arXiv subjects

Nandini Sahu

Publications and source records attributed to Nandini Sahu.

15 recordsLinked to original sources

arXiv2026

Most Strong Lensing Deflectors in the AGEL Survey Are in Group and Cluster Environments

The environments of deflectors in strong lensing systems affect our ability to test cosmological models and constrain evolutionary properties of galaxies. Here we measure the deflector scale (Einstein mass) and deflector environment (halo mass) of 89 spectroscopically confirmed strong lenses in the ASTRO3D Galaxy Evolution With Lenses (AGEL) survey. We classify deflector scale by measuring $θ_{\rm{E}}$ to determine the mass enclosed by the Einstein radius, $M(<θ_{\rm{E}})$. We quantify deflector environment by using photometric redshifts to determine the galaxy surface density to the fifth-nearest neighbor $Σ_5(z)$. We find that 47.2% of our deflectors are embedded in cluster environments, whereas only 9.0% have cluster-scale Einstein radii (masses). We measure a weak correlation ($r = 0.38$) between Einstein mass and $Σ_5(z)$, suggesting that the assumption of single galaxy-scale deflectors in lens modeling is overly-simplified. We hypothesize that the weak correlation results from galaxy-scale bias in the original AGEL selection and the observational challenge of detecting faint arcs with large Einstein radii. Comparing number densities, $N_{\rm{gal}}$, between AGEL and control fields, we find that AGEL deflectors are in systematically denser environments. Our study provides a method to identify strong lenses as a function of deflector environment and approximate the impact of large-scale environment in lens modeling. We provide the measured lensing parameters for our 89 AGEL systems as well as $z_{\rm{phot}}$ and $r$-mag (AB) maps of the line-of-sight.

astro-ph.GA↗

arXiv2026

The Carousel Lens I: A Spectroscopic Survey of the Carousel Lens Field

We present a spectroscopic survey of field galaxies and lensed sources in the vicinity of the strong lensing galaxy cluster known as the Carousel lens at z=0.49. Using both Gemini/GMOS slitmask spectra and deep VLT/MUSE observations, we bring the total number of lensed sources up to 12, including three which were not previously known from imaging observations but are apparent in the MUSE data as emission-line sources. Of these sources, 10 have confident redshifts, and an additional 2 have tentative redshifts from likely Ly$\alpha$ emission (including seven new redshifts determined here adding to those presented previously in \cite{Sheu.Cikota.ea2024}). In total, we identify 42 images of these 12 sources. This lens system is remarkably symmetric and well-modeled by a simpler lens model than typical cluster lenses, and the large number of sources and their large range of redshifts make this cluster ideal for constraining cosmological parameters such as $w$ and $\Omega_m$ as well as the cluster density profile. Additionally, we present a catalog of 57 unlensed field galaxies with confident redshifts, of which 49 are associated with the cluster. We measure a cluster velocity dispersion of about 1100 km s$^{-1}$ from which we estimate a halo mass $M_{200c} \sim 1.2 \times 10^{15} M_\odot$.

astro-ph.GA↗

arXiv2025

Constraining Cosmology with Double-source-plane Strong Gravitational Lenses from the AGEL Survey

Double-source-plane strong gravitational lenses (DSPLs), with two sources at different redshifts, are independent cosmological probes of the dark energy equation of state parameter $w$ and the matter density parameter $Ω_{\rm m}$. We present the lens model for the DSPL AGEL035346$-$170639 and infer cosmological constraints from this system for flat $Λ$ cold dark matter and flat $w$CDM cosmologies. From the joint posterior of $w$ and $Ω_{\rm m}$ in the flat $w$CDM cosmology, we extract the following median values and 1$σ$ uncertainties: $w = -1.52^{+0.49}_{-0.33}$ and $Ω_{\rm m} = 0.192^{+0.305}_{-0.131}$ from AGEL0353 alone. Combining our measurements with two previously analyzed DSPLs, we present the joint constraint on these parameters from a sample of three, the largest galaxy-scale DSPL sample used for cosmological measurement to date. The combined precision of $w$ from three DSPLs is higher by 15% over AGEL0353 alone. Combining DSPL and cosmic microwave background (CMB) measurements improves the precision of $w$ from CMB-only constraints by 39%, demonstrating the complementarity of DSPLs with the CMB. Despite their promising constraining power, DSPLs are limited by sample size, with only a handful discovered so far. Although ongoing and near-future wide-area sky surveys will increase the number of known DSPLs by up to two orders of magnitude, these systems will still require dedicated high-resolution imaging and spectroscopic follow-ups like those presented in this paper. Our ASTRO 3D Galaxy Evolution with Lenses collaboration is undertaking such follow-up campaigns for several newly discovered DSPLs and will provide cosmological measurements from larger samples of DSPLs in the future.

