System NGC Research Articles

Constraining the interaction history of Arp 269 using stellar population synthesis modelling

ABSTRACT We present stellar population synthesis modelling of the nearby interacting galaxy system NGC 4485/90 or Arp 269 using Code Investigating GALaxy Emission. Model results are used to constrain its interaction history and to examine the origin of structures within the system. We have used multiwavelength observations ranging from far-ultraviolet to radio wavelengths to create, model, and fit spectral energy distributions and obtain physical properties of different regions. Our analysis reveals a young and an underlying much older stellar population in both NGC 4485 and 4490. We find the bridge connecting the two galaxies to be formed quite recently, after the second perigalactic encounter between the two. Our analysis shows that the previously identified faint stellar extension associated with NGC 4490 was also formed after the second encounter, which agrees with previous N-body and test-particle simulations. Additionally, we investigate the H i gas distribution in NGC 4485 and find that a mass of H i gas comparable to a dwarf galaxy has been relocated to the south-west part of NGC 4485. This is consistent with the scenario in which the interstellar medium of NGC 4485 is being removed via ram pressure stripping.

A co-rotating gas and satellite structure around the interacting galaxy pair NGC 4490/85

ABSTRACT The interacting binary system NGC 4490/85 = Arp 269 is intermediate in mass between the Milky Way/Large Magellanic Cloud and the Large/Small Magellanic Cloud binary systems. It is a system of 14 known galaxies. We estimate the total Newtonian gravitating mass of the NGC 4490/85 group to be $M_\mathrm{ T} = (1.37\pm 0.43) \times 10^{12} \, \mathrm{M}_{\odot }$ using radial velocities and projected separations of its 13 candidate members. The system of dwarf satellites in the group demonstrates signs of coherent rotation in the same direction as that of the extended H i-shell surrounding the central interacting galaxy pair. The origin of this phase-space correlated population of star-forming late-type satellite galaxies raises questions in view of the planes-of-satellites observed around more massive galaxy pairs that are, however, made up of old early-type dwarf galaxies. We also report the detection of a candidate stellar Plume near the binary. This elongated structure of low surface brightness is a likely optical counterpart to the H i-tail north of NGC 4490/85, recently discovered by the Five-Hundred-meter Aperture Spherical radio telescope.

The TELPERION survey for distant [O iii] clouds around luminous and hibernating AGN

ABSTRACT We present a narrow-band [O iii] imaging survey of 111 active galactic nucleus (AGN) hosts and 17 merging-galaxy systems, in search of distant extended emission-line regions (EELRs) around AGNs (either extant or faded). Our data reach deeper than detection from the broad-band SDSS data and cover a wider field than some early emission-line surveys used to study extended structure around AGNs. Spectroscopic follow-up confirms two new distant AGN-ionized clouds, in the merging systems NGC 235 and NGC 5514, projected at 26 and 75 kpc from the nuclei (respectively). We also recover the previously known region in NGC 7252. These results strengthen the connection between EELRs and tidal features; kinematically quiescent distant EELRs are virtually always photoionized tidal debris. We see them in ≈10 per cent of the galaxies in our sample with tidal tails. Energy budgets suggest that the AGN in NGC 5514 has faded by >3 times during the extra light traveltime ≈250 000 yr from the nucleus to the cloud and then to the observer; strong shock emission in outflows masks the optical signature of the AGN. For NGC 235 our data are consistent with but do not unequivocally require variation over ≈85 000 yr. In addition to these very distant ionized clouds, we find luminous and extensive line emission within four galaxies – IC 1481, ESO 362-G08, NGC 5514, and NGC 7679. Among these, IC 1481 shows apparent ionization cones, a rare combination with its LINER AGN spectrum. In NGC 5514, we measure a 7-kpc shell expanding at ≈370 km s−1 west of the nucleus.

