arXiv subjects

Mark Durré

Publications and source records attributed to Mark Durré.

10 recordsLinked to original sources

arXiv2025

Infrared and Optical Emission-line Diagnostics

We study a catalogue of over 130 emission-line galaxies with matched near infra-red (NIR) and optical spectra, where we examine the relationship between the respective nuclear activity classifications, diagnosed by the flux ratios of emission lines. We match the standard NIR classification with four different optical classifications. While there is a broad agreement between the two regimes, there are mismatches and overlaps caused either by aperture effects and/or NIR radiation penetrating obscuring dust and "seeing deeper" into the nuclear region, thus exposing AGN activity. We examine the relationship between the equivalent widths (EW) of H$α$ and Pa$β$, as well as the ratios [N II]/H$α$ vs. [Fe II]/Pa$β$, and find reasonable correlations. We thus propose a new diagnostic (EW of Pa$β$ with Fe - WPF) in the NIR (analogous to the WHaN classification), using the [Fe II]/Pa$β$ flux ratio and the EW of the Pa$β$ line. We show, within the limitations of the catalogue size, that the regions of the standard NIR diagram can be reasonably replicated in this new scheme. This diagnostic has the advantage that only one wavelength range needs to be observed, thus being economical with telescope time.

astro-ph.GA↗

arXiv2023

Infrared Spectroscopy of Nearby Radio Active Early-Type Galaxies -- II: Spectral Atlas

We present a near infrared spectroscopic atlas of nearby, bright early-type galaxies with radio emission, containing 163 galaxies observed by the Palomar 200" TripleSpec instrument, measuring the emission line fluxes for H, He, [Fe II] and H$_2$ and determined the nuclear excitation mechanisms. By stacking spectra, we deduced the H$_2$ excitation temperature ($1957\pm182$ K) and dominant excitation mechanism (thermal and shock heating combined) from the $\textit{K}$-band emission line sequence. Stacking also produces an "average" spectrum of absorption features and spectral indices from the literature; the CO12 absorption line index vs. $\textit{J-K}$ colour shows a trend of stronger nuclear activity producing a weaker CO12 index and a redder (flatter) continuum. The correlations between the radio and the emission-line luminosities finds a trend with radio power; however, the large scatter in the upper limits shows that the two are not directly coupled and the duty cycles of SF and AGN activity are not synchronised.

astro-ph.GA↗

arXiv2021

The Southern Hemisphere Narrow-Line Seyfert 1 Infrared Survey

We present a near-infrared spectroscopic survey of narrow-line Seyfert 1 galaxies in the southern hemisphere (using the SOFI instrument on the ESO-NTT telescope), sampled from optical surveys. We examine the kinematics of the broad-line region, probed by the emission line width of hydrogen (Pa$α$ and H$β$). We observed 57 objects, of which we could firmly measure Pa$α$ in 49 cases. We find that a single Lorentzian fit (preferred on theoretical grounds) is preferred over multi-component Gaussian fits to the line profiles; a lack of narrow-line region emission, overwhelmed by the pole-on view of the broad line region (BLR) light, supports this. We recompute the catalog black hole (BH) mass estimates, using the values of FWHM and luminosity of H$β$, both from catalog values and re-fitted Lorentzian values. We find a relationship slope greater than unity compared to the catalog values. We ascribe this to contamination by galactic light or difficulties with line flux measurements. However, the comparison of masses computed by the fitted Lorentzian and Gaussian measurements show a slope close to unity. Comparing the BH masses estimated from both Pa$α$ and H$β$, the line widths and fluxes shows deviations from expected; in general, however, the computed BH masses are comparable. We posit a scenario where an intermixture of dusty and dust-free clouds (or alternately a structured atmosphere) differentially absorbs the line radiation of the BLR, due to dust absorption and hydrogen bound-free absorption.

astro-ph.GA↗

arXiv2020

Keck Cosmic Web Imager (KCWI) Spectra of Globular Clusters and Ultra Compact Dwarfs in the Halo of M87