astro-ph.CO↗

arXiv2025

Cosmography with the Double Source Plane Strong Gravitational Lens AGEL150745+052256

Strong gravitational lenses with two background sources at widely separated redshifts are a powerful and independent probe of cosmological parameters. We can use these systems, known as Double-Source-Plane Lenses (DSPLs), to measure the ratio ($β$) of angular-diameter distances of the sources, which is sensitive to the matter density ($Ω_m$) and the equation-of-state parameter for dark-energy ($w$). However, DSPLs are rare and require high-resolution imaging and spectroscopy for detection, lens modeling, and measuring $β$. Here we report only the second DSPL ever used to measure cosmological parameters. We model the DSPL AGEL150745+052256 from the ASTRO 3D Galaxy Evolution with Lenses (AGEL) survey using HST/WFC3 imaging and Keck/KCWI spectroscopy. The spectroscopic redshifts for the deflector and two sources in AGEL1507 are $z_{\rm defl}=0.594$, $z_{\rm S1}=2.163$, and $z_{\rm S2}=2.591$. We measure a stellar velocity dispersion of $σ_{\rm obs}=109 \pm 27$ km s$^{-1}$ for the nearer source. Using $σ_{\rm obs}$ for the main deflector (from literature) and S1, we test the robustness of our DSPL model. We measure $β=0.953^{+0.008}_{-0.010}$ for AGEL1507 and infer $Ω_{\rm m}=0.33^{+0.38}_{-0.23}$ for $Λ$CDM cosmology. Combining AGEL1507 with the published model of the Jackpot lens improves the precision on $Ω_{\rm m}$ ($Λ$CDM) and w (wCDM) by $\sim 10 \%$. The inclusion of DSPLs significantly improves the constraints when combined with Plancks cosmic microwave background observations, enhancing precision on w by $30 \%$. This paper demonstrates the constraining power of DSPLs and their complementarity to other standard cosmological probes. Tighter future constraints from larger DSPL samples discovered from ongoing and forthcoming large-area sky surveys would provide insights into the nature of dark energy.

astro-ph.CO↗

arXiv2025

The AGEL Survey Data Release 2: A Gravitational Lens Sample for Galaxy Evolution and Cosmology

The ASTRO 3D Galaxy Evolution with Lenses (AGEL) Survey is an ongoing effort to spectroscopically confirm a diverse sample of gravitational lenses with high spatial resolution imaging, to facilitate a broad range of science outcomes. The AGEL systems span single galaxy-scale deflectors to groups and clusters, and include rare targets such as galaxy-scale lenses with multiple sources, lensed quiescent galaxies, and Einstein rings. We build on the 77 systems presented in Tran et al. 2022 (AGEL data release 1) to present a total 138 lenses, and high resolution F140W and F200LP Hubble Space Telescope images for 71 lenses from a completed HST SNAP program. Lens candidates were originally identified by convolutional neural networks in the DES and DECaLS imaging fields, and of the targets with follow-up spectroscopy we find a high (96%) success rate. Compared with other spectroscopic lens samples, AGEL lenses tend to have both higher redshift deflectors and sources. We briefly discuss the common causes of false-positive candidates, and strategies for mitigating false-positives in next generation lens searches. Lastly, we present 6 galaxy-scale double-source plane lenses useful for cosmological analyses. With next-generation telescopes and surveys such as Euclid, Vera Rubin's Legacy Survey of Space and Time, Keck Observatory's KAPA program, and 4MOST's 4SLSLS surveys on the horizon, the AGEL survey represents a pathfinder for refining automated candidate search methods and identifying and triaging candidates for followup based on scientific potential.

