arXiv subjects

Beena Meena

Publications and source records attributed to Beena Meena.

14 recordsLinked to original sources

arXiv2026

An Analysis of AGN Feedback in the Compact Galaxy Group Stephan's Quintet

Compact galaxy groups are ideal laboratories for studying the effects of interactions between AGN and multiple nearby galaxies. Recent JWST observations of the nearby compact group Stephan's Quintet highlight tidal flows between the interacting galaxies as well as outflows from the active galaxy NGC 7319. To study the kinematics on a large scale throughout the group, we obtained spatially-resolved long-slit spectra of Stephan's Quintet at multiple slit positions with Apache Point Observatory's Kitt Peak Ohio State Multi-Object Spectrograph. We fit multiple Gaussians to the H$\alpha$ $\lambda$6563 \r{A} and [N II] $\lambda\lambda$6548, 6583 \r{A} emission lines to isolate the different kinematic components. We used the kinematics to develop the first biconical outflow model of the narrow-line region of NGC 7319. Using a combination of galactic rotation models, biconical outflow models, and kinematic maps of the ionized gas, we disentangled the outflows, rotation, and tidal flows in the group. We found outflow radial velocities up to 550 km s$^{-1}$ peaking at 2.6 kpc from the central supermassive black hole, and a transition from AGN-powered outflows to gravitationally-powered tidal flows at a projected distance between 2.4 -- 6.3 kpc. We performed a line ratio analysis and determined the gas shows Seyfert-like ionization out to 6.3 kpc (projected), which supports our finding that gas outside this radius is predominantly powered by tidal flows. Our separation of kinematic components in Stephan's Quintet will enable future studies of the physical conditions and dynamical forces in the ionized gas to better quantify the feeding and feedback processes of AGN in compact groups.

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arXiv2025

Isolated massive star candidates in NGC 4242 with GULP

$\textit{Context.}$ There is considerable debate on how massive stars form, including whether a high-mass star must always form with a population of low-mass stars or whether it can also form in isolation. Massive stars found in the field are often considered to be runaways from star clusters or OB associations. However, there is evidence in the Milky Way and the Small Magellanic Cloud of high-mass stars that appear isolated in the field and cannot be related to any known star cluster or OB association. Studies of more distant galaxies have been lacking so far. $\textit{Aims.}$ In this work, we identified massive star candidates that appear isolated in the field of the nearby spiral galaxy NGC 4242 (distance: 5.3 Mpc), to explore how many candidates for isolated star formation we find in a galaxy outside the Local Group. $\textit{Methods.}$ We identified 234 massive ($M_{ini}\geq15M_{\odot}$) and young ($\leq 10$ Myr) field stars in NGC 4242 using the Hubble Space Telescope's Solar Blind Channel of the Advanced Camera for Surveys, the UVIS channel of the Wide Field Camera 3 from the Galaxy UV Legacy Project (GULP) and optical data from the Legacy ExtraGalactic UV Survey (LEGUS). We investigated the surroundings of our targets within the range of projected distances expected for runaway stars, $74$ pc and $204$ pc. $\textit{Results.}$ We find that between $9.8\%$ and $34.6\%$ of our targets have no young stellar groups or massive stars within the threshold radii, making them appear isolated. This fraction reduces to $3.2\%-11.5\%$ when we consider the total number of massive stars expected from the observed UV star formation rate. $\textit{Conclusions.}$ Our results show that there is a small population of young and massive, potentially isolated field stars in NGC 4242.

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arXiv2025

Spatially Resolved, Multiphase Mass Outflows of the Seyfert 1 Galaxy NGC 3227

We present spatially resolved mass outflow rates of the ionized and molecular gas in the narrow line region of the Seyfert 1 galaxy NGC 3227. Using long-slit spectroscopy and [O III] imaging from from Hubble Space Telescope's Space Telescope Imaging Spectrograph and Apache Point Observatory's Kitt Peak Ohio State Multi-Object Spectrograph, in conjunction with Cloudy photoionization models and emission line diagnostics, we find a peak ionized mass outflow rate of $\dot M_{\text{ion}} =$ $19.9\pm9.2$ M$_\odot$ yr$^{-1}$ at a distance of $47\pm6$ pc from the supermassive black hole (SMBH). Using archival data from the Gemini-North Near-infrared Field Spectrograph measuring H$_2$ $\lambda2.1218$ $\mu$m emission, we find a maximum peak warm molecular outflow rate of $\dot M_{\mathrm{H_2}} \le 9 \times 10^{-4}$ M$_\odot$ yr$^{-1}$ at a distance of $36\pm6$ pc from the SMBH. Using archival data from the Atacama Large Millimeter/submillimeter Array measuring CO(2-1) emission, we find a maximum peak cold molecular gas mass outflow rate of $\dot M_{\mathrm{CO}} \le$ $23.1$ M$_\odot$ year$^{-1}$ at a distance of $57\pm6$ pc from the SMBH. For the first time, we calculate spatially resolved gas evacuation timescales for the cold molecular gas reservoirs ostensibly sourcing the outflows, and find that evacuating gas to $\sim$400 pc from the SMBH occurs on timescales of $10^{6.0} - 10^{7.6}$ years. These results indicate that the multi-phase AGN outflows are effective in clearing the inner few hundred parsecs of NGC 3227's gas content on timescales that may set the AGN duty cycle of $10^5 - 10^8$ years.

