Mousumi Das

Indian Institute of Astrophysics | IIAP · Research Division Stellar and Galactic Astronomy

We report superluminal jet motion with an apparent speed of β app = 1.65 ± 0.57 in the radio-quiet (RQ) low-ionization nuclear emission-line region (LINER) galaxy KISSR 872. This result comes from two-epoch phase-referenced very long baseline interferometry observations at 5 GHz. The detection of bulk relativistic motion in the jet of this extremel...

In the last decade, there have been several discoveries of Active Galactic Nuclei (AGN) in dwarf galaxies including an AGN in an ultra-compact dwarf galaxy with a Black Hole mass >10⁶ M⊙. However, finding a Supermassive Black Hole (SMBH) in a dwarf Low Surface Brightness (LSB) galaxy is rare. We report the discovery of a Seyfert type-2 class AGN wh...

We have used the Ultraviolet Imaging Telescope (UVIT) aboard AstroSat to study star formation in a sample of nine dual nuclei galaxies with separations ⪅ 11 kpc, which is an expected outcome of galaxy mergers. To minimize the contribution of active galactic nuclei (AGN) emission, we have used mid-IR colour cut-offs and masked the AGN-dominated nucl...

We present a study of the morphology of star formation and the associated nuclear activity in a sample of 8 closely interacting southern galaxies, which are in different stages of interaction, starting with nearly merged nuclei that have one prominent bulge to more widely spaced interacting galaxies. We have used Far-Ultraviolet (FUV) observations...

We present a study of the morphology of star formation and the associated nuclear activity in a sample of 8 closely interacting southern galaxies, which are in different stages of interaction, starting with nearly merged nuclei that have one prominent bulge to more widely spaced interacting galaxies. We have used Far-Ultraviolet (FUV) observations...

We present a method to measure the the oblateness parameter q of the dark matter halos of gas rich galaxies that have extended HI disks. We have applied our model to a sample of 20 nearby galaxies that are gas rich and close to face-on, of which 6 are large disk galaxies, 8 have moderate stellar masses and 6 are low surface brightness (LSB) dwarf g...

We present a novel algorithm to detect double nuclei galaxies (DNG) called Gothic (Graph-bOosTed iterated HIll Climbing) - that detects whether a given image of a galaxy has two or more closely separated nuclei. Our aim is to test for the presence of dual/multiple active galactic nuclei (AGN) in galaxies that visually represent a DNG. Although gala...

Dark matter (DM) halo angular momentum is very challenging to determine from observations of galaxies. In this study, we present a new hybrid method of estimating the dimensionless halo angular momentum, halo spin of a gas-rich dwarf barred galaxy UGC5288 using N-Body/SPH simulations. We forward model the galaxy disk properties: stellar and gas mas...

Dark matter (DM) halo properties are extensively studied in cosmological simulations but are very challenging to estimate from observations. The DM halo density profile of observed galaxies is modelled using multiple probes that trace the dark matter potential. However, the angular momentum distribution of DM halos is still a subject of debate. In...

Dark matter (DM) halo properties are extensively studied in cosmological simulations but are very challenging to estimate from observations. The DM halo density profile of observed galaxies is modelled using multiple probes that trace the dark matter potential. However, the angular momentum distribution of DM halos is still a subject of debate. In...

We derive the oblateness parameter q of the dark matter halo of a sample of gas-rich, face-on disk galaxies. We have assumed that the halos are triaxial in shape but their axes in the disk plane ( a and b ) are equal, so that q = c / a measures the halo flattening. We have used the H i velocity dispersion, derived from the stacked H i emission line...

One of the major science goals of square kilometre array (SKA) is to understand the role played by atomic hydrogen (Hi) gas in the evolution of galaxies throughout cosmic time. The hyperfine transition line of the hydrogen atom at 21-cm is one of the best tools to detect and study the properties of Hi gas associated with galaxies. In this paper, we...

We present a novel algorithm to detect double nuclei galaxies (DNG) called GOTHIC (Graph-Boosted iterated Hill Climbing)-that detects whether a given image of a galaxy has two or more closely separated nuclei. Our aim is to detect samples of dual or multiple active galactic nuclei (AGN) in galaxies. Although galaxy mergers are common, the detection...

It is now clear that the stars in the Solar neighbourhood display large-scale coherent vertical breathing motions. At the same time, Milky Way-like galaxies experience tidal interactions with satellites/companions during their evolution. While these tidal interactions can excite vertical oscillations, it is still not clear whether vertical breathin...