astro-ph.GA↗

arXiv2024

Gravitational Lensing Reveals Cool Gas within 10-20 kpc around a Quiescent Galaxy

While quiescent galaxies have comparable amounts of cool gas in their outer circumgalactic medium (CGM) compared to star-forming galaxies, they have significantly less interstellar gas. However, open questions remain on the processes causing galaxies to stop forming stars and stay quiescent . Theories suggest dynamical interactions with the hot corona prevent cool gas from reaching the galaxy, therefore predicting the inner regions of quiescent galaxy CGMs are devoid of cool gas. However, there is a lack of understanding of the inner regions of CGMs due to the lack of spatial information in quasar-sightline methods. We present integral-field spectroscopy probing 10--20~kpc (2.4--4.8 R\textsubscript{e}) around a massive quiescent galaxy using a gravitationally lensed star-forming galaxy. We detect absorption from Magnesium (MgII) implying large amounts of cool atomic gas (10\textsuperscript{8.4} -- 10\textsuperscript{9.3} M\textsubscript{$\odot$} with T$\sim$10\textsuperscript{4} Kelvin), in comparable amounts to star-forming galaxies. Lens modeling of Hubble imaging also reveals a diffuse asymmetric component of significant mass consistent with the spatial extent of the MgII absorption, and offset from the galaxy light profile. This study demonstrates the power of galaxy-scale gravitational lenses to not only probe the gas around galaxies, but to also independently probe the mass of the CGM due to it's gravitational effect.

astro-ph.GA↗

arXiv2024

AGEL: Is the Conflict Real? Investigating Galaxy Evolution Models using Strong Lensing at 0.3 < z < 0.9

Observed evolution of the total mass distribution with redshift is crucial to testing galaxy evolution theories. To measure the total mass distribution, strong gravitational lenses complement the resolved dynamical observations currently limited to $z \lesssim 0.5$. Here we present the lens models for a pilot sample of seven galaxy-scale lenses from the ASTRO3D Galaxy Evolution with Lenses (AGEL) survey. The AGEL lenses, modeled using HST/WFC3-F140W images with Gravitational Lens Efficient Explorer (GLEE) software, have deflector redshifts between $0.3 < z_{\rm defl} < 0.9$. Assuming a power-law density profile with slope $γ$, we measure the total density profile for the deflector galaxies via lens modeling. We also measure the stellar velocity dispersions ($σ_{\rm obs}$) for four lenses and obtain $σ_{\rm obs}$ from SDSS-BOSS for the remaining lenses to test our lens models by comparing observed and model-predicted velocity dispersions. For the seven AGEL lenses, we measure an average density profile slope of $-1.95 \pm 0.09$ and a $γ$--$z$ relation that does not evolve with redshift at $z<1$. Although our result is consistent with some observations and simulations, it differs from other studies at $z<1$ that suggest the $γ$--$z$ relation evolves with redshift. The apparent conflicts among observations and simulations may be due to a combination of 1) systematics in the lensing and dynamical modeling; 2) challenges in comparing observations with simulations; and 3) assuming a simple power-law for the total mass distribution. By providing more lenses at $z_{\rm defl} > 0.5$, the AGEL survey will provide stronger constraints on whether the mass profiles evolve with redshift as predicted by current theoretical models.

astro-ph.GA↗

arXiv2023

Reading the tea leaves in the $M_{\rm bh}$-$M_{\rm *,sph}$ and $M_{\rm bh}$-$R_{\rm e,sph}$ diagrams: dry and gaseous mergers with remnant angular momentum

