More Like this

1. Infall Profiles for Supercluster-scale Filaments

   https://doi.org/10.3847/1538-4357/ac815b  

   Odekon, Mary Crone ; Jones, Michael G. ; Graham, Lucas ; Kelley-Derzon, Jessica ; Halstead, Evan ( August 2022 , The Astrophysical Journal)

   We present theoretical expectations for infall toward supercluster-scale cosmological filaments, motivated by the Arecibo Pisces–Perseus Supercluster Survey (APPSS) to map the velocity field around the Pisces–Perseus Supercluster (PPS) filament. We use a minimum spanning tree applied to dark matter halos the size of galaxy clusters to identify 236 large filaments within the Millennium simulation. Stacking the filaments along their principal axes, we determine a well-defined, sharp-peaked velocity profile function that can be expressed in terms of the maximum infall rateV_maxand the distanceρ_maxbetween the location of maximum infall and the principal axis of the filament. This simple, two-parameter functional form is surprisingly universal across a wide range of linear mass densities.V_maxis positively correlated with the halo mass per length along the filament, andρ_maxis negatively correlated with the degree to which the halos are concentrated along the principal axis. We also assess an alternative, single-parameter method usingV₂₅, the infall rate at a distance of 25 Mpc from the axis of the filament. Filaments similar to the PPS have$V_{\max }=612\pm$116 km s⁻¹,${\rho }_{\max }=8.9\pm 2.1$Mpc, andV₂₅= 329 ± 68 km s⁻¹. We create mock observations to model uncertainties associated with viewing angle, lack of three-dimensional velocity information, limited sample size, and distance uncertainties. Our results suggest that it would be especially useful to measure infall for a larger sample of filaments to test our predictions for the shape of the infall profile and the relationships among infall rates and filament properties.

    

   more » « less
2. Surface Brightness Profile of Lyman-α Halos out to 320 kpc in HETDEX

   https://doi.org/10.3847/1538-4357/ac5cb8  

   Lujan Niemeyer, Maja ; Komatsu, Eiichiro ; Byrohl, Chris ; Davis, Dustin ; Fabricius, Maximilian ; Gebhardt, Karl ; Hill, Gary J. ; Wisotzki, Lutz ; Bowman, William P. ; Ciardullo, Robin ; et al ( April 2022 , The Astrophysical Journal)

   We present the median-stacked Lyman-α (Lyα) surface brightness profiles of 968 spectroscopically selected Lyαemitting galaxies (LAEs) at redshifts 1.9 <z< 3.5 in the early data of the Hobby-Eberly Telescope Dark Energy Experiment. The selected LAEs are high-confidence Lyαdetections with high signal-to-noise ratios observed with good seeing conditions (point-spread function FWHM <1.″4), excluding active galactic nuclei. The Lyαluminosities of the LAEs are 10^42.4–10⁴³erg s⁻¹. We detect faint emission in the median-stacked radial profiles at the level of$(3.6\pm 1.3)\times {10}^{-20}\mathrm{erg}{\mathrm{s}}^{-1}{\mathrm{cm}}^{-2}{\mathrm{arcsec}}^{-2}$from the surrounding Lyαhalos out tor≃ 160 kpc (physical). The shape of the median-stacked radial profile is consistent atr< 80 kpc with that of much fainter LAEs at 3 <z< 4 observed with the Multi Unit Spectroscopic Explorer (MUSE), indicating that the median-stacked Lyαprofiles have similar shapes at redshifts 2 <z< 4 and across a factor of 10 in Lyαluminosity. While we agree with the results from the MUSE sample atr< 80 kpc, we extend the profile over a factor of two in radius. Atr> 80 kpc, our profile is flatter than the MUSE model. The measured profile agrees at most radii with that of galaxies in the Byrohl et al. cosmological radiative transfer simulation atz= 3. This suggests that the surface brightness of a Lyαhalo atr≲ 100 kpc is dominated by resonant scattering of Lyαphotons from star-forming regions in the central galaxy, whereas atr> 100 kpc, it is dominated by photons from galaxies in surrounding dark matter halos.