It is now clear that the stars in the Solar neighbourhood display large-scale coherent vertical breathing motions. At the same time, Milky Way-like galaxies experience tidal interactions with satellites/companions during their evolution. While these tidal interactions can excite vertical oscillations, it is still not clear whether vertical breathin...

We report the discovery of a nearby large, diffuse galaxy that shows star formation using Ultra Violet Imaging Telescope (UVIT) far-UV observations and archival optical data from Multi-Unit Spectroscopic Explorer (MUSE), Dark Energy Camera Legacy Survey, and InfraRed Survey Facility near-infrared observations. The galaxy was not detected earlier du...

We report the discovery of a nearby large, diffuse galaxy that shows star formation, using Ultra Violet Imaging Telescope (UVIT) far-UV observations, archival optical data from Multi-Unit Spectroscopic Explorer (MUSE) and Dark Energy Camera Legacy Survey (DECaLS), and InfraRed Survey Facility (IRSF) near-infrared observations. The galaxy was not de...

It is well established that bars evolve significantly after they form in galaxy discs, often changing shape both in and out of the disc plane. In some cases they may bend or buckle out of the disc plane resulting in the formation of boxy/peanut/x-shape bulges. In this paper we show that the dark matter halo shape affects bar formation and buckling....

It is well established that bars evolve significantly after they form in galaxy discs, often changing shape both in and out of the disc plane. In some cases they may bend or buckle out of the disc plane resulting in the formation of boxy/peanut/x-shape bulges. In this paper we show that the dark matter halo shape affects bar formation and buckling....

We present a UV study of 3 extended UV (XUV) galaxies that we have observed with the UVIT and the GMRT. XUV galaxies show filamentary or diffuse star formation well beyond their optical disks, in regions where the disk surface density lies below the threshold for star formation. GALEX observations found that surprisingly 30% of all the nearby spira...

Double-peaked emission-line AGN (DPAGN) have been regarded as binary black hole candidates. We present here results from parsec-scale radio observations with the Very Long Baseline Array (VLBA) of five DPAGN belonging to the KISSR sample of emission-line galaxies. This work concludes our pilot study of nine type 2 Seyfert and LINER DPAGN from the K...

Context. Galaxy interactions and mergers can lead to supermassive black hole (SMBH) binaries, which become active galactic nucleus (AGN) pairs when the SMBHs start accreting mass. If there is a third galaxy involved in the interaction, then a triple-AGN system can form. Aims. Our goal is to investigate the nature of the nuclear emission from the ga...

Context. Galaxy interactions and mergers can lead to supermassive black hole (SMBH) binaries which become active galactic nuclei (AGN) pairs when the SMBHs start accreting mass. If there is a third galaxy involved in the interaction, then a triple AGN system can form. Aims. Our goal is to investigate the nature of the nuclear emission from the gala...

Context: Galaxy interactions and mergers can lead to supermassive black hole (SMBH) binaries which become active galactic nuclei (AGN) pairs when the SMBHs start accreting mass. If there is a third galaxy involved in the interaction, then a triple AGN system can form. Aims: Our goal is to investigate the nature of the nuclear emission from the gala...

Galaxy flybys are as common as mergers in low redshift universe and are important for galaxy evolution as they involve the exchange of significant amounts of mass and energy. In this study we investigate the effect of minor flybys on the bulges, disks, and spiral arms of Milky Way mass galaxies for two types of bulges – classical bulges and boxy/pe...

Double-peaked emission line AGN (DPAGN) have been regarded as binary black hole candidates. We present here results from parsec-scale radio observations with the Very Long Baseline Array (VLBA) of five DPAGN belonging to the KISSR sample of emission-line galaxies. This work concludes our pilot study of nine type 2 Seyfert and LINER DPAGN from the K...

Galaxy flybys are as common as mergers in low redshift universe and are important for galaxy evolution as they involve the exchange of significant amounts of mass and energy. In this study we investigate the effect of minor flybys on the bulges, disks, and spiral arms of Milky Way mass galaxies for two types of bulges - classical bulges and boxy/pe...

We present a far-UV (FUV) study of the star-forming complexes (SFCs) in three nearby galaxies using the Ultraviolet Imaging Telescope. The galaxies are close to face-on and show significant outer disk star formation. Two of them are isolated (NGC 628 and NGC 6946), and one is interacting with distant companions (NGC 5457). We compared the propertie...