We recently revealed that bulges and elliptical galaxies broadly define distinct, super-linear relations in the $M_{\rm bh}$-$M_{\rm *,sph}$ diagram, with the order-of-magnitude lower $M_{\rm bh}/M_{\rm *,sph}$ ratios in the elliptical galaxies due to major (disc-destroying, elliptical-building) dry mergers. Here we present a more nuanced picture. Galaxy mergers, in which the net orbital angular momentum does not cancel, can lead to systems with a rotating disc. This situation can occur with either wet (gas-rich) mergers involving one or two spiral galaxies, e.g., NGC~5128, or dry (relatively gas-poor) collisions involving one or two lenticular galaxies, e.g., NGC~5813. The spheroid and disc masses of the progenitor galaxies and merger remnant dictate the shift in the $M_{\rm bh}$-$M_{\rm *,sph}$ and $M_{\rm bh}$-$R_{\rm e,sph}$ diagrams. We show how this explains the (previously excluded merger remnant) Sersic S0 galaxies near the bottom of the elliptical sequence and core-Sersic S0 galaxies at the top of the bulge sequence, neither of which are faded spiral galaxies. Different evolutionary pathways in the scaling diagrams are discussed. We also introduce two ellicular (ES) galaxy types, explore the location of brightest cluster galaxies and stripped `compact elliptical' galaxies in the $M_{\rm bh}$-$M_{\rm *,sph}$ diagram, and present a new merger-built $M_{\rm bh}$-$M_{\rm *,sph}$ relation which may prove helpful for studies of nanohertz gravitational waves. This work effectively brings into the fold many systems previously considered outliers with either overly massive or undermassive black holes relative to the near-linear $M_{\rm bh}$-$M_{\rm *,sph}$ `red sequence' patched together with select bulges and elliptical galaxies.

astro-ph.GA↗

arXiv2022

The size--mass and other structural parameter ($n, μ_z, R_z$) relations for local bulges/spheroids from multicomponent decompositions

We analyse the bulge/spheroid size-(stellar mass), $R_{\rm e,Sph}-M_{\rm *,Sph}$, relation and spheroid structural parameters for 202 local (predominantly $\lesssim 110~\rm Mpc$) galaxies spanning $ M_*\sim 3\times10^{9}-10^{12}~\rm M_{\odot}$ and $ 0.1 \lesssim R_{\rm e, Sph}\lesssim32~\rm kpc$ from multicomponent decomposition. The correlations between the spheroid Sérsic index ($n_{\rm Sph}$), central surface brightness ($μ_{\rm 0, Sph}$), effective half-light radius ($R_{\rm e, Sph}$), absolute magnitude ($\mathfrak{M}_{\rm Sph}$) and stellar mass ($M_{\rm *,Sph}$) are explored. We also investigate the consequences of using different scale radii, $R_{z,\rm Sph}$, encapsulating a different fraction ($z$, from 0 to 1) of the total luminosity. The correlation strengths for projected mass densities, $Σ_z$ and $\langle Σ\rangle_z$, vary significantly with the choice of $z$. Spheroid size ($R_{\rm z, Sph}$) and mass ($M_{\rm *,Sph}$) are strongly correlated for all light fractions $z$. We find: $\log(R_{\rm e,Sph}/\rm kpc) = 0.88\log(M_{\rm *,Sph}/\rm M_{\odot})-9.15$ with a small scatter of $Δ_{rms} = 0.24~\rm dex$. This result is discussed relative to the \textit{curved} size-mass relation for early-type galaxies due to their discs yielding larger galaxy radii at lower masses. Moreover, the slope of our spheroid size-mass relation is a factor of $\sim3$, steeper than reported bulge size-mass relations, and with bulge sizes at $M_{\rm *,sph}\sim 3\times10^9~M_\odot$ which are 2 to 3 times smaller. Finally, we show that the local spheroids align well with quiescent galaxies at $z\sim1.25$--$2.25$. In essence, local spheroids and high-$z$ quiescent galaxies appear structurally similar, likely dictated by the virial theorem.

astro-ph.GA↗

arXiv2022

Quashing a suspected selection bias in galaxy samples having dynamically-measured supermassive black holes

