ABSTRACT We present Hα-derived star-formation rates for the z = 0.845 galaxy cluster CL J0023+042... more ABSTRACT We present Hα-derived star-formation rates for the z = 0.845 galaxy cluster CL J0023+0423B and demonstrate that near-infrared, narrow-band Hα imaging is a powerful way to sample the entire star-forming and post-starburst galaxy population in distant clusters. Comparison with spectroscopy shows that the number of false detections is low, and our Hα equivalent widths show reasonable correlation with spectroscopically determined [O II] equivalent widths. We compare the number of star-forming galaxies detected in our narrow-band images with the number found by a previously published spectroscopic survey and estimate that the spectroscopic survey is missing over 60% of star-forming galaxies in this cluster. Results on our entire sample of seven z ≅ 0.8 clusters will be published in the near future, and we will be able to form a more comprehensive picture of the star-formation properties of z ≅ 0.8 galaxy clusters.
Monthly Notices of the Royal Astronomical Society, Mar 3, 2023
We investigate the role of dense environments in suppressing star formation by studying log 10 (M... more We investigate the role of dense environments in suppressing star formation by studying log 10 (M ★ /M) > 9.7 star-forming galaxies in nine clusters from the Local Cluster Survey (0.0137 < < 0.0433) and a large comparison field sample drawn from the Sloan Digital Sky Survey. We compare the star-formation rate (SFR) versus stellar mass relation as a function of environment and morphology. After carefully controlling for mass, we find that in all environments, the degree of SFR suppression increases with increasing bulge-to-total (/) ratio. In addition, the SFRs of cluster and infall galaxies at a fixed mass are more suppressed than their field counterparts at all values of /. These results suggest a quenching mechanism that is linked to bulge growth that operates in all environments and an additional mechanism that further reduces the SFRs of galaxies in dense environments. We limit the sample to / ≤ 0.3 galaxies to control for the trends with morphology and find that the excess population of cluster galaxies with suppressed SFRs persists. We model the timescale associated with the decline of SFRs in dense environments and find that the observed SFRs of the cluster core galaxies are consistent with a range of models including: a mechanism that acts slowly and continuously over a long (2 − 5 Gyr) timescale, and a more rapid (< 1 Gyr) quenching event that occurs after a delay period of 1 − 6 Gyr. Quenching may therefore start immediately after galaxies enter clusters.
The goal of the Local Cluster Survey is to look for evidence of environmentally driven quenching ... more The goal of the Local Cluster Survey is to look for evidence of environmentally driven quenching among star-forming galaxies in nearby galaxy groups and clusters. Quenching is linked with environment and stellar mass, and much of the current observational evidence comes from the integrated properties of galaxies. However, the relative size of the stellar and star-forming disk is sensitive to environmental processing and can help identify the mechanisms that lead to a large fraction of quenched galaxies in dense environments. Toward this end, we measure the size of the star-forming disks for 224 galaxies in nine groups and clusters (0.02 < z < 0.04; SFR > 0.1 M yr −1) using 24µm imaging from the Spitzer Space Telescope. We normalize the 24µm effective radius (R 24) by the size of the stellar disk (R d). We find that star-forming galaxies with higher bulge-to-total ratios (B/T) and galaxies in more dense environments have more centrally concentrated star formation. Comparison with H I mass fractions and NUV−r colors indicates that a galaxy's transition from gas-rich and blue to depleted and red is accompanied by an increase in the central concentration of star formation. We build a simple model to constrain the timescale over which the star-forming disks shrink in the cluster environment. Our results are consistent with a long-timescale (> 2 Gyr) mechanism that produces outside-in quenching, such as the removal of the extended gas halo or weak stripping of the cold disk gas.
We investigate the role of dense environments in suppressing star formation by studying $\rm \log... more We investigate the role of dense environments in suppressing star formation by studying $\rm \log _{10}(M_\star /M_\odot) \gt 9.7$ star-forming galaxies in nine clusters from the Local Cluster Survey (0.0137 < z < 0.0433) and a large comparison field sample drawn from the Sloan Digital Sky Survey. We compare the star formation rate (SFR) with stellar mass relation as a function of environment and morphology. After carefully controlling for mass, we find that in all environments, the degree of SFR suppression increases with increasing bulge-to-total (B/T) ratio. In addition, the SFRs of cluster and infall galaxies at a fixed mass are more suppressed than their field counterparts at all values of B/T. These results suggest a quenching mechanism that is linked to bulge growth that operates in all environments and an additional mechanism that further reduces the SFRs of galaxies in dense environments. We limit the sample to B/T ≤ 0.3 galaxies to control for the trends with morphol...