A Machine-learning Approach to Integral Field Unit Spectroscopy Observations. III. Disentangling Multiple Components in H ii Regions

Abstract In the first two papers of this series, we demonstrated the dynamism of machine learning applied to optical spectral analysis by using neural networks to extract kinematic parameters and emission-line ratios directly from the spectra observed by the SITELLE instrument located at the Canada–France–Hawai’i Telescope. In this third installment, we develop a framework using a convolutional neural network trained on synthetic spectra to determine the number of line-of-sight components present in the SN3 filter (656–683 nm) spectral range of SITELLE. We compare this methodology to standard practice using Bayesian inference. Our results demonstrate that a neural network approach returns more accurate results and uses fewer computational resources over a range of spectral resolutions. Furthermore, we apply the network to SITELLE observations of the merging galaxy system NGC 2207/IC 2163. We find that the closest interacting sector and the central regions of the galaxies are best characterized by two line-of-sight components while the outskirts and spiral arms are well-constrained by a single component. Determining the number of resolvable components is crucial in disentangling different galactic components in merging systems and properly extracting their respective kinematics.

Exploring the 100 au Scale Structure of the Protobinary System NGC 2264 CMM3 with ALMA

Abstract We have observed the young protostellar system NGC 2264 CMM3 in the 1.3 mm and 2.0 mm bands at a resolution of about 0.″1 (70 au) with ALMA. The structures of two distinct components, CMM3A and CMM3B, are resolved in the continuum images of both bands. CMM3A has an elliptical structure extending along the direction almost perpendicular to the known outflow, while CMM3B reveals a round shape. We have fitted two 2D Gaussian components to the elliptical structure of CMM3A and CMM3B and have separated the disk and envelope components for each source. The spectral index α between 2.0 and 0.8 mm is derived to be 2.4–2.7 and 2.4–2.6 for CMM3A and CMM3B, respectively, indicating optically thick dust emission and/or grain growth. A velocity gradient in the disk/envelope direction is detected for CMM3A in the CH3CN, CH3OH, and 13CH3OH lines detected in the 1.3 mm band, which can be interpreted as the rotation of the disk/envelope system. From this result, the protostellar mass of CMM3A is roughly evaluated to be 0.1–0.5 M ⊙ by assuming Keplerian rotation. The mass accretion rate is thus estimated to be 5 × 10−5 − 4 × 10−3 M ⊙ yr−1, which is higher than the typical mass accretion rate of low-mass protostars. The OCS emission line shows a velocity gradient in both outflow direction and disk/envelope direction. A hint of outflow rotation is found, and the specific angular momentum of the outflow is estimated to be comparable to that of the disk. These results provide us with novel information on the initial stage of a binary/multiple system.

The Extraordinary Outburst in the Massive Protostellar System NGC 6334 I-MM1: Strong Increase in Mid-Infrared Continuum Emission

Abstract In recent years, dramatic outbursts have been identified toward massive protostars via infrared and millimeter dust continuum and molecular maser emission. The longest lived outburst (>6 yr) persists in NGC 6334 I-MM1, a deeply embedded object with no near-IR counterpart. Using FORCAST and HAWC+ on SOFIA, we have obtained the first mid-IR images of this field since the outburst began. Despite being undetected in pre-outburst ground-based 18 μm images, MM1 is now the brightest region at all three wavelengths (25, 37, and 53 μm), exceeding the UCHII region MM3 (NGC 6334 F). Combining the SOFIA data with ALMA imaging at four wavelengths, we construct a spectral energy distribution of the combination of MM1 and the nearby hot core MM2. The best-fit Robitaille radiative transfer model yields a luminosity of (4.9 ± 0.8) × 104 L ⊙. Accounting for an estimated pre-outburst luminosity ratio MM1:MM2 = 2.1 ± 0.4, the luminosity of MM1 has increased by a factor of 16.3 ± 4.4. The pre-outburst luminosity implies a protostar of mass 6.7 M ⊙, which can produce the ionizing photon rate required to power the pre-outburst HCHII region surrounding the likely outbursting protostar MM1B. The total energy and duration of the outburst exceed the S255IR-NIRS3 outburst by a factor of ≳3, suggesting a different scale of event involving expansion of the protostellar photosphere (to ≳20 R ⊙), thereby supporting a higher accretion rate (≳0.0023 M ⊙ yr−1) and reducing the ionizing photon rate. In the grid of hydrodynamic models of Meyer et al., the combination of outburst luminosity and magnitude (3) places the NGC 6334 I-MM1 event in the region of moderate total accretion (∼0.1–0.3 M ⊙) and hence long duration (∼40–130 yr).