Local early-type galaxies with directly-measured black hole masses, $M_{\rm bh}$, have been reported to represent a biased sample relative to the population at large. Such galaxies with Spitzer Space Telescope imaging have been purported to possess velocity dispersions, $σ$, at least $\sim$0.1 dex larger for a given galaxy stellar mass, $M_{\rm *,gal}$, than is typically observed among thousands of early-type galaxies imaged by the Sloan Digital Sky Survey. This apparent offset led Shankar et al. to reduce the normalisation of the observed $M_{\rm bh} \propto σ^5$ relation by at least $\sim$0.5 dex to give their "intrinsic relations", including $σ$-based modifications to the $M_{\rm bh}$-$M_{\rm *,gal}$ relation. These modifications were based on the untested assumption that the stellar masses had been derived consistently between the two samples. Here, we provide the necessary check using galaxies common to the Spitzer Survey of Stellar Structure in Galaxies (S$^4$G) and the Sloan Digital Sky Survey (SDSS). We find that the stellar masses of galaxies with and without directly measured black holes had appeared offset from each other due to the use of inconsistent stellar mass-to-light ratios, $Υ_*$, for the optical and infrared data. We briefly discuss the "intrinsic relations" and why some of these will at times appear to have had partial success when applied to data based on similarly inconsistent values of $Υ_*$. Finally, we reiterate the importance of the $\upsilon$ (lower-case $Υ$) term, which we previously introduced into the $M_{\rm bh}$-$M_{\rm *}$ relations to help avoid $Υ_*$-related mismatches.

astro-ph.GA↗

arXiv2022

Appreciating mergers for understanding the non-linear $M_{\rm bh}$-$M_{\rm ,spheroid}$ and $M_{\rm bh}$-$M_{\rm ,galaxy}$ relations, updated herein, and the implications for the (reduced) role of AGN feedback

We present revised (black hole mass)-(spheroid stellar mass) and (black hole mass)-(galaxy stellar mass) scaling relations based on colour-dependent stellar mass-to-light ratios. Our 3.6 micron luminosities were obtained from multicomponent decompositions, which accounted for bulges, discs, bars, ansae, rings, nuclear components, etc. The lenticular galaxy bulges (not associated with recent mergers) follow a steep M_bh~M_{*,bulge}^{1.53+/-0.15} relation, offset by roughly an order of magnitude in black hole mass from the M_bh~M_{*,ellip}^{1.64+/-0.17} relation defined by the elliptical (E) galaxies which, in Darwinian terms, are shown to have evolved by punctuated equilibrium rather than gradualism. We use the spheroid, i.e., bulge and elliptical, size-mass relation to reveal how disc-galaxy mergers explain this offset and the dramatically lower M_bh/M_{*,sph} ratios in the elliptical galaxies. The popular but deceptive near-linear M_bh-M_{*,sph} `red sequence', followed by neither the bulge population nor the elliptical galaxies, is shown to be an artefact of sample selection, combining bulges and elliptical galaxies from disparate M_bh-M_{*,sph} sequences. Moreover, both small bulges with `undermassive' black holes and big lenticular galaxies (including relic `red nuggets') with `overmassive' black holes - relative to the near-linear M_bh-M_{*,sph} sequence - are no longer viewed as outliers. We confirm a steep M_bh~M_{*,bulge}^{2.25+/-0.39} relation for spiral galaxies and discuss numerous implications of this work, including how mergers, rather than (only) feedback from active galactic nuclei, have shaped the high-mass end of the galaxy mass function. We also explain why there may be no useful M_bh-M_{*,sph}-R_{e,sph} plane due to M_{*,sph} scaling nearly linearly with R_{e,sph}.

astro-ph.GA↗

arXiv2021

The (Black Hole Mass)-(Spheroid Stellar Density) Relations: $M_{\rm BH}$--$μ$ (and $M_{\rm BH}$--$Σ$) and $M_{\rm BH}$--$ρ$