We present radio observations of ultraluminous infrared galaxies (ULIRGs) using the Giant Metrewave Radio Telescope (GMRT) and combine them with archival multifrequency observations to understand whether ULIRGs are the progenitors of the powerful radio loud galaxies in the local Universe. ULIRGs are characterized by large infrared luminosities (LIR...

We present a far-UV (FUV) study of the star-forming complexes (SFCs) in three nearby galaxies using the Ultraviolet Imaging Telescope (UVIT). The galaxies are close to face-on and show significant outer disk star formation. Two of them are isolated (NGC 628, NGC 6946), and one is interacting with distant companions (NGC 5457). We compared the prope...

We present radio observations of ultraluminous infrared galaxies (ULIRGs) using the Giant Metrewave Radio Telescope (GMRT) and combine them with archival multi-frequency observations to understand whether ULIRGs are the progenitors of the powerful radio loud galaxies in the local Universe. ULIRGs are characterized by large infrared luminosities ($L...

Low Surface Brightness (LSB) galaxies have very diffuse, low surface density stellar disks which appear faint in optical images. They are very rich in neutral hydrogen (HI) gas, which extends well beyond the stellar disks. Their extended HI rotation curves and stellar disks indicate that they have very massive dark matter (DM) halos compared to nor...

It is now well established that galaxy interactions and mergers play a crucial role in the hierarchical growth of structure in our universe. Galaxy mergers can lead to the formation of elliptical galaxies and larger disk galaxies, as well as drive galaxy evolution through star formation and nuclear activity. During mergers, the nuclei of the indivi...

We present radio observations of the galaxy merger remnant Mrk 212 with the Karl G. Jansky Very Large Array (VLA) and the upgraded Giant Meter Radio Telescope (uGMRT). Mrk 212 has two previously known radio sources associated with the two optical nuclei, S1 and S2, with a projected separation of ∼6 kpc, making it a dual active galactic nuclei (AGN)...

We present radio observations of the galaxy merger remnant Mrk 212 with the Karl G. Jansky Very Large Array (VLA) and the upgraded Giant Meter Radio Telescope (uGMRT). Mrk 212 has two previously known radio sources associated with the two optical nuclei, S1 and S2, with a projected separation of ~6 kpc, making it a dual active galactic nuclei (AGN)...

Analysing PSO from the angle of Chaos Theory. Also devising a novel algorithm for reversing the PSO algorithm itself.

Earlier studies have shown that massive bulges impede bar formation in disk galaxies. Recent N -body simulations have derived a bar formation criterion that depends on the radial bulge force in a galaxy disk. We use those simulations to show that bars can form only when the force constant F B < 0.13, where F B depends on the ratio of the bulge forc...

Earlier studies have shown that massive bulges impede bar formation in disk galaxies. Recent N-body simulations have derived a bar formation criterion that depends on the radial bulge force in a galaxy disk. We use those simulations to show that bars can form only when the force constant FB < 0.13, where FB depends on the ratio of the bulge force t...

One of the major and widely known small scale problem with the Lambda CDM model of cosmology is the core-cusp problem. In this study we investigate whether this problem can be resolved using bar instabilities. We see that all the initial bars are thin (b/a $<$ 0.3) in our simulations and the bar becomes thick (b/a $>$ 0.3$) faster in the high resol...

We report the detection of an intriguing parsec-scale radio source in the “offset AGN” candidate, KISSR 102. The elliptical host galaxy includes two optical nuclei at a projected separation of 1.54 kpc, N1 and N2, to the southeast and northwest, respectively. Phase-referenced Very Long Baseline Array observations at 1.5 and 4.9 GHz of this low ioni...

We present a method to derive the dynamical mass of face-on galaxy disks using their neutral hydrogen (H i ) velocity dispersion ( σ H i ). We have applied the method to nearby, gas-rich galaxies that have extended H i gas disks and have low inclinations. The galaxy sample includes four large disk galaxies, NGC 628, NGC 6496, NGC 3184, and NGC 4214...

We report the detection of an intriguing parsec-scale radio source in the "offset AGN" candidate, KISSR 102. The elliptical host galaxy includes two optical nuclei at a projected separation of 1.54 kpc, N1 and N2, to the south-east and north-west, respectively. Phase-referenced VLBA observations at 1.5 and 4.9 GHz of this LINER galaxy, have detecte...

