...and exponential decline in ≲30 d after peak). We discovered 72 events, including 37 transients with a spectroscopic redshift from host galaxy spectral features. The 37 events increase the total number of rapid optical transients by more than a factor of two. They are found at a wide range of redshifts (0.05 < z < 1.56) and peak brightnesses (-15.75 > Mg > -22.25). The multiband photometry is well fit by a blackbody up to few weeks after peak. The events appear to be hot (T ≈ 10 000–30 000 K) and large (R ≈ 1014 - 2 × 1015 cm) at peak, and generally expand and cool in time, though some events show evidence for a receding photosphere with roughly constant temperature. Spectra taken around peak are dominated by a blue featureless continuum consistent with hot, optically thick ejecta. We compare our events with a previously suggested physical scenario involving shock breakout in an optically thick wind surrounding a core-collapse supernova, we conclude that current models for such a scenario might need an additional power source to describe the exponential decline. We find that these transients tend to favour star-forming host galaxies, which could be consistent with a core-collapse origin. However, more detailed modelling of the light curves is necessary to determine their physical origin.
Abstract
Introduction
Smoking continues to be a leading cause of preventable death. Mobile health (mHealth) can extend the reach of smoking cessation programs; however, user dropout, especially in ...real-world implementations of these programs, limit their potential effectiveness. Research is needed to understand patterns of engagement in mHealth cessation programs.
Methods
SmokefreeTXT (SFTXT) is the National Cancer Institute’s 6–8 week smoking cessation text-messaging intervention. Latent growth mixture modeling was used to identify unique classes of engagement among SFTXT users using real-world program data from 7090 SFTXT users. Survival analysis was conducted to model program dropout over time by class, and multilevel modeling was used to explore differences in abstinence over time.
Results
We identified four unique patterns of engagement groups. The largest percentage of users (61.6%) were in the low-engagers declining group; these users started off with low level of engagement and their engagement decreased over time. Users in this group were more likely to drop out from the program and less likely to be abstinent than users in the other groups. Users in the high engagers–maintaining group (ie, the smallest but most engaged group) were less likely to be daily smokers at baseline and were slightly older than those in the other groups. They were most likely to complete the program and report being abstinent.
Conclusions
Our findings show the importance of maintaining active engagement in text-based cessation programs. Future research is needed to elucidate predictors of the various levels of engagement, and to assess whether strategies aimed at increasing engagement result in higher abstinence rates.
Implications
The current study enabled us to investigate differing engagement patterns in non-incentivized program participants, which can help inform program modifications in real-world settings. Lack of engagement and dropout continue to impede the potential effectiveness of mHealth interventions, and understanding patterns and predictors of engagement can enhance the impact of these programs.
Abstract
SN 2023emq is a fast-evolving transient initially classified as a rare Type Icn supernova (SN), interacting with a H- and He-free circumstellar medium (CSM) around maximum light. Subsequent ...spectroscopy revealed the unambiguous emergence of narrow He lines, confidently placing SN 2023emq in the more common Type Ibn class. Photometrically, SN 2023emq has several uncommon properties regardless of its class, including its extreme initial decay (faster than >90% of Type Ibn/Icn SNe) and sharp transition in the decline rate from 0.20 to 0.07 mag day
−1
at +20 days. The bolometric light curve can be modeled as CSM interaction with 0.32
M
⊙
of ejecta and 0.12
M
⊙
of CSM, with 0.006
M
⊙
of nickel, as expected of fast, interacting SNe. Furthermore, broadband polarimetry at +8.7 days (
P
= 0.55% ± 0.30%) is consistent with spherical symmetry. A discovery of a transitional Type Icn/Ibn SN would be unprecedented and would give valuable insights into the nature of mass loss suffered by the progenitor just before death, but we favor an interpretation that SN 2023emq is a Type Ibn SN that exhibited flash-ionized features in the earliest spectrum, as the features are not an exact match with other Type Icn SNe to date. However, the feature at 5700 Å, in the region of C
iii
and N
ii
emission, is significantly stronger in SN 2023emq than in the few other flash-ionized Type Ibn SNe, and if it is related to C
iii
, it possibly implies a continuum of properties between the two classes.
•Nonlinear microscopy utilizes nonlinear interactions between light and matter to image fluorescence and scattering phenomena in biological tissues with inherent optical sectioning.•Samples in ...nonlinear microscopy range from single cells, ex vivo tissues and larger cleared specimens to in vivo imaging of brains and whole small organisms.•Excitation in the infrared reduces light scattering in biological tissues to extend imaging depths to up to 1 mm.•Multiple contrast mechanisms enable virtual histology of fresh unlabelled or labelled whole tissue samples without extensive tissue preparation.•Polarization nonlinear microscopy extends imaging by additional degrees of freedom to detect molecular order and orientation of molecules.
Nonlinear microscopy is a technique that utilizes nonlinear interactions between light and matter to image fluorescence and scattering phenomena in biological tissues. Very high peak intensities from focused short pulsed lasers are required for nonlinear excitation due to the extremely low probability of the simultaneous arrival of multiple photons of lower energy to excite fluorophores or interact with selective structures for harmonic generation. Combined with reduced scattering from the utilization of longer wavelengths, the inherent spatial confinement associated with achieving simultaneous arrival of photons within the focal volume enables deep imaging with low out-of-focus background for nonlinear imaging. This review provides an introduction to the different contrast mechanisms available with nonlinear imaging and instrumentation commonly used in nonlinear microscopy. Furthermore, we discuss some recent advances in nonlinear microscopy to extend the imaging penetration depth, conduct histopathological investigations on fresh tissues and examine the molecular order and orientation of molecules using polarization nonlinear microscopy.
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