Interest in engineering at early stages of the educational career is one important precursor to c... more Interest in engineering at early stages of the educational career is one important precursor to choosing to study engineering in college, and engineeringrelated clubs are designed to foster such interest and diversify the engineering pipeline. In this study, the researchers employed a social cognitive career theory framework to examine level of interest in studying engineering and expected educational attainment among underrepresented low-income middle and high school students participating in materials science and engineering (MSE) clubs. Questionnaire data were collected from over 200 MSE club participants in low-income public middle and high schools in Puerto Rico. The results indicate that perceived value of engineering is useful in predicting career interest among underrepresented middle and high school students; however, traditional predictors of educational interests and attainment (gender, mother's education, parent expectations) exert the strongest influence on engineering interest and attainment expectations.
arXiv: Instrumentation and Methods for Astrophysics, 2019
The NSF-sponsored Undergraduate ALFALFA Team (UAT) promotes long-term collaborative research oppo... more The NSF-sponsored Undergraduate ALFALFA Team (UAT) promotes long-term collaborative research opportunities for faculty and students from 23 U.S. public and private primarily undergraduate institutions (PUIs) within the context of the extragalactic ALFALFA HI blind legacy survey project. Over twelve project years of partnering with Arecibo and Green Bank Observatories, the UAT has had a demonstrable impact on the health of a legacy astronomy project, science education, and equity/inclusion in astronomy, with successful outcomes for 373 UAT students (39% women; ~30% members of underrepresented groups) and 34 faculty (44% women). The UAT model is adaptable to many large scientific projects and can be supported by relatively modest funding. We recommend that granting agencies identify funding resources to support the model, either as an add-on to legacy grant support or as a stand-alone funding source. This could include encouragement of UAT-like components in large scale projects curre...
We present the Electricity and Magnetism Conceptual Assessment (EMCA), a new assessment aligned w... more We present the Electricity and Magnetism Conceptual Assessment (EMCA), a new assessment aligned with second-semester introductory physics courses. Topics covered include electrostatics, electric fields, circuits, magnetism, and induction. We have two motives for writing a new assessment. First, we find other assessments such as the Brief Electricity and Magnetism Assessment and the Conceptual Survey on Electricity and Magnetism not well aligned with the topics and content depth of our courses. We want to test introductory physics content at a level appropriate for our students. Second, we want the assessment to yield scores and gains comparable to the widely used Force Concept Inventory (FCI). After five testing and revision cycles, the assessment was finalized in early 2015 and is available online. We present performance results for a cohort of 225 students at Siena College who were enrolled in our algebra-and calculus-based physics courses during the spring 2015 and 2016 semesters. We provide pretest, post-test, and gain analyses, as well as individual question and whole test statistics to quantify difficulty and reliability. In addition, we compare EMCA and FCI scores and gains, and we find that students' FCI scores are strongly correlated with their performance on the EMCA. Finally, the assessment was piloted in an algebra-based physics course at George Washington University (GWU). We present performance results for a cohort of 130 GWU students and we find that their EMCA scores are comparable to the scores of students in our calculus-based physics course.
We present the catalog of ∼31500 extragalactic HI line sources detected by the completed ALFALFA ... more We present the catalog of ∼31500 extragalactic HI line sources detected by the completed ALFALFA survey out to z < 0.06 including both high signal-to-noise ratio (> 6.5) detections and ones of lower quality which coincide in both position and recessional velocity with galaxies of known redshift. We review the observing technique, data reduction pipeline, and catalog construction process, focusing on details of particular relevance to understanding the catalog's compiled parameters. We further describe and make available the digital HI line spectra associated with the catalogued sources. In addition to the extragalactic HI line detections, we report nine confirmed OH megamasers and ten OH megamaser candidates at 0.16 < z < 0.22 whose OH line signals are redshifted into the ALFALFA frequency band. Because of complexities in data collection and processing associated with the use of a feed-horn array on a complex single-dish antenna in the terrestrial radio frequency interference environment, we also present a list of suggestions and caveats for consideration by users of the ALFALFA extragalactic catalog for future scientific investigations.
We present Hubble Space T elescope (HST) Wide Field Planetary Camera 2 (WFPC2) data on the large-... more We present Hubble Space T elescope (HST) Wide Field Planetary Camera 2 (WFPC2) data on the large-scale environments of 16 0.39 < z < 0.51 quasars from the Large Bright Quasar Survey (LBQS). The LBQS quasars are representative of the radio-quiet population, and this is the first look at their large-scale environments. We compare the LBQS environments with the environments of 27 0.15 < z < 0.55 quasars selected from the HST Archive. The majority of the Archive quasars are from the PG and PKS surveys, and these quasars are more luminous on average than the LBQS. By comparing the LBQS and Archive environments, we investigate whether previous quasar environment studies have been biased due to studying unusually radio or optically luminous quasars. We compare observed galaxy number counts with expected counts predicted from the CNOC2 field-galaxy luminosity function in order to look for statistical excesses of galaxies around the quasars. We detect a significant excess around the Archive quasars but find no such excess around the LBQS quasars. We calculate the amplitude of the spatial correlation function and find that the LBQS environments are consistent with that of the typical galaxy while the Archive environments are slightly
Publications of the Astronomical Society of the Pacific, 2001
Wide-field-of-view infrared cameras, operating on the new generation of large telescopes, offer u... more Wide-field-of-view infrared cameras, operating on the new generation of large telescopes, offer unprecedented gains in the detection of faint sources and in observing efficiency for both direct imaging and spectroscopy. With a pixel, 1-2.5 mm detector, the PISCES camera provides 8Ј .5 and 3Ј .16 fields 1024 # 1024 at the 2.3 m Bok telescope and 6.5 m Multiple Mirror Telescope, respectively. Its refractive optics utilize all spherical surfaces and standard glasses. A cold pupil stop suppresses the thermal background produced by the emissive surfaces normally present in Cassegrain optical configurations. The optical design is directly extendable to wider fields with larger detector formats. Future upgrades include low-resolution (-500) multiobject R p 200 spectroscopy.
