arXiv subjects

Saili Dutta

Publications and source records attributed to Saili Dutta.

5 recordsLinked to original sources

arXiv2026

The Stellar Mass Function of Gas-Rich Galaxies and the Underlying $M_{\rm HI}-M_{\rm star}$ Scaling Relation in the Local Universe

We estimate the Galaxy Stellar Mass Function (GSMF) of HI gas-rich galaxies using the 100\% ALFALFA ($\alpha$) catalog, $\sim 98\%$ of which have optical counterparts in the Sloan Digital Sky Survey (SDSS) and a subset of them have counterparts in GALEX SDSS WISE Legacy Catalogue-2(GSWLC-2). We use the mass estimates from this subset which combines UV, optical and IR bands with individual dust corrections to recalibrate optical stellar mass estimates. We use a non-parametric method to estimate the GSMF of these gas-rich galaxies. The resulting, HI-selected GSMF is consistent with a single Schechter function with best-fit parameters $\left\{\phi_* (10^{-3}\, h_{70}^{3}\,\mathrm{Mpc}^{-3}\,\mathrm{dex}^{-1}), \log_{10} (M_*/M_{\odot}) + 2\log_{10} h_{70}, \alpha \right\} = \left\{2.30^{+0.12}_{-0.12}, \,10.83^{+0.01}_{-0.01},\, -1.14^{+0.02}_{-0.02}\right\} $. Additionally, the red and blue populations are each well described by a single Schechter function. After correcting for selection effects, we find that the red population accounts for only $\sim18\%$ of gas-rich galaxies by number, yet contributes $\sim54\%$ of the total stellar mass, with the blue population accounting for the rest. Using an optically selected sample and a joint optical-HI sample, we find gas-rich galaxies represent $\sim 33\%$ of the total stellar mass density and $\sim 39\%$ of the total galaxy number counts in the local Universe. We use the GSMF and the HI mass function (HIMF) of the HI-selected sample to obtain the $M_{\rm HI}-M_{\rm star}$ relation, which is free from selection bias.

astro-ph.GA↗

arXiv2024

HI Imaging of a Blueberry Galaxy Suggests a Merger Origin

Blueberry galaxies (BBs) are fainter, less massive, and lower redshift counterparts of the Green pea galaxies. They are thought to be the nearest analogues of the high redshift Lyman Alpha (Ly$α$) emitters. We report the interferometric imaging of HI 21 cm emission from a Blueberry galaxy, J1509+3731, at redshift, z = 0.03259, using the Giant Metrewave Radio Telescope (GMRT). We find that this Blueberry galaxy has an HI mass of $M_{\text{HI}} \approx 3\times 10^8 \, M_{\odot}$ and an HI-to-stellar mass ratio $M_{\text{HI}}/M_* \approx$ 2.4. Using SFR estimates from the H$β$ emission line, we find that it has a short HI depletion time scale of $\approx 0.2$ Gyr, which indicates a significantly higher star-formation efficiency compared to typical star-forming galaxies at the present epoch. Interestingly, we find an offset of $\approx 2$ kpc between the peak of the HI 21 cm emission and the optical centre which suggests a merger event in the past. Our study highlights the important role of mergers in triggering the starburst in BBs and their role in the possible leakage of Lyman-$α$ and Lyman-continuum photons which is consistent with the previous studies on BB galaxies.