The Wolf–Rayet + Black Hole Binary NGC 300 X-1: What is the Mass of the Black Hole?

Abstract We present new X-ray and UV observations of the Wolf–Rayet + black hole (BH) binary system NGC 300 X-1 with the Chandra X-ray Observatory and the Hubble Space Telescope Cosmic Origins Spectrograph. When combined with archival X-ray observations, our X-ray and UV observations sample the entire binary orbit, providing clues to the system geometry and interaction between the BH accretion disk and the donor star wind. We measure a binary orbital period of 32.7921 ± 0.0003 hr, in agreement with previous studies, and perform phase-resolved spectroscopy using the X-ray data. The X-ray light curve reveals a deep eclipse, consistent with inclination angles of i = 60°–75°, and a pre-eclipse excess consistent with an accretion stream impacting the disk edge. We further measure radial velocity variations for several prominent far-UV spectral lines, most notably H ii λ1640 and C iv λ1550. We find that the He ii emission lines systematically lag the expected Wolf–Rayet star orbital motion by a phase difference of Δϕ ∼ 0.3, while C iv λ1550 matches the phase of the anticipated radial velocity curve of the Wolf–Rayet donor. We assume the C iv λ1550 emission line follows a sinusoidal radial velocity curve (semi-amplitude = 250 km s−1) and infer a BH mass of 17 ± 4 M ⊙. Our observations are consistent with the presence of a wind-Roche lobe overflow accretion disk, where an accretion stream forms from gravitationally focused wind material and impacts the edge of the BH accretion disk.

Interacting system NGC 7805/6 (Arp 112) and its tidal dwarf galaxy candidate

We present results from our Giant Metrewave Radio Telescope (GMRT) Hi, Himalayan Chandra Telescope (HCT) Hα, 1 m Sampurnanand Telescope (ST) and 1.3 m Devasthal Fast Optical Telescope (DFOT) deep optical observations of the NGC 7805/6 (Arp 112) system to test KUG 2359+311’s tidal dwarf galaxy (TDG) candidacy and explore the properties of the interacting system. Our GMRT H I map shows no H I detection associated with KUG 2359+311, nor any H I tail or bridge-like structure connecting KUG 2359+311 to the NGC 7805/6 system. Our HCT Hα image, on the other hand, displays strong detections in KUG 2359+311, with net SFR ∼ 0.035 ± 0.009 M ⊙ yr−1. The Hα data constrain the redshift of KUG 2359+311 to 0.00 ≤ z ≤ 0.043, compared to the redshift of NGC 7806 of ∼ 0.015. TDGs detected to date have all been H i rich, and displayed H i, ionised gas and stellar tidal debris trails (bridges or tails) linking them to their parent systems. However, neither our H i data nor our optical imaging, while three magnitudes deeper than SDSS, reveals a tidal trail connecting KUG 2359+311 to NGC 7805/6. Lack of H i, presence of an old stellar population, ongoing star formation and reasonably high SFR compared to normal dwarf galaxies suggest that KUG 2359+311 may not be an Arp 112 TDG. It is most likely a case of a regular gas-rich dwarf galaxy undergoing a morphological transformation after having lost its entire gas content to an interaction with the Arp 112 system. Redshift and metallicity from future spectroscopic observations of KUG 2359+311 would help clarify the nature of this enigmatic structure.