Simulations expect an enhanced star-formation and active galactic nuclei (AGN) activity during galaxy mergers, which can lead to formation of binary/dual AGN. AGN feedback can enhance or suppress star-formation. We have carried out a pilot study of a sample of 10 dual nuclei galaxies with AstroSat's Ultraviolet Imaging Telescope (UVIT). Here, we pr...

We present a method to derive the dynamical mass of face-on galaxy disks using their neutral hydrogen (HI) velocity dispersion. We have applied the method to nearby, gas rich galaxies that have extended HI gas disks and have low inclinations. The galaxy sample includes 4 large disk galaxies; NGC628, NGC6496, NGC3184, NGC4214 and 3 dwarf galaxies DD...

We present a study of the effect of bulge mass on the evolution of bar pattern speed in isolated disk galaxies using N-body simulations. Earlier studies have shown that disk stars at the inner resonances can transfer a significant amount of angular momentum to the dark matter halo and this results in the slow down of the bar pattern speed. In this...

Low Surface Brightness (LSB) galaxies are thought to be one of the most dark matter (DM) dominated galaxies in our Universe. They have very diffuse, low surface density stellar disks that have poor star formation rates and hence appear faint in optical images. LSB galaxies are also very rich in neutral hydrogen (HI) gas which usually extends well b...

We present a study of the effect of bulge mass on the evolution of bar pattern speed in isolated disk galaxies using N-body simulations. Earlier studies have shown that disk stars at the inner resonances can transfer a significant amount of angular momentum to the dark matter halo and this results in the slow down of the bar pattern speed. In this...

Simulations expect an enhanced star-formation and active galactic nuclei (AGN) activity during galaxy mergers, which can lead to formation of binary/dual AGN. AGN feedback can enhance or suppress star-formation. We have carried out a pilot study of a sample of ˜10 dual nuclei galaxies with AstroSat’s Ultraviolet Imaging Telescope (UVIT). Here, we p...

A problem that lends itself to the application of machine learning is classifying matched sources in the GALEX (Galaxy Evolution Explorer) and SDSS (Sloan Digital Sky Survey) catalogs into stars and quasars based on color-color plots. The problem is daunting because stars and quasars are still inextricably mixed elsewhere in the color-color plots a...

One of the major and widely known small scale problem with the Lambda CDM model of cosmology is the “core-cusp” problem. In this study we investigate whether this problem can be resolved using bar instabilities. We see that all the initial bars are thin ( b / a < 0.3) in our simulations and the bar becomes thick ( b / a > 0.3) faster in the high re...

We investigate the minor interactions of two disk galaxies with mass ratio of 10:1 in fly-by encounters that do not lead to the merging of the galaxies. In our N-body simulations, we vary only the pericenter distances to see the effect of the fly-by on the bulge of the major galaxy over the course of the trajectory. At different time steps of the e...

We explore the efficacy of neural network based classification techniques in discriminating between Stars and Quasars using GALEX and SDSS photometric data. We have used those objects with associated spectroscopic information as our training-set and built neural network and ensemble classifiers that appropriately classify photometric samples withou...

Double-peaked emission lines in the narrow- and/or broad-line spectra of active galactic nuclei (AGNs) have been suggested to arise as a result of disky broad/narrow-line regions, jet-medium interaction, or the presence of binary supermassive black holes. We present the results from 1.5 and 4.9 GHz phase-referenced very long baseline interferometry...

Supermassive black hole (SMBH) binaries form due to galaxy mergers and minor accretion events. When the SMBHs are accreting, they form dual or binary AGN and can give rise to double-peaked emission lines in the optical spectra of the merger remnant. The double-peaked emission lines could also be due to jet-ISM interaction or rotating disks. One of...

We present H I, optical, and near-infrared observations of the nearby bulgeless, dwarf spiral galaxy NGC 4701. The galaxy lies on the Virgo filament and is one of the most gas-rich dwarfs in our local environment. Our aim is to understand the gas-disk morphology of the galaxy and see how it relates to the star formation in its disk. Our Hα observat...

Double-peaked emission lines in the narrow- and/or broad-line spectra of AGN have been suggested to arise due to disky broad/narrow line regions, jet-medium interaction, or the presence of binary supermassive black holes. We present the results from 1.5 and 4.9 GHz phase-referenced Very Long Baseline Interferometry (VLBI) observations of the Seyfer...