astro-ph.GA↗

arXiv2021

The Dark Matter Halos of HI Selected Galaxies

We present the neutral hydrogen mass ($M_{\text{HI}}$) function (HIMF) and velocity width ($w_{50}$) function (HIWF) based on a sample of 7857 galaxies from the 40% data release of the ALFALFA survey ($α.40$). The low mass (velocity width) end of the HIMF (HIWF) is dominated by the blue population of galaxies whereas the red population dominates the HIMF (HIWF) at the high mass (velocity width) end. We use a deconvolution method to estimate the HI rotational velocity ($V_{\text{rot}}$) functions (HIVF) from the HIWF for the total, red, and blue samples. The HIWF and HIVF for the red and blue samples are well separated at the knee of the function compared to their HIMFs. We then use recent stacking results from the ALFALFA survey to constrain the halo mass ($M_{\text{h}}$) function of HI-selected galaxies. This allows us to obtain various scaling relations between $M_{\text{HI}} - w_{50} - V_{\text{rot}} - M_{\text{h}}$, which we present. The $M_{\text{HI}} - M_{\text{h}}$ relation has a steep slope ~2.10 at small masses and flattens to ~0.34 at masses larger than a transition halo mass, $\log_{10}(M_{\text{ht}} h^2_{70}/M_{\odot})=10.62$. Our scaling relation is robust and consistent with a volume-limited sample of $α.40$. The $M_{\text{HI}} - M_{\text{h}}$ relation is qualitatively similar to the $M_{\text{star}} - M_{\text{h}}$ relation but the transition halo mass is smaller by ~1.4 dex compared to that of the $M_{\text{star}} - M_{\text{h}}$ relation. Our results suggest that baryonic processes like heating and feedback in larger mass halos suppress HI gas on a shorter time scale compared to star-formation.

astro-ph.GA↗

arXiv2020

The Distribution of Neutral Hydrogen in the Color-Magnitude Plane of Galaxies

We present the conditional HI (neutral hydrogen) Mass Function (HIMF) conditioned on observed optical properties, $M_{\text{r}}$ ($r$-band absolute magnitude) and $C_{\text{ur}}$ ($u-r$ color), for a sample of 7709 galaxies from ALFALFA (40% data release - $α.40$) which overlaps with a common volume in SDSS DR7. Based on the conditional HIMF we find that the luminous red, luminous blue and faint blue populations dominate the total HIMF at the high-mass end, knee and the low-mass end respectively. We use the conditional HIMF to derive the underlying distribution function of $Ω_{\text{HI}}$ (HI density parameter), $p(Ω_{\text{HI}})$, in the color-magnitude plane of galaxies. The distribution, $p(Ω_{\text{HI}})$, peaks in the blue cloud at $M_{\text{r}}^{\text{max}}=$ $-19.25, C_{\text{ur}}^{\text{max}}=1.44$ but is skewed. It has a long tail towards faint blue galaxies and luminous red galaxies. We argue that $p(Ω_{\text{HI}})$ can be used to reveal the underlying relation between cold gas, stellar mass and the star formation rate (SFR) in an unbiased way; that is the derived relation does not suffer from survey or sample selection.

astro-ph.GA↗

arXiv2020

The Population of Galaxies that Contribute to The HI Mass Function

We look at the contribution of different galaxy populations to the atomic hydrogen (HI) mass function (HIMF) and the HI density parameter, $Ω_{\text{HI}}$, in the local Universe. Our analysis is based on a sample of 7857 HI-selected galaxies selected from a volume common to the SDSS and ALFALFA surveys (40$\%$ catalog -- $α.40$). We define different populations of galaxies in the color(u-r)-magnitude($M_{\text{r}}$) plane and compute the HIMF for each of them. Additionally we compute the HIMF for dark galaxies; these are undetected in SDSS and represent $\sim 2\%$ of the total sample. We find that the luminous red population dominates the total HIMF for $\log_{10}(M_{\text{HI}}h^2_{70}/M_{\odot}) \geq 10.4$. The full red population -- luminous and faint -- represents about $\sim 17\%$ of the $Ω_{\text{HI}}$ budget, while that of the dark population is $\sim 3\%$. The HIMF about the knee, $\log_{10}(M_{\text{HI}}h^2_{70}/M_{\odot}) \in [8,10.4]$, is dominated by the faint and luminous blue populations, the latter dominating at larger masses in this interval. Their total contribution to $Ω_{\text{HI}}$ is $\sim 55-70\%$, the variation depending on the definition of population. The dominant populations at the low mass end, $\log_{10}(M_{\text{HI}}h^2_{70}/M_{\odot}) \leq 8.0$ are the faint blue and faint bluer populations, the latter's dominance being sensitive to its definition. The full blue (blue--bluer luminous and faint) population represents $\sim 80\%$ of $Ω_{\text{HI}}$. A bimodal HIMF suggested by our results is however not seen since the amplitude of the HIMF of the luminous red population is small compared to that of the luminous blue population.

astro-ph.GA↗