We tested the effectiveness on learning of hands-on, night-time laboratories that challenged stud... more We tested the effectiveness on learning of hands-on, night-time laboratories that challenged student misconceptions in a non-major introductory astronomy class at Rensselaer Polytechnic Institute. We present a new assessment examination used to assess learning in this study. We were able to increase learning, at the 8.0 sigma level, on one of the moon phase objectives that was addressed in a cloudy night activity. There is weak evidence of some improvement on a broader range of learning objectives. We show evidence that the overall achievement levels of the four sections of the class is correlated with the amount of clear whether the sections had for observing, even though the learning objectives were addressed primarily in activities that did not require clear skies. This last result should be confirmed with future studies. We describe our first attempt to cycle the students through different activity stations in an attempt to handle 18 students at a time in the laboratories, and lessons learned from this.
II. Molecular gas in galaxy clusters and their large-scale structure: low gas fraction galaxies, ... more II. Molecular gas in galaxy clusters and their large-scale structure: low gas fraction galaxies, the case of CL1301.7−1139
Virgo is the nearest galaxy cluster; it is thus ideal for studies of galaxy evolution in dense en... more Virgo is the nearest galaxy cluster; it is thus ideal for studies of galaxy evolution in dense environments in the local universe. It is embedded in a complex filamentary network of galaxies and groups, which represents the skeleton of the large-scale Laniakea supercluster. Here we assemble a comprehensive catalog of galaxies extending up to ∼12 virial radii in projection from Virgo to revisit the cosmic-web structure around it. This work is the foundation of a series of papers that will investigate the multiwavelength properties of galaxies in the cosmic web around Virgo. We match spectroscopically confirmed sources from several databases and surveys including HyperLeda, NASA Sloan Atlas, NASA/IPAC Extragalactic Database, and ALFALFA. The sample consists of ∼7000 galaxies. By exploiting a tomographic approach, we identify 13 filaments, spanning several megaparsecs in length. Long >17 h –1 Mpc filaments, tend to be thin (<1 h –1 Mpc in radius) and with a low-density contrast (...
We present an HI-optical catalog of ∼ 30,000 galaxies based on the 100% complete Arecibo Legacy F... more We present an HI-optical catalog of ∼ 30,000 galaxies based on the 100% complete Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) survey combined with data from the Sloan Digital Sky Survey (SDSS). Our goal is to facilitate public use of the completed ALFALFA catalog by providing carefully determined matches to SDSS counterparts, including matches for ∼ 12,000 galaxies that do not have SDSS spectra. These identifications can provide a basis for further cross-matching with other surveys using SDSS photometric IDs as a reference point. We derive absolute magnitudes and stellar masses for each galaxy using optical colors combined with an internal reddening correction designed for small-and intermediate-mass galaxies with active star formation. We also provide measures of stellar masses and star formation rates based on infrared and/or ultraviolet photometry for galaxies that are detected by the Wide-field Infrared Survey Explorer (WISE) and/or the Galaxy Evolution Explorer (GALEX). Finally, we compare the galaxy population in the ALFALFA-SDSS sample with the populations in several other publicly-available galaxy catalogs, and confirm that ALFALFA galaxies typically have lower masses and bluer colors.
We present results from a low-resolution spectroscopic survey for 21 galaxy clusters at 0.4<z<... more We present results from a low-resolution spectroscopic survey for 21 galaxy clusters at 0.4<z<0.8 selected from the ESO Distant Cluster Survey. We measured spectra using the low-dispersion prism in IMACS on the Magellan Baade telescope and calculate redshifts with an accuracy of σ z =0.007. We find 1763 galaxies that are brighter than R=22.9 in the large-scale cluster environs. We identify the galaxies expected to be accreted by the clusters as they evolve to z=0 using spherical infall models and find that ∼30%-70% of the z=0 cluster population lies outside the virial radius at z∼0.6. For analogous clusters at z=0, we calculate that the ratio of galaxies that have fallen into the clusters since z∼0.6 to those that were already in the core at that redshift is typically between ∼0.3 and 1.5. This wide range of ratios is due to intrinsic scatter and is not a function of velocity dispersion, so a variety of infall histories is to be expected for clusters with current velocity dispersions of 300 km s −1 σ1200 km s −1. Within the infall regions of z∼0.6 clusters, we find a larger red fraction of galaxies than in the field and greater clustering among red galaxies than blue. We interpret these findings as evidence of "preprocessing," where galaxies in denser local environments have their star formation rates affected prior to their aggregation into massive clusters, although the possibility of backsplash galaxies complicates the interpretation.