We have classified a sample of 37,492 objects from SDSS into QSOs, galaxies and stars using photometric data over five wave bands (u, g, r, i and z) and UV GALEX data over two wave bands (near-UV and far-UV) based on a template fitting method. The advantage of this method of classification is that it does not require any spectroscopic data and henc...

We present a far-UV (FUV) and near-UV (NUV) imaging study at 1.2 resolution of recent star formation in the nearby spiral galaxy NGC 2336 using the Ultraviolet Imaging Telescope (UVIT) on-board AstroSat. NGC 2336 is nearly face-on in orientation and has a multi-armed, branching spiral structure which is associated with star forming regions distribu...

We present a far-UV (FUV) and near-UV (NUV) imaging study of recent star formation in the nearby spiral galaxy NGC 2336 using the Ultraviolet Imaging Telescope (UVIT). NGC 2336 is nearly face-on in morphology and has a multi-armed, branching spiral structure which is associated with star forming regions distributed mainly along the spiral arms and...

We present a study of the HI and optical properties of nearby ($z$ $\le$ 0.1) Low Surface Brightness galaxies (LSBGs). We started with a literature sample of $\sim$900 LSBGs and divided them into three morphological classes: spirals, irregulars and dwarfs. Of these, we could use $\sim$490 LSBGs to study their HI and stellar masses, colours and colo...

Binary or dual active galactic nuclei (DAGN) are expected from galaxy formation theories. However, confirmed DAGN are rare and finding these systems has proved to be challenging. Recent systematic searches for DAGN using double-peaked emission lines have yielded several new detections. As have the studies of samples of merging galaxies. In this pap...

We use N-body simulations of bar formation in isolated galaxies to study the effect of bulge mass and bulge concentration on bar formation. Bars are global disk instabilities that evolve by transferring angular momentum from the inner to outer disks and to the dark matter halo. It is well known that a massive spherical component such as halo in a d...

Triangulum-II, a newly discovered dwarf spheroidal galaxy, is a strong candidate for the indirect search of dark matter through the detection of {\gamma}-ray emission that could originate from the pair- annihilation of weakly interacting massive particles (WIMPs). We here report on the analysis of almost seven years Fermi Gamma-Ray Space Telescope...

Galaxy mergers play a crucial role in the formation of massive galaxies and the buildup of their bulges. An important aspect of the merging process is the in-spiral of the supermassive black-holes (SMBHs) to the centre of the merger remnant and the eventual formation of a SMBH binary. If both the SMBHs are accreting they will form a dual or binary...

We present the results from 1.5 and 5 GHz phase-referenced VLBA and 1.5 GHz Karl G. Jansky Very Large Array (VLA) observations of the Seyfert 2 galaxy KISSR1219, which exhibits double peaked emission lines in its optical spectrum. The VLA and VLBA data reveal a one-sided core-jet structure at roughly the same position angles, providing evidence of...

We present high resolution radio continuum observations with the Karl G. Jansky Very Large Array at 6, 8.5, 11.5 and 15 GHz of the double-peaked emission-line galaxy 2MASXJ12032061+1319316. The radio emission has a prominent S-shaped morphology with highly symmetric radio jets that extend over a distance of $\sim1.5^{\prime\prime}$ (1.74~kpc) on ei...

We present detailed science cases that a large fraction of the Indian AGN community is interested in pursuing with the upcoming Square Kilometre Array (SKA). These interests range from understanding low luminosity active galactic nuclei in the nearby Universe to powerful radio galaxies at high redshifts. Important unresolved science questions in AG...

We present HI observations of four giant low surface brightness (GLSB) galaxies UGC 1378, UGC 1922, UGC 4422 and UM 163 using the Giant Meterwave Radio Telescope (GMRT). We include HI results on UGC 2936, UGC 6614 and Malin 2 from literature. HI is detected from all the galaxies and the extent is roughly twice the optical size; in UM 163, HI is det...

We present a near-infrared (NIR) imaging study of barred low surface brightness (LSB) galaxies using the TIFR near-infrared Spectrometer and Imager (TIRSPEC). LSB galaxies are dark matter dominated, late type spirals that have low luminosity stellar disks but large neutral hydrogen (HI) gas disks. Using SDSS images of a very large sample of LSB gal...

