We present an atlas of ultraviolet and infrared images of ∼15,750 local (d 50 Mpc) galaxies, as observed by NASA's Wide-field Infrared Survey Explorer (WISE) and Galaxy Evolution Explorer (GALEX) ...missions. These maps have matched resolution (FWHM 7 5 and 15″), matched astrometry, and a common procedure for background removal. We demonstrate that they agree well with resolved intensity measurements and integrated photometry from previous surveys. This atlas represents the first part of a program (the z = 0 Multiwavelength Galaxy Synthesis) to create a large, uniform database of resolved measurements of gas and dust in nearby galaxies. The images and associated catalogs will be publicly available at the NASA/IPAC Infrared Science Archive. This atlas allows us estimate local and integrated star formation rates (SFRs) and stellar masses (M ) across the local galaxy population in a uniform way. In the appendix, we use the population synthesis fits of Salim et al. to calibrate integrated M and SFR estimators based on GALEX and WISE. Because they leverage a Sloan Digital Sky Survey (SDSS)-based training set of >100,000 galaxies, these calibrations have high precision and allow us to rigorously compare local galaxies to SDSS results. We provide these SFR and M estimates for all galaxies in our sample and show that our results yield a "main sequence" of star-forming galaxies comparable to previous work. We also show the distribution of intensities from resolved galaxies in NUV-to-WISE1 versus WISE1-to-WISE3 space, which captures much of the key physics accessed by these bands.
Abstract
We analyze HCN and HNC emission in the nearby starburst galaxy NGC 253 to investigate its effectiveness in tracing heating processes associated with star formation. This study uses multiple ...HCN and HNC rotational transitions observed using the Atacama Large Millimeter/submillimeter Array via the ALCHEMI Large Program. To understand the conditions and associated heating mechanisms within NGC 253's dense gas, we employ Bayesian nested sampling techniques applied to chemical and radiative transfer models, which are constrained using our HCN and HNC measurements. We find that the volume density
n
H
2
and cosmic-ray ionization rate (CRIR)
ζ
are enhanced by about an order of magnitude in the galaxy’s central regions as compared to those further from the nucleus. In NGC 253's central giant molecular clouds (GMCs), where observed HCN/HNC abundance ratios are the lowest,
n
∼ 10
5.5
cm
−3
and
ζ
∼ 10
−12
s
−1
(greater than 10
4
times the average Galactic rate). We find a positive correlation in the association of both density and CRIR with the number of star formation-related heating sources (supernova remnants, H
ii
regions, and super hot cores) located in each GMC, as well as a correlation between CRIRs and supernova rates. Additionally, we see an anticorrelation between the HCN/HNC ratio and CRIR, indicating that this ratio will be lower in regions where
ζ
is higher. Though previous studies suggested HCN and HNC may reveal strong mechanical heating processes in NGC 253's CMZ, we find cosmic-ray heating dominates the heating budget, and mechanical heating does not play a significant role in the HCN and HNC chemistry.
Local Environments of Low-redshift Supernovae Cronin, Serena A.; Utomo, Dyas; Leroy, Adam K. ...
Astrophysical journal/The Astrophysical journal,
12/2021, Letnik:
923, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
We characterize the local (2 kpc sized) environments of Type Ia, II, and Ib/c supernovae (SNe) that have recently occurred in nearby (
d
≲ 50 Mpc) galaxies. Using ultraviolet (UV; from ...Galaxy Evolution Explorer) and infrared (IR; from Wide-field Infrared Survey Explorer) maps of 359 galaxies and a sample of 472 SNe, we measure the star formation rate surface density (Σ
SFR
) and stellar mass surface density (Σ
⋆
) in a 2 kpc beam centered on each SN site. We show that core-collapse SNe are preferentially located along the resolved galactic star-forming main sequence, whereas Type Ia SNe are extended to lower values of Σ
SFR
at fixed Σ
⋆
, indicative of locations inside quiescent galaxies or quiescent regions of galaxies. We also test how well the radial distribution of each SN type matches the radial distributions of UV and IR light in each host galaxy. We find that, to first order, the distributions of all types of SNe mirror those of both near-IR light (3.4 and 4.5
μ
m, tracing the stellar mass distribution) and mid-IR light (12 and 22
μ
m, tracing emission from hot, small grains), and also resemble our best-estimate Σ
SFR
. All types of SNe appear more radially concentrated than the UV emission of their host galaxies. In more detail, the distributions of Type II SNe show small statistical differences from those of near-IR light. We attribute this overall structural uniformity to the fact that within any individual galaxy, Σ
SFR
and Σ
⋆
track one another well, with variations in Σ
SFR
/Σ
⋆
most visible when comparing between galaxies.