The goal of the Local Cluster Survey is to look for evidence of environmentally driven quenching ... more The goal of the Local Cluster Survey is to look for evidence of environmentally driven quenching among starforming galaxies in nearby galaxy groups and clusters. Quenching is linked with environment and stellar mass, and much of the current observational evidence comes from the integrated properties of galaxies. However, the relative size of the stellar and star-forming disk is sensitive to environmental processing and can help identify the mechanisms that lead to a large fraction of quenched galaxies in dense environments. Toward this end, we measure the size of the star-forming disks for 224 galaxies in nine groups and clusters (0.02 < z < 0.04; SFR > 0.1 M e yr −1) using 24 μm imaging from the Spitzer Space Telescope. We normalize the 24 μm effective radius (R 24) by the size of the stellar disk (R d). We find that star-forming galaxies with higher bulge-to-total ratios (B/T) and galaxies in more dense environments have more centrally concentrated star formation. Comparison with H I mass fractions and NUV−r colors indicates that a galaxy's transition from gas-rich and blue to depleted and red is accompanied by an increase in the central concentration of star formation. We build a simple model to constrain the timescale over which the star-forming disks shrink in the cluster environment. Our results are consistent with a long-timescale (>2 Gyr) mechanism that produces outside-in quenching, such as the removal of the extended gas halo or weak stripping of the cold disk gas.
We present a detailed study of the colours of late-type galaxy discs for ten of the EDisCS galaxy... more We present a detailed study of the colours of late-type galaxy discs for ten of the EDisCS galaxy clusters with 0.5 z 0.8. Our cluster sample contains 172 spiral galaxies, and our control sample is composed of 96 field disc galaxies. We deconvolved their ground-based V and I images obtained with FORS2 at the VLT with initial spatial resolutions between 0.4 and 0.8 arcsec to achieve a final resolution of 0.1 arcsec with 0.05 arcsec pixels, which is close to the resolution of the ACS at the HST. After removing the central region of each galaxy to avoid pollution by the bulges, we measured the V − I colours of the discs. We find that 50% of cluster spiral galaxies have disc V − I colours redder by more than 1σ of the mean colours of their field counterparts. This is well above the 16% expected for a normal distribution centred on the field disc properties. The prominence of galaxies with red discs depends neither on the mass of their parent cluster nor on the distance of the galaxies to the cluster cores. Passive spiral galaxies constitute 20% of our sample. These systems are not abnormally dusty. They are are made of old stars and are located on the cluster red sequences. Another 24% of our sample is composed of galaxies that are still active and star forming, but less so than galaxies with similar morphologies in the field. These galaxies are naturally located in the blue sequence of their parent cluster colour-magnitude diagrams. The reddest of the discs in clusters must have stopped forming stars more than ∼5 Gyr ago. Some of them are found among infalling galaxies, suggesting preprocessing. Our results confirm that galaxies are able to continue forming stars for some significant period of time after being accreted into clusters, and suggest that star formation can decline on seemingly long (1 to 5 Gyr) timescales.
We present Hα-derived star-formation rates for the z = 0.845 galaxy cluster CL J0023+0423B and de... more We present Hα-derived star-formation rates for the z = 0.845 galaxy cluster CL J0023+0423B and demonstrate that near-infrared, narrow-band Hα imaging is a powerful way to sample the entire star-forming and post-starburst galaxy population in distant clusters. Comparison with spectroscopy shows that the number of false detections is low, and our Hα equivalent widths show reasonable correlation with spectroscopically determined [O II] equivalent widths. We compare the number of star-forming galaxies detected in our narrow-band images with the number found by a previously published spectroscopic survey and estimate that the spectroscopic survey is missing over 60% of star-forming galaxies in this cluster. Results on our entire sample of seven z ≅ 0.8 clusters will be published in the near future, and we will be able to form a more comprehensive picture of the star-formation properties of z ≅ 0.8 galaxy clusters.
Using a sample of 299 Hα-selected galaxies at z ≈ 0.8, we study the relationship between galaxy s... more Using a sample of 299 Hα-selected galaxies at z ≈ 0.8, we study the relationship between galaxy stellar mass, gas-phase metallicity, and star formation rate (SFR), and compare to previous results. We use deep optical spectra obtained with the IMACS spectrograph at the Magellan telescope to measure strong oxygen lines. We combine these spectra and metallicities with (1) rest-frame UV-tooptical imaging, which allows us to determine stellar masses and dust attenuation corrections, and (2) Hα narrowband imaging, which provides a robust measure of the instantaneous SFR. Our sample spans stellar masses of ∼10 9 to 6 × 10 11 M ⊙ , SFRs of 0.4 to 270 M ⊙ yr −1 , and metal abundances of 12 + log(O/H) ≈ 8.3-9.1 (≈ 0.4-2.6 Z ⊙). The correlations that we find between the Hα-based SFR and stellar mass (i.e., the star-forming "main sequence"), and between the stellar mass and metallicity, are both consistent with previous z ∼ 1 studies of star-forming galaxies. We then study the relationship between the three properties using various plane-fitting techniques (Lara-López et al.) and a curve-fitting projection (Mannucci et al.). In all cases, we exclude strong dependence of the M ⋆-Z relation on SFR, but are unable to distinguish between moderate and no dependence. Our results are consistent with previous mass-metallicity-SFR studies. We check whether dataset limitations may obscure a strong dependence on the SFR by using mock samples drawn from the SDSS. These experiments reveal that the adopted signal-to-noise cuts may have a significant effect on the measured dependence. Further work is needed to investigate these results, and to test whether a "fundamental metallicity relation" or a "fundamental plane" describes star-forming galaxies across cosmic time.