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arXiv2025

Detection of a Deeply Embedded Protocluster Candidate in NGC 602 with JWST

JWST NIRCam and MIRI photometry of NGC 602, a low-metallicity young star cluster in the Small Magellanic Cloud, reveals an extended mid-infrared bright emission feature designated as MZS-1. This feature is prominent between 10 and 25.5 microns, but is extremely faint at 7.7 microns and entirely undetected at shorter wavelengths. MZS-1 exhibits an elliptical morphology with a major axis of approximately 8 arcseconds and a minor axis of about 4 arcseconds. Its elongated shape and multiple emission peaks in the two-dimensional flux map suggest a group of deeply embedded sources with blackbody-like temperatures ranging from 100 K to 140 K. SED fitting using the Robitaille 2017 model grids identifies these sources as Stage I young stellar objects (YSOs) with masses below approximately 3 solar masses and a total stellar mass of the protocluster of about 300 solar masses (based on a Salpeter IMF). The low YSO masses are consistent with their absence in Spitzer-based catalogs due to sensitivity limits. By revealing a deeply embedded, low-mass protocluster invisible in previous surveys, this work highlights JWST's unparalleled resolution and sensitivity in uncovering the earliest stages of low-mass cluster formation in the metal-poor regime.

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arXiv2025

The Shape of AGN-Driven Winds in the Seyfert Galaxy NGC 3516

Active galactic nuclei (AGN) are known to drive ionized gas into their host galaxies, which may affect the evolution of both the central supermassive black holes and their hosts. In the case of NGC 3516, a nearby Seyfert 1 galaxy, these AGN winds have historically proven difficult to disentangle from galactic rotation. Using long slit spectroscopy at multiple position angles from the Hubble Space Telescope Space Telescope Imaging Spectrograph and the Apache Point Observatory Kitt Peak Ohio State Multi Object Spectrograph, we separate these kinematic components by fitting multiple Gaussians to the H{\alpha}, N II, H{\beta}, and O III emission lines along the slits. We present a biconical outflow model that agrees well with the observed kinematics of the outflowing gas in the narrow-line region (NLR). Our results indicate that the structure of the O III emission is explained by dusty gas spirals in the galactic disk that are illuminated by the ionizing bicone, which is viewed along one edge, resulting in the complex nuclear kinematics. Our view into the bicone edge is consistent with the multiple, deep components of ionized absorption lines seen in UV and X-ray spectra of NGC 3516. The observed turnover in the velocity of the NLR clouds matches that from a simple dynamical model of radiative acceleration by the AGN and gravitational deceleration by the AGN and galaxy, indicating they are the principal forces at work on the gas clouds. Finally, the model launch radii indicate that the outflowing clouds originate primarily from the inner dusty spirals near the AGN.

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arXiv2025

GULP II: Hierarchical Distribution and Evolution of Young Stellar Structures in NGC 4449

We investigate the hierarchical distribution and evolution of young stellar structures in the dwarf starburst galaxy NGC 4449 using data from the GULP survey. By analyzing the spatial distribution of field stars younger than 100 Myr, we identify large-scale stellar complexes and substructures using HDBSCAN -- a density-based clustering algorithm -- and trace their evolution over time. While comparing these stellar structures in different regions of the galaxy, we find that the central bar-like region shows a clear expansion of the structures within the first $\sim$ 60 Myrs, while the arm-like structure in the NE shows no discernible trend, possibly due to external perturbations from tidal interactions with a neighboring galaxy. An age-dependent two point correlation function (TPCF) analysis shows that young stars exhibit a strong hierarchical distribution, with clustering strength decreasing over time. The power-law slope of the TPCF, which starts at $\alpha \sim 0.65$ for stars younger than 5 Myr, shows a slight decline to $\alpha \sim 0.4$ for stars older than 50 Myr, though it does not reach a completely flat (random) distribution. This trend indicates a subtle weakening of structural hierarchy among young ($<$100 Myr) stars, which is primarily driven by internal stellar motions. Future work will extend this analysis to the remaining 26 galaxies in the GULP survey to better constrain the role of the galactic environment in shaping the hierarchical evolution of young stellar populations.