Using the Keck Cosmic Web Imager we obtain spectra of several globular clusters (GCs), ultra compact dwarfs (UCDs) and the inner halo starlight of M87, at a similar projected galactocentric radius of $\sim$5 kpc. This enables us, for the first time, to apply the same stellar population analysis to the GCs, UCDs and starlight consistently to derive ages, metallicities and alpha-element abundances in M87. We find evidence for a dual stellar population in the M87 halo light, i.e an $\sim$80\% component by mass which is old and metal-rich and a $\sim$20\% component which is old but metal-poor. Two red GCs share similar stellar populations to the halo light suggesting they may have formed contemporaneously with the dominant halo component. Three UCDs, and one blue GC, have similar stellar populations, with younger mean ages, lower metallicities and near solar alpha-element abundances. Combined with literature data, our findings are consistent with the scenario that UCDs are the remnant nucleus of a stripped galaxy. We further investigate the discrepancy in the literature for M87's kinematics at large radii, favouring a declining velocity dispersion profile. This work has highlighted the need for more self-consistent studies of galaxy halos.

astro-ph.GA↗

arXiv2020

An AGB Star with a Thick Circumstellar Shell

The Asymptotic Giant Branch (AGB) is the terminal phase of red giant evolution with timescales of millions of years and a total mass lost from the star that is a significant fraction of the initial mass. Investigation of one of these stars, WISEA J173046.10-344455.5, a kpc in the direction of the center of the Galaxy, reveals a cool oxygen rich star with a dust shell of black-body temperature 1305 K.

astro-ph.SR↗

arXiv2018

The AGN Ionization Cones of NGC 5728 : II - Kinematics

We explore the gas morphology and excitation mechanisms of the ionization cones of the Type II Seyfert galaxy NGC~5728. Kinematics derived from near-IR and optical data from the SINFONI and MUSE IFUs on the VLT reveal AGN-driven outflows powered by a super-massive black hole (SMBH) of mass 3.4$\times$10$^2$ M$_\odot$, bolometric luminosity of 1.46$\times$10$^{44}$ erg/s, Eddington ratio 3.3$\times$10$^{-2}$ and an accretion rate of 2.7$\times$10$^2$ M$_\odot$/yr. The symmetric bicone outflows show rapid acceleration to $\pm$250 km/s at $\sim$250 pc, then decelerating to $\sim$130 km/s at 500 pc from the AGN, with an estimated mass outflow rate of 38 M$_\odot$/yr, the mass ratio of outflows to accretion is 1415. The kinetic power is 1.5$\times$10$^{42}$ erg/s, 1$\%$ of the bolometric luminosity. Over the AGN active lifetime of $\sim$10$^7$ years, 1.6$\times$10$^8$ M$_\odot$ of gas can become gravitationally unbound from the galaxy, a large proportion of the gas mass available for star formation in the nuclear region. The bicone internal opening angle (50°.2) and the inclination to the LOS (47°.6) were determined from [Fe II] line profiles, the outflow axis is nearly parallel to the plane of the galaxy. This geometry supports the Unified Model of AGN, as these angles preclude seeing the accretion disk, which is obscured by the dusty torus.

astro-ph.GA↗

arXiv2018

The AGN Ionization Cones of NGC 5728 : I - Excitation and Nuclear Structure

We explore the gas morphology and excitation mechanisms of the ionization cones of the Type II Seyfert galaxy NGC 5728. Near-IR and optical data from the SINFONI and MUSE IFUs on the VLT are combined with $HST$ optical images, $Chandra$ X-ray data and VLA radio observations. The complex nuclear structure has a star-forming (SF) ring with a diameter of 2 kpc. A radio jet impacts on the ISM at about 200 pc from the nucleus, with the SN remnants in the SF ring also present. Emission-line ratios of [Fe II] and H II show heavy extinction towards the nucleus, moderate extinction in the SF ring and reduced extinction in the ionization cones. The AGN is hidden by a dust bar with up to 19 magnitudes of visual extinction; the dust temperature at the nuclear position is ~870 K. An X-ray jet is aligned with the ionization cones, and associated with high-excitation emission lines of [Si VI] in a coronal-line region extending 300 pc from the nucleus. Molecular hydrogen is spatially independent of the cones, concentrated in a disk equatorial to the star-forming ring, but also showing entrainment along the sides of the bicone. Gas masses for warm and cold H$_2$, H I and H II are estimated, and the excitation mechanisms for ionized and molecular gas are elucidated, from both optical (which shows a clean SF-AGN mixing sequence) and infrared diagnostics (which show more complicated, multi-component excitation regimes).