ABSTRACT We present Hα-derived star-formation rates for the z = 0.845 galaxy cluster CL J0023+042... more ABSTRACT We present Hα-derived star-formation rates for the z = 0.845 galaxy cluster CL J0023+0423B and demonstrate that near-infrared, narrow-band Hα imaging is a powerful way to sample the entire star-forming and post-starburst galaxy population in distant clusters. Comparison with spectroscopy shows that the number of false detections is low, and our Hα equivalent widths show reasonable correlation with spectroscopically determined [O II] equivalent widths. We compare the number of star-forming galaxies detected in our narrow-band images with the number found by a previously published spectroscopic survey and estimate that the spectroscopic survey is missing over 60% of star-forming galaxies in this cluster. Results on our entire sample of seven z ≅ 0.8 clusters will be published in the near future, and we will be able to form a more comprehensive picture of the star-formation properties of z ≅ 0.8 galaxy clusters.
Monthly Notices of the Royal Astronomical Society, Mar 3, 2023
We investigate the role of dense environments in suppressing star formation by studying log 10 (M... more We investigate the role of dense environments in suppressing star formation by studying log 10 (M ★ /M) > 9.7 star-forming galaxies in nine clusters from the Local Cluster Survey (0.0137 < < 0.0433) and a large comparison field sample drawn from the Sloan Digital Sky Survey. We compare the star-formation rate (SFR) versus stellar mass relation as a function of environment and morphology. After carefully controlling for mass, we find that in all environments, the degree of SFR suppression increases with increasing bulge-to-total (/) ratio. In addition, the SFRs of cluster and infall galaxies at a fixed mass are more suppressed than their field counterparts at all values of /. These results suggest a quenching mechanism that is linked to bulge growth that operates in all environments and an additional mechanism that further reduces the SFRs of galaxies in dense environments. We limit the sample to / ≤ 0.3 galaxies to control for the trends with morphology and find that the excess population of cluster galaxies with suppressed SFRs persists. We model the timescale associated with the decline of SFRs in dense environments and find that the observed SFRs of the cluster core galaxies are consistent with a range of models including: a mechanism that acts slowly and continuously over a long (2 − 5 Gyr) timescale, and a more rapid (< 1 Gyr) quenching event that occurs after a delay period of 1 − 6 Gyr. Quenching may therefore start immediately after galaxies enter clusters.
The goal of the Local Cluster Survey is to look for evidence of environmentally driven quenching ... more The goal of the Local Cluster Survey is to look for evidence of environmentally driven quenching among star-forming galaxies in nearby galaxy groups and clusters. Quenching is linked with environment and stellar mass, and much of the current observational evidence comes from the integrated properties of galaxies. However, the relative size of the stellar and star-forming disk is sensitive to environmental processing and can help identify the mechanisms that lead to a large fraction of quenched galaxies in dense environments. Toward this end, we measure the size of the star-forming disks for 224 galaxies in nine groups and clusters (0.02 < z < 0.04; SFR > 0.1 M yr −1) using 24µm imaging from the Spitzer Space Telescope. We normalize the 24µm effective radius (R 24) by the size of the stellar disk (R d). We find that star-forming galaxies with higher bulge-to-total ratios (B/T) and galaxies in more dense environments have more centrally concentrated star formation. Comparison with H I mass fractions and NUV−r colors indicates that a galaxy's transition from gas-rich and blue to depleted and red is accompanied by an increase in the central concentration of star formation. We build a simple model to constrain the timescale over which the star-forming disks shrink in the cluster environment. Our results are consistent with a long-timescale (> 2 Gyr) mechanism that produces outside-in quenching, such as the removal of the extended gas halo or weak stripping of the cold disk gas.
We investigate the role of dense environments in suppressing star formation by studying $\rm \log... more We investigate the role of dense environments in suppressing star formation by studying $\rm \log _{10}(M_\star /M_\odot) \gt 9.7$ star-forming galaxies in nine clusters from the Local Cluster Survey (0.0137 < z < 0.0433) and a large comparison field sample drawn from the Sloan Digital Sky Survey. We compare the star formation rate (SFR) with stellar mass relation as a function of environment and morphology. After carefully controlling for mass, we find that in all environments, the degree of SFR suppression increases with increasing bulge-to-total (B/T) ratio. In addition, the SFRs of cluster and infall galaxies at a fixed mass are more suppressed than their field counterparts at all values of B/T. These results suggest a quenching mechanism that is linked to bulge growth that operates in all environments and an additional mechanism that further reduces the SFRs of galaxies in dense environments. We limit the sample to B/T ≤ 0.3 galaxies to control for the trends with morphol...