The Extraordinary Outburst in the Massive Protostellar System NGC 6334 I-MM1: Spatiokinematics of Water Masers during a Contemporaneous Flare Event

Abstract Following an eruptive accretion event in NGC 6334I-MM1, flares in the various maser species, including water masers, were triggered. We report the observed relative proper motion of the highly variable water masers associated with the massive star-forming region, NGC 6334I. High velocity H2O maser proper motions were detected in five maser clusters, CM2-W2 (bow-shock structure), MM1-W1, MM1-W3, UCHII-W1, and UCHII-W3. The overall average of the derived relative proper motion is 85 km s−1. This mean proper motion is in agreement with the previous results from VLA multiepoch observations. Our position as well as the velocity variance and covariance matrix analyses of the maser proper motions show its major axis to have a position angle of −79.°4, cutting through the dust cavity around MM1B and being aligned in the northwest–southeast direction. We interpret this as the axis of the jet driving the CM2 shock and the maser motion. The complicated proper motions in MM1-W1 can be explained by the combined influence of the MM1 northeast–southwest bipolar outflow, the CS(6−5) north–south collimated bipolar outflow, and the radio jet. The relative proper motions of the H2O masers in UCHII-W1 are likely not driven by the jets of the MM1B protostar but by MM3-UCHII. Overall, the post-accretion burst relative proper motions of the H2O masers trace shocks of jet motion.

The Molecular Gas in the NGC 6240 Merging Galaxy System at the Highest Spatial Resolution

Abstract We present the highest-resolution—15 pc (0.″03)—ALMA 12CO(2–1) line emission and 1.3 mm continuum maps, tracers of the molecular gas and dust, respectively, in the nearby merging galaxy system NGC 6240, which hosts two supermassive black holes growing simultaneously. These observations provide an excellent spatial match to existing Hubble Space Telescope (HST) optical and near-infrared observations of this system. A significant molecular gas mass, ∼9 × 109 M ⊙, is located between the two nuclei, forming a clumpy stream kinematically dominated by turbulence, rather than a smooth rotating disk, as previously assumed from lower-resolution data. Evidence for rotation is seen in the gas surrounding the southern nucleus but not in the northern one. Dynamical shells can be seen, likely associated with nuclear supernova remnants. We further detect the presence of significant high-velocity outflows, some of them reaching velocities >500 km s−1, affecting a significant fraction, ∼11%, of the molecular gas in the nuclear region. Inside the spheres of influence of the northern and southern supermassive black holes, we find molecular masses of 7.4 × 108 and 3.3 × 109 M ⊙, respectively. We are thus directly imaging the reservoir of gas that can accrete onto each supermassive black hole. These new ALMA maps highlight the critical need for high-resolution observations of molecular gas in order to understand the feeding of supermassive black holes and its connection to galaxy evolution in the context of a major galaxy merger.

The Extraordinary Outburst in the Massive Protostellar System NGC 6334I-MM1: Flaring of the Water Masers in a North–South Bipolar Outflow Driven by MM1B

Abstract We compare multi-epoch sub-arcsecond Very Large Array imaging of the 22 GHz water masers toward the massive protocluster NGC 6334I observed before and after the recent outburst of MM1B in (sub)millimeter continuum. Since the outburst, the water maser emission toward MM1 has substantially weakened. Simultaneously, the strong water masers associated with the synchrotron continuum point source CM2 have flared by a mean factor of 6.5 (to 4.2 kJy) with highly blueshifted features (up to 70 km s−1 from the LSR) becoming more prominent. The strongest flaring water masers reside 3000 au north of MM1B and form a remarkable bow shock pattern whose vertex coincides with CM2 and tail points back to MM1B. Excited OH masers trace a secondary bow shock located ∼120 au downstream. Atacama Large Millimeter Array images of CS (6–5) reveal a highly collimated north–south structure encompassing the flaring masers to the north and the nonflaring masers to the south seen in projection toward the MM3-UCHII region. Proper motions of the southern water masers over 5.3 years indicate a bulk projected motion of 117 km s−1 southward from MM1B with a dynamical time of 170 years. We conclude that CM2, the water masers, and many of the excited OH masers trace the interaction of the high-velocity bipolar outflow from MM1B with ambient molecular gas. The previously excavated outflow cavity has apparently allowed the radiative energy of the current outburst to propagate freely until terminating at the northern bow shock where it strengthened the masers. Additionally, water masers have been detected toward MM7 for the first time, and a highly collimated CS (6–5) outflow has been detected toward MM4.