This paper is the fourth in a series presenting (galaxy morphology, and thus galaxy formation)-dependent black hole mass, $M_{\rm BH}$, scaling relations. We have used a sample of 119 galaxies with directly-measured $M_{\rm BH}$ and host spheroid parameters obtained from multi-component decomposition of, primarily, $3.6\,μ$m Spitzer images. Here, we investigate the correlations between $M_{\rm BH}$ and the projected luminosity density $μ$, the projected stellar mass density $Σ$, and the deprojected (internal) stellar mass density $ρ$, for various spheroid radii. We discover the predicted $M_{\rm BH}$--$μ_{\rm 0,sph}$ relation and present the first $M_{\rm BH}$--$μ_{\rm e, sph}$ and $M_{\rm BH}$--$ρ_{\rm e,int, sph}$ diagrams displaying slightly different (possibly curved) trends for early- and late-type galaxies (ETGs and LTGs) and an offset between ETGs with (fast-rotators, ES/S0) and without (slow-rotators, E) a disk. The scatter about various $M_{\rm BH}$--$\langleΣ\rangle_{\rm R,sph}$ (and $\langleρ\rangle_{\rm r,sph}$) relations is shown to systematically decrease as the enclosing aperture (and volume) increases, dropping from 0.69~dex when using the spheroid \enquote{compactness}, $\langleΣ\rangle_{\rm 1kpc,sph}$, to 0.59~dex when using $\langleΣ\rangle_{\rm 5kpc,sph}$. We also reveal that $M_{\rm BH}$ correlates with the internal density, $ρ_{\rm soi,sph}$, at the BH's sphere-of-influence radius, such that core-Sérsic (high Sérsic index, $n$) and (low-$n$) Sérsic galaxies define different relations with total rms scatters 0.21~dex and 0.77~dex, respectively.(Abridged)

astro-ph.GA↗

arXiv2021

Defining the (Black Hole)-Spheroid Connection with the Discovery of Morphology-Dependent Substructure in the $M_{\rm BH}$--$\rm n_{sph}$ and $M_{\rm BH}$--$\rm R_{e, sph}$ Diagrams: New Tests for Advanced Theories and Realistic Simulations

For 123 local galaxies with directly-measured black hole masses ($M_{\rm BH}$), we provide the host spheroid's Sérsic index ($\rm n_{sph}$), effective half-light radius ($\rm R_{e,sph}$), and effective surface brightness ($μ_e$), obtained from careful multi-component decompositions, and we use these to derive the morphology-dependent $M_{\rm BH}$--$\rm n_{sph}$ and $M_{\rm BH}$--$\rm R_{e,sph}$ relations. We additionally present the morphology-dependent $M_{\rm *,sph}$--$\rm n_{sph}$ and $M_{\rm *,sph}$--$\rm R_{e,sph}$ relations. We explored differences due to: early-type galaxies (ETGs) versus late-type galaxies (LTGs); Sérsic versus core-Sérsic galaxies; barred versus non-barred galaxies; and galaxies with and without a stellar disk. We detect two different $M_{\rm BH}$--$\rm n_{sph}$ relations due to ETGs and LTGs with power-law slopes $3.95\pm0.34$ and $2.85\pm 0.31$. We additionally quantified the correlation between $M_{\rm BH}$ and the spheroid's central concentration index, which varies monotonically with the Sérsic index. Furthermore, we observe a single, near-linear $M_{\rm *,sph}$--$\rm R_{e,sph}^{1.08\pm 0.04}$ relation for ETGs and LTGs, which encompasses both classical and alleged pseudobulges. In contrast, ETGs and LTGs define two distinct $M_{\rm BH}$--$\rm R_{e,sph}$ relations with $Δ_{\rm rms|BH}\sim\rm 0.60~dex$ (cf.\ $\sim$0.51~dex for the $M_{\rm BH}$--$σ$ relation and $\sim$0.58~dex for the $M_{\rm BH}$--$M_{\rm *,sph}$ relation), and the ETGs alone define two steeper $M_{\rm BH}$--$\rm R_{e,sph}$ relations, offset by $\sim$1~dex in the $\log M_{\rm BH}$-direction, depending on whether they have a disk or not and explaining their similar offset in the $M_{\rm BH}$--$M_{\rm *,sph}$ diagram. This trend holds using $10 \%$, $50 \%$, or $90 \%$ radii.(Abridged)

astro-ph.GA↗

arXiv2019

Revealing Hidden Substructures in the $M_{BH}$-$σ$ Diagram, and Refining the Bend in the $L$-$σ$ Relation