Interest in engineering at early stages of the educational career is one important precursor to c... more Interest in engineering at early stages of the educational career is one important precursor to choosing to study engineering in college, and engineeringrelated clubs are designed to foster such interest and diversify the engineering pipeline. In this study, the researchers employed a social cognitive career theory framework to examine level of interest in studying engineering and expected educational attainment among underrepresented low-income middle and high school students participating in materials science and engineering (MSE) clubs. Questionnaire data were collected from over 200 MSE club participants in low-income public middle and high schools in Puerto Rico. The results indicate that perceived value of engineering is useful in predicting career interest among underrepresented middle and high school students; however, traditional predictors of educational interests and attainment (gender, mother's education, parent expectations) exert the strongest influence on engineering interest and attainment expectations.
arXiv: Instrumentation and Methods for Astrophysics, 2019
The NSF-sponsored Undergraduate ALFALFA Team (UAT) promotes long-term collaborative research oppo... more The NSF-sponsored Undergraduate ALFALFA Team (UAT) promotes long-term collaborative research opportunities for faculty and students from 23 U.S. public and private primarily undergraduate institutions (PUIs) within the context of the extragalactic ALFALFA HI blind legacy survey project. Over twelve project years of partnering with Arecibo and Green Bank Observatories, the UAT has had a demonstrable impact on the health of a legacy astronomy project, science education, and equity/inclusion in astronomy, with successful outcomes for 373 UAT students (39% women; ~30% members of underrepresented groups) and 34 faculty (44% women). The UAT model is adaptable to many large scientific projects and can be supported by relatively modest funding. We recommend that granting agencies identify funding resources to support the model, either as an add-on to legacy grant support or as a stand-alone funding source. This could include encouragement of UAT-like components in large scale projects curre...
We present the Electricity and Magnetism Conceptual Assessment (EMCA), a new assessment aligned w... more We present the Electricity and Magnetism Conceptual Assessment (EMCA), a new assessment aligned with second-semester introductory physics courses. Topics covered include electrostatics, electric fields, circuits, magnetism, and induction. We have two motives for writing a new assessment. First, we find other assessments such as the Brief Electricity and Magnetism Assessment and the Conceptual Survey on Electricity and Magnetism not well aligned with the topics and content depth of our courses. We want to test introductory physics content at a level appropriate for our students. Second, we want the assessment to yield scores and gains comparable to the widely used Force Concept Inventory (FCI). After five testing and revision cycles, the assessment was finalized in early 2015 and is available online. We present performance results for a cohort of 225 students at Siena College who were enrolled in our algebra-and calculus-based physics courses during the spring 2015 and 2016 semesters. We provide pretest, post-test, and gain analyses, as well as individual question and whole test statistics to quantify difficulty and reliability. In addition, we compare EMCA and FCI scores and gains, and we find that students' FCI scores are strongly correlated with their performance on the EMCA. Finally, the assessment was piloted in an algebra-based physics course at George Washington University (GWU). We present performance results for a cohort of 130 GWU students and we find that their EMCA scores are comparable to the scores of students in our calculus-based physics course.
We present the catalog of ∼31500 extragalactic HI line sources detected by the completed ALFALFA ... more We present the catalog of ∼31500 extragalactic HI line sources detected by the completed ALFALFA survey out to z < 0.06 including both high signal-to-noise ratio (> 6.5) detections and ones of lower quality which coincide in both position and recessional velocity with galaxies of known redshift. We review the observing technique, data reduction pipeline, and catalog construction process, focusing on details of particular relevance to understanding the catalog's compiled parameters. We further describe and make available the digital HI line spectra associated with the catalogued sources. In addition to the extragalactic HI line detections, we report nine confirmed OH megamasers and ten OH megamaser candidates at 0.16 < z < 0.22 whose OH line signals are redshifted into the ALFALFA frequency band. Because of complexities in data collection and processing associated with the use of a feed-horn array on a complex single-dish antenna in the terrestrial radio frequency interference environment, we also present a list of suggestions and caveats for consideration by users of the ALFALFA extragalactic catalog for future scientific investigations.
We present Hubble Space T elescope (HST) Wide Field Planetary Camera 2 (WFPC2) data on the large-... more We present Hubble Space T elescope (HST) Wide Field Planetary Camera 2 (WFPC2) data on the large-scale environments of 16 0.39 < z < 0.51 quasars from the Large Bright Quasar Survey (LBQS). The LBQS quasars are representative of the radio-quiet population, and this is the first look at their large-scale environments. We compare the LBQS environments with the environments of 27 0.15 < z < 0.55 quasars selected from the HST Archive. The majority of the Archive quasars are from the PG and PKS surveys, and these quasars are more luminous on average than the LBQS. By comparing the LBQS and Archive environments, we investigate whether previous quasar environment studies have been biased due to studying unusually radio or optically luminous quasars. We compare observed galaxy number counts with expected counts predicted from the CNOC2 field-galaxy luminosity function in order to look for statistical excesses of galaxies around the quasars. We detect a significant excess around the Archive quasars but find no such excess around the LBQS quasars. We calculate the amplitude of the spatial correlation function and find that the LBQS environments are consistent with that of the typical galaxy while the Archive environments are slightly
Publications of the Astronomical Society of the Pacific, 2001
Wide-field-of-view infrared cameras, operating on the new generation of large telescopes, offer u... more Wide-field-of-view infrared cameras, operating on the new generation of large telescopes, offer unprecedented gains in the detection of faint sources and in observing efficiency for both direct imaging and spectroscopy. With a pixel, 1-2.5 mm detector, the PISCES camera provides 8Ј .5 and 3Ј .16 fields 1024 # 1024 at the 2.3 m Bok telescope and 6.5 m Multiple Mirror Telescope, respectively. Its refractive optics utilize all spherical surfaces and standard glasses. A cold pupil stop suppresses the thermal background produced by the emissive surfaces normally present in Cassegrain optical configurations. The optical design is directly extendable to wider fields with larger detector formats. Future upgrades include low-resolution (-500) multiobject R p 200 spectroscopy.