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arXiv2025

Quantifying Feedback from Narrow Line Region Outflows in Nearby Active Galaxies. V. The Expanded Sample

We present spatially-resolved measurements of the ionized gas masses and mass outflow rates for six low-redshift ($z \leq$ 0.02) active galaxies. In this study, we expand our sample to galaxies with more complex gas kinematics modeled as outflows along a galactic disk that is ionized by the active galactic nucleus (AGN) bicone. We use Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) spectroscopy, Wide Field Camera 3 (WFC3) narrow-band imaging, and the photoionization modeling technique that we developed in Revalski et al. (2022) to calculate ionized gas masses using the [O III]/H$\beta$ ratios at each radius. We combine these with existing kinematic models to derive mass and energy outflow rates, which exhibit substantial radial variations due to changes in the outflow velocities. The full sample of 12 galaxies from this series of studies spans 10$^3$ in bolometric luminosity, and we find that the outflows contain ionized gas masses of $M \approx 10^{4.6} - 10^{7.2}$ $M_{\odot}$, reach maximum mass outflow rates of $\dot M_{out} \approx 0.1 - 13$ $M_{\odot}$ yr$^{-1}$, and encompass kinetic energies of $E \approx 10^{52} - 10^{56}$ erg. These energetic properties positively correlate with AGN luminosity. The outflow energetics are less than benchmarks for effective feedback from theoretical models, but the evacuation of gas and injection of energy may still generate long term effects on star-formation in these nearby galaxies. These results highlight the necessity of high spatial resolution imaging and spectroscopy for accurately modeling ionized outflows in active galaxies.

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arXiv2024

Determining the Extents, Geometries, and Kinematics of Narrow-Line Region Outflows in Nearby Seyfert Galaxies

Outflowing gas from supermassive black holes in the centers of active galaxies has been postulated as a major contributor to galactic evolution. To explore the interaction between narrow-line region (NLR) outflows and their host galaxies, we use Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) spectra and Wide Field Camera 3 (WFC3) images of 15 nearby (z < 0.02) active galactic nuclei (AGN) to determine the extents and geometries of their NLRs. We combine new HST WFC3 continuum and [O III] $\lambda$5007A images of 11 AGN with 4 archival AGN to match existing spectra from HST STIS. For the 6 AGN with suitable long-slit coverage of their NLRs, we use isophotal fitting of ground-based images, continuum-subtracted [O III] images, and the STIS spectra, to resolve, measure, and de-project the gas kinematics to the plane of the host galaxy disk and distinguish NLR outflows from galaxy rotation and/or kinematically disturbed gas. We find an average [O III] extent of $\sim$680pc with a correlation between gas extent and [O III] luminosity of R$_\mathrm{[O III]}$ $\propto$ L$_{\text{[O III]}}^{0.39}$. The measured extents depend strongly on the depth of the [O III] images, highlighting the importance of adopting uniform thresholds when analyzing scaling relationships. The outflows reach from 39-88% of the full NLR extents, and we find that all 6 of the AGN with STIS coverage of their entire NLRs show strong kinematic evidence for outflows, despite previous uncertainty for these AGN. This suggests that NLR outflows are ubiquitous in moderate luminosity AGN and that standard criteria for kinematic modeling are essential for identifying outflows.