The cosmic-ray ionization rate (CRIR) is a key parameter in understanding the physical and chemical processes in the interstellar medium. Cosmic rays are a significant source of energy in star ...formation regions, impacting the physical and chemical processes that drive the formation of stars. Previous studies of the circum-molecular zone of the starburst galaxy NGC 253 have found evidence for a high CRIR value: 103–106 times the average CRIR within the Milky Way. This is a broad constraint, and one goal of this study is to determine this value with much higher precision. We exploit ALMA observations toward the central molecular zone of NGC 253 to measure the CRIR. We first demonstrate that the abundance ratio of H3O+ and SO is strongly sensitive to the CRIR. We then combine chemical and radiative transfer models with nested sampling to infer the gas properties and CRIR of several star-forming regions in NGC 253 from emission from their transitions. We find that each of the four regions modeled has a CRIR in the range (1–80) × 10−14 s−1 and that this result adequately fits the abundances of other species that are believed to be sensitive to cosmic rays, including C2H, HCO+, HOC+, and CO. From shock and photon-dominated/X-ray dominated region models, we further find that neither UV-/X-ray-driven nor shock-dominated chemistry is a viable single alternative as none of these processes can adequately fit the abundances of all of these species.
Abstract
Molecular abundances are sensitive to the UV photon flux and cosmic-ray ionization rate. In starburst environments, the effects of high-energy photons and particles are expected to be ...stronger. We examine these astrochemical signatures through multiple transitions of HCO
+
and its metastable isomer HOC
+
in the center of the starburst galaxy NGC 253 using data from the Atacama Large Millimeter/submillimeter Array large program ALMA Comprehensive High-resolution Extragalactic Molecular inventory. The distribution of the HOC
+
(1−0) integrated intensity shows its association with “superbubbles,” cavities created either by supernovae or expanding H
ii
regions. The observed HCO
+
/HOC
+
abundance ratios are ∼10–150, and the fractional abundance of HOC
+
relative to H
2
is ∼1.5 × 10
−11
–6 × 10
−10
, which implies that the HOC
+
abundance in the center of NGC 253 is significantly higher than in quiescent spiral arm dark clouds in the Galaxy and the Galactic center clouds. Comparison with chemical models implies either an interstellar radiation field of
G
0
≳ 10
3
if the maximum visual extinction is ≳5, or a cosmic-ray ionization rate of
ζ
≳ 10
−14
s
−1
(3–4 orders of magnitude higher than that within clouds in the Galactic spiral arms) to reproduce the observed results. From the difference in formation routes of HOC
+
, we propose that a low-excitation line of HOC
+
traces cosmic-ray dominated regions, while high-excitation lines trace photodissociation regions. Our results suggest that the interstellar medium in the center of NGC 253 is significantly affected by energy input from UV photons and cosmic rays, sources of energy feedback.
ABSTRACT
The role played by magnetic field during star formation is an important topic in astrophysics. We investigate the correlation between the orientation of star-forming cores (as defined by the ...core major axes) and ambient magnetic field directions in (i) a 3D magnetohydrodynamic simulation, (ii) synthetic observations generated from the simulation at different viewing angles, and (iii) observations of nearby molecular clouds. We find that the results on relative alignment between cores and background magnetic field in synthetic observations slightly disagree with those measured in fully 3D simulation data, which is partly because cores identified in projected 2D maps tend to coexist within filamentary structures, while 3D cores are generally more rounded. In addition, we examine the progression of magnetic field from pc to core scale in the simulation, which is consistent with the anisotropic core formation model that gas preferably flows along the magnetic field towards dense cores. When comparing the observed cores identified from the Green Bank Ammonia Survey and Planck polarization-inferred magnetic field orientations, we find that the relative core–field alignment has a regional dependence among different clouds. More specifically, we find that dense cores in the Taurus molecular cloud tend to align perpendicular to the background magnetic field, while those in Perseus and Ophiuchus tend to have random (Perseus) or slightly parallel (Ophiuchus) orientations with respect to the field. We argue that this feature of relative core–field orientation could be used to probe the relative significance of the magnetic field within the cloud.