IRASF 15001+1433 : Signature of radio jets or outflows SUMMARY 1. We have started a study of low frequency radio emission from ULIRGs. As a first step we carried out 1280 MHz scans of 22 ULIRGs using the GMRT in 2007. The data quality was not very good. However about 18 sources have data good enough to image. 2. Preliminary analysis shows that most...

We present radio continuum observations of a sample of ultraluminous infrared galaxies (ULIRGs) at 1280MHz with the GMRT. ULIRGs are gas rich merger remnants that are in the process of transforming into elliptical galaxies. They are very luminous objects (L >10 12 L *) with high star formation rates. Active Galactic Nuclei (AGN) have been detected...

We present the detection of molecular gas from galaxies located in nearby voids using the CO line emission as a tracer. The observations were done using the 45m Nobeyama Radio Telescope. Void galaxies lie in the most under dense parts of our universe and a significant fraction of them are gas rich, late type spiral galaxies. Although isolated, they...

We present an analysis of the optical nuclear spectra from the active galactic nuclei (AGN) in a sample of low surface brightness (LSB) galaxies. Using data from the Sloan Digital Sky Survey (SDSS), we derived the virial black hole (BH) masses of 24 galaxies from their broad Hα parameters. We find that our estimates of nuclear BH masses lie in the...

We discuss results from very long baseline interferometry (VLBI) observations of two Seyfert galaxies with double peaked emission lines in their SDSS optical spectra. Such AGN are potential candidates for the presence of binary black holes, which can be resolved on parsec-scales with VLBI. Our observations do not detect twin radio cores but rather...

The TMT Detailed Science Case describes the transformational science that the Thirty Meter Telescope will enable. Planned to begin science operations in 2024, TMT will open up opportunities for revolutionary discoveries in essentially every field of astronomy, astrophysics and cosmology, seeing much fainter objects much more clearly than existing t...

NGC 5905 is one of the few galaxies with no prior evidence for an active galactic nucleus (AGN) in which an X-ray flare was detected by the ROSAT All Sky Survey (RASS) in 1990–1991. Follow-up studies showed that the X-ray flare was due to the tidal disruption of a star by the massive black hole in the center of the galaxy. In this study we present...

We present an analysis of the optical nuclear spectra from the active galactic nuclei (AGN) in a sample of giant low surface brightness (GLSB) galaxies. GLSB galaxies are extreme late type spirals that are large, isolated and poorly evolved compared to regular spiral galaxies. Earlier studies have indicated that their nuclei have relatively low mas...

Searching for Signatures of Radio Jets and Outflows from Ultraluminous Infrared Galaxies

We present a multifrequency radio continuum study of seven giant low surface brightness (GLSB) galaxies using the Giant Metrewave Radio Telescope (GMRT). GLSB galaxies are optically faint, dark-matter-dominated systems that are poorly evolved and have large H i gas discs. Our sample consists of GLSB galaxies that show signatures of nuclear activity...

We present here the results from dual-frequency phase-referenced VLBI observations of the Seyfert galaxy KISSR1494, which exhibits double peaked emission lines in its SDSS spectrum. We detect a single radio component at 1.6 GHz, but not at 5 GHz implying a spectral index steeper than $-1.5\pm0.5$ ($S_\nu\propto\nu^\alpha$). The high brightness temp...

We present the detection of molecular gas using CO(1-0) line emission and follow up Halpha imaging observations of galaxies located in nearby voids. The CO(1-0) observations were done using the 45m telescope of the Nobeyama Radio Observatory (NRO) and the optical observations were done using the Himalayan Chandra Telescope (HCT). Although void gala...

NGC 5905 is one of the few galaxies in which an X-ray flare was discovered by the ROSAT All Sky Survey (RASS). This flare was supposed to have occurred due to tidal disruption of a star by the central black hole. In this work we present analysis of multi-wavelength follow-up observations made in X-ray, mid-infrared and radio using data obtained fro...

Giant Low Surface Brightness (GLSB) galaxies are amongst the most massive spiral galaxies that we know of in our Universe. Although they fall in the class of late type spiral galaxies, their properties are far more extreme. They have very faint stellar disks that are extremely rich in neutral hydrogen gas but low in star formation and hence low in...

We present an x-ray and radio study of the barred spiral galaxy NGC5905. This is a low surface brightness galaxy that has a Seyfert2 type nucleus associated with a compact bulge. Not much is known about the x-ray or radio properties of this class of low luminosity, dark matter dominated systems. NGC5905 is interacting with a nearby companion galaxy...