We tested the effectiveness on learning of hands-on, night-time laboratories that challenged stud... more We tested the effectiveness on learning of hands-on, night-time laboratories that challenged student misconceptions in a non-major introductory astronomy class at Rensselaer Polytechnic Institute. We present a new assessment examination used to assess learning in this study. We were able to increase learning, at the 8.0 sigma level, on one of the moon phase objectives that was addressed in a cloudy night activity. There is weak evidence of some improvement on a broader range of learning objectives. We show evidence that the overall achievement levels of the four sections of the class is correlated with the amount of clear whether the sections had for observing, even though the learning objectives were addressed primarily in activities that did not require clear skies. This last result should be confirmed with future studies. We describe our first attempt to cycle the students through different activity stations in an attempt to handle 18 students at a time in the laboratories, and lessons learned from this.
II. Molecular gas in galaxy clusters and their large-scale structure: low gas fraction galaxies, ... more II. Molecular gas in galaxy clusters and their large-scale structure: low gas fraction galaxies, the case of CL1301.7−1139
Virgo is the nearest galaxy cluster; it is thus ideal for studies of galaxy evolution in dense en... more Virgo is the nearest galaxy cluster; it is thus ideal for studies of galaxy evolution in dense environments in the local universe. It is embedded in a complex filamentary network of galaxies and groups, which represents the skeleton of the large-scale Laniakea supercluster. Here we assemble a comprehensive catalog of galaxies extending up to ∼12 virial radii in projection from Virgo to revisit the cosmic-web structure around it. This work is the foundation of a series of papers that will investigate the multiwavelength properties of galaxies in the cosmic web around Virgo. We match spectroscopically confirmed sources from several databases and surveys including HyperLeda, NASA Sloan Atlas, NASA/IPAC Extragalactic Database, and ALFALFA. The sample consists of ∼7000 galaxies. By exploiting a tomographic approach, we identify 13 filaments, spanning several megaparsecs in length. Long >17 h –1 Mpc filaments, tend to be thin (<1 h –1 Mpc in radius) and with a low-density contrast (...
We present an HI-optical catalog of ∼ 30,000 galaxies based on the 100% complete Arecibo Legacy F... more We present an HI-optical catalog of ∼ 30,000 galaxies based on the 100% complete Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) survey combined with data from the Sloan Digital Sky Survey (SDSS). Our goal is to facilitate public use of the completed ALFALFA catalog by providing carefully determined matches to SDSS counterparts, including matches for ∼ 12,000 galaxies that do not have SDSS spectra. These identifications can provide a basis for further cross-matching with other surveys using SDSS photometric IDs as a reference point. We derive absolute magnitudes and stellar masses for each galaxy using optical colors combined with an internal reddening correction designed for small-and intermediate-mass galaxies with active star formation. We also provide measures of stellar masses and star formation rates based on infrared and/or ultraviolet photometry for galaxies that are detected by the Wide-field Infrared Survey Explorer (WISE) and/or the Galaxy Evolution Explorer (GALEX). Finally, we compare the galaxy population in the ALFALFA-SDSS sample with the populations in several other publicly-available galaxy catalogs, and confirm that ALFALFA galaxies typically have lower masses and bluer colors.
We present results from a low-resolution spectroscopic survey for 21 galaxy clusters at 0.4<z<... more We present results from a low-resolution spectroscopic survey for 21 galaxy clusters at 0.4<z<0.8 selected from the ESO Distant Cluster Survey. We measured spectra using the low-dispersion prism in IMACS on the Magellan Baade telescope and calculate redshifts with an accuracy of σ z =0.007. We find 1763 galaxies that are brighter than R=22.9 in the large-scale cluster environs. We identify the galaxies expected to be accreted by the clusters as they evolve to z=0 using spherical infall models and find that ∼30%-70% of the z=0 cluster population lies outside the virial radius at z∼0.6. For analogous clusters at z=0, we calculate that the ratio of galaxies that have fallen into the clusters since z∼0.6 to those that were already in the core at that redshift is typically between ∼0.3 and 1.5. This wide range of ratios is due to intrinsic scatter and is not a function of velocity dispersion, so a variety of infall histories is to be expected for clusters with current velocity dispersions of 300 km s −1 σ1200 km s −1. Within the infall regions of z∼0.6 clusters, we find a larger red fraction of galaxies than in the field and greater clustering among red galaxies than blue. We interpret these findings as evidence of "preprocessing," where galaxies in denser local environments have their star formation rates affected prior to their aggregation into massive clusters, although the possibility of backsplash galaxies complicates the interpretation.