astro-ph.GA↗

arXiv2017

IC 630: Piercing the Veil of the Nuclear Gas

IC 630 is a nearby early-type galaxy with a mass of $6 \times 10^{10} M_{\odot}$ with an intense burst of recent (6 Myr) star formation. It shows strong nebular emission lines, with radio and X-ray emission, which classifies it as an AGN. With VLT-SINFONI and Gemini North-NIFS adaptive optics observations (plus supplementary ANU 2.3m WiFeS optical IFU observations), the excitation diagnostics of the nebular emission species show no sign of standard AGN engine excitation; the stellar velocity dispersion also indicate that a super-massive black hole (if one is present) is small ($M_{\bullet} = 2.25 \times 10^{5}~M_{\odot}$). The luminosity at all wavelengths is consistent with star formation at a rate of about $1-2 M_{\odot}$/yr. We measure gas outflows driven by star formation at a rate of $0.18 M_{\odot}$/yr in a face-on truncated cone geometry. We also observe a nuclear cluster or disk and other clusters. Photo-ionization from young, hot stars is the main excitation mechanism for [Fe II] and hydrogen, whereas shocks are responsible for the H$_2$ excitation. Our observations are broadly comparable with simulations where a Toomre-unstable, self-gravitating gas disk triggers a burst of star formation, peaking after about 30 Myr and possibly cycling with a period of about 200 Myr.

astro-ph.GA↗

arXiv2016

A normal supermassive black hole in NGC 1277

The identification of galaxies with `overly massive' black holes requires two measurements: a black hole mass (M_bh) and a host spheroid mass (M_sph,*). Here we provide our measurements for NGC 1277. Our structural decomposition reveals that NGC 1277 is dominated by a `classical' spheroid with a Sersic index n=5.3, a half-light radius R_e=2.1 kpc, and a stellar mass of 2.7x10^{11} M_sun (using M_*/L_V=11.65, Martin-Navarro et al.). This mass is an order of magnitude greater than originally reported. Using the latest (M_bh)-n, (M_bh)-(M_sph,*) and (M_bh)-sigma relations, the expected black hole mass is respectively (0.57^{+1.29}_{-0.40})x10^9 M_sun, (1.58^{+4.04}_{-1.13})x10^9 M_sun, and (2.27^{+4.04}_{-1.44})x10^9 M_sun (using sigma=300 km/s) for which the `sphere-of-influence' is 0".31. Our new kinematical maps obtained from laser guide star assisted, adaptive optics on the Keck I Telescope dramatically reaffirm the presence of the inner, nearly edge-on, disk seen in this galaxy's image. We also report that this produces a large velocity shear (~400 km/s) across the inner 0".2 (70 pc) plus elevated values of sqrt{sigma^2+(V_rot)^2} across the inner 3".8x0".6 region of the galaxy. Our new multi-Gaussian expansion (MGE) models and Jeans Anisotropic MGE (JAM) analysis struggled to match this extended component. Our optimal black hole mass, albeit a probable upper limit because of the disk, is 1.2x10^9 M_sun (M/L_V=12.3). This is an order of magnitude smaller than originally reported and 4 times smaller than recently reported. It gives an M_bh/M_sph,* ratio of 0.45% in agreement with the median (~0.5%) and range (0.1 to 5.0%) observed in non-dwarf, early-type galaxies. This result highlights the need for caution with inner disks.

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arXiv2014

Young Star Clusters In The Circumnuclear Region Of NGC 2110

High-resolution observations in the near infrared show star clusters around the active galactic nucleus (AGN) of the Seyfert 1 NGC2110, along with a 90 x 35 pc bar of shocked gas material around its nucleus. These are seen for the first time in our imaging and gas kinematics of the central 100pc with the Keck OSIRIS instrument with adaptive optics. Each of these clusters is 2-3 times brighter than the Arches cluster close to the centre of the Milky Way. The core star formation rate (SFR) is 0.3 M$_\odot$/yr. The photoionized gas (He I) dynamics imply an enclosed mass of 3-4 x 10$^8$ M$_\odot$. These observations demonstrate the physical linkage between AGN feedback, which triggers star formation in massive clusters, and the resulting stellar (and SNe) winds, which cause the observed [Fe II] emission and feed the black hole.

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