Two separate outflows in the dual supermassive black hole system NGC 6240.

Theoretical models and numerical simulations have established a framework of galaxy evolution in which galaxies merge and create dual supermassive black holes (with separations of one to ten kiloparsecs), which eventually sink into the centre of the merger remnant, emit gravitational waves and coalesce. The merger also triggers star formation and supermassive black hole growth, and gas outflows regulate the stellar content1-3. Although this theoretical picture is supported by recent observations of starburst-driven and supermassive black hole-driven outflows4-6, it remains unclear how these outflows interact with the interstellar medium. Furthermore, the relative contributions of star formation and black hole activity to galactic feedback remain unknown7-9. Here we report observations of dual outflows in the central region of the prototypical merger NGC 6240. We find a black-hole-driven outflow of [O III] to the northeast and a starburst-driven outflow of Hα to the northwest. The orientations and positions of the outflows allow us to isolate them spatially and study their properties independently. We estimate mass outflow rates of 10 and 75 solar masses per year for the Hα bubble and the [O III] cone, respectively. Their combined mass outflow is comparable to the star formation rate 10 , suggesting that negative feedback on star formation is occurring.

Discovery of Striking Difference of Molecular-emission-line Richness in the Potential Proto-binary System NGC 2264 CMM3

We have conducted an interferometric line survey in the 0.8 mm band toward the young high-mass protostar candidate NGC 2264 CMM3 with ALMA. CMM3 is resolved into the two continuum peaks, CMM3A and CMM3B, at an angular separation of 0.9". Thus, CMM3 is found to be a binary system candidate. We have detected molecular outflows associated with CMM3A and CMM3B each, indicating active star formation. In addition to the two peaks, six faint continuum peaks are detected around CMM3A and CMM3B, most of which are thought to be evolved low-mass protostars. CMM3A is found to be rich in molecular line emission including complex organic molecules such as HCOOCH3 and CH3OCH3. The emission of complex organic molecules is distributed within a compact region around the continuum peak of CMM3A. Hence, CMM3A apparently harbors a hot core. On the other hand, CMM3B is deficient in molecular line emission, although its continuum flux is almost comparable to that of CMM3A. Possible origins of the striking difference between CMM3A and CMM3B are discussed.

Turbulent gas accretion between supermassive black-holes and star-forming rings in the circumnuclear disk

While supermassive black holes are known to co-evolve with their host galaxy, the precise nature and origin of this co-evolution is not clear. We here explore the possible connection between star formation and black hole growth in the circumnuclear disk (CND) to probe this connection in the vicinity close to the black hole. We adopt here the circumnuclear disk model developed by Kawakatu & Wada (2008) and Wutschik et al. (2013), and explore both the dependence on the star formation recipe as well as the role of the gravitational field, which can be dominated by the central black hole, the CND itself or the host galaxy. A specific emphasis is put on the turbulence regulated star formation model by Krumholz et al. (2005) to explore the impact of a realistic star formation recipe. It is shown that this model helps to introduce realistic fluctuations in the black hole and star formation rate, without overestimating them. Consistent with previous works, we show that the final black hole masses are rather insensitive to the masses of the initial seeds, even for seed masses of up to 10^6 M_sol. In addition, we apply our model to the formation of high-redshift quasars, as well as to the nearby system NGC 6951, where a tentative comparison is made in spite of the presence of a bar in the galaxy. We show that our model can reproduce the high black hole masses of the high-redshift quasars within a sufficiently short time, provided a high mass supply rate from the host galaxy. In addition, it reproduces several of the properties observed in NGC 6951. With respect to the latter system, our analysis suggests that supernova feedback may be important to create the observed fluctuations in the star formation history as a result of negative feedback effects.