The goal of the Local Cluster Survey is to look for evidence of environmentally driven quenching ... more The goal of the Local Cluster Survey is to look for evidence of environmentally driven quenching among starforming galaxies in nearby galaxy groups and clusters. Quenching is linked with environment and stellar mass, and much of the current observational evidence comes from the integrated properties of galaxies. However, the relative size of the stellar and star-forming disk is sensitive to environmental processing and can help identify the mechanisms that lead to a large fraction of quenched galaxies in dense environments. Toward this end, we measure the size of the star-forming disks for 224 galaxies in nine groups and clusters (0.02 < z < 0.04; SFR > 0.1 M e yr −1) using 24 μm imaging from the Spitzer Space Telescope. We normalize the 24 μm effective radius (R 24) by the size of the stellar disk (R d). We find that star-forming galaxies with higher bulge-to-total ratios (B/T) and galaxies in more dense environments have more centrally concentrated star formation. Comparison with H I mass fractions and NUV−r colors indicates that a galaxy's transition from gas-rich and blue to depleted and red is accompanied by an increase in the central concentration of star formation. We build a simple model to constrain the timescale over which the star-forming disks shrink in the cluster environment. Our results are consistent with a long-timescale (>2 Gyr) mechanism that produces outside-in quenching, such as the removal of the extended gas halo or weak stripping of the cold disk gas.
We present a detailed study of the colours of late-type galaxy discs for ten of the EDisCS galaxy... more We present a detailed study of the colours of late-type galaxy discs for ten of the EDisCS galaxy clusters with 0.5 z 0.8. Our cluster sample contains 172 spiral galaxies, and our control sample is composed of 96 field disc galaxies. We deconvolved their ground-based V and I images obtained with FORS2 at the VLT with initial spatial resolutions between 0.4 and 0.8 arcsec to achieve a final resolution of 0.1 arcsec with 0.05 arcsec pixels, which is close to the resolution of the ACS at the HST. After removing the central region of each galaxy to avoid pollution by the bulges, we measured the V − I colours of the discs. We find that 50% of cluster spiral galaxies have disc V − I colours redder by more than 1σ of the mean colours of their field counterparts. This is well above the 16% expected for a normal distribution centred on the field disc properties. The prominence of galaxies with red discs depends neither on the mass of their parent cluster nor on the distance of the galaxies to the cluster cores. Passive spiral galaxies constitute 20% of our sample. These systems are not abnormally dusty. They are are made of old stars and are located on the cluster red sequences. Another 24% of our sample is composed of galaxies that are still active and star forming, but less so than galaxies with similar morphologies in the field. These galaxies are naturally located in the blue sequence of their parent cluster colour-magnitude diagrams. The reddest of the discs in clusters must have stopped forming stars more than ∼5 Gyr ago. Some of them are found among infalling galaxies, suggesting preprocessing. Our results confirm that galaxies are able to continue forming stars for some significant period of time after being accreted into clusters, and suggest that star formation can decline on seemingly long (1 to 5 Gyr) timescales.
We present Hα-derived star-formation rates for the z = 0.845 galaxy cluster CL J0023+0423B and de... more We present Hα-derived star-formation rates for the z = 0.845 galaxy cluster CL J0023+0423B and demonstrate that near-infrared, narrow-band Hα imaging is a powerful way to sample the entire star-forming and post-starburst galaxy population in distant clusters. Comparison with spectroscopy shows that the number of false detections is low, and our Hα equivalent widths show reasonable correlation with spectroscopically determined [O II] equivalent widths. We compare the number of star-forming galaxies detected in our narrow-band images with the number found by a previously published spectroscopic survey and estimate that the spectroscopic survey is missing over 60% of star-forming galaxies in this cluster. Results on our entire sample of seven z ≅ 0.8 clusters will be published in the near future, and we will be able to form a more comprehensive picture of the star-formation properties of z ≅ 0.8 galaxy clusters.
Using a sample of 299 Hα-selected galaxies at z ≈ 0.8, we study the relationship between galaxy s... more Using a sample of 299 Hα-selected galaxies at z ≈ 0.8, we study the relationship between galaxy stellar mass, gas-phase metallicity, and star formation rate (SFR), and compare to previous results. We use deep optical spectra obtained with the IMACS spectrograph at the Magellan telescope to measure strong oxygen lines. We combine these spectra and metallicities with (1) rest-frame UV-tooptical imaging, which allows us to determine stellar masses and dust attenuation corrections, and (2) Hα narrowband imaging, which provides a robust measure of the instantaneous SFR. Our sample spans stellar masses of ∼10 9 to 6 × 10 11 M ⊙ , SFRs of 0.4 to 270 M ⊙ yr −1 , and metal abundances of 12 + log(O/H) ≈ 8.3-9.1 (≈ 0.4-2.6 Z ⊙). The correlations that we find between the Hα-based SFR and stellar mass (i.e., the star-forming "main sequence"), and between the stellar mass and metallicity, are both consistent with previous z ∼ 1 studies of star-forming galaxies. We then study the relationship between the three properties using various plane-fitting techniques (Lara-López et al.) and a curve-fitting projection (Mannucci et al.). In all cases, we exclude strong dependence of the M ⋆-Z relation on SFR, but are unable to distinguish between moderate and no dependence. Our results are consistent with previous mass-metallicity-SFR studies. We check whether dataset limitations may obscure a strong dependence on the SFR by using mock samples drawn from the SDSS. These experiments reveal that the adopted signal-to-noise cuts may have a significant effect on the measured dependence. Further work is needed to investigate these results, and to test whether a "fundamental metallicity relation" or a "fundamental plane" describes star-forming galaxies across cosmic time.
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Papers by Rose Finn