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arXiv2024

An Analysis of AGN-Driven Outflows in the Seyfert 1 Galaxy NGC 3227

We have characterized the ionized, neutral, and warm molecular gas kinematics in the Seyfert 1 galaxy NGC 3227 using observations from the Hubble Space Telescope Space Telescope Imaging Spectrograph, Apache Point Observatory's Kitt Peak Ohio State Multi-Object Spectrograph, Gemini-North's Near-Infrared Integral Field Spectrometer, and the Atacama Large Millimeter Array. We fit multiple Gaussians to several spatially-resolved emission lines observed with long-slit and integral-field spectroscopy and isolate the kinematics based on apparent rotational and outflowing motions. We use the kinematics to determine an orientation for the bicone along which the outflows travel, and find that the biconical structure has an inclination of $40 ^{+5}_{-4}${\deg} from our line of sight, and a half-opening angle with an inner and outer boundary of $47 ^{+6}_{-2}${\deg} and $68 ^{+1}_{-1}${\deg}, respectively. We observe ionized outflows traveling 500 km s$^{-1}$ at distances up to 7$''$ (800 pc) from the SMBH, and disturbed ionized gas up to a distance of 15$''$ (1.7 kpc). Our analysis reveals that the ionized outflows are launched from within 20 pc of the SMBH, at the same location as a bridge of cold gas across the nucleus detected in ALMA CO(2-1) observations. We measure a turnover radius where the gas starts decelerating at a distance of $26 \pm 6$ pc from the AGN. Compared to a turnover radius in the range of $31- 63$ pc from a radiative driving model, we confirm that radiative driving is the dominant acceleration mechanism for the narrow line region (NLR) outflows in NGC 3227.

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arXiv2022

Investigating the Narrow Line Region Dynamics in Nearby Active Galaxies

We present dynamical models of the narrow line region (NLR) outflows in the nearby Seyfert galaxies Mrk 3, Mrk 78, NGC 1068, and NGC 4151 using observations from the Hubble Space Telescope and Apache Point Observatory. We employ long-slit spectroscopy to map the spatially-resolved outflow and rotational velocities of the ionized gas. We also perform surface brightness decompositions of host galaxy images to constrain the enclosed stellar mass distributions as functions of distance from the supermassive black holes (SMBHs). Assuming that the NLR gas is accelerated by AGN radiation pressure, and subsequently decelerated by the host galaxy and SMBH gravitational potentials, we derive outflow velocity profiles where the gas is launched in situ at multiple distances from the SMBH. We find a strong correlation between the turnover (from acceleration to deceleration) radii from our models, with the turnovers seen in the observed velocities and spatially-resolved mass outflow rates for the AGN with bolometric luminosities $>$ 10$^{44}$ erg sec$^{-1}$. This consistency indicates that radiation pressure is the dominant driving mechanism behind the NLR outflows in these moderate-luminosity AGN, with a force multiplier $\sim$500 yielding the best agreement between the modeled and observed turnover radii. However, in Meena2021 we found that this trend may not hold at lower luminosities, where our modeled turnover distance for NGC 4051 is much smaller than in the observed kinematics. This result may indicate that either additional force(s) are responsible for accelerating the NLR outflows in low-luminosity AGN, or higher spatial resolution observations are required to quantify their turnover radii.

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arXiv2022

Quantifying Feedback from Narrow Line Region Outflows in Nearby Active Galaxies. IV. The Effects of Different Density Estimates on the Ionized Gas Masses and Outflow Rates

Active galactic nuclei (AGN) can launch outflows of ionized gas that may influence galaxy evolution, and quantifying their full impact requires spatially resolved measurements of the gas masses, velocities, and radial extents. We previously reported these quantities for the ionized narrow-line region (NLR) outflows in six low-redshift AGN, where the gas velocities and extents were determined from Hubble Space Telescope long-slit spectroscopy. However, calculating the gas masses required multi-component photoionization models to account for radial variations in the gas densities, which span $\sim$6 orders of magnitude. In order to simplify this method for larger samples with less spectral coverage, we compare these gas masses with those calculated from techniques in the literature. First, we use a recombination equation with three different estimates for the radial density profiles. These include constant densities, those derived from [S II], and power-law profiles based on constant values of the ionization parameter ($U$). Second, we use single-component photoionization models with power-law density profiles based on constant $U$, and allow $U$ to vary with radius based on the [O III]/H$β$ ratios. We find that assuming a constant density of $n_\mathrm{H} =$ 10$^2$ cm$^{-3}$ overestimates the gas masses for all six outflows, particularly at small radii where the outflow rates peak. The use of [S II] marginally matches the total gas masses, but also overestimates at small radii. Overall, single-component photoionization models where $U$ varies with radius are able to best match the gas mass and outflow rate profiles when there are insufficient emission lines to construct detailed models.