A 2.4% DETERMINATION OF THE LOCAL VALUE OF THE HUBBLE CONSTANT*

ABSTRACT We use the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) to reduce the uncertainty in the local value of the Hubble constant from 3.3% to 2.4%. The bulk of this improvement comes from new near-infrared (NIR) observations of Cepheid variables in 11 host galaxies of recent type Ia supernovae (SNe Ia), more than doubling the sample of reliable SNe Ia having a Cepheid-calibrated distance to a total of 19; these in turn leverage the magnitude-redshift relation based on ∼300 SNe Ia at z < 0.15. All 19 hosts as well as the megamaser system NGC 4258 have been observed with WFC3 in the optical and NIR, thus nullifying cross-instrument zeropoint errors in the relative distance estimates from Cepheids. Other noteworthy improvements include a 33% reduction in the systematic uncertainty in the maser distance to NGC 4258, a larger sample of Cepheids in the Large Magellanic Cloud (LMC), a more robust distance to the LMC based on late-type detached eclipsing binaries (DEBs), HST observations of Cepheids in M31, and new HST-based trigonometric parallaxes for Milky Way (MW) Cepheids. We consider four geometric distance calibrations of Cepheids: (i) megamasers in NGC 4258, (ii) 8 DEBs in the LMC, (iii) 15 MW Cepheids with parallaxes measured with HST/FGS, HST/WFC3 spatial scanning and/or Hipparcos, and (iv) 2 DEBs in M31. The Hubble constant from each is 72.25 ± 2.51, 72.04 ± 2.67, 76.18 ± 2.37, and 74.50 ± 3.27 km s−1 Mpc−1, respectively. Our best estimate of H 0 = 73.24 ± 1.74 km s−1 Mpc−1 combines the anchors NGC 4258, MW, and LMC, yielding a 2.4% determination (all quoted uncertainties include fully propagated statistical and systematic components). This value is 3.4σ higher than 66.93 ± 0.62 km s−1 Mpc−1 predicted by ΛCDM with 3 neutrino flavors having a mass of 0.06 eV and the new Planck data, but the discrepancy reduces to 2.1σ relative to the prediction of 69.3 ± 0.7 km s−1 Mpc−1 based on the comparably precise combination of WMAP+ACT+SPT+BAO observations, suggesting that systematic uncertainties in CMB radiation measurements may play a role in the tension. If we take the conflict between Planck high-redshift measurements and our local determination of H 0 at face value, one plausible explanation could involve an additional source of dark radiation in the early universe in the range of ΔN eff ≈ 0.4–1. We anticipate further significant improvements in H 0 from upcoming parallax measurements of long-period MW Cepheids.

THE GLOBULAR CLUSTER SYSTEM OF THE COMA CD GALAXY NGC 4874 FROM HUBBLE SPACE TELESCOPE ACS AND WFC3/IR IMAGING*

ABSTRACT We present new Hubble Space Telescope (HST) optical and near-infrared (NIR) photometry of the rich globular cluster (GC) system NGC 4874, the cD galaxy in the core of the Coma cluster (Abell 1656). NGC 4874 was observed with the HST Advanced Camera for Surveys in the F475W (g 475) and F814W (I 814) passbands and with the Wide Field Camera 3 IR Channel in F160W (H 160). The GCs in this field exhibit a bimodal optical color distribution with more than half of the GCs falling on the red side at g 475−I 814 > 1. Bimodality is also present, though less conspicuously, in the optical-NIR I 814−H 160 color. Consistent with past work, we find evidence for nonlinearity in the g 475−I 814 versus I 814−H 160 color–color relation. Our results thus underscore the need for understanding the detailed form of the color–metallicity relations in interpreting observational data on GC bimodality. We also find a very strong color–magnitude trend, or “blue tilt,” for the blue component of the optical color distribution of the NGC 4874 GC system. A similarly strong trend is present for the overall mean I 814−H 160 color as a function of magnitude; for M 814 < −10 mag, these trends imply a steep mass–metallicity scaling with Z ∝ M GC 1.4 ± 0.4 , but the scaling is not a simple power law and becomes much weaker at lower masses. As in other similar systems, the spatial distribution of the blue GCs is more extended than that of the red GCs, partly because of blue GCs associated with surrounding cluster galaxies. In addition, the center of the GC system is displaced by 4 ± 1 kpc toward the southwest from the luminosity center of NGC 4874, in the direction of NGC 4872. Finally, we remark on a dwarf elliptical galaxy with a noticeably asymmetrical GC distribution. Interestingly, this dwarf has a velocity of nearly −3000 km s−1 with respect to NGC 4874; we suggest it is on its first infall into the cluster core and is undergoing stripping of its GC system by the cluster potential.