    

   more » « less
3. On the Metallicities and Kinematics of the Circumgalactic Media of Damped Lyα Systems at z ∼ 2.5*

   https://doi.org/10.3847/1538-4357/acd34a  

   Urbano Stawinski, Stephanie M. ; Rubin, Kate H. R. ; Prochaska, J. Xavier ; Hennawi, Joseph F. ; Tejos, Nicolas ; Fumagalli, Michele ; Rafelski, Marc ; Kirby, Evan N. ; Lusso, Elisabeta ; Hafen, Zachary ( July 2023 , The Astrophysical Journal)

   We use medium- and high-resolution spectroscopy of close pairs of quasars to analyze the circumgalactic medium (CGM) surrounding 32 damped Lyαabsorption systems (DLAs). The primary quasar sightline in each pair probes an intervening DLA in the redshift range 1.6 <z_abs< 3.5, such that the secondary sightline probes absorption from Lyαand a large suite of metal-line transitions (including Oi, Cii, Civ, Siii, and Siiv) in the DLA host galaxy’s CGM at transverse distances 24 kpc ≤R_⊥≤ 284 kpc. Analysis of Lyαin the CGM sightlines shows an anticorrelation betweenR_⊥and Hicolumn density (N_HI) with 99.8% confidence, similar to that observed around luminous galaxies. The incidences of Ciiand SiiiwithN> 10¹³cm⁻²within 100 kpc of DLAs are larger by 2σthan those measured in the CGM of Lyman break galaxies (C_f(N_CII) > 0.89 and${\mathrm{C}}_f(N_{\mathrm{Si}\mathrm{II}})={0.75}_{-0.17}^{+0.12}$). Metallicity constraints derived from ionic ratios for nine CGM systems with negligible ionization corrections andN_HI> 10^18.5cm⁻²show a significant degree of scatter (with metallicities/limits across the range$-2.06\lesssim \log Z/Z_{\odot }\lesssim -0.75$), suggesting inhomogeneity in the metal distribution in these environments. Velocity widths of Civλ1548 and low-ionization metal species in the DLA versus CGM sightlines are strongly (>2σ) correlated, suggesting that they trace the potential well of the host halo overR_⊥≲ 300 kpc scales. At the same time, velocity centroids for Civλ1548 differ in DLA versus CGM sightlines by >100 km s⁻¹for ∼50% of velocity components, but few components have velocities that would exceed the escape velocity assuming dark matter host halos of ≥10¹²M_⊙.

    

   more » « less
4. Using Maximum Circular Velocity in Halo Occupation Distribution Models to Predict Galaxy Clustering

   https://doi.org/10.3847/2515-5172/ac67f3  

   Mezini, Lorena ; Wang, Kuan ; Mao, Yao-Yuan ; Zentner, Andrew R. ( April 2022 , Research Notes of the AAS)

   Standard halo occupation distribution (HOD) models predict how galaxies occupy halos based on a single property, the virial mass,M_vir. To incorporate galaxy assembly bias, we consider alternative halo mass proxies to use in the HOD. A promising replacement is maximum circular velocity,$V_{\max }$, which measures the halo’s potential well, and successfully predicts galaxy clustering in subhalo abundance matching models. We fit galaxy clustering measurements from SDSS DR7 with two modified HODs besides the standardM_vir-based model: one where$V_{\max }$is used as the halo property that determines galaxy occupation, and the other adopting an adjustable combination ofM_virand$V_{\max }$. Except for the reduced volumeM_r < − 20 threshold sample fit with$V_{\max }$alone, neither change improves the model performance in predicting the projected two-point correlation function,w_p. We conclude that switching the primary variable to$V_{\max }$does not significantly improve the HOD model’s ability to fit galaxy clustering.

    

   more » « less
5. Substructure at High Speed. II. The Local Escape Velocity and Milky Way Mass with Gaia eDR3

   https://doi.org/10.3847/1538-4357/ac4244  

   Necib, Lina ; Lin, Tongyan ( February 2022 , The Astrophysical Journal)

   Measuring the escape velocity of the Milky Way is critical in obtaining the mass of the Milky Way, understanding the dark matter velocity distribution, and building the dark matter density profile. In Necib & Lin, we introduced a strategy to robustly measure the escape velocity. Our approach takes into account the presence of kinematic substructures by modeling the tail of the stellar distribution with multiple components, including the stellar halo and the debris flow called the Gaia Sausage (Enceladus). In doing so, we can test the robustness of the escape velocity measurement for different definitions of the “tail” of the velocity distribution and the consistency of the data with different underlying models. In this paper, we apply this method to the Gaia eDR3 data release and find that a model with two components is preferred, although results from a single-component fit are also consistent. Based on a fit to retrograde data with two bound components to account for the relaxed halo and the Gaia Sausage, we find the escape velocity of the Milky Way at the solar position to be$v_{\mathrm{esc}}={445}_{-8}^{+25}$km s⁻¹. A fit with a single component to the same data gives$v_{\mathrm{esc}}={472}_{-12}^{+17}$km s⁻¹. Assuming a Navarro−Frenck−White dark matter profile, we find a Milky Way concentration of$c_{200}={19}_{-7}^{+11}$and a mass of$M_{200}={4.6}_{-0.8}^{+1.5}\times {10}^{11}{M}_{\odot }$, which is considerably lighter than previous measurements.

    

   more » « less