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arXiv2021

Radiative Driving of the AGN Outflows in the Narrow-Line Seyfert 1 Galaxy NGC 4051

We explore the properties of ionized gas in the nuclear and circumnuclear environment of the narrow-line Seyfert 1 galaxy NGC 4051 using spectroscopic and imaging observations from the Hubble Space Telescope (HST) and Apache Point Observatory (APO)'s ARC 3.5m Telescope. We identify an unresolved moderate-density intermediate width component and a high-density broad component in the optical emission lines from the active nucleus, as well as spatially-resolved emission extending up to $\sim$1 kpc in the AGN ionized narrow-line region (NLR) and $\sim$8 kpc in the stellar ionized host galaxy. The HST narrow-band image reveals a distinct conical structure in [O III] emission towards the NE, and the ionized gas kinematics shows up to two blueshifted velocity components, indicating outflows along the edges of a cone. We introduce an improved model of biconical outflow, with our line of sight passing through the wall of the cone, which suggests that the large number of outflowing UV absorbers seen in NGC 4051 are NLR clouds in absorption. Using the de-projection factors from the biconical geometry, we measure true outflow velocities up to 680 km s$^{-1}$ at a distance of $\sim$350 pc, however, we do not find any rotational signature inside a projected distance $\leq$ 10'' ($\sim$800 pc) from the nucleus. We compare the gas kinematics with analytical models based on a radiation-gravity formalism, which show that most of the observed NLR outflows are launched within $\sim$0.5 pc of the nucleus and can travel up to $\sim$1 kpc from this low-luminosity AGN.

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arXiv2021

Quantifying Feedback from Narrow Line Region Outflows in Nearby Active Galaxies. III. Results for the Seyfert 2 Galaxies Markarian 3, Markarian 78, and NGC 1068

Outflows of ionized gas driven by active galactic nuclei (AGN) may significantly impact the evolution of their host galaxies. However, determining the energetics of these outflows is difficult with spatially unresolved observations that are subject to strong global selection effects. We present part of an ongoing study using Hubble Space Telescope (HST) and Apache Point Observatory (APO) spectroscopy and imaging to derive spatially-resolved mass outflow rates and energetics for narrow line region (NLR) outflows in nearby AGN that are based on multi-component photoionization models to account for spatial variations in the gas ionization, density, abundances, and dust content. This expanded analysis adds Mrk 3, Mrk 78, and NGC 1068, doubling the sample in Revalski (2019). We find that the outflows contain total ionized gas masses of $M \approx 10^{5.5} - 10^{7.5}$ $M_{\odot}$ and reach peak velocities of $v \approx 800 - 2000$ km s$^{-1}$. The outflows reach maximum mass outflow rates of $\dot M_{out} \approx 3 - 12$ $M_{\odot}$ yr$^{-1}$ and encompass total kinetic energies of $E \approx 10^{54} - 10^{56}$ erg. The outflows extend to radial distances of $r \approx 0.1 - 3$ kpc from the nucleus, with the gas masses, outflow energetics, and radial extents positively correlated with AGN luminosity. The outflow rates are consistent with in-situ ionization and acceleration where gas is radiatively driven at multiple radii. These radial variations indicate that spatially-resolved observations are essential for localizing AGN feedback and determining the most accurate outflow parameters.

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arXiv2021

Tully-Fisher Distances and Dynamical Mass Constraints for 24 Host Galaxies of Reverberation-Mapped AGN

We present Tully-Fisher distances for 24 AGN host galaxies with black hole mass ($M_\textrm{BH}$) measurements from reverberation mapping, as well as the first calibration of the $V-$band Tully-Fisher relation. Combining our measurements of HI 21cm emission with $HST$ and ground-based optical and near-infrared images allows multiple distance measurements for 19 galaxies and single measurements for the remaining 5. Separation of the nucleus from its host galaxy via surface brightness decomposition yields galaxy-only luminosities, thus allowing measurements of the distance moduli free of contamination from the AGN. For 14 AGN hosts, these are the first reported distances independent of redshift, and hence independent of peculiar velocities. For the remaining galaxies, we show good agreement between our distances and those previously reported from surface brightness fluctuations (SBF) and Cepheids. We also determine the total galaxy mass enclosed within the estimated HI radius, which when compared to the baryonic content allows for constraints on the dark matter masses. We find a typical mass fraction of $M_{\textrm{DM}}$/$M_{\textrm{DYN}}$ = 62\%, and find significant correlations between $M_{\textrm{BH}}$ $-$ $M_{\textrm{DYN}}$ and $M_{\textrm{BH}}$ $-$ $M_{\textrm{DM}}$. Finally, we scale our galaxy radii based on estimated relationships between visible and halo radii and assume a flat rotation curve out to the halo radius to approximate $M_{\textrm{HALO}}$. Over the range of $M_{\textrm{BH}}$ and $M_{\textrm{HALO}}$ in this sample, we find good agreement with observationally-constrained relationships between $M_{\textrm{BH}}$ and $M_{\textrm{HALO}}$ and with hydrodynamical simulations.

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