Jet multiplicity in the proto-binary system NGC 1333-IRAS4A

Context. Owing to the paucity of sub-arcsecond (sub)mm observations required to probe the innermost regions of newly forming protostars, several fundamental questions are still being debated, such as the existence and coevality of close multiple systems.

Large scale direct galaxy collision simulations with central supermassive binary black holes

AbstractWe present a set of, large scale direct N-body simulations of the galaxy collision with the central Supermassive Black Hole Binary (SMBHB) system. Based on our simulations which include the accurate Post Newtonian (PN) relativistic dynamical corrections we can estimated the merging time for the real astrophysical object. Each galaxy initially was represented as a set of particles (up to N=500k) with Plummer distribution. The SMBHBs system is described using the two special high mass, i.e. “relativistic”, particles. The interaction between these two particles have an extra PN correction terms (up to 3.5PN). Merging time upper limit was obtained for the closely interacting galaxy system NGC 6240.

A longslit spectroscopic survey of bulges in disc galaxies

AbstractWe use the Marcario Low Resolution Spectrograph (LRS) at the Hobby-Eberly-Telescope (HET) to study the kinematics of pseudobulges and classical bulges in 45 S0-Sc type galaxies in the nearby universe. Our high-resolution (instrumental σ ≈ 39 km s−1) spectra allo only to resolve the typical velocity dispersions of our targets but also to derive the h3 and h4 Gauss-Hermite moments. We demonstrate for the first time that purely kinematic diagnostics of the bulge dichotomy agree systematically with those based on Sérsic index. Low Sérsic index bulges have both increased rotational support (higher v/σ values) and on average lower central velocity dispersions. Pseudobulges have systematically shallower velocity dispersion profiles. The same correlation also holds when visual morphologies are used to diagnose bulge type. Finally, we present evidence for formerly undetected counter rotation in the two systems NGC 3945 and NGC 4736. With these, a total of 16% of the systems in or sample show signs for stellar counter rotation.

KINEMATIC SIGNATURES OF BULGES CORRELATE WITH BULGE MORPHOLOGIES AND SÉRSIC INDEX

We use the Marcario Low Resolution Spectrograph (LRS) at the Hobby-Eberly-Telescope (HET) to study the kinematics of pseudobulges and classical bulges in the nearby universe. We present major-axis rotational velocities, velocity dispersions, and h3 and h4 moments derived from high-resolution (sigma ~ 39 km/s) spectra for 45 S0 to Sc galaxies; for 27 of the galaxies we also present minor axis data. We combine our kinematics with bulge-to-disk decompositions. We demonstrate for the first time that purely kinematic diagnostics of the bulge dichotomy agree systematically with those based on S\'ersic index. Low S\'ersic index bulges have both increased rotational support (higher v/sigma values) and on average lower central velocity dispersions. Furthermore, we confirm that the same correlation also holds when visual morphologies are used to diagnose bulge type. The previously noted trend of photometrically flattened bulges to have shallower velocity dispersion profiles turns to be significant and systematic if the S\'ersic index is used to distinguish between pseudobulges and classical bulges. The correlation between h3 and v/sigma observed in elliptical galaxies is also observed in intermediate type galaxies, irrespective of bulge type. Finally, we present evidence for formerly undetected counter rotation in the two systems NGC 3945 and NGC 4736. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universit\"at M\"unchen, and Georg-August-Universit\"at G\"ottingen.