Using 145 early- and late-type galaxies (ETGs and LTGs) with directly-measured super-massive black hole masses, $M_{BH}$, we build upon our previous discoveries that: (i) LTGs, most of which have been alleged to contain a pseudobulge, follow the relation $M_{BH}\propto\,M_{*,sph}^{2.16\pm0.32}$; and (ii) the ETG relation $M_{BH}\propto\,M_{*,sph}^{1.27\pm0.07}$ is an artifact of ETGs with/without disks following parallel $M_{BH}\propto\,M_{*,sph}^{1.9\pm0.2}$ relations which are offset by an order of magnitude in the $M_{BH}$-direction. Here, we searched for substructure in the $M_{BH}$--(central velocity dispersion, $σ$) diagram using our recently published, multi-component, galaxy decompositions; investigating divisions based on the presence of a depleted stellar core (major dry-merger), a disk (minor wet/dry-merger, gas accretion), or a bar (evolved unstable disk). The Sérsic and core-Sérsic galaxies define two distinct relations: $M_{BH}\proptoσ^{5.75\pm0.34}$ and $M_{BH}\proptoσ^{8.64\pm1.10}$, with $Δ_{rms|BH}=0.55$ and $0.46$~dex, respectively. We also report on the consistency with the slopes and bends in the galaxy luminosity ($L$)--$σ$ relation due to Sérsic and core-Sérsic ETGs, and LTGs which all have Sérsic light-profiles. Two distinct relations (superficially) reappear in the $M_{BH}$--$σ$ diagram upon separating galaxies with/without a disk (primarily for the ETG sample), while we find no significant offset between barred and non-barred galaxies, nor between galaxies with/without active galactic nuclei. We also address selection biases purported to affect the scaling relations for dynamically-measured $M_{BH}$ samples. Our new, (morphological type)-dependent, $M_{BH}$--$σ$ relations more precisely estimate $M_{BH}$ in other galaxies, and hold implications for galaxy/black hole co-evolution theories, and simulations. (Abridged)

astro-ph.GA↗

arXiv2019

Black Hole Mass Scaling Relations for Early-Type Galaxies: $M_{BH}$-$M_{,sph}$ and $M_{BH}$-$M_{,gal}$

Analyzing a sample of 84 early-type galaxies with directly-measured super-massive black hole masses---nearly doubling the sample size of such galaxies with multi-component decompositions---a symmetric linear regression on the reduced (merger-free) sample of 76 galaxies reveals $M_{BH}\propto M_{*,sph}^{1.27\pm 0.07}$ with a total scatter of $Δ_{rms}=$ 0.52 dex in the $\log(M_{BH})$ direction. However, and importantly, we discover that the ES/S0-type galaxies with disks are offset from the E-type galaxies by more than a factor of ten in their $M_{BH}/M_{*,sph}$ ratio, with ramifications for formation theories, simulations, and some virial factor measurements used to convert AGN virial masses into $M_{BH}$. Separately, each population follows a steeper relation with slopes of $1.86\pm0.20$ and $1.90\pm0.20$, respectively. The offset mass ratio is mainly due to the exclusion of the disk mass, with the two populations offset by only a factor of two in their $M_{BH}/M_{*,gal}$ ratio in the $M_{BH}$-$M_{*,gal}$ diagram where $M_{BH}\propto M_{*,gal}^{1.8\pm 0.2}$ and $Δ_{rms}=0.6\pm 0.1$ dex depending on the sample. For $M_{BH} \gtrsim 10^7 M_{\odot}$, we detect no significant bend nor offset in either the $M_{BH}$-$M_{*,sph}$ or $M_{BH}$-$M_{*,gal}$ relations due to barred versus non-barred, or core-Sérsic versus Sérsic, early-type galaxies. For reference, the ensemble of late-type galaxies (which invariably are Sérsic galaxies) follow $M_{BH}$-$M_{*,sph}$ and $M_{BH}$-$M_{*,gal}$ relations with slopes equal to $2.16\pm 0.32$ and $3.05\pm 0.70$, respectively. Finally, we provide some useful conversion coefficients, $\upsilon$, accounting for the different stellar mass-to-light ratios used in the literature, and we report the discovery of a local, compact massive spheroid in NGC 5252.

astro-ph.GA↗