Reviews the book, Qualitative Strategies for Ethnocultural Research by D. K. Nagata, L. Kohn-Wood, and L. Suzuki (see record 2011-26948-000). This book is an informative and instructive resource for ...conducting research among diverse ethnic groups. It offers strategies in conducting research when issues or considerations arise that often cannot be addressed using conventional quantitative methods. It provides a variety of models for developing and describing qualitative research and includes descriptions and examples of a variety of qualitative research methods. It also provides guidelines and recommendations for other professionals about how to develop and write about qualitative research and findings effectively. (PsycInfo Database Record (c) 2024 APA, all rights reserved)
The Self‐Directed Search (SDS; Holland, ) is sometimes administered to large student groups outside of counseling to address common career development needs. This study evaluated the effectiveness of ...the SDS as a stand‐alone intervention by comparing a general sample of college students who completed the SDS (n = 39) with a no‐treatment control group (n = 41) on several outcomes. Completion of the SDS related to an increase in the number of career alternatives being considered 4 weeks later but did not relate to career exploration, career decision‐making self‐efficacy, career indecision, and seeking of career counseling services. If the SDS is used outside of counseling with broad student samples, the authors suggest providing additional intervention to ensure that it promotes exploration of any additional careers being considered.
Sororities have been identified as placing young women at risk for body image concerns due to a focus on traditional gender role norms and objectification of women. Objective: This study assessed the ...relationship between conformity to feminine gender role norms, self-objectification, and body image surveillance among undergraduate women. Participants: In a random sample of undergraduates, the authors examined data from sorority and nonsorority women. Methods: In a random sample of undergraduate women, the authors assessed the impact of traditional feminine gender role norms on self-objectification, body image, and feedback regarding physical appearance for sorority and nonsorority undergraduate women. Results: Three linear regressions were conducted, and only conformity to feminine gender role norms contributed significantly in each regression model. Conclusions: Regardless of sorority membership, conformity to feminine gender role norms was found to significantly contribute to increased body consciousness, negative body image, and feedback on physical appearance.
Abstract
We present a spatially resolved excitation analysis for the central molecular zone (CMZ) of the starburst galaxy NGC 253 using the data from the Atacama Large Millimeter/submillimeter Array ...Comprehensive High-resolution Extragalactic Molecular Inventory, whereby we explore parameters distinguishing NGC 253 from the quiescent Milky Way’s Galactic center (GC). Non-LTE analyses employing a hierarchical Bayesian framework are applied to Band 3–7 transitions from nine molecular species to delineate the position–position–velocity distributions of column density (
N
H
2
), volume density (
n
H
2
), and temperature (
T
kin
) at 27 pc resolution. Two distinct components are detected: a low-density component with
(
n
H
2
,
T
kin
)
∼
(
10
3.3
cm
−
3
,
85
K
)
and a high-density component with
(
n
H
2
,
T
kin
)
∼
(
10
4.4
cm
−
3
,
110
K
)
, separated at
n
H
2
∼
10
3.8
cm
−
3
. NGC 253 has ∼10 times the high-density gas mass and ∼3 times the dense-gas mass fraction of the GC. These properties are consistent with their HCN/CO ratio but cannot alone explain the factor of ∼30 difference in their star formation efficiencies (SFEs), contradicting the dense-gas mass to star formation rate scaling law. The
n
H
2
histogram toward NGC 253 exhibits a shallow declining slope up to
n
H
2
∼
10
6
cm
−
3
, while that of the GC steeply drops in
n
H
2
≳
10
4.5
cm
−
3
and vanishes at 10
5
cm
−3
. Their dense-gas mass fraction ratio becomes consistent with their SFEs when the threshold
n
H
2
for the dense gas is taken at ∼10
4.2−4.6
cm
−3
. The rich abundance of gas above this density range in the NGC 253 CMZ, or its scarcity in the GC, is likely to be the critical difference characterizing the contrasting star formation in the centers of